Cerebral cavernous malformations: from genes to proteins to disease

Clinical article

Full access

Over the past half century molecular biology has led to great advances in our understanding of angio- and vasculogenesis and in the treatment of malformations resulting from these processes gone awry. Given their sporadic and familial distribution, their developmental and pathological link to capillary telangiectasias, and their observed chromosomal abnormalities, cerebral cavernous malformations (CCMs) are regarded as akin to cancerous growths. Although the exact pathological mechanisms involved in the formation of CCMs are still not well understood, the identification of 3 genetic loci has begun to shed light on key developmental pathways involved in CCM pathogenesis. Cavernous malformations can occur sporadically or in an autosomal dominant fashion. Familial forms of CCMs have been attributed to mutations at 3 different loci implicated in regulating important processes such as proliferation and differentiation of angiogenic precursors and members of the apoptotic machinery. These processes are important for the generation, maintenance, and pruning of every vessel in the body. In this review the authors highlight the latest discoveries pertaining to the molecular genetics of CCMs, highlighting potential new therapeutic targets for the treatment of these lesions.

Abbreviations used in this paper: BAC = bacterial artificial chromosome; CCM = cerebral cavernous malformation; ERK = extracellular signal-regulated kinase; ICAP-1 = integrin cytoplasmic domain–associated protein 1; lod score = logarithm of odds score; MAPK = mitogen-activated protein kinase; MEKK3 = MAPK-ERK kinase kinase 3; MLPA = multiplex ligation-dependent probe amplification; PAC = plasmid artificial chromosome; PTB = phosphotyrosine binding; YAC = yeast artificial chromosome.

The estimated prevalence of stroke in the US in 2006 was 6,400,000 cases. Although ischemic stroke is by far the more frequent presentation, 10% of all strokes are hemorrhagic in nature.62 One of the causes of hemorrhagic stroke is the presence of vascular malformations with friable vessels that are prone to rupture due to changes in systemic blood pressure or stressors. Cerebral cavernous malformations account for 5%–15% of all vascular malformations in the CNS.19,31,63,73,84 In this review we focus on the entity of the CCM in terms of the causal interactions of genes and proteins that lead to disease. For the reader it is important to note terminology: mouse and other animal genes are notated differently from their human counterparts. For example, CCM2 names the human gene, while Ccm2 is the Mus musculus (mouse) gene and ccm2 is the Danio rerio (zebrafish) gene. The protein is signified by CCM2.

Cavernous malformations are slow-flow anomalies characterized by densely packed vascular sinusoids embedded in a collagen matrix without intervening neural tissue.71,86 Cavernous malformation clusters are well defined and consist of enlarged capillary channels, lined by a thin endothelium and rare subendothelial cells, without smooth muscle and elastic tissue (Figs. 1 and 2). The capillary channels of cavernous malformations may be filled with blood at various stages of thrombosis and organization, producing a mulberry-like appearance.11 Generally, CCMs lack tight junctions between endothelial cells and astrocyte foot processes, have diminished laminin and collagen IV within their endothelial cells, and are associated with a hypertrophic surrounding basal lamina.12,42,109

Fig. 1.
Fig. 1.

Photomicrograph of CCM section highlighting the enlarged capillary channels lined by a thin endothelium, a characteristic finding in this disease. H & E. Original magnification × 40.

Fig. 2.
Fig. 2.

Axial (upper) and coronal (lower) T1-weighted MR images of a cavernous malformation in the brainstem. The lesion demonstrates the heterogeneous signal characteristics of hemorrhage in various stages of resolution.

Cavernous malformations are usually occult lesions that are discovered by an episode of symptomatic hemorrhage causing intraluminal thrombosis and usually subsequent recanalization.97,110 Usually, patients clinically present with CCMs between the 2nd and 5th decades of life, but symptoms can start in early infancy or in old age.16,73,84,110 Following their first episode of hemorrhage, patients with CCM may be relatively asymptomatic or they may be neurologically devastated. The onset of symptoms is usually abrupt, although patients may present with gradual and nonspecific symptoms. The most common presenting signs include headaches, seizures, and focal neurological deficits caused by cerebral hemorrhages. Seizures are the most common symptom in various series, representing 40%–60% of the symptoms at presentation.20,30,93,100,110

The prevalence of CCM in the general population has been estimated to be about 0.3%–0.5%, accounting for approximately 24 million people worldwide. In the US, more than 1 million people (mostly of Hispanic origin) are known to harbor CCMs and are subject to a 1%–5% per year cumulative risk (estimated 50%–70% lifetime risk) of hemorrhage, epilepsy, and other neurological sequelae.16,71,76,84 In youth, CCM hemorrhage accounts for more than 10% of intracerebral hemorrhages.1,25,74,76

Cerebral cavernous malformations can be both sporadic and familial (further discussion to follow).5,11,49,53,72 Approximately half of CCM cases are familial in nature and are inherited in an autosomal dominant fashion with variable penetrance.5,43,83,110 Labauge et al.55 demonstrated that 75% of sporadic cases of CCMs are actually familial cases. Similarly, others have identified familial mutations in nearly 60% of sporadic cases with multiple lesions, further demonstrating the variable penetrance of this autosomal dominant trait.18

Familial CCMs are characterized by the presence of multiple lesions identified on cerebral MR imaging.83,110 A multiplicity of lesions is characteristic in up to 84% of familial cases,20,37,43,57,110 whereas it is reported in 10%–33% of supposed sporadic cases.16,83,84 The annual symptomatic hemorrhage rate in familial cases can reach 6.4%,110 a significantly higher rate than reported in series of sporadic cases (range 1.6%–3.1%).51,73,81

Hispanic populations of Mexican descent appear to be more susceptible to dominantly inherited CCMs.4,43,69,110 Linkage mapping in family-based studies in the mid-1990s aided in localizing the first gene responsible for CCMs to the long arm of chromosome 7.54,68 Gunel et al.38 identified a strong founder effect when studying several unrelated Hispanic kindreds affected by familial CCM. This study and others identified identical haplotypes over a region of at least 22 cM over the short segment of chromosome 7q.29,46 A large study assessing French families also revealed linkage to the CCM1 locus, but without a founder effect.56

Although the CCM1 locus initially explained the cause of CCMs in certain cohorts, it became apparent that these malformations were genetically heterogeneous and caused by mutations at other loci. The identification of 2 additional loci on 7p and 3q partially reconciled clinical findings in other patient populations.13 To date, 3 distinct loci have been mapped in different families, and 3 CCM genes, namely CCM1/KRIT1, CCM2/MGC4607, and CCM3/PDCD10, have been identified. Germline mutations in these 3 genes have been shown to lead to the development of CCM. Although the precise functions of these genes are still not fully understood, they seem to orchestrate angiogenesis throughout embryonic development12,39,57,106 and vascular pruning in the postnatal stages of development.

The 3 identified loci account for 70%–80% of all cases of familial CCMs.18,23,26 Multilocus linkage analysis showed that CCM1 accounts for nearly 40% of inherited cases, CCM2 for 20%, and CCM3 for 40%.3,8,13,17 However, genetic screening data have revealed a higher frequency of CCM2 mutations; a lower frequency of mutations in CCM3 has also been reported as well, suggesting the existence of additional genes involved in the pathogenesis of CCM.18,59,60 Clinical penetrance has been shown to vary according to the involved locus, with an estimated 100% penetrance in CCM2 families and 63% penetrance in CCM3 members.13 Clinical penetrance in CCM1 families varies between 60% and 88%.15 Generally, kindreds affected with CCM1 mutations exhibit little clinical variance,64 but this is not the rule.37,38

The products of CCM genes, CCM1/Krit1, CCM2/malcavernin, and CCM3/PDCD10, have been shown to be specifically expressed in the endothelium, neurons, and astrocytes and their foot processes.91,96 Negative immunostaining of defective CCM proteins suggests that the endothelial cells are the cell of origin for causing CCM.32,77

Identification of a Genetic Locus Responsible for CCM Formation: CCM1

In 1982, an initial attempt at linkage mapping of the CCM genes by using 12 biochemical and serological markers in 36 Hispanic individuals was unsuccessful.21 In 1994, Kurth et al.54 mapped a gene for CCM to the q11–q12 region of chromosome 7 by using linkage analysis and short tandem repeat polymorphism analysis in a large Hispanic family. Broad shared haplotypes among affected individuals in this group allowed for further restriction of the gene to an interval of approximately 33 cM on the map from D7S502 to D7S479. Concurrently, Marchuk et al.68 identified linkage between CCM and genetic markers on the proximal long arm of chromosome 7 in studying a Hispanic and an Italian-American family. They identified a locus between D7S502 and D7S515, with an interval of 41 cM as harboring the gene of interest. This interval was further refined to 15 cM by Gil-Nagel et al.29 who bracketed the interval of interest between D7S660 and D7S558 while studying a large 4-generation non-Hispanic family harboring the familial form of the disease. Performing multipoint linkage analysis, Günel et al.37 found an lod score of 6.88 for linkage of CCM and locus D7S699 at a recombination fraction of 0. Moreover, their data placed the CCM gene in a 7-cM region within an interval centromeric to D7S802 and telomeric to ELN (elastin) in 7q11.2–q21.

Further refinement of the techniques for the largescale study of DNA allowed the region likely to contain the CCM1 gene to be reduced to a 4-cM segment of the human 7q21–q22. It was later shown that D7S2410 and D7S689 bounded the CCM1 critical region.34,35,46 Using a YAC-based sequence-tagged site content mapping strategy, all markers within the refined chromosomal segment were located on a single YAC contig estimated to be 2 Mb in size.

The CCM1 gene was finally identified with a positional cloning strategy based on genomic sequencing of the involved candidate interval within the human chromosome, using then-new microsatellite markers to provide fine haplotype analysis of families linked to the CCM1 locus.88 A detailed physical map of chromosome 7 was crucial to identify the disease gene, KRIT1 or CCM1.7 Aligning the genomic DNA sequence with the KRIT1 cDNA sequence again revealed its organization in 12 exons distributed over approximately 37.7 kb of DNA. Fluorescent in situ hybridization allowed KRIT1 cDNA to be mapped to 7q21–q22.92 Interestingly, the 7q21–q22 locus is often deleted or amplified in various malignant tumors.48,75

In 1999, identification of the CCM1 gene was confirmed in French families with hereditary CCM.57 Using a published YAC contig and genomic sequence information on chromosome 7,7 BAC and PAC contigs spanning the CCM1 interval were constructed. Twenty families with a high probability of linkage to CCM1 were assessed for high-resolution mapping of this locus, with polymorphic markers identified in BAC/PAC sequences. Using this technique, investigators were successful in reducing the previously determined interval from MS2456 and D7S689 because of a recombination event observed in an affected individual. In addition, they mapped 574 expressed sequence tags, clustering them in 53 potential transcriptional units comprising 6 characterized human genes, including CCM1. They also showed the 12 exons aligning the KRIT1 cDNA sequence to the BAC HSAC000120 sequence.92 Later, it was demonstrated that the gene has 20 exons, the first 3 of which are noncoding sequences.8,22,87,113

CCM1 encodes Krit1, a 736-amino acid microtubule-associated protein containing 4 ankyrin domains, a C-terminal FERM domain (that is, band 4.1, ezrin, radixin, moesin), and multiple N-terminal NPXY (Asn-Pro-XTyr) motifs.2,39,87,114

Seven different germline mutations within CCM1 have been identified, consisting of 2 single base transversions and 1 transition leading to nonsense (stop) codons, 2 single base transitions (splice site mutations), and 2 single base deletions leading to frameshift mutations and premature termination; all of these changes are loss-of-function mutations. Laberge-le Couteulx et al.57 also searched for mutations in CCM1 in persons belonging to the aforementioned French families by using single-strand conformation polymorphism analysis, direct genomic DNA sequencing, and screening of CCM1 cDNA for deletions. Accordingly, they found point mutations leading to premature stop codons and deletions resulting in frameshift and premature chain termination. All of these lesions resulted in loss of function via an early termination codon, generation of unstable mRNA, or truncated Krit1 proteins completely or partially devoid of the putative Rap1A-interacting region. Screening several unrelated families from different countries, Davenport et al.15 reported 10 new mutations related to CCM1, all of them leading to the loss of Krit1 protein function. Interestingly, a de novo germline mutation was reported in a patient harboring 2 CCMs, corresponding to a deletion of 2 base pairs in exon 6.65

Uncovering the total genomic structure of CCM1 allowed for mapping of mutations to the critical domains in the protein product. Mutational analysis revealed that 75% of mutations in 52 probands linked to CCM1 occurred in the C-terminus of the gene, mainly within exons 13, 15, and 17.8 Nonsense or frameshift mutations leading to a premature stop codon are responsible for 96.2% of all mutations, with the other 2 cases causing small in-frame deletion in the C-terminus. Other studies99 have revealed that point mutations result in the production of truncated proteins without biological function. Finally, the introduction of MLPA screening refined the identification of large deletions and duplications that might not be seen by the direct sequencing of genomic DNA.26,89 Thus, large deletions spanning the entire coding sequence of the CCM1 gene and producing loss of function have been reported in German families following MLPA.26 Concurrently, Liquori and colleagues59,61 also identified large deletions using MLPA in American and Italian CCM families that tested negative for mutations in CCM1, CCM2, and CCM3; only 5% of such deletions in the American cohort occurred within CCM1, whereas 50% of them in the Italian cohort were found within the CCM1. A rare multiexon duplication from exon 7 to 17 was identified in a Swiss patient.23

The elevated number of loss-of-function mutations leading to an mRNA decay of the mutated allele may imply that CCM1 acts as a tumor suppressor where somatic mutations resulting in a loss of the balancing wild-type allele predispose to the loss of growth control and tumor formation.15,57,88 For this reason and because of the dissimilarity between the characteristic multiplicity of lesions in the inherited form and the presence of a solitary lesion in a majority of sporadic cases, a 2-hit mechanism similar to the Knudson model for tumor suppressor gene (Fig. 3) has been proposed to explain CCM.47,50,77 Indeed, further studies have revealed biallelic mutations in CCM1 in the same cells, characterized by a germline transition within exon 14 and a somatic 34-nucleotide deletion within exon 15, truncating Krit1.27 The consistent finding of the complete and specific absence of CCM proteins, within cavernous malformation endothelial cells in patients carrying germline mutations, supports the 2-hit model.77

Fig. 3.
Fig. 3.

Schematic representation of the Knudson 2-hit hypothesis for the generation of cancer. The Knudson hypothesis proposes that multiple “hits” are needed for the transformation of a cell into an uncontrolled state of growth. The initial genomic changes can be inherited or acquired during development. It is the accumulation of multiple genomic hits rendering critical growth and remodeling pathways that results in the loss of cell cycle control and unregulated expansion of cell populations in cancer.

Identification of Two New Loci: CCM2 and CCM3

The assessment of some non-Hispanic families harboring familial CCM without evidence of involvement of CCM1 pointed to the possibility of the involvement of other loci.13,17

Therefore, a genome-wide linkage search across all 22 autosomes was undertaken in 7 non-Hispanic families, which did not reveal linkage to CCM1.13 After genotyping 312 loci, CCM inheritance in that group could not be linked to a single locus. When 3 large kindreds were evaluated separately, evidence began to emerge for linkage to a segment on 7p in 1 family and to a small interval on 3q in 2 others. Being aware of the 3 genetic intervals involved with CCM, a multipoint analysis of linkage was performed in 17 more kindreds, which provided an interesting distribution, with 40% of families being linked to 7q, 20% to 7p, and 40% to 3q (maximum multilocus lod score of 14.11). Such robust evidence denoted locus heterogeneity for CCM. The use of a 4-locus model initially failed to produce evidence of a fourth locus.13

The CCM2 Gene

The CCM2 gene has been mapped to 7p15-p13, spanning a region of 11 cM defined by markers D7S2846 and D7S1818.13 From 55 known or putative genes then identified within this region, Liquori et al.58 selected 8 that were probably involved in the genesis of CCM (CAMK2B, CDC10, CDC2L5, HIP-55, MGC4607, MYLC2A, RALA, and STK17A). Among them, MGC4607 contains a PTB domain and was predicted to interact with Krit1.

In 2004, Denier et al.17 confirmed the identification of CCM2 or MGC4607, a gene containing 10 coding exons on 7p13. First, these authors reduced the previously reported CCM2 interval from 22 to 7.5 cM via genetic linkage analysis by using 32 microsatellite markers on families not linked to both CCM1 and CCM3.13 They identified 2 large deletions involving at least exon 1 as well as 8 different point mutations, all resulting in loss of function.17 More recently, the use of MLPA allowed a significant increment in the identification of large deletions within CCM2;59,61 combining these data with previous DNA sequencing results produced a mutation rate of approximately 40%, indicating that the prevalence of CCM2 is much higher than the value provided by a previous large multilocus linkage study.13 Therefore, large mutations within CCM2 may represent a major mechanism in the pathogenesis of CCM. Identification of a deletion specifically encompassing exons 2 to 10, primarily found in American families, was not reproduced in French, German, and Swiss series, pointing to a founder effect.3,17,23,26,57 Altogether, the mutations encountered so far invariably lead to loss of function.

The CCM2 protein, or malcavernin, is required for normal cytoskeletal structure, cell-cell interactions, and lumen formation in endothelial cells. The 444-amino acid product of CCM2, containing a PTB domain, is a scaffold protein in a signaling cascade that controls the activation of p38 MAPK (by binding to MAPK kinase 3).58,98,111,112 It also interacts with Krit1, actin, and Rac1, a small GTPase involved in signal transduction pathways that controls proliferation, adhesion, actin cytoskeleton reorganization, and migration of cells.70,112

The CCM3 Gene

Genetic analysis of patients with familial CCM helped map a third autosomal dominant locus. The third CCM locus, CCM3, is located on 3q25.2–27. This locus was identified within a 22-cM interval flanked by D3S1763 and D3S1262.13 In 2005, Bergametti et al.3 screened 20 unrelated families harboring the familial form of CCM but lacking mutations within the CCM1 and CCM2 loci. A high-density microsatellite genotyping of that interval allowed searching for putative null alleles, as identified in CCM2.17 Once they found a de novo deletion in an interval bracketed by markers D3S3668 and D3S1614 and overlapping D3S1763, the authors could outline the interval containing the candidate gene within a 970-kb region, now bracketed by D3S1763 and D3S1614. Of 5 genes already mapped to this interval (FLJ33620, GOLPH4, LOC389174, PDCD10, and SERPINI1), the programmed cell death 10 gene, PDCD10, appeared as a likely candidate because of its putative role in apoptosis.3

The PDCD10 gene was initially identified in relation to its upregulation in the TF-1 premyeloid cell line granulocyte during deprivation of the granulocyte-macrophage colony-stimulating factor.103 The highly conserved gene has 7 coding exons and 3 noncoding ones on 3q26.1, producing a 212-amino acid protein. Examples of point mutations identified on genomic DNA sequence analysis include direct nonsense mutations and splice-site mutations leading to a frameshift.3,60 Interestingly, the frequency of mutations in CCM3 has been reported to be low in large studies assessing nonCCM1, nonCCM2 kindreds,3,18,59,60 in contrast with a 40% expected frequency in inherited cases reported in the classic aforementioned linkage analysis by Craig et al.13 Additionally, the frequency of affected members per family is significantly lower in CCM3 families than in families harboring CCM1 and CCM2.18

Apparently, the CCM3 or PDCD10 protein takes part in the aforementioned complex involving Krit1 and CCM2.91,94,101 This can be explained by the fact that apoptosis within smooth muscle cells is mediated by the β1 integrin signaling pathway,104 which interacts with the other CCM proteins. Furthermore, Chen et al.10 demonstrated that such protein is both necessary and sufficient to promote apoptosis, and thus CCM may originate from aberrant apoptosis, impairing the equilibrium between neural cells and endothelium within the CNS.

Are Other Genes Involved?

The existence of a fourth CCM gene was postulated after unexpected low frequencies of CCM3 mutations had been obtained in families without a CCM1 and CCM2 gene mutation.3,18,59,60 The existence of an additional gene within a short distance of the 3 other loci or missed in the original report on multilocus linkage analysis for familial CCM could explain such a fact.3 The examination of haplotypes in kindreds linked to CCM3 locus given that linkage mapping revealed a particular recombination event excluding CCM3 in a family with strong linkage; CCM4 would be located in or close to 3q26.3–3q27.2.3,13

A balanced translocation involving the long arms of chromosomes 3 and X, t(X;3)(q22.3;q12.3) was encountered in a patient with CCM, without any mutation within the known CCM genes.28 After narrowing the breakpoint position to a 200-kb interval on 3q12.3, a potential interval of interest, the zona pellucida–like domain containing 1 gene (ZPLD1) was found to span this region. This highly conserved gene comprises 19 exons, spanning approximately 500 kb of genomic DNA. The 2 isoforms, ZPLD1a and ZPLD1b, contain 431 and 415 amino acids, respectively. Expression levels of ZPLD1 mRNA were reduced in that patient as compared with controls, with an allelic loss of gene expression. However, mutation screening of this gene in CCM families negative for mutations in known CCM genes was unsuccessful. Finally, the translocation did not promote dysregulation of the expression of any CCM genes. Future studies are necessary to assess the structure and role of ZPLD1 products and their possible interaction with the CCM proteins and a link to a fourth locus.

Other targets of interest are the protein products of the ephrin genes. Ephrin-B2 (EFNB2) is associated with vascular development, mainly in arterial differentiation.102 Efnb2 is downregulated within arterial endothelium in mice lacking Ccm1, indicating a compromised arterial identity.106 Members of the transforming growth factor β signaling pathway, notably Notch genes, have been shown to interact with EFNB2 and to regulate critical steps during embryonic vascular development and remodeling.52 Dll4 and Notch4 expressions are also downregulated within arteries in Ccm1–/– embryos, even before the onset of blood flow.106 Importantly, a corresponding reduced expression of Notch 4 was seen in surgical specimens obtained from patients carrying mutations in CCM1, suggesting that mutations in the transforming growth factor β signaling pathway may cause the formation of CCMs.

Lessons Learned From Various Animal Models of CCM

Given the rare nature of CCMs, animal models have been the key source for studying CCM pathology. Animal models have helped to establish the role of CCM genes in vascular development and the pathobiology of CCM lesion development and to explain their focal nature. Zhang et al.114 mapped the mouse Krit1 gene to a region of chromosome 5 that shares homology of synteny with human 7q21–q22. Further, knockout alleles of the murine orthologs of CCM1 and CCM2 have been generated.106

Heterozygous mutant animals, which are the appropriate genotype for the autosomal dominant disorder, do not recapitulate the disease phenotype with appreciable penetrance.106 A Ccm1 mutant allele was generated by disrupting the gene at the first ankyrin repeat. Mice lacking Ccm1 suffer from generalized developmental arrest after E9.5, retaining a primitive yolk sac vascular network, and thus dying by E11 with prominent vascular defects associated with inappropriate angiogenic remodeling but apparently normal neuronal development.106 Pathological study of these animals revealed that they possessed numerous vascular dilations related to altered arterial fate and increased endothelial mitosis. The animals failed to recruit arterial smooth muscle cells and generate a normal vascular channel. Importantly, the Ccm1–/– model contributed to defining the role of CCM1 in arterial morphogenesis; primary defects in such a model were vascular, without preceding impairment in neural or cardiac development.

An alternative mouse model was developed by gene trap insertion in the Ccm2 gene. The Ccm2–/– mice are embryonic lethal. On the other hand, Ccm2+/– revealed the expected phenotype, albeit with a low penetrance.80 Expression of CCM2 is mostly neuronal but is also present in the choroid plexus and vascular endothelium.40

Based on the Knudson 2-hit mutation mechanism, Plummer et al.79 conducted the development of heterozygous Ccm1 mutations into mutant genetic backgrounds with increased somatic instability. One mechanism of introducing genetic instability is via the deletion of the p53 tumor suppressor gene. In many mouse models of disease, the addition of p53 mutations causes exacerbation of the phenotype of the mutated gene. The development of vascular malformations and hemangiosarcomas in the CNS due to polyoma virus infection in rats is mediated by the suppression of p53 activity associated with such a virus.24 Additionally, the loss of the tumor suppressor gene Trp53 (p53) leads to the development of CCM in a heterozygous mouse with a target mutation of Ccm1. However, no mutation in TP53 had been found while sequencing the DNA of human CCM specimens.79 Indeed, the absence of CCM development in Ccm1+/+ Trp53–/– mice also supports the notion that the isolated loss of p53 does not independently induce CCM.

Ccm1+/– individuals develop vascular malformations only when they are also homozygous for a loss of p53, which increases the rate of somatic mutations. Ccm1–/– Trp53–/– double-mutant mice exhibited cerebrovascular lesions in 55% of cases, whereas all other genotypes failed to show the phenotype.

The zebrafish dilated-heart mutants santa and valentine correspond to CCM1 and CCM2, respectively.67 Hogan et al.45 found that the deletion of ccm1 in this model expressed a phenotype similar to that of human and murine CCM. Vascular dilation was associated with the progressive spreading of endothelial cells and thinning of vessel walls during vascular morphogenesis, consisting of an alteration of cell shape but not of endothelial cell-cell adhesion, cell fate, or number. The Ccm1 mutants, ccm2 mutants, and ccm1/ccm2 double mutants had indistinguishable vascular phenotypes, suggesting conservation of function. Finally, these authors corroborated that the CCM proteins regulate endothelial development.

Molecular Interaction of CCM Gene Products With Other Developmental Pathways

Molecular proteomic evidence suggests that the protein products of the 3 identified CCM genes in concert with other cellular machinery form ternary complexes that regulate key steps in blood vessel formation and maintenance. It is postulated that the inability to compose these protein complexes leads to the dysfunctional vascular cavities and pathology noted.

Krit1/Rap1A

The CCM1 gene product, Krit1, interacts with the Ras-related protein 1A (Rap1a or Krev1), an evolutionarily conserved Ras-family GTPase encoded by the gene RAP1A through its C-terminal region.78,85 One of the functions of Rap1A homologs in yeast and Drosophila melanogaster is to regulate GTPase signal transduction cascades participating in cell differentiation, morphogenesis, polarity, and cytoskeletal structure.6,78,92 The Krit1 binds strongly to Rap1A. Accordingly, Serebriiskii et al.92 initially suggested that Krit1 might help in localizing Rap1A to a proper cell compartment for function, given the common association of ankyrin repeat proteins with the cytoskeleton.90 Indeed, several groups have identified high expression of Rap1A within vascular smooth muscle cells in various organs including the CNS107 and have shown that structural changes altering this interaction results in an inability of endothelial cells to organize correctly and leads to the formation of dramatically enlarged blood vessels in mouse models.44,108 Using anti-KRIT1 antibodies, Gunel et al.39 demonstrated Krit1 expression within endothelial cells, in association with microtubules (tubulin). By interacting with microtubules and because of its particular distribution in cells during mitosis, the authors proposed that Krit1 could act in targeting microtubules. The initial stages of angiogenesis involve tube formation by endothelial cells and are modulated by cell intrinsic and extrinsic signals. The platelet endothelial cell adhesion molecule-1 (PECAM-1) is an important regulator of endothelial tubulogenesis and activates the GTPase activity of RAP1a, which ultimately interacts with the microtubule cytoskeleton.39,82,92 Effector molecules such as Krit1 bind to Rap1A in endothelial cells, enhancing the stability of endothelial adherent junctions, and thus reducing vascular fragility.22,111,113,114

Krit1/ICAP1α/SNX17

The α isoform of the β1 ICAP-1 binds to Krit1 through its NPXY motif.9 It is a modulator of β1 integrin signal transduction and is involved in cell adhesion and migration. The binding of the α isoform of the β1 ICAP-1 to Krit1 inhibits its ability to bind to microtubules. As stated previously, Krit1 interaction with the microtubule machinery regulates cell adhesion and cell-cell junction formation. Interestingly, ICAP-1 also binds with the cytoplasmic tail of β1 integrin complex.2 This complex is crucial in supporting endothelial cell proliferation for the formation of new vessels from vascular cores. The inability of Krit1 to bind with ICAP-1 results in ICAP-1's inability to initiate the β1 complex, and thus impairing capillary formation and/or maintenance, leading to vascular leaks.40,41 Another player involved in this intricate protein machinery is the SNX17 protein (sorting nexin 17), a nonself-assembling and phosphatidylinositol 3-phosphate high affinity protein that interacts with ICAP-1.14 Again, mutations that abolish ICAP-1/SNX17 interaction appear to have a similar phenotype preventing cytoskeletal recruitment. These data quickly begin to reveal a highly interconnected network of signaling events needed for the proper sprouting of new blood vessels. Loss of interaction with the cytoskeletal machinery appears to be an initial inciting event in the formation of CCM lesions (Fig. 4).

Fig. 4.
Fig. 4.

Schematic depicting the role of CCM gene products in the organizing of sprouting vascular channels. Modified from Dashti et al.: Neurosurg Focus 21 (1):E2, 2006.

Krit1/CCM2

The critical role of Krit1 as an anchoring protein with the cytoskeletal matrix means that any deficiencies in interaction between this protein and other members of the skeletal machinery are likely to result in the development of a CCM phenotype. There is a critical interaction between the CCM1 gene product and the CCM2/MEKK3 complex.112 Note that CCM2 is required as a scaffold for MEKK3-mediated p38 MAPK phosphorylation, while a mutation of the gene leads to a decrease in p38 MAPK activation, suggesting that CCM2 may be part of a protein complex that regulates the p38 pathway. The CCM1 binds to the CCM2/MEKK3 complex through their PTB domains. Mutation of the CCM2/MGC4607 gene results in abnormal PTB domains, which blocks CCM1 binding to the CCM2/MGC4607 complex and thus affects regulation of the p38 MAPK pathway. It is hypothesized that CCM1/ICAP-1 binds with the CCM2/MEKK3 complex, acting as a nuclear-cytoplasmic shuttling agent, with CCM1/ICAP-1 localized in the nucleus, and then CCM2/MEKK3 signals it into the cytoplasm where they bind with one another to form a ternary complex that becomes a part of the signaling pathway for p38 MAPK.112 Dysregulation of the p38 MAPK pathway, caused by an inability to form the ternary complex CCM1/CCM2/MEKK3, could contribute to the abnormal development of vessels in CCMs.

PDCD10/MST4

Proteomic studies have identified several critical components of the ternary complex needed for proper blood vessel sprouting. Among the players involved in the formation of the ternary complex, PDCD10, which is linked to CCM3, has been identified in association with several of the CCM cases. The PDCD10 gene product interacts with a member of the Ste20-related kinases, MST4. The over-expression of PDCD10 results in an increase in the MST4 kinase activity, which in turn results in increased cell proliferation.66 It is postulated that the formation of the PDCD10/MST4 complex mediates cell growth by the modulation of the ERK-MAPK pathway. The ERK-MAPK pathway is very important in the regulation of cell proliferation and is involved in pathogenesis, suggesting that there may be a link between CCM pathogenesis and the ERK-MAPK pathway via the PDCD10/MST4 complex.66

CCM3/PDCD10

During the process of angiogenesis, PDCD10 is expressed in neocortex and ventricular and subventricular zones. Given the important role of this protein in apoptosis, it is interesting to postulate that the angiogenic machinery utilizes the protein product of this locus to prune newly developed blood vessels and that deficiencies in this pruning ability result in the formation of CCMs.

RhoA-ROCK Pathway

The 3 CCM protein products are crucial for the stabilization of the newly formed blood vessels during development. It has been shown that the CCM products interact with the RhoA-ROCK (Rho kinase) pathway, and those mutations in any of the CCM genes results in hyperactivation of the ROCK pathway. Note that RhoA activates ROCK (a putative RhoA effector), which leads to an increase in actin stress fiber (microtubules) production.95 By increasing the myosin light chain phosphorylation, ROCK mediates the formation of microtubules. Phosphorylation of the myosin light chain allows the myosin cross-bridge to bind to the actin filaments, and thus increasing the cellular contraction rate. The resultant enhanced cell contractility can disrupt the cell-cell adhesion of the endothelial cells mediated via beta-catenin and vascular endothelial cadherin (adherin junctions) lining the vascular walls,33 resulting in enlargement of the blood vessels and making it very difficult for them to restabilize, and thus leading to vascular leakage and initiating the cascade to CCM formation.105

Conclusions

Although the exact mechanism underlying the pathogenesis of CCMs is unknown, the study of families with autosomal dominant inherited and sporadic CCMs has shed light on the importance of the machinery involved in the proliferation and differentiation of angiogenic precursors and on members of the apoptotic machinery as key regulators of the pathogenesis of CCM. Despite the utility of animal models, they have inherent shortcomings such as low expression of the desired phenotype. The generation of an in vivo human model of the disease via the isolation of CCM progenitor cells and their transplantation into an immunodeficient animal, as has been recently described for hemangiomas,36 may allow both the study of human forms of CCMs and a robust model for imaging and drug trials. Another exciting frontier of research is the sequencing of the entire genome of patients afflicted with CCM by using next-generation sequencing technology. Obtaining the full genomic profile of patients with multiple CCMs will provide further mechanistic clues about the role of other genes and gene regulatory machinery, such as small RNAs, in the pathogenesis of CCMs.

Disclosure

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author contributions to the study and manuscript preparation include the following. Conception and design: Cavalcanti, Kalani, Martirosyan. Acquisition of data: Cavalcanti, Kalani, Martirosyan, Eales. Analysis and interpretation of data: Cavalcanti, Kalani, Martirosyan. Drafting the article: Cavalcanti, Kalani. Critically revising the article: Preul, Cavalcanti, Kalani, Spetzler, Martirosyan. Reviewed final version of the manuscript and approved it for submission: Preul, Spetzler, Martirosyan. Administrative/technical/material support: Spetzler, Preul. Study supervision: Spetzler, Preul.

References

  • 1

    Abe MKjellberg RNAdams RD: Clinical presentations of vascular malformations of the brain stem: comparison of angiographically positive and negative types. J Neurol Neurosurg Psychiatry 52:1671751989

  • 2

    Béraud-Dufour SGautier RAlbiges-Rizo CChardin PFaurobert E: Krit 1 interactions with microtubules and membranes are regulated by Rap1 and integrin cytoplasmic domain associated protein-1. FEBS J 274:551855322007

  • 3

    Bergametti FDenier CLabauge PArnoult MBoetto SClanet M: Mutations within the programmed cell death 10 gene cause cerebral cavernous malformations. Am J Hum Genet 76:42512005

  • 4

    Bicknell JM: Familial cavernous angioma of the brain stem dominantly inherited in Hispanics. Neurosurgery 24:1021051989

  • 5

    Bicknell JMCarlow TJKornfeld MStovring JTurner P: Familial cavernous angiomas. Arch Neurol 35:7467491978

  • 6

    Bos JL: All in the family? New insights and questions regarding interconnectivity of Ras, Rap1 and Ral. EMBO J 17:677667821998

  • 7

    Bouffard GGIdol JRBraden VVIyer LMCunningham AFWeintraub LA: A physical map of human chromosome 7: an integrated YAC contig map with average STS spacing of 79 kb. Genome Res 7:6736921997

  • 8

    Cavé-Riant FDenier CLabauge PCécillon MMaciazek JJoutel A: Spectrum and expression analysis of KRIT1 mutations in 121 consecutive and unrelated patients with cerebral cavernous malformations. Eur J Hum Genet 10:7337402002

  • 9

    Chang DDWong CSmith HLiu J: ICAP-1, a novel beta1 integrin cytoplasmic domain-associated protein, binds to a conserved and functionally important NPXY sequence motif of beta1 integrin. J Cell Biol 138:114911571997

  • 10

    Chen LTanriover GYano HFriedlander RLouvi AGunel M: Apoptotic functions of PDCD10/CCM3, the gene mutated in cerebral cavernous malformation 3. Stroke 40:147414812009

  • 11

    Clark JV: Familial occurrence of cavernous angiomata of the brain. J Neurol Neurosurg Psychiatry 33:8718761970

  • 12

    Clatterbuck REEberhart CGCrain BJRigamonti D: Ultrastructural and immunocytochemical evidence that an incompetent blood-brain barrier is related to the pathophysiology of cavernous malformations. J Neurol Neurosurg Psychiatry 71:1881922001

  • 13

    Craig HDGünel MCepeda OJohnson EWPtacek LSteinberg GK: Multilocus linkage identifies two new loci for a mendelian form of stroke, cerebral cavernous malformation, at 7p15-13 and 3q25.2–27. Hum Mol Genet 7:185118581998

  • 14

    Czubayko MKnauth PSchlüter TFlorian VBohnensack R: Sorting nexin 17, a non-self-assembling and a PtdIns(3)P high class affinity protein, interacts with the cerebral cavernous malformation related protein KRIT1. Biochem Biophys Res Commun 345:126412722006

  • 15

    Davenport WJSiegel AMDichgans JDrigo PMammi IPereda P: CCM1 gene mutations in families segregating cerebral cavernous malformations. Neurology 56:5405432001

  • 16

    Del Curling O JrKelly DL JrElster ADCraven TE: An analysis of the natural history of cavernous angiomas. J Neurosurg 75:7027081991

  • 17

    Denier CGoutagny SLabauge PKrivosic VArnoult MCousin A: Mutations within the MGC4607 gene cause cerebral cavernous malformations. Am J Hum Genet 74:3263372004

  • 18

    Denier CLabauge PBergametti FMarchelli FRiant FArnoult M: Genotype-phenotype correlations in cerebral cavernous malformations patients. Ann Neurol 60:5505562006

  • 19

    Di Rocco CIannelli ATamburrini G: Cavernous angiomas of the brain stem in children. Pediatr Neurosurg 27:92991997

  • 20

    Dobyns WBMichels VVGroover RVMokri BTrautmann JCForbes GS: Familial cavernous malformations of the central nervous system and retina. Ann Neurol 21:5785831987

  • 21

    Dubovsky JZabramski JMKurth JSpetzler RFRich SSOrr HT: A gene responsible for cavernous malformations of the brain maps to chromosome 7q. Hum Mol Genet 4:4534581995

  • 22

    Eerola IMcIntyre BVikkula M: Identification of eight novel 5′-exons in cerebral capillary malformation gene-1 (CCM1) encoding KRIT1. Biochim Biophys Acta 1517:4644672001

  • 23

    Felbor UGaetzner SVerlaan DJVijzelaar RRouleau GASiegel AM: Large germline deletions and duplication in isolated cerebral cavernous malformation patients. Neurogenetics 8:1491532007

  • 24

    Flocks JSWeis TPKleinman DCKirsten WH: Dose-response studies to polyoma virus in rats. J Natl Cancer Inst 35:2592841965

  • 25

    Fritschi JAReulen HJSpetzler RFZabramski JM: Cavernous malformations of the brain stem. A review of 139 cases. Acta Neurochir (Wien) 130:35461994

  • 26

    Gaetzner SStahl SSürücü OSchaafhausen AHalliger-Keller BBertalanffy H: CCM1 gene deletion identified by MLPA in cerebral cavernous malformation. Neurosurg Rev 30:1551602007

  • 27

    Gault JShenkar RRecksiek PAwad IA: Biallelic somatic and germ line CCM1 truncating mutations in a cerebral cavernous malformation lesion. Stroke 36:8728742005

  • 28

    Gianfrancesco FEsposito TPenco SMaglione VLiquori CLPatrosso MC: ZPLD1 gene is disrupted in a patient with balanced translocation that exhibits cerebral cavernous malformations. Neuroscience 155:3453492008

  • 29

    Gil-Nagel ADubovsky JWilcox KJStewart JMAnderson VELeppik IE: Familial cerebral cavernous angioma: a gene localized to a 15-cM interval on chromosome 7q. Ann Neurol 39:8078101996. (Erratum in Ann Neurol 39:

  • 30

    Gil-Nagel AWilcox KJStewart JMAnderson VELeppik IERich SS: Familial cerebral cavernous angioma: clinical analysis of a family and phenotypic classification. Epilepsy Res 21:27361995

  • 31

    Giombini SMorello G: Cavernous angiomas of the brain. Account of fourteen personal cases and review of the literature. Acta Neurochir (Wien) 40:61821978

  • 32

    Glading AHan JStockton RAGinsberg MH: KRIT-1/CCM1 is a Rap1 effector that regulates endothelial cell cell junctions. J Cell Biol 179:2472542007

  • 33

    Glading AJGinsberg MH: Rap1 and its effector KRIT1/CCM1 regulate beta-catenin signaling. Dis Model Mech 3:73832010

  • 34

    Green EDBraden VVFulton RSLim RUeltzen MSPeluso DC: A human chromosome 7 yeast artificial chromosome (YAC) resource: construction, characterization, and screening. Genomics 25:1701831995

  • 35

    Green EDGreen P: Sequence-tagged site (STS) content mapping of human chromosomes: theoretical considerations and early experiences. PCR Methods Appl 1:77901991

  • 36

    Greenberger SBoscolo EAdini IMulliken JBBischoff J: Corticosteroid suppression of VEGF-A in infantile hemangioma-derived stem cells. N Engl J Med 362:100510132010

  • 37

    Günel MAwad IAAnson JLifton RP: Mapping a gene causing cerebral cavernous malformation to 7q11.2–q21. Proc Natl Acad Sci U S A 92:662066241995

  • 38

    Gunel MAwad IAFinberg KAnson JASteinberg GKBatjer HH: A founder mutation as a cause of cerebral cavernous malformation in Hispanic Americans. N Engl J Med 334:9469511996

  • 39

    Gunel MLaurans MSShin DDiLuna MLVoorhees JChoate K: KRIT1, a gene mutated in cerebral cavernous malformation, encodes a microtubule-associated protein. Proc Natl Acad Sci U S A 99:10677106822002

  • 40

    Guzeloglu-Kayisli OAmankulor NMVoorhees JLuleci GLifton RPGunel M: KRIT1/cerebral cavernous malformation 1 protein localizes to vascular endothelium, astrocytes, and pyramidal cells of the adult human cerebral cortex. Neurosurgery 54:9439492004

  • 41

    Guzeloglu-Kayisli OKayisli UAAmankulor NMVoorhees JRGokce ODiLuna ML: Krev1 interaction trapped-1/cerebral cavernous malformation-1 protein expression during early angiogenesis. J Neurosurg 100:5 Suppl Pediatrics4814872004

  • 42

    Hallmann RHorn NSelg MWendler OPausch FSorokin LM: Expression and function of laminins in the embryonic and mature vasculature. Physiol Rev 85:97910002005

  • 43

    Hayman LAEvans RAFerrell REFahr LMOstrow PRiccardi VM: Familial cavernous angiomas: natural history and genetic study over a 5-year period. Am J Med Genet 11:1471601982

  • 44

    Henkemeyer MRossi DJHolmyard DPPuri MCMbamalu GHarpal K: Vascular system defects and neuronal apoptosis in mice lacking ras GTPase-activating protein. Nature 377:6957011995

  • 45

    Hogan BMBussmann JWolburg HSchulte-Merker S: Ccm1 cell autonomously regulates endothelial cellular morphogenesis and vascular tubulogenesis in zebrafish. Hum Mol Genet 17:242424322008

  • 46

    Johnson EWIyer LMRich SSOrr HTGil-Nagel AKurth JH: Refined localization of the cerebral cavernous malformation gene (CCM1) to a 4-cM interval of chromosome 7q contained in a well-defined YAC contig. Genome Res 5:3683801995

  • 47

    Kehrer-Sawatzki HWilda MBraun VMRichter HPHameister H: Mutation and expression analysis of the KRIT1 gene associated with cerebral cavernous malformations (CCM1). Acta Neuropathol 104:2312402002

  • 48

    Kere JRuutu TDavies KARoninson IBWatkins PCWinqvist R: Chromosome 7 long arm deletion in myeloid disorders: a narrow breakpoint region in 7q22 defined by molecular mapping. Blood 73:2302341989

  • 49

    Kidd HACumings JN: Cerebral angiomata in an Icelandic family. Lancet 1:7471947

  • 50

    Knudson AG: Two genetic hits (more or less) to cancer. Nat Rev Cancer 1:1571622001

  • 51

    Kondziolka DLunsford LDKestle JR: The natural history of cerebral cavernous malformations. J Neurosurg 83:8208241995

  • 52

    Krebs LTXue YNorton CRShutter JRMaguire MSundberg JP: Notch signaling is essential for vascular morphogenesis in mice. Genes Dev 14:134313522000

  • 53

    Kufs H: Über heredofamiliare Angiomatose des Gehirns und der Retina, ihre Beziehungen zueinander und zur Angiomatose der Haut. Z Gesamte Neurol Psychiatr 113:6516861928

  • 54

    Kurth JHZabramski JMDubovsky J: Genetic linkage of the familial cavernous malformation (CM) gene to chromosome 7q. Am J Hum Genet 55:Suppl 3A151994. (http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=133322

  • 55

    Labauge PLaberge SBrunereau LLevy CTournier-Lasserve E: Hereditary cerebral cavernous angiomas: clinical and genetic features in 57 French families. Société Française de Neurochirurgie. Lancet 352:189218971998

  • 56

    Laberge SLabauge PMaréchal EMaciazek JTournier-Lasserve E: Genetic heterogeneity and absence of founder effect in a series of 36 French cerebral cavernous angiomas families. Eur J Hum Genet 7:4995041999

  • 57

    Laberge-le Couteulx SJung HHLabauge PHoutteville JPLescoat CCecillon M: Truncating mutations in CCM1, encoding KRIT1, cause hereditary cavernous angiomas. Nat Genet 23:1891931999

  • 58

    Liquori CLBerg MJSiegel AMHuang EZawistowski JSStoffer T: Mutations in a gene encoding a novel protein containing a phosphotyrosine-binding domain cause type 2 cerebral cavernous malformations. Am J Hum Genet 73:145914642003

  • 59

    Liquori CLBerg MJSquitieri FLeedom TPPtacek LJohnson EW: Deletions in CCM2 are a common cause of cerebral cavernous malformations. Am J Hum Genet 80:69752007

  • 60

    Liquori CLBerg MJSquitieri FOttenbacher MSorlie MLeedom TP: Low frequency of PDCD10 mutations in a panel of CCM3 probands: potential for a fourth CCM locus. Hum Mutat 27:1182006

  • 61

    Liquori CLPenco SGault JLeedom TPTassi LEsposito T: Different spectra of genomic deletions within the CCM genes between Italian and American CCM patient cohorts. Neurogenetics 9:25312008

  • 62

    Lloyd-Jones DAdams RJBrown TMCarnethon MDai SDe Simone G: Heart disease and stroke statistics—2010 update: a report from the American Heart Association. Circulation 121:e46e2152010. (Erratum in Circulation 121:

  • 63

    Lonjon MRoche JLGeorge BMourier KLPaquis PLot G: [Intracranial cavernoma. 30 cases.]. Presse Med 22:9909941993. (Fr)

  • 64

    Lucas MCosta AFGarcía-Moreno JMSolano FGamero MAIzquierdo G: Variable expression of cerebral cavernous malformations in carriers of a premature termination codon in exon 17 of the Krit1 gene. BMC Neurol 3:52003

  • 65

    Lucas MCosta AFMontori MSolano FZayas MDIzquierdo G: Germline mutations in the CCM1 gene, encoding Krit1, cause cerebral cavernous malformations. Ann Neurol 49:5295322001

  • 66

    Ma XZhao HShan JLong FChen YChen Y: PDCD10 interacts with Ste20-related kinase MST4 to promote cell growth and transformation via modulation of the ERK pathway. Mol Biol Cell 18:196519782007

  • 67

    Mably JDChuang LPSerluca FCMohideen MAChen JNFishman MC: Santa and valentine pattern concentric growth of cardiac myocardium in the zebrafish. Development 133:313931462006

  • 68

    Marchuk DAGallione CJMorrison LAClericuzio CLHart BLKosofsky BE: A locus for cerebral cavernous malformations maps to chromosome 7q in two families. Genomics 28:3113141995

  • 69

    Mason IAase JMOrrison WWWicks JDSeigel RSBicknell JM: Familial cavernous angiomas of the brain in an Hispanic family. Neurology 38:3243261988

  • 70

    Matos PSkaug JMarques BBeck SVeríssimo FGespach C: Small GTPase Rac1: structure, localization, and expression of the human gene. Biochem Biophys Res Commun 277:7417512000

  • 71

    McCormick WF: The pathology of vascular (“arteriovenous”) malformations. J Neurosurg 24:8078161966

  • 72

    Michael JCLevin PM: Multiple telangiectases of the brain: a discussion of hereditary factors in their development. Arch Neurol Psychiatry 36:5145291936

  • 73

    Moriarity JLWetzel MClatterbuck REJavedan SSheppard JMHoenig-Rigamonti K: The natural history of cavernous malformations: a prospective study of 68 patients. Neurosurgery 44:116611731999

  • 74

    Moussa RHarb AMenassa LRisk TNohra GSamaha E: [Etiologic spectrum of intracerebral hemorrhage in young patients.]. Neurochirurgie 52:2–3 Pt 11051092006. (Fr)

  • 75

    Nibert MHeim S: Uterine leiomyoma cytogenetics. Genes Chromosomes Cancer 2:3131990

  • 76

    Otten PPizzolato GPRilliet BBerney J: [131 cases of cavernous angioma (cavernomas) of the CNS, discovered by retrospective analysis of 24,535 autopsies.]. Neurochirurgie 35:82831989. (Fr)

  • 77

    Pagenstecher AStahl SSure UFelbor U: A two-hit mechanism causes cerebral cavernous malformations: complete inactivation of CCM1, CCM2 or CCM3 in affected endothelial cells. Hum Mol Genet 18:9119182009

  • 78

    Pizon VChardin PLerosey IOlofsson BTavitian A: Human cDNAs rap1 and rap2 homologous to the Drosophila gene Dras3 encode proteins closely related to ras in the ‘effector’ region. Oncogene 3:2012041988

  • 79

    Plummer NWGallione CJSrinivasan SZawistowski JSLouis DNMarchuk DA: Loss of p53 sensitizes mice with a mutation in Ccm1 (KRIT1) to development of cerebral vascular malformations. Am J Pathol 165:150915182004

  • 80

    Plummer NWSquire TLSrinivasan SHuang EZawistowski JSMatsunami H: Neuronal expression of the Ccm2 gene in a new mouse model of cerebral cavernous malformations. Mamm Genome 17:1191282006

  • 81

    Porter PJWillinsky RAHarper WWallace MC: Cerebral cavernous malformations: natural history and prognosis after clinical deterioration with or without hemorrhage. J Neurosurg 87:1901971997

  • 82

    Reedquist KARoss EKoop EAWolthuis RMZwartkruis FJvan Kooyk Y: The small GTPase, Rap1, mediates CD31-induced integrin adhesion. J Cell Biol 148:115111582000

  • 83

    Rigamonti DHadley MNDrayer BPJohnson PCHoenig-Rigamonti KKnight JT: Cerebral cavernous malformations. Incidence and familial occurrence. N Engl J Med 319:3433471988

  • 84

    Robinson JRAwad IALittle JR: Natural history of the cavernous angioma. J Neurosurg 75:7097141991

  • 85

    Ruggieri RBender AMatsui YPowers STakai YPringle JR: RSR1, a ras-like gene homologous to Krev-1 (smg21A/rap1A): role in the development of cell polarity and interactions with the Ras pathway in Saccharomyces cerevisiae. Mol Cell Biol 12:7587661992

  • 86

    Russell DSRubinstein LJ: Pathology of Tumours of the Nervous System LondonE. Arnold1989. 730736

  • 87

    Sahoo TGoenaga-Diaz ESerebriiskii IGThomas JWKotova ECuellar JG: Computational and experimental analyses reveal previously undetected coding exons of the KRIT1 (CCM1) gene. Genomics 71:1231262001

  • 88

    Sahoo TJohnson EWThomas JWKuehl PMJones TLDokken CG: Mutations in the gene encoding KRIT1, a Krev-1/rap1a binding protein, cause cerebral cavernous malformations (CCM1). Hum Mol Genet 8:232523331999

  • 89

    Schouten JPMcElgunn CJWaaijer RZwijnenburg DDiepvens FPals G: Relative quantification of 40 nucleic acid sequences by multiplex ligation-dependent probe amplification. Nucleic Acids Res 30:e572002

  • 90

    Sedgwick SGSmerdon SJ: The ankyrin repeat: a diversity of interactions on a common structural framework. Trends Biochem Sci 24:3113161999

  • 91

    Seker APricola KLGuclu BOzturk AKLouvi AGunel M: CCM2 expression parallels that of CCM1. Stroke 37:5185232006

  • 92

    Serebriiskii IEstojak JSonoda GTesta JRGolemis EA: Association of Krev-1/rap1a with Krit1, a novel ankyrin repeatcontaining protein encoded by a gene mapping to 7q21–22. Oncogene 15:104310491997

  • 93

    Simard JMGarcia-Bengochea FBallinger WE JrMickle JPQuisling RG: Cavernous angioma: a review of 126 collected and 12 new clinical cases. Neurosurgery 18:1621721986

  • 94

    Stahl SGaetzner SVoss KBrackertz BSchleider ESürücü O: Novel CCM1, CCM2, and CCM3 mutations in patients with cerebral cavernous malformations: in-frame deletion in CCM2 prevents formation of a CCM1/CCM2/CCM3 protein complex. Hum Mutat 29:7097172008

  • 95

    Stockton RAShenkar RAwad IAGinsberg MH: Cerebral cavernous malformations proteins inhibit Rho kinase to stabilize vascular integrity. J Exp Med 207:8818962010

  • 96

    Tanriover GBoylan AJDiluna MLPricola KLLouvi AGunel M: PDCD10, the gene mutated in cerebral cavernous malformation 3, is expressed in the neurovascular unit. Neurosurgery 62:9309382008

  • 97

    Tomlinson FHHouser OWScheithauer BWSundt TM JrOkazaki HParisi JE: Angiographically occult vascular malformations: a correlative study of features on magnetic resonance imaging and histological examination. Neurosurgery 34:7928001994

  • 98

    Uhlik MTAbell ANJohnson NLSun WCuevas BDLobel-Rice KE: Rac-MEKK3-MKK3 scaffolding for p38 MAPK activation during hyperosmotic shock. Nat Cell Biol 5:110411102003

  • 99

    Verlaan DJSiegel AMRouleau GA: Krit1 missense mutations lead to splicing errors in cerebral cavernous malformation. Am J Hum Genet 70:156415672002

  • 100

    Voigt KYaşargil MG: Cerebral cavernous haemangiomas or cavernomas. Incidence, pathology, localization, diagnosis, clinical features and treatment Review of the literature and report of an unusual case. Neurochirurgia (Stuttg) 19:59681976

  • 101

    Voss KStahl SSchleider EUllrich SNickel JMueller TD: CCM3 interacts with CCM2 indicating common pathogenesis for cerebral cavernous malformations. Neurogenetics 8:2492562007

  • 102

    Wang HUChen ZFAnderson DJ: Molecular distinction and angiogenic interaction between embryonic arteries and veins revealed by ephrin-B2 and its receptor Eph-B4. Cell 93:7417531998

  • 103

    Wang YLiu HZhang YMa D: cDNA cloning and expression of an apoptosis-related gene, humanTFAR15 gene. Sci China C Life Sci 42:3233291999

  • 104

    Wernig FMayr MXu Q: Mechanical stretch-induced apoptosis in smooth muscle cells is mediated by beta1-integrin signaling pathways. Hypertension 41:9039112003

  • 105

    Whitehead KJChan ACNavankasattusas SKoh WLondon NRLing J: The cerebral cavernous malformation signaling pathway promotes vascular integrity via Rho GTPases. Nat Med 15:1771842009. (Erratum in Nat Med 15:

  • 106

    Whitehead KJPlummer NWAdams JAMarchuk DALi DY: Ccm1 is required for arterial morphogenesis: implications for the etiology of human cavernous malformations. Development 131:143714482004

  • 107

    Wienecke RMaize JC JrReed JAde Gunzburg JYeung RSDeClue JE: Expression of the TSC2 product tuberin and its target Rap1 in normal human tissues. Am J Pathol 150:43501997

  • 108

    Wojnowski LZimmer AMBeck TWHahn HBernal RRapp UR: Endothelial apoptosis in Braf-deficient mice. Nat Genet 16:2932971997

  • 109

    Wong JHAwad IAKim JH: Ultrastructural pathological features of cerebrovascular malformations: a preliminary report. Neurosurgery 46:145414592000

  • 110

    Zabramski JMWascher TMSpetzler RFJohnson BGolfinos JDrayer BP: The natural history of familial cavernous malformations: results of an ongoing study. J Neurosurg 80:4224321994

  • 111

    Zawistowski JSSerebriiskii IGLee MFGolemis EAMarchuk DA: KRIT1 association with the integrin-binding protein ICAP-1: a new direction in the elucidation of cerebral cavernous malformations (CCM1) pathogenesis. Hum Mol Genet 11:3893962002

  • 112

    Zawistowski JSStalheim LUhlik MTAbell ANAncrile BBJohnson GL: CCM1 and CCM2 protein interactions in cell signaling: implications for cerebral cavernous malformations pathogenesis. Hum Mol Genet 14:252125312005

  • 113

    Zhang JClatterbuck RERigamonti DChang DDDietz HC: Interaction between krit1 and icap1alpha infers perturbation of integrin beta1-mediated angiogenesis in the pathogenesis of cerebral cavernous malformation. Hum Mol Genet 10:295329602001

  • 114

    Zhang JClatterbuck RERigamonti DDietz HC: Cloning of the murine Krit1 cDNA reveals novel mammalian 5′ coding exons. Genomics 70:3923952000

Article Information

Address correspondence to: Mark C. Preul, M.D., c/o Neuroscience Publications, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, Arizona 85013. email: mark.preul@chw.edu.

Please include this information when citing this paper: published online September 30, 2011; DOI: 10.3171/2011.8.JNS101241.

© AANS, except where prohibited by US copyright law."

Headings

Figures

  • View in gallery

    Photomicrograph of CCM section highlighting the enlarged capillary channels lined by a thin endothelium, a characteristic finding in this disease. H & E. Original magnification × 40.

  • View in gallery

    Axial (upper) and coronal (lower) T1-weighted MR images of a cavernous malformation in the brainstem. The lesion demonstrates the heterogeneous signal characteristics of hemorrhage in various stages of resolution.

  • View in gallery

    Schematic representation of the Knudson 2-hit hypothesis for the generation of cancer. The Knudson hypothesis proposes that multiple “hits” are needed for the transformation of a cell into an uncontrolled state of growth. The initial genomic changes can be inherited or acquired during development. It is the accumulation of multiple genomic hits rendering critical growth and remodeling pathways that results in the loss of cell cycle control and unregulated expansion of cell populations in cancer.

  • View in gallery

    Schematic depicting the role of CCM gene products in the organizing of sprouting vascular channels. Modified from Dashti et al.: Neurosurg Focus 21 (1):E2, 2006.

References

1

Abe MKjellberg RNAdams RD: Clinical presentations of vascular malformations of the brain stem: comparison of angiographically positive and negative types. J Neurol Neurosurg Psychiatry 52:1671751989

2

Béraud-Dufour SGautier RAlbiges-Rizo CChardin PFaurobert E: Krit 1 interactions with microtubules and membranes are regulated by Rap1 and integrin cytoplasmic domain associated protein-1. FEBS J 274:551855322007

3

Bergametti FDenier CLabauge PArnoult MBoetto SClanet M: Mutations within the programmed cell death 10 gene cause cerebral cavernous malformations. Am J Hum Genet 76:42512005

4

Bicknell JM: Familial cavernous angioma of the brain stem dominantly inherited in Hispanics. Neurosurgery 24:1021051989

5

Bicknell JMCarlow TJKornfeld MStovring JTurner P: Familial cavernous angiomas. Arch Neurol 35:7467491978

6

Bos JL: All in the family? New insights and questions regarding interconnectivity of Ras, Rap1 and Ral. EMBO J 17:677667821998

7

Bouffard GGIdol JRBraden VVIyer LMCunningham AFWeintraub LA: A physical map of human chromosome 7: an integrated YAC contig map with average STS spacing of 79 kb. Genome Res 7:6736921997

8

Cavé-Riant FDenier CLabauge PCécillon MMaciazek JJoutel A: Spectrum and expression analysis of KRIT1 mutations in 121 consecutive and unrelated patients with cerebral cavernous malformations. Eur J Hum Genet 10:7337402002

9

Chang DDWong CSmith HLiu J: ICAP-1, a novel beta1 integrin cytoplasmic domain-associated protein, binds to a conserved and functionally important NPXY sequence motif of beta1 integrin. J Cell Biol 138:114911571997

10

Chen LTanriover GYano HFriedlander RLouvi AGunel M: Apoptotic functions of PDCD10/CCM3, the gene mutated in cerebral cavernous malformation 3. Stroke 40:147414812009

11

Clark JV: Familial occurrence of cavernous angiomata of the brain. J Neurol Neurosurg Psychiatry 33:8718761970

12

Clatterbuck REEberhart CGCrain BJRigamonti D: Ultrastructural and immunocytochemical evidence that an incompetent blood-brain barrier is related to the pathophysiology of cavernous malformations. J Neurol Neurosurg Psychiatry 71:1881922001

13

Craig HDGünel MCepeda OJohnson EWPtacek LSteinberg GK: Multilocus linkage identifies two new loci for a mendelian form of stroke, cerebral cavernous malformation, at 7p15-13 and 3q25.2–27. Hum Mol Genet 7:185118581998

14

Czubayko MKnauth PSchlüter TFlorian VBohnensack R: Sorting nexin 17, a non-self-assembling and a PtdIns(3)P high class affinity protein, interacts with the cerebral cavernous malformation related protein KRIT1. Biochem Biophys Res Commun 345:126412722006

15

Davenport WJSiegel AMDichgans JDrigo PMammi IPereda P: CCM1 gene mutations in families segregating cerebral cavernous malformations. Neurology 56:5405432001

16

Del Curling O JrKelly DL JrElster ADCraven TE: An analysis of the natural history of cavernous angiomas. J Neurosurg 75:7027081991

17

Denier CGoutagny SLabauge PKrivosic VArnoult MCousin A: Mutations within the MGC4607 gene cause cerebral cavernous malformations. Am J Hum Genet 74:3263372004

18

Denier CLabauge PBergametti FMarchelli FRiant FArnoult M: Genotype-phenotype correlations in cerebral cavernous malformations patients. Ann Neurol 60:5505562006

19

Di Rocco CIannelli ATamburrini G: Cavernous angiomas of the brain stem in children. Pediatr Neurosurg 27:92991997

20

Dobyns WBMichels VVGroover RVMokri BTrautmann JCForbes GS: Familial cavernous malformations of the central nervous system and retina. Ann Neurol 21:5785831987

21

Dubovsky JZabramski JMKurth JSpetzler RFRich SSOrr HT: A gene responsible for cavernous malformations of the brain maps to chromosome 7q. Hum Mol Genet 4:4534581995

22

Eerola IMcIntyre BVikkula M: Identification of eight novel 5′-exons in cerebral capillary malformation gene-1 (CCM1) encoding KRIT1. Biochim Biophys Acta 1517:4644672001

23

Felbor UGaetzner SVerlaan DJVijzelaar RRouleau GASiegel AM: Large germline deletions and duplication in isolated cerebral cavernous malformation patients. Neurogenetics 8:1491532007

24

Flocks JSWeis TPKleinman DCKirsten WH: Dose-response studies to polyoma virus in rats. J Natl Cancer Inst 35:2592841965

25

Fritschi JAReulen HJSpetzler RFZabramski JM: Cavernous malformations of the brain stem. A review of 139 cases. Acta Neurochir (Wien) 130:35461994

26

Gaetzner SStahl SSürücü OSchaafhausen AHalliger-Keller BBertalanffy H: CCM1 gene deletion identified by MLPA in cerebral cavernous malformation. Neurosurg Rev 30:1551602007

27

Gault JShenkar RRecksiek PAwad IA: Biallelic somatic and germ line CCM1 truncating mutations in a cerebral cavernous malformation lesion. Stroke 36:8728742005

28

Gianfrancesco FEsposito TPenco SMaglione VLiquori CLPatrosso MC: ZPLD1 gene is disrupted in a patient with balanced translocation that exhibits cerebral cavernous malformations. Neuroscience 155:3453492008

29

Gil-Nagel ADubovsky JWilcox KJStewart JMAnderson VELeppik IE: Familial cerebral cavernous angioma: a gene localized to a 15-cM interval on chromosome 7q. Ann Neurol 39:8078101996. (Erratum in Ann Neurol 39:

30

Gil-Nagel AWilcox KJStewart JMAnderson VELeppik IERich SS: Familial cerebral cavernous angioma: clinical analysis of a family and phenotypic classification. Epilepsy Res 21:27361995

31

Giombini SMorello G: Cavernous angiomas of the brain. Account of fourteen personal cases and review of the literature. Acta Neurochir (Wien) 40:61821978

32

Glading AHan JStockton RAGinsberg MH: KRIT-1/CCM1 is a Rap1 effector that regulates endothelial cell cell junctions. J Cell Biol 179:2472542007

33

Glading AJGinsberg MH: Rap1 and its effector KRIT1/CCM1 regulate beta-catenin signaling. Dis Model Mech 3:73832010

34

Green EDBraden VVFulton RSLim RUeltzen MSPeluso DC: A human chromosome 7 yeast artificial chromosome (YAC) resource: construction, characterization, and screening. Genomics 25:1701831995

35

Green EDGreen P: Sequence-tagged site (STS) content mapping of human chromosomes: theoretical considerations and early experiences. PCR Methods Appl 1:77901991

36

Greenberger SBoscolo EAdini IMulliken JBBischoff J: Corticosteroid suppression of VEGF-A in infantile hemangioma-derived stem cells. N Engl J Med 362:100510132010

37

Günel MAwad IAAnson JLifton RP: Mapping a gene causing cerebral cavernous malformation to 7q11.2–q21. Proc Natl Acad Sci U S A 92:662066241995

38

Gunel MAwad IAFinberg KAnson JASteinberg GKBatjer HH: A founder mutation as a cause of cerebral cavernous malformation in Hispanic Americans. N Engl J Med 334:9469511996

39

Gunel MLaurans MSShin DDiLuna MLVoorhees JChoate K: KRIT1, a gene mutated in cerebral cavernous malformation, encodes a microtubule-associated protein. Proc Natl Acad Sci U S A 99:10677106822002

40

Guzeloglu-Kayisli OAmankulor NMVoorhees JLuleci GLifton RPGunel M: KRIT1/cerebral cavernous malformation 1 protein localizes to vascular endothelium, astrocytes, and pyramidal cells of the adult human cerebral cortex. Neurosurgery 54:9439492004

41

Guzeloglu-Kayisli OKayisli UAAmankulor NMVoorhees JRGokce ODiLuna ML: Krev1 interaction trapped-1/cerebral cavernous malformation-1 protein expression during early angiogenesis. J Neurosurg 100:5 Suppl Pediatrics4814872004

42

Hallmann RHorn NSelg MWendler OPausch FSorokin LM: Expression and function of laminins in the embryonic and mature vasculature. Physiol Rev 85:97910002005

43

Hayman LAEvans RAFerrell REFahr LMOstrow PRiccardi VM: Familial cavernous angiomas: natural history and genetic study over a 5-year period. Am J Med Genet 11:1471601982

44

Henkemeyer MRossi DJHolmyard DPPuri MCMbamalu GHarpal K: Vascular system defects and neuronal apoptosis in mice lacking ras GTPase-activating protein. Nature 377:6957011995

45

Hogan BMBussmann JWolburg HSchulte-Merker S: Ccm1 cell autonomously regulates endothelial cellular morphogenesis and vascular tubulogenesis in zebrafish. Hum Mol Genet 17:242424322008

46

Johnson EWIyer LMRich SSOrr HTGil-Nagel AKurth JH: Refined localization of the cerebral cavernous malformation gene (CCM1) to a 4-cM interval of chromosome 7q contained in a well-defined YAC contig. Genome Res 5:3683801995

47

Kehrer-Sawatzki HWilda MBraun VMRichter HPHameister H: Mutation and expression analysis of the KRIT1 gene associated with cerebral cavernous malformations (CCM1). Acta Neuropathol 104:2312402002

48

Kere JRuutu TDavies KARoninson IBWatkins PCWinqvist R: Chromosome 7 long arm deletion in myeloid disorders: a narrow breakpoint region in 7q22 defined by molecular mapping. Blood 73:2302341989

49

Kidd HACumings JN: Cerebral angiomata in an Icelandic family. Lancet 1:7471947

50

Knudson AG: Two genetic hits (more or less) to cancer. Nat Rev Cancer 1:1571622001

51

Kondziolka DLunsford LDKestle JR: The natural history of cerebral cavernous malformations. J Neurosurg 83:8208241995

52

Krebs LTXue YNorton CRShutter JRMaguire MSundberg JP: Notch signaling is essential for vascular morphogenesis in mice. Genes Dev 14:134313522000

53

Kufs H: Über heredofamiliare Angiomatose des Gehirns und der Retina, ihre Beziehungen zueinander und zur Angiomatose der Haut. Z Gesamte Neurol Psychiatr 113:6516861928

54

Kurth JHZabramski JMDubovsky J: Genetic linkage of the familial cavernous malformation (CM) gene to chromosome 7q. Am J Hum Genet 55:Suppl 3A151994. (http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=133322

55

Labauge PLaberge SBrunereau LLevy CTournier-Lasserve E: Hereditary cerebral cavernous angiomas: clinical and genetic features in 57 French families. Société Française de Neurochirurgie. Lancet 352:189218971998

56

Laberge SLabauge PMaréchal EMaciazek JTournier-Lasserve E: Genetic heterogeneity and absence of founder effect in a series of 36 French cerebral cavernous angiomas families. Eur J Hum Genet 7:4995041999

57

Laberge-le Couteulx SJung HHLabauge PHoutteville JPLescoat CCecillon M: Truncating mutations in CCM1, encoding KRIT1, cause hereditary cavernous angiomas. Nat Genet 23:1891931999

58

Liquori CLBerg MJSiegel AMHuang EZawistowski JSStoffer T: Mutations in a gene encoding a novel protein containing a phosphotyrosine-binding domain cause type 2 cerebral cavernous malformations. Am J Hum Genet 73:145914642003

59

Liquori CLBerg MJSquitieri FLeedom TPPtacek LJohnson EW: Deletions in CCM2 are a common cause of cerebral cavernous malformations. Am J Hum Genet 80:69752007

60

Liquori CLBerg MJSquitieri FOttenbacher MSorlie MLeedom TP: Low frequency of PDCD10 mutations in a panel of CCM3 probands: potential for a fourth CCM locus. Hum Mutat 27:1182006

61

Liquori CLPenco SGault JLeedom TPTassi LEsposito T: Different spectra of genomic deletions within the CCM genes between Italian and American CCM patient cohorts. Neurogenetics 9:25312008

62

Lloyd-Jones DAdams RJBrown TMCarnethon MDai SDe Simone G: Heart disease and stroke statistics—2010 update: a report from the American Heart Association. Circulation 121:e46e2152010. (Erratum in Circulation 121:

63

Lonjon MRoche JLGeorge BMourier KLPaquis PLot G: [Intracranial cavernoma. 30 cases.]. Presse Med 22:9909941993. (Fr)

64

Lucas MCosta AFGarcía-Moreno JMSolano FGamero MAIzquierdo G: Variable expression of cerebral cavernous malformations in carriers of a premature termination codon in exon 17 of the Krit1 gene. BMC Neurol 3:52003

65

Lucas MCosta AFMontori MSolano FZayas MDIzquierdo G: Germline mutations in the CCM1 gene, encoding Krit1, cause cerebral cavernous malformations. Ann Neurol 49:5295322001

66

Ma XZhao HShan JLong FChen YChen Y: PDCD10 interacts with Ste20-related kinase MST4 to promote cell growth and transformation via modulation of the ERK pathway. Mol Biol Cell 18:196519782007

67

Mably JDChuang LPSerluca FCMohideen MAChen JNFishman MC: Santa and valentine pattern concentric growth of cardiac myocardium in the zebrafish. Development 133:313931462006

68

Marchuk DAGallione CJMorrison LAClericuzio CLHart BLKosofsky BE: A locus for cerebral cavernous malformations maps to chromosome 7q in two families. Genomics 28:3113141995

69

Mason IAase JMOrrison WWWicks JDSeigel RSBicknell JM: Familial cavernous angiomas of the brain in an Hispanic family. Neurology 38:3243261988

70

Matos PSkaug JMarques BBeck SVeríssimo FGespach C: Small GTPase Rac1: structure, localization, and expression of the human gene. Biochem Biophys Res Commun 277:7417512000

71

McCormick WF: The pathology of vascular (“arteriovenous”) malformations. J Neurosurg 24:8078161966

72

Michael JCLevin PM: Multiple telangiectases of the brain: a discussion of hereditary factors in their development. Arch Neurol Psychiatry 36:5145291936

73

Moriarity JLWetzel MClatterbuck REJavedan SSheppard JMHoenig-Rigamonti K: The natural history of cavernous malformations: a prospective study of 68 patients. Neurosurgery 44:116611731999

74

Moussa RHarb AMenassa LRisk TNohra GSamaha E: [Etiologic spectrum of intracerebral hemorrhage in young patients.]. Neurochirurgie 52:2–3 Pt 11051092006. (Fr)

75

Nibert MHeim S: Uterine leiomyoma cytogenetics. Genes Chromosomes Cancer 2:3131990

76

Otten PPizzolato GPRilliet BBerney J: [131 cases of cavernous angioma (cavernomas) of the CNS, discovered by retrospective analysis of 24,535 autopsies.]. Neurochirurgie 35:82831989. (Fr)

77

Pagenstecher AStahl SSure UFelbor U: A two-hit mechanism causes cerebral cavernous malformations: complete inactivation of CCM1, CCM2 or CCM3 in affected endothelial cells. Hum Mol Genet 18:9119182009

78

Pizon VChardin PLerosey IOlofsson BTavitian A: Human cDNAs rap1 and rap2 homologous to the Drosophila gene Dras3 encode proteins closely related to ras in the ‘effector’ region. Oncogene 3:2012041988

79

Plummer NWGallione CJSrinivasan SZawistowski JSLouis DNMarchuk DA: Loss of p53 sensitizes mice with a mutation in Ccm1 (KRIT1) to development of cerebral vascular malformations. Am J Pathol 165:150915182004

80

Plummer NWSquire TLSrinivasan SHuang EZawistowski JSMatsunami H: Neuronal expression of the Ccm2 gene in a new mouse model of cerebral cavernous malformations. Mamm Genome 17:1191282006

81

Porter PJWillinsky RAHarper WWallace MC: Cerebral cavernous malformations: natural history and prognosis after clinical deterioration with or without hemorrhage. J Neurosurg 87:1901971997

82

Reedquist KARoss EKoop EAWolthuis RMZwartkruis FJvan Kooyk Y: The small GTPase, Rap1, mediates CD31-induced integrin adhesion. J Cell Biol 148:115111582000

83

Rigamonti DHadley MNDrayer BPJohnson PCHoenig-Rigamonti KKnight JT: Cerebral cavernous malformations. Incidence and familial occurrence. N Engl J Med 319:3433471988

84

Robinson JRAwad IALittle JR: Natural history of the cavernous angioma. J Neurosurg 75:7097141991

85

Ruggieri RBender AMatsui YPowers STakai YPringle JR: RSR1, a ras-like gene homologous to Krev-1 (smg21A/rap1A): role in the development of cell polarity and interactions with the Ras pathway in Saccharomyces cerevisiae. Mol Cell Biol 12:7587661992

86

Russell DSRubinstein LJ: Pathology of Tumours of the Nervous System LondonE. Arnold1989. 730736

87

Sahoo TGoenaga-Diaz ESerebriiskii IGThomas JWKotova ECuellar JG: Computational and experimental analyses reveal previously undetected coding exons of the KRIT1 (CCM1) gene. Genomics 71:1231262001

88

Sahoo TJohnson EWThomas JWKuehl PMJones TLDokken CG: Mutations in the gene encoding KRIT1, a Krev-1/rap1a binding protein, cause cerebral cavernous malformations (CCM1). Hum Mol Genet 8:232523331999

89

Schouten JPMcElgunn CJWaaijer RZwijnenburg DDiepvens FPals G: Relative quantification of 40 nucleic acid sequences by multiplex ligation-dependent probe amplification. Nucleic Acids Res 30:e572002

90

Sedgwick SGSmerdon SJ: The ankyrin repeat: a diversity of interactions on a common structural framework. Trends Biochem Sci 24:3113161999

91

Seker APricola KLGuclu BOzturk AKLouvi AGunel M: CCM2 expression parallels that of CCM1. Stroke 37:5185232006

92

Serebriiskii IEstojak JSonoda GTesta JRGolemis EA: Association of Krev-1/rap1a with Krit1, a novel ankyrin repeatcontaining protein encoded by a gene mapping to 7q21–22. Oncogene 15:104310491997

93

Simard JMGarcia-Bengochea FBallinger WE JrMickle JPQuisling RG: Cavernous angioma: a review of 126 collected and 12 new clinical cases. Neurosurgery 18:1621721986

94

Stahl SGaetzner SVoss KBrackertz BSchleider ESürücü O: Novel CCM1, CCM2, and CCM3 mutations in patients with cerebral cavernous malformations: in-frame deletion in CCM2 prevents formation of a CCM1/CCM2/CCM3 protein complex. Hum Mutat 29:7097172008

95

Stockton RAShenkar RAwad IAGinsberg MH: Cerebral cavernous malformations proteins inhibit Rho kinase to stabilize vascular integrity. J Exp Med 207:8818962010

96

Tanriover GBoylan AJDiluna MLPricola KLLouvi AGunel M: PDCD10, the gene mutated in cerebral cavernous malformation 3, is expressed in the neurovascular unit. Neurosurgery 62:9309382008

97

Tomlinson FHHouser OWScheithauer BWSundt TM JrOkazaki HParisi JE: Angiographically occult vascular malformations: a correlative study of features on magnetic resonance imaging and histological examination. Neurosurgery 34:7928001994

98

Uhlik MTAbell ANJohnson NLSun WCuevas BDLobel-Rice KE: Rac-MEKK3-MKK3 scaffolding for p38 MAPK activation during hyperosmotic shock. Nat Cell Biol 5:110411102003

99

Verlaan DJSiegel AMRouleau GA: Krit1 missense mutations lead to splicing errors in cerebral cavernous malformation. Am J Hum Genet 70:156415672002

100

Voigt KYaşargil MG: Cerebral cavernous haemangiomas or cavernomas. Incidence, pathology, localization, diagnosis, clinical features and treatment Review of the literature and report of an unusual case. Neurochirurgia (Stuttg) 19:59681976

101

Voss KStahl SSchleider EUllrich SNickel JMueller TD: CCM3 interacts with CCM2 indicating common pathogenesis for cerebral cavernous malformations. Neurogenetics 8:2492562007

102

Wang HUChen ZFAnderson DJ: Molecular distinction and angiogenic interaction between embryonic arteries and veins revealed by ephrin-B2 and its receptor Eph-B4. Cell 93:7417531998

103

Wang YLiu HZhang YMa D: cDNA cloning and expression of an apoptosis-related gene, humanTFAR15 gene. Sci China C Life Sci 42:3233291999

104

Wernig FMayr MXu Q: Mechanical stretch-induced apoptosis in smooth muscle cells is mediated by beta1-integrin signaling pathways. Hypertension 41:9039112003

105

Whitehead KJChan ACNavankasattusas SKoh WLondon NRLing J: The cerebral cavernous malformation signaling pathway promotes vascular integrity via Rho GTPases. Nat Med 15:1771842009. (Erratum in Nat Med 15:

106

Whitehead KJPlummer NWAdams JAMarchuk DALi DY: Ccm1 is required for arterial morphogenesis: implications for the etiology of human cavernous malformations. Development 131:143714482004

107

Wienecke RMaize JC JrReed JAde Gunzburg JYeung RSDeClue JE: Expression of the TSC2 product tuberin and its target Rap1 in normal human tissues. Am J Pathol 150:43501997

108

Wojnowski LZimmer AMBeck TWHahn HBernal RRapp UR: Endothelial apoptosis in Braf-deficient mice. Nat Genet 16:2932971997

109

Wong JHAwad IAKim JH: Ultrastructural pathological features of cerebrovascular malformations: a preliminary report. Neurosurgery 46:145414592000

110

Zabramski JMWascher TMSpetzler RFJohnson BGolfinos JDrayer BP: The natural history of familial cavernous malformations: results of an ongoing study. J Neurosurg 80:4224321994

111

Zawistowski JSSerebriiskii IGLee MFGolemis EAMarchuk DA: KRIT1 association with the integrin-binding protein ICAP-1: a new direction in the elucidation of cerebral cavernous malformations (CCM1) pathogenesis. Hum Mol Genet 11:3893962002

112

Zawistowski JSStalheim LUhlik MTAbell ANAncrile BBJohnson GL: CCM1 and CCM2 protein interactions in cell signaling: implications for cerebral cavernous malformations pathogenesis. Hum Mol Genet 14:252125312005

113

Zhang JClatterbuck RERigamonti DChang DDDietz HC: Interaction between krit1 and icap1alpha infers perturbation of integrin beta1-mediated angiogenesis in the pathogenesis of cerebral cavernous malformation. Hum Mol Genet 10:295329602001

114

Zhang JClatterbuck RERigamonti DDietz HC: Cloning of the murine Krit1 cDNA reveals novel mammalian 5′ coding exons. Genomics 70:3923952000

TrendMD

Metrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 73 73 73
PDF Downloads 18 18 18
EPUB Downloads 0 0 0

PubMed

Google Scholar