{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Cerebral cavernous malformation 2 (CCM2) is emerging as an essential adaptor protein that coordinates several signaling mechanisms to maintain vascular integrity. CCM2 directly interacts with KRIT1 (CCM1) through its phosphotyrosine‐binding domain, a binding that is critical for proper localization of the CCM complex at endothelial cell–cell junctions ["}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": "]. Disruption of this interaction—often by mutations such as in-frame deletions that prevent CCM1 binding—impairs endothelial adhesion, leading to defective lumen formation and increased vascular permeability as demonstrated in murine models ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "]."}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition, CCM2 exerts control over the actin cytoskeleton by modulating RhoA signaling. It accomplishes this, at least in part, by binding to the ubiquitin ligase Smurf1 to promote targeted degradation of RhoA, thereby reducing abnormal contractility and preserving junctional stability ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": "]. Moreover, CCM2 associates with the protein kinase MEKK3 through its harmonin homology domain; this interaction is required for proper endothelial gene expression and neurovascular integrity ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": "]."}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Molecular genetic studies of familial cases, including analyses of mutations that hinder the ability of CCM2 to bind its partners, have underscored a loss‐of‐function mechanism that disrupts these pathways and contributes to cerebral cavernous malformation (CCM) pathogenesis ["}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": "]. Collectively, these findings indicate that CCM2 functions as a central scaffold integrating signals from junctional adhesion, cytoskeletal dynamics, and mitogen‐activated protein kinase pathways to ensure vascular stability. Loss of CCM2 function thereby leads to compromised endothelial barrier function and is instrumental in the development of CCM lesions.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Jon S Zawistowski, Lisa Stalheim, Mark T Uhlik, et al. "}, {"type": "b", "children": [{"type": "t", "text": "CCM1 and CCM2 protein interactions in cell signaling: implications for cerebral cavernous malformations pathogenesis."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Hum Mol Genet (2005)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1093/hmg/ddi256"}], "href": "https://doi.org/10.1093/hmg/ddi256"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "16037064"}], "href": "https://pubmed.ncbi.nlm.nih.gov/16037064"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Jun Zhang, Daniele Rigamonti, Harry C Dietz, et al. 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