Cerebral cavernous malformations (CCMs) are common, familial vascular malformations that arise due to mutations in three genes, KRIT1, CCM2 and PDCD10. Adaptor proteins encoded by the CCM genes bind each other and the cell surface receptor, Heart of Glass (HEG). Genetic studies in mice have revealed that HEG-CCM signaling is required in endothelial cells for early vascular development, while dilated hearts in deficient fish have also suggested that CCM signaling guides heart development and growth. How CCM signaling alters endothelial cell function in the setting of cardiovascular development and CCM disease remains unclear. We have used a new Nfatc1Cre allele to delete CCM signaling exclusively in the endocardium of the heart, thereby bypassing the requirement for this pathway in early vessel growth. We find that endocardial loss of CCM signaling results in heart failure associated with loss of cardiac jelly and over-expression of the ADAMTS5 protease and the KLF2 transcription factor. Reduced expression of either gene rescues the heart defects in ccm-deficient fish, demonstrating causal, functional roles for these new downstream CCM signaling effectors. The present proposal will define this new pathway downstream of CCM signaling by (i) testing CCM regulation of cardiac and vascular matrix, (ii) defining the role of CCM regulation of KLF2 in cardiac development and vascular disease models, and (iii) testing the hypothesis that CCM signaling affects matrix and KLF2 and ADAMTS5 gene expression through regulation of MEKK3 activity and MAPK signaling. These studies are expected to yield new insight into how the endocardium regulates cardiac development, and how CCM signaling affects endothelial cell function in the context of cardiovascular development and vascular disease.

Public Health Relevance

This proposal investigates a newly discovered role for the Cerebral Cavernous Malformation pathway in heart development. This pathway is known to cause human vascular malformations, but the mechanism by which it does so is not understood. Our studies reveal a new role for the pathway in the developing heart, and new molecular information regarding how the pathway works in endothelial cells. These findings are therefore relevant to both cardiac development and the pathogenesis of vascular malformations.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Cardiovascular Differentiation and Development Study Section (CDD)
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Gao, Yunling
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University of Pennsylvania
Internal Medicine/Medicine
Schools of Medicine
United States
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Goddard, Lauren M; Duchemin, Anne-Laure; Ramalingan, Harini et al. (2017) Hemodynamic Forces Sculpt Developing Heart Valves through a KLF2-WNT9B Paracrine Signaling Axis. Dev Cell 43:274-289.e5
Tang, Alan T; Choi, Jaesung P; Kotzin, Jonathan J et al. (2017) Endothelial TLR4 and the microbiome drive cerebral cavernous malformations. Nature 545:305-310
Zhou, Zinan; Tang, Alan T; Wong, Weng-Yew et al. (2016) Cerebral cavernous malformations arise from endothelial gain of MEKK3-KLF2/4 signalling. Nature 532:122-6
Girard, Romuald; Zeineddine, Hussein A; Orsbon, Courtney et al. (2016) Micro-computed tomography in murine models of cerebral cavernous malformations as a paradigm for brain disease. J Neurosci Methods 271:14-24
Zhou, Zinan; Rawnsley, David R; Goddard, Lauren M et al. (2015) The cerebral cavernous malformation pathway controls cardiac development via regulation of endocardial MEKK3 signaling and KLF expression. Dev Cell 32:168-80
Zheng, Xiangjian; Riant, Florence; Bergametti, Fran├žoise et al. (2014) Cerebral cavernous malformations arise independent of the heart of glass receptor. Stroke 45:1505-1509
Zheng, Xiangjian; Xu, Chong; Smith, Annie O et al. (2012) Dynamic regulation of the cerebral cavernous malformation pathway controls vascular stability and growth. Dev Cell 23:342-55
Zheng, Xiangjian; Xu, Chong; Di Lorenzo, Annarita et al. (2010) CCM3 signaling through sterile 20-like kinases plays an essential role during zebrafish cardiovascular development and cerebral cavernous malformations. J Clin Invest 120:2795-804
Kleaveland, Benjamin; Zheng, Xiangjian; Liu, Jian J et al. (2009) Regulation of cardiovascular development and integrity by the heart of glass-cerebral cavernous malformation protein pathway. Nat Med 15:169-76