• Krishna K Singh, Praphulla C Shukla, Adrian Quan, Mohammed Al-Omran, Fina Lovren, Yi Pan, Christine Brezden-Masley, Alistair J Ingram, William L Stanford, Hwee Teoh, and Subodh Verma.
• Division of Cardiac Surgery, Li Ka Shing Knowledge Institute at St Michael's Hospital, Toronto, Ontario, Canada; Keenan Research Centre, Li Ka Shing Knowledge Institute at St Michael's Hospital, Toronto, Ontario, Canada.
• J. Thorac. Cardiovasc. Surg.. 2013 Oct 1;146(4):949-960.e4.

ObjectiveBRCA1, a tumor suppressor gene implicated in breast and ovarian cancers, exerts multiple effects on DNA repair and affords resistance against cellular stress responses. We hypothesized that BRCA1 limits endothelial cell apoptosis and dysfunction, and via this mechanism attenuates atherosclerosis.MethodsLoss and gain of function were achieved in cultured endothelial cells by silencing and overexpressing BRCA1, respectively. In vivo loss and gain of function were performed by generating endothelial cell-specific knockout (EC-BRCA1(-/-)) mice and administering a BRCA1 adenovirus. Well-established cell and animal models of angiogenesis and atherosclerosis were used.ResultsBRCA1 is basally expressed in endothelial cells. BRCA1 overexpression protected and BRCA1 silencing exaggerated inflammation- and doxorubicin-induced endothelial cell apoptosis. Key indices of endothelial function were modulated in a manner consistent with an effect of BRCA1 to limit endothelial cell apoptosis and improve endothelial function. BRCA1 overexpression strongly attenuated the production of reactive oxygen species and upregulated endothelial nitric oxide synthase, phosphorylated endothelial nitric oxide synthase, phosphorylated Akt, and vascular endothelial growth factor-a expression. BRCA1 overexpression also improved capillary density and promoted blood flow restoration in mice subjected to hind-limb ischemia. BRCA1-overexpressing ApoE(-/-) mice fed a Western diet developed significantly less aortic plaque lesions, exhibited reduced macrophage infiltration, and generated less reactive oxygen species. Lung sections and aortic segments from EC-BRCA1(-/-) mice demonstrated greater inflammation-associated apoptosis and impaired endothelial function, respectively. BRCA1 expression was attenuated in the plaque region of human atherosclerotic carotid artery samples compared with the adjacent plaque-free area.ConclusionsThese data collectively highlight a previously unrecognized role of BRCA1 as a gatekeeper of inflammation-induced endothelial cell function and a target to limit atherosclerosis. Translational studies evaluating endothelial function and atherosclerosis in individuals with BRCA1 mutations are suggested.Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

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