Koch Institute for Integrative Cancer Research, MIT, Cambridge, MA (P.A.M., N.J., A.M.D.R., S.B., R.O.H.).
UCONN Health, Center for Vascular Biology and Calhoun Cardiology Center, Farmington, CT (P.A.M., S.-A.N., A.K.).
Arterioscler Thromb Vasc Biol. 2021 Jan;41(1):e18-e32. doi: 10.1161/ATVBAHA.120.314013. Epub 2020 Nov 19.
Exposure of the arterial endothelium to low and disturbed flow is a risk factor for the erosion and rupture of atherosclerotic plaques and aneurysms. Circulating and locally produced proteins are known to contribute to an altered composition of the extracellular matrix at the site of lesions, and to contribute to inflammatory processes within the lesions. We have previously shown that alternative splicing of FN (fibronectin) protects against flow-induced hemorrhage. However, the impact of alternative splicing of FN on extracellular matrix composition remains unknown. Approach and Results: Here, we perform quantitative proteomic analysis of the matrisome of murine carotid arteries in mice deficient in the production of FN splice isoforms containing alternative exons EIIIA and EIIIB (FN-EIIIAB null) after exposure to low and disturbed flow in vivo. We also examine serum-derived and endothelial-cell contributions to the matrisome in a simplified in vitro system. We found flow-induced differences in the carotid artery matrisome that were impaired in FN-EIIIAB null mice. One of the most interesting differences was reduced recruitment of FBLN1 (fibulin-1), abundant in blood and not locally produced in the intima. This defect was validated in our in vitro assay, where FBLN1 recruitment from serum was impaired by the absence of these alternatively spliced segments.
Our results reveal the extent of the dynamic alterations in the matrisome in the acute response to low and disturbed flow and show how changes in the splicing of FN, a common response in vascular inflammation and remodeling, can affect matrix composition.
动脉内皮暴露于低血流和紊乱流是导致动脉粥样硬化斑块和动脉瘤侵蚀和破裂的危险因素。已知循环和局部产生的蛋白质有助于病变部位细胞外基质的组成改变，并有助于病变部位的炎症过程。我们之前已经表明，FN（纤连蛋白）的选择性剪接可以防止血流诱导的出血。然而，FN 选择性剪接对细胞外基质组成的影响尚不清楚。方法和结果：在这里，我们对体内暴露于低血流和紊乱流后缺乏包含交替外显子 EIIIA 和 EIIIB 的 FN 剪接异构体的小鼠的颈动脉基质进行了定量蛋白质组学分析。我们还在简化的体外系统中研究了血清衍生和内皮细胞对基质的贡献。我们发现，在 FN-EIIIAB 缺失小鼠中，颈动脉基质的血流诱导差异受损。最有趣的差异之一是 FBLN1（纤连蛋白 1）的募集减少，FBLN1 在血液中丰富，在内膜中不局部产生。这一缺陷在我们的体外测定中得到了验证，其中缺乏这些选择性剪接片段会损害血清中 FBLN1 的募集。结论：我们的结果揭示了急性低血流和紊乱流反应中基质的动态改变的程度，并显示了血管炎症和重塑中常见的 FN 剪接变化如何影响基质组成。
