Center for Molecular and Translational Medicine, Georgia State University, Atlanta, Georgia, USA.
Clinic Center of Human Gene Research, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Nat Commun. 2021 May 10;12(1):2616. doi: 10.1038/s41467-021-22771-3.
FUN14 domain-containing protein 1 (FUNDC1) is an integral mitochondrial outer-membrane protein, and mediates the formation of mitochondria-associated endoplasmic reticulum membranes (MAMs). This study aims to determine the contributions of FUNDC1-mediated MAMs to angiogenesis in vitro and in vivo. In cultured endothelial cells, VEGF significantly increases the formation of MAMs and MAM-related proteins, including FUNDC1. Endothelial cell-specific deletion of FUNDC1, which disrupts MAM formation in endothelial cells, lowers VEGFR2 expression and reduces tube formation, spheroid-sprouting, and functional blood vessel formation in vitro and in vivo. Conversely, increased MAM formation using MAM linkers mimics the effects of VEGF and promotes endothelial angiogenesis. Mechanistically, increased MAMs formation led to increased levels of Ca in cytosol, promoted the phosphorylation of serum response factor (SRF) and enhanced the binding of SRF to VEGFR2 promoter, resulting in increased VEGFR2 production, with consequent angiogenesis. Moreover, blocking FUNDC1-related MAM formation with a cell-penetrating inhibitory peptide significantly suppresses the expressions of downstream angiogenic genes and inhibits tumor angiogenesis. We conclude that decreased MAMs formation by silencing FUNDC1 can inhibit angiogenesis by decreasing VEGFR2 expression, and targeting FUNDC1-dependent MAMs might be a promising approach for treating human disorders characterized by defective angiogenesis.
FUN14 结构域包含蛋白 1（FUNDC1）是一种完整的线粒体外膜蛋白，介导线粒体相关内质网膜（MAMs）的形成。本研究旨在确定 FUNDC1 介导的 MAMs 对体外和体内血管生成的贡献。在培养的内皮细胞中，VEGF 显著增加 MAMs 的形成和 MAM 相关蛋白，包括 FUNDC1。内皮细胞特异性敲除 FUNDC1 会破坏内皮细胞中 MAM 的形成，降低 VEGFR2 的表达，并减少体外和体内的管腔形成、球体发芽和功能性血管形成。相反，使用 MAM 接头增加 MAM 形成模拟了 VEGF 的作用，并促进了内皮细胞的血管生成。在机制上，增加的 MAMs 形成导致细胞质中 Ca 水平升高，促进血清反应因子（SRF）的磷酸化，并增强 SRF 与 VEGFR2 启动子的结合，导致 VEGFR2 产生增加，从而促进血管生成。此外，用穿透细胞的抑制性肽阻断 FUNDC1 相关的 MAM 形成可显著抑制下游血管生成基因的表达，并抑制肿瘤血管生成。我们得出结论，沉默 FUNDC1 可减少 MAMs 的形成，通过降低 VEGFR2 的表达来抑制血管生成，靶向 FUNDC1 依赖性 MAMs 可能是治疗以血管生成缺陷为特征的人类疾病的一种有前途的方法。
