內皮細胞中的MCPIP1：血管新生的調節因子

Abstract

血管新生是指新的血管於既有的血管上形成的過程，此過程需要被嚴格的控制以確保傷口癒合無虞，而失控的血管增生則會促進癌細胞的轉移。本研究旨在探討單核細胞趨化蛋白-1誘導蛋白-1 (MCP-1 induced protein-1, MCPIP1) 於血管新生調控中扮演的角色。先前的研究指出MCPIP1能促進內皮細胞的血管新生能力，但最近的癌症相關研究卻指出MCPIP1的表現量與癌細胞的轉移呈現負相關。由於MCPIP1在血管新生中的調控機制不明，所以目前MCPIP1在血管新生中扮演的角色尚無定論。本研究發現在兩種不同的內皮細胞中降低MCPIP1的表現，會導致血管新生相關基因的表現量增加，並且促進細胞爬行以及血管新生的能力。我們也發現血管內皮生長因子 (Vascular endothelial growth factor, VEGF) 能夠引發血管新生並且誘導MCPIP1的表現，進而進行反饋抑制的工作，避免血管新生失控。利用在內皮細胞中成功執行的增強交聯與免疫沈澱 (enhanced crosslinking and immunoprecipitation, eCLIP) 結合與轉錄組學 (transcriptomic) 的交互分析我找到了七個MCPIP1的目標基因，且證實因為MCPIP1表現量降低，使得ADAM15和 CDH5的穩定度增加導致其總體表現量增加，進而促進血管新生。此外，我更進一步探究MCPIP1對目標信使核醣核酸 (mRNA) 作用的分子機制，發現該蛋白會透過與目標基因3端非轉譯區域 (3′UTR) 上的雙莖環結構 (double stem-loop structure) 結合來標的並降解目標基因。總的來說，我的研究為MCPIP1對血管新生的調控機制提供了新的見解，並闡明了其標靶的分子機制，該機制透過辨識雙莖環結構來調控信使核醣核酸的降解。

Angiogenesis is a critical process in which new blood vessels form from a pre-exist one. The process must be tightly controlled to ensure proper wound healing, as uncontrolled angiogenesis can promote cancer cell metastasis. In this study, I investigated the role of MCP-1 induced protein 1 (MCPIP1) in the regulation of angiogenesis. Previous studies have suggested a pro-angiogenic role for MCPIP1, but recent cancer-related studies have shown conflicting results. However, the mechanisms underlying MCPIP1 modulation of angiogenesis is remain unclear, the regulatory role of MCPIP1 is still controversial. This study found that knockdown of MCPIP1 promotes the expression of angiogenesis marker genes, migration rate, and tube formation in both HMEC-1 and HUVECs. The expression of MCPIP1 is induced by vascular endothelial growth factor (VEGF), and act as a feedback inhibitor of VEGF-mediated angiogenesis in both cell types. Applying the first enhanced crosslinking and immunoprecipitation (eCLIP) in endothelial cells (HMEC-1) and combining the analysis with transcriptomic result, I identified seven MCPIP1 targets and confirmed that knockdown of MCPIP1 promotes angiogenesis by the elevating of the expression of ADAM15 and CDH5. Furthermore, I investigated the molecular mechanism of MCPIP1 targeting, identifying a double stem-loop structure in the 3′UTR region of targets RNAs. Overall, these findings provide new insights into the regulation of angiogenesis by MCPIP1 and shed light on its targeting mechanism, which involves mRNA degradation through the double stem-loop structure.