脑血管周细胞调节血脑屏障特异基因Mfsd2a表达的分子机制研究

脑血管内皮细胞对血脑屏障起最主要的决定作用，其主要特征包括特异的紧密连接以及极低水平的穿胞运输（transcytosis）等。Mfsd2a是目前报导的唯一能够抑制脑血管内皮细胞穿胞运输的基因，它在脑血管内皮细胞中特异高表达。血管周细胞缺陷可导致Mfsd2a 的转录水平和蛋白水平显著下降、穿胞运输增强以及血脑屏障渗漏，但是周细胞如何调节Mfsd2a表达的分子机制尚不清楚。本项目将从三个方面进行研究：1）用体外细胞共培养体系鉴定周细胞对Mfsd2a表达的调节；2）利用BioID法发现并验证脑血管周细胞中与Mfsd2a有直接相互作用的膜蛋白分子；3）筛选并鉴定周细胞分泌的、对Mfsd2a表达有调节功能的生长因子，并研究其下游的信号通路以及关键转录因子。项目研究成果为进一步阐明血脑屏障功能的分子调节机制提供科学依据，也将为跨血脑屏障靶向药物的研发提供新的思路。

The blood-brain barrier (BBB) provides a constant homeostatic brain microenvironment that is essential for proper neural functions, which contains two structural features, specialized tight junctions and low levels of transcytosis. Mfsd2a is highly expressed in brain microvascular endothelial cell (BMEC) and is the only reported protein which can suppress transcytosis. Transcytosis is increased and BBB is disrupted in Mfsd2a knockout mouse. The pericytes also have a role in regulating mfsd2a expression. Pericyte defeciency leads to downregulated Mfsd2a expression, elevated transcytosis and broken BBB, but the molecular regulation of Mfsd2a by pericyte is still unknown. The project includes 1) determine the regulation of Mfsd2a expression by pericyte in BMEC using the co-culture system in vitro；2) identify the proteins in pericyte that directly interact with Mfsd2a; 3) screen and verify the growth factors that can regulate mfsd2a expression secreted by pericytes, and identify the downstream signaling pathway and the related transcription factors. The project will further elucidate the molecular regulatory mechanism of BBB functions, that could help developing therapeutic approaches for efficient drug delivery to the CNS.