基于NOTCH3基因R544C点突变小鼠神经血管单元损伤的CADASIL脑微出血发生机制研究

脑微出血的数量与认知障碍和脑出血的风险呈正相关，但因缺乏可靠的研究模型，其发病机制仍不清楚，且缺乏有效防控手段。NOTCH3基因突变引起的CADASIL是最常见的单基因遗传性脑小血管病，解析其发病机制有助于推进脑小血管病的整体认识。我们CADASIL队列结果提示，R544C点突变合并脑微出血率高达89%，远高于其他位点。在我们构建的R544C点突变小鼠观察到多发脑微出血，成功模拟了临床表型，并检测到神经血管单元损伤和基质金属蛋白酶MMP-9表达增加。为了探究R544C点突变在脑微出血中的作用及机制，本项目将通过R544C点突变小鼠与MMP-9基因敲除小鼠杂交，探索该点突变是否通过NF-κB和/或PI3K/Cdc42/JNK信号通路来调控MMP-9表达，进而破坏神经血管单元，导致脑微出血。本课题将为脑微出血的研究提供新的动物模型，为解析脑微出血的发生机制及防治提供新的理论支持和治疗靶点。

Cerebral microbleeds (CMBs) have been found to be associated with cerebral hemorrhage and cognitive impairment, but the underlying mechanism is unclear and no treatment is available for their prevention and treatment due to the lack of a reliable research model. CADASIL is the most common monogenic hereditary cerebral small vessel disease caused by the mutation of NOTCH3 gene. In the genetic epidemiology study, we observed that the rate of CMBs with the R544C point mutation is 89%, which is much higher than the mutations of any other loci. We have constructed a transgenic mouse line with R544C mutation of NOTCH3 and multiple CMBs were observed in these mice, simulating the clinical CADASIL phenotype. In addition, damage of neurovascular unit and the increase of matrix metalloproteinase-9 (MMP-9) expression were detected in this model. We hypothesize that R544C mutation regulates the expression of MMP-9 through NF-κB and / or PI3K / Cdc42 / JNK signaling pathway, thereby damage the neurovascular unit and lead to CMBs. We proposed to crossbreed our R544C point mutation mouse line with MMP-9 gene knockout mouse line to explore the role of MMP-9 and underlying mechanism of NOTCH3 R544C mutation induced CMBs. The results derived from our proposed studies will provide novel insights for the mechanism underlying CMBs and identification of potential therapeutic targets for CMBs.