人特异性miRNA-F1对人脑发育调控研究

Humans distinguish themselves from other species with their uniquely enlarged brains, increased thickness of brain cortex, and the presence of sulci and gyri on the brain surface. Certain genes, such as Trnp1, are able to regulate the brain development through their dynamic expression in various neural stem cells, resulting in a concurrent tangential and radial expansion of the brain cortex. However, the mechanisms underlying these key features are still largely unknown. Here, we identified a new miRNA-miR-F1 that is highly expressed in human brain and get increased in the brains of Alzheimer's patients, indicating its unique roles in the evolutionary complex human brain. We will use the system we developed for differentiated human embryonic stem cell into neural lineage, together with other techniques such as 3D organoids culture, electroporation of miR-F1 into the embryonic mouse brain, transgenic mouse to study how miR-F1 regulates the human neural development and we will also try to explain the possible role of this miRNA, especially regarding the presence of oSVZ in humans and on the pathogenesis of neural degeneration diseases such as AD. We will further identify the target genes of this miRNA and elucidate the mechanisms of how this evolutionary younger element contributes to the structural and functional complexity of human brains.

人脑区别于其他动物的特征是皮层增厚、表面积增加、沟回显著以及高级功能发达，但机制并不清楚。某些基因如Trnp1等可动态调控切向和纵向细胞迁移与扩增，从而调控皮层结构及沟回形成，但是这些基因进化相对保守，其自身功能无法解释人脑的特异性与复杂性。在寻找人特异表达的调控基因时，我们发现一个新的人科组织特异表达的microRNA--miR-F1。初步研究表明miR-F1在人脑组织中高度表达，并且在AD大脑组织中表达进一步升高，提示miR-F1可能参与人脑发育调控和独特性状的形成。我们拟利用已建立的人多能干细胞神经分化体系结合组织胚胎、胚胎电转、转基因动物等技术，通过过表达和敲降等实验研究miR-F1在干细胞向神经细胞分化过程中对人脑特异皮层结构形成及在AD等神经退行性疾病的中作用。我们将结合生物信息学预测和高通量分析进一步确定miR-F1作用靶点，揭示调控人脑的调控机制和区别于其他动物的本质特征。

本项目旨在研究人特异表达的miR-F1对人类大脑皮层发育及沟回形成的作用及分子机制。本项目通过建立人胚干细胞神经分化体系及3D端脑类器官模型，首先检测了miR-F1在神经分化过程中的表达模式，发现在分化至35天左右开始出现miR-F1比较高的表达水平。然后在3D端脑类器官模型中通过过表达、敲降等方式证明miR-F1影响神经前体细胞和外层放射状胶质细胞的比例，长期过表达使类器官表面积和体积增加且出现表面突起，这些突起由神经元迁移形成，可能与大脑皮层沟回的形成有关。最后，通过胚胎电转以基因动物等方法在小鼠大脑中过表达miR-F1，使得小鼠大脑出现了类似沟回的皮层结构。这些结果表明了miR-F1促进大脑皮质神经前体细胞的增殖和分化，并通过促进皮质中放射状胶质细胞的增殖来促进皮层结构的发展，有助于大脑皮质产生折叠、形成沟回褶皱结构，从而使大脑皮层获得更大的体积和表面积。此外，通过高通量筛选，找到了两个miR-F1作用的靶基因，为进一步探索miR-F1作用通路提供基础数据。综上，本项目阐释了miR-F1调控人脑发育的作用机制，为探索人脑发育的独特形状和区别于其他动物的本质特征提供了新的证据。