A study of the entire multi-subunit BAF (mSWI/SNF) complex loss in global epigenetic regulation of cerebral cortex development

大脑皮层投射神经元的多样性是由多能性脑室径向胶质祖细胞（vRGs）产生的。在胚胎干细胞等系统中，染色质和表观遗传调控对于适当和及时的基因表达至关重要。然而，在皮质发育中vrg获得不同神经细胞命运的过程中，这种机制被认为是协调基因表达程序的激活或抑制的机制，在很大程度上是未知的。在本研究中，我们研究了多亚基染色质重塑BAF复合物在皮质发育中的作用。至少有15个亚基组合在一起，在特定组织中产生广泛多样的具有特殊功能的复合物。一个BAF亚基的缺失通常会影响局部染色质结构和特定的转录程序。然而，到目前为止，由于缺乏整个多亚基BAF复合物的动物突变体，因此不可能充分了解BAF复合物的发育过程。最近，我们生成了BAF155和BAF170亚基的皮质特异性双条件敲除（dcKO）小鼠。引人注目的是，在dcKO突变体中，BAF155和BAF170亚基的缺失消除了皮质组织和初级神经元中所有已知的BAF亚基。此外，BAF复合物的缺失导致抑制标记的整体增加，同时染色质活性标记的总体减少。因此，生成的dcKO突变体为研究整个BAF复合物在皮质发育中的作用提供了一种新的有力工具。本项目的主要目的是研究染色质重塑在皮质神经发生中的作用，重点关注BAF复合物的染色质调控如何在皮质神经发生过程中控制神经基因表达程序，采用遗传操作，基因组学和蛋白质组学方法相结合。

The diversity of projection neurons in cerebral cortex is generated from pluripotent ventricular radial glial progenitors (vRGs). The chromatin and epigenetic regulation are essential for appropriate and timely gene expression in systems such as embryonic stem cells.However, such mechanism assumed to coordinate the activation or repression of gene expression programs during the acquisition of distinct neural cell fates of vRGs in cortical development, are largely unknown. In this proposal, we investigate the roles of multi-subunit chromatin remodeling BAF complexes in cortical development. At least 15 subunits assemble combinatorially to generate an extensive diversity of complexes with specialized functions in specific tissues. A loss of one BAF subunit often affects the local chromatin structure and a specific transcriptional program. Nevertheless, thus far a full understanding of BAF complexes in development is not possible due to the lack of animal mutants for the entire multi-subunit BAF complexes. Recently, we generated cortex-specific double conditional knock-out (dcKO) mice for BAF155 and BAF170 subunits. Strikingly, the loss of BAF155 and BAF170 subunits in dcKO mutants eliminates all known BAF subunits in cortical tissues and primary neurons. In addition, the loss of BAF complex resulted in a global increase in repressive marks with a concurrent overall reduction in active marks of chromatins. The generated dcKO mutants thus provide a novel powerful tool to investigate the roles of entire BAF complexes in cortical development. The main aim of this project is to examine the roles of chromatin remodeling in corticogenesis, with a focus on how chromatin regulation by BAF complex controls neural gene expression programs during cortical neurogenesis, using a combination of genetic manipulation, genomic and proteomic approaches.