Epigenomic mapping approaches for cell-type classification in the brain

 描述(由申请人提供)：了解大脑区域中准确的细胞类型组成是整合生理、行为和神经化学数据以系统了解大脑结构和功能的基础。目前，虽然大脑中存在的细胞类型的主要类别已经被定义，但这些类别中的不同亚型以及它们的位置和连通性还远未被了解。DNA甲基化(MC)是一种稳定的共价修饰，在有丝分裂后细胞的一生中持续存在，定义了它们的细胞身份。最近的研究表明，大脑中的MC模式高度发达。 在整个发育过程中是动态的，在啮齿动物和人类的皮质中，主要类型的细胞，即神经元和胶质细胞之间存在明显的差异。这些分析更进一步，产生了细胞类型水平的数据，表明每种神经元类型在其基因组中携带特定的MC特征，这些特征定义了它们所属的群体。这些结果现在开启了在大脑中产生由甲基组特征定义的细胞类型目录的可能性。这项提议将利用这种特定于细胞类型的碱基分辨率甲基组数据，在原位生成啮齿动物大脑中细胞类型的完整地图，并通过这种方法，基于对它们分子身份的综合看法，开发一份系统的清单和大脑中细胞类型的普查。基于初步结果显示特定神经元类型的甲基组之间存在明显的差异，我们建议使用尖端技术来发现和测试特定的差异甲基化区域，这些区域在分子水平上定义了小鼠额叶皮质中的细胞群体。所获得的结果将公之于众，并将作为基础，在一个大脑区域产生一个完整的细胞类型基因组普查，可以扩展到整个大脑。如果成功，这种方法最终可能会在灵长类动物的大脑中进行测试。因此，该建议是对RFA MH-14-215“大脑倡议：大脑中细胞类型分类的变革性方法(U01)”的响应。

 DESCRIPTION (provided by applicant): Understanding the exact cell-type composition in brain regions is fundamental to integrating physiological, behavioral and neurochemical data to systematically understand the brain structure and function. At present, although the major categories of cell-types present in brain have been defined, the different subtypes within these categories, as well as their location and connectivity are far from understood. DNA methylation (mC) is a stable covalent modification that persists in post-mitotic cells throughout their lifetim, defining their cellular identity. It was recently demonstrated that mC patterns in brain are highly dynamic throughout development, and that there are clear differences between the major types of cells i.e., neurons and glia, in the rodent and human cortex. These analyses have been taken a step further and have produced data at the cell-type level that shows that each neuronal type carry specific mC signatures in their genomes that define the population they belong to. These results now open the possibility of producing a catalog of cell-types in brain defined by methylome signatures. This proposal will utilize this cell-type-specific base-resolution methylome data to produce complete maps of cell-types in the rodent brain in situ, and by this means develop a systematic inventory and census of cell types in the brain based on an integrated view of their molecular identity. Based on preliminary results showing clear-cut differences between the methylomes of specific neuronal types, we propose to use cutting edge technology to discover and test specific differentially methylated regions that define, at the molecular level, cell-populations in the frontal cortex of mice. The results obtained will be made publically available, and will serve as foundation to produce a complete genomic census of cell-types in a brain region that can be scaled to the whole brain. If successful, the approach could be ultimately tested in the primate brain. This proposal is thus responsive to RFA MH-14-215 "BRAIN Initiative: Transformative Approaches for Cell-Type Classification in the Brain (U01)".