Ueno Kazuko, Iwagawa Toshiro, Ochiai Genki, Koso Hideto, Nakauchi Hiromitsu, Nagasaki Masao, Suzuki Yutaka, Watanabe Sumiko
Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Division of Biomedical Information Analysis, Department of Integrative Genomics, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi, Japan.
Sci Rep. 2017 Jun 15;7(1):3578. doi: 10.1038/s41598-017-03874-8.
Retinal neurons and Müller glia are generated from a common population of multipotent retinal progenitor cells. We purposed to identify Müller glia-specific molecular signatures during retinal development. Using transgenic mice carrying the Hes1 promoter (pHes1) followed by EGFP, we purified EGFP-positive Müller glia and other EGFP-negative retinal cells from developing retinas and subjected them to RNA sequencing analysis. Gene expression pattern of EGFP-positive cell was similar to genes expressed in retinal progenitors, and they were downregulated in other cell lineages. Then, we examined the modification profiles of H3K27me3 and H3K4me3 by referring to chromatin immunoprecipitation-sequencing data of rods and other cells. Clustering of the H3K4me3 and H3K27me3 values followed by ontology analysis revealed a high incidence of transcription factors including Hes1 in clusters with high H3K27me3 levels. Hes1 expression level decreased dramatically, and the H3K27me3 level at the Hes1-locus was upregulated strongly during retinal development. Furthermore, the Hes1 expression level was upregulated in an Ezh2-knockout retina. These results suggest that downregulation of Müller glia-related genes in other lineage rather than upregulation of them in Müller glia contributed Müller-specific molecular features, and a role for modified H3K27me3 in suppressing Müller glia-related genes in other retinal cell lineages to avoid unfavorable expression.
视网膜神经元和穆勒胶质细胞由多能视网膜祖细胞共同产生。我们旨在确定视网膜发育过程中穆勒胶质细胞特异性分子特征。利用携带Hes1启动子（pHes1）并接有EGFP的转基因小鼠，我们从发育中的视网膜中纯化出EGFP阳性的穆勒胶质细胞和其他EGFP阴性的视网膜细胞，并对它们进行RNA测序分析。EGFP阳性细胞的基因表达模式与视网膜祖细胞中表达的基因相似，且在其他细胞谱系中下调。然后，我们参考视杆细胞和其他细胞的染色质免疫沉淀测序数据，研究了H3K27me3和H3K4me3的修饰谱。对H3K4me3和H3K27me3值进行聚类并随后进行本体分析，结果显示在H3K27me3水平高的簇中，包括Hes1在内的转录因子发生率很高。在视网膜发育过程中，Hes1表达水平急剧下降，且Hes1基因座处的H3K27me3水平强烈上调。此外，在Ezh2基因敲除的视网膜中，Hes1表达水平上调。这些结果表明，穆勒胶质细胞相关基因在其他谱系中的下调而非在穆勒胶质细胞中的上调促成了穆勒胶质细胞特异性分子特征，并且修饰的H3K27me3在抑制其他视网膜细胞谱系中穆勒胶质细胞相关基因以避免不利表达方面发挥了作用。
