Wu Fuguo, Kaczynski Tadeusz J, Sethuramanujam Santhosh, Li Renzhong, Jain Varsha, Slaughter Malcolm, Mu Xiuqian
Department of Ophthalmology/Ross Eye Institute, Developmental Genomics Group, New York State Center of Excellence in Bioinformatics and Life Sciences, State University of New York Eye Institute.
Department of Ophthalmology/Ross Eye Institute, Developmental Genomics Group, New York State Center of Excellence in Bioinformatics and Life Sciences, State University of New York Eye Institute, Neuroscience Graduate Program, and.
Proc Natl Acad Sci U S A. 2015 Mar 31;112(13):E1559-68. doi: 10.1073/pnas.1421535112. Epub 2015 Mar 16.
As with other retinal cell types, retinal ganglion cells (RGCs) arise from multipotent retinal progenitor cells (RPCs), and their formation is regulated by a hierarchical gene-regulatory network (GRN). Within this GRN, three transcription factors--atonal homolog 7 (Atoh7), POU domain, class 4, transcription factor 2 (Pou4f2), and insulin gene enhancer protein 1 (Isl1)--occupy key node positions at two different stages of RGC development. Atoh7 is upstream and is required for RPCs to gain competence for an RGC fate, whereas Pou4f2 and Isl1 are downstream and regulate RGC differentiation. However, the genetic and molecular basis for the specification of the RGC fate, a key step in RGC development, remains unclear. Here we report that ectopic expression of Pou4f2 and Isl1 in the Atoh7-null retina using a binary knockin-transgenic system is sufficient for the specification of the RGC fate. The RGCs thus formed are largely normal in gene expression, survive to postnatal stages, and are physiologically functional. Our results indicate that Pou4f2 and Isl1 compose a minimally sufficient regulatory core for the RGC fate. We further conclude that during development a core group of limited transcription factors, including Pou4f2 and Isl1, function downstream of Atoh7 to determine the RGC fate and initiate RGC differentiation.
与其他视网膜细胞类型一样，视网膜神经节细胞（RGCs）起源于多能视网膜祖细胞（RPCs），其形成受层次化基因调控网络（GRN）的调节。在这个GRN中，三种转录因子——无调性同源物7（Atoh7）、POU结构域4类转录因子2（Pou4f2）和胰岛素基因增强子蛋白1（Isl1）——在RGC发育的两个不同阶段占据关键节点位置。Atoh7位于上游，是RPCs获得RGC命运能力所必需的，而Pou4f2和Isl1位于下游，调节RGC分化。然而，RGC命运特化这一RGC发育关键步骤的遗传和分子基础仍不清楚。在这里我们报告，使用二元敲入转基因系统在Atoh7缺失的视网膜中异位表达Pou4f2和Isl1足以实现RGC命运的特化。如此形成的RGCs在基因表达上基本正常，存活到出生后阶段，并且具有生理功能。我们的结果表明，Pou4f2和Isl1构成了RGC命运的一个最小充分调控核心。我们进一步得出结论，在发育过程中，包括Pou4f2和Isl1在内的一组有限的核心转录因子在Atoh7下游发挥作用，以确定RGC命运并启动RGC分化。
