Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.
Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Sci Rep. 2020 Jul 9;10(1):11293. doi: 10.1038/s41598-020-68016-z.
The ciliary marginal zone (CMZ) of the zebrafish retina contains a population of actively proliferating resident stem cells, which generate retinal neurons throughout life. The maintenance methyltransferase, dnmt1, is expressed within the CMZ. Loss of dnmt1 function results in gene misregulation and cell death in a variety of developmental contexts, however, its role in retinal stem cell (RSC) maintenance is currently unknown. Here, we demonstrate that zebrafish dnmt1 mutants possess severe defects in RSC maintenance within the CMZ. Using a combination of immunohistochemistry, in situ hybridization, and a transgenic reporter assay, our results demonstrate a requirement for dnmt1 activity in the regulation of RSC proliferation, gene expression and in the repression of endogenous retroelements (REs). Ultimately, cell death is elevated in the dnmt1 CMZ, but in a p53-independent manner. Using a transgenic reporter for RE transposition activity, we demonstrate increased transposition in the dnmt1 CMZ. Taken together our data identify a critical role for dnmt1 function in RSC maintenance in the vertebrate eye.
斑马鱼视网膜的纤毛边缘区（CMZ）包含一群活跃增殖的常驻干细胞，这些细胞在整个生命过程中产生视网膜神经元。维持甲基转移酶 dnmt1 在 CMZ 内表达。dnmt1 功能丧失会导致多种发育背景下的基因失调和细胞死亡，然而，其在视网膜干细胞（RSC）维持中的作用尚不清楚。在这里，我们证明斑马鱼 dnmt1 突变体在 CMZ 内的 RSC 维持中存在严重缺陷。我们使用免疫组织化学、原位杂交和转基因报告基因分析的组合，结果表明 dnmt1 活性在调节 RSC 增殖、基因表达和抑制内源性逆转录元件（REs）方面是必需的。最终，dnmt1 CMZ 中的细胞死亡增加，但不依赖于 p53。我们使用一个用于 RE 转位活性的转基因报告基因，证明了 dnmt1 CMZ 中转位活性的增加。总的来说，我们的数据表明 dnmt1 功能在脊椎动物眼睛的 RSC 维持中起着关键作用。
