Miwa Takashi, Takasaki Teruaki, Inoue Kunio, Sakamoto Hiroshi
Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan.
Genes Cells. 2015 Nov;20(11):932-42. doi: 10.1111/gtc.12285. Epub 2015 Sep 3.
The chromodomain protein MRG-1 is an essential maternal factor for proper germline development that protects germ cells from cell death in C. elegans. Unlike germ granules, which are exclusively segregated to the germline blastomeres at each cell division from the first cleavage of the embryo, MRG-1 is abundant in all cells in early embryos and is then gradually restricted to the primordial germ cells (PGCs) by the morphogenesis stage. Here, we show that this characteristic spatiotemporal expression pattern is dictated by the mrg-1 3'UTR and is differentially regulated at the RNA level between germline and somatic cells. Asymmetric segregation of germ granules is not necessary to localize MRG-1 to the PGCs. We found that MES-4, an essential chromatin regulator in germ cells, also accumulates in the PGCs in a germ granule-independent manner. We propose that C.elegans PGCs have a novel mechanism to accumulate at least some chromatin-associated proteins that are essential for germline immortality.
色域蛋白MRG-1是生殖系正常发育所必需的母体因子，可保护秀丽隐杆线虫的生殖细胞免于细胞死亡。与生殖颗粒不同，生殖颗粒在胚胎第一次分裂后的每次细胞分裂中仅被隔离到生殖系卵裂球中，MRG-1在早期胚胎的所有细胞中都很丰富，然后在形态发生阶段逐渐局限于原始生殖细胞（PGC）。在这里，我们表明这种独特的时空表达模式由mrg-1 3'UTR决定，并且在生殖系和体细胞之间的RNA水平上受到差异调节。生殖颗粒的不对称分离对于将MRG-1定位到PGC并非必需。我们发现MES-4是生殖细胞中一种必需的染色质调节因子，它也以一种不依赖生殖颗粒的方式在PGC中积累。我们提出，秀丽隐杆线虫的PGC具有一种新机制，可积累至少一些对生殖系永生至关重要的染色质相关蛋白。
