近日，美国约翰霍普金斯大学Xin Chen及其研究团队发现不对称的着丝粒差异性与有丝分裂机器协调，以确保在生殖系干细胞中偏向性姊妹染色单体的分离。相关论文2019年9月26日在线发表于国际学术期刊《细胞—干细胞》。

研究人员报告了一系列时空调节的不对称成分，可确保果蝇雄性种系干细胞（GSC）在不对称细胞分裂（ACD）期间有偏向的姐妹染色单体附着和分离。首先，姊妹着丝粒富含着丝粒特化和动粒功能的蛋白质。其次，时间上不对称的微管活动和极化的核膜破裂使微管能够优先识别并附着在不对称的姊妹动粒和姊妹着丝粒上。不对称姐妹着丝粒或不对称微管活性的干扰导致随机的姐妹染色单体分离。因此，这些结果提供了在干细胞ACD期间划分表观遗传学上不同的姐妹染色单体的细胞基础，这为在其他生物学背景下研究这些机制打开了新的方向。

据了解，许多干细胞利用ACD来产生自我更新的干细胞和分化的子细胞。如何很好地理解非基因信息差异遗传以建立独特的细胞命运尚不十分清楚。

附：英文原文

Title: Asymmetric Centromeres Differentially Coordinate with Mitotic Machinery to Ensure Biased Sister Chromatid Segregation in Germline Stem Cells

Author: Rajesh Ranjan, Jonathan Snedeker, Xin Chen

Issue&Volume: 26 September 2019

Abstract: 

Many stem cells utilize asymmetric cell division (ACD) to produce a self-renewed stem cell and a differentiating daughter cell. How non-genic information could be inherited differentially to establish distinct cell fates is not well understood. Here, we report a series of spatiotemporally regulated asymmetric components, which ensure biased sister chromatid attachment and segregation during ACD of Drosophila male germline stem cells (GSCs). First, sister centromeres are differentially enriched with proteins involved in centromere specification and kinetochore function. Second, temporally asymmetric microtubule activities and polarized nuclear envelope breakdown allow for the preferential recognition and attachment of microtubules to asymmetric sister kinetochores and sister centromeres. Abolishment of either the asymmetric sister centromeres or the asymmetric microtubule activities results in randomized sister chromatid segregation. Together, these results provide the cellular basis for partitioning epigenetically distinct sister chromatids during stem cell ACDs, which opens new directions to study these mechanisms in other biological contexts.

DOI: 10.1016/j.stem.2019.08.014

Source: https://www.cell.com/cell-stem-cell/fulltext/S1934-5909(19)30349-2