Department of Biochemistry, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, 693-8501, Japan.
KNC Laboratories Co. Ltd., Kobe, Hyogo, 651-2271, Japan.
Curr Genet. 2019 Feb;65(1):87-91. doi: 10.1007/s00294-018-0866-0. Epub 2018 Jul 4.
Heat-shock protein 90 (Hsp90) was recently identified as a silencing factor required for RNA interference (RNAi)-dependent heterochromatin assembly in the fission yeast Schizosaccharomyces pombe. As Hsp90 is known to contribute to the formation of small RNA-containing effector complexes, it would be expected that Hsp90 is also involved in the RNAi pathway in fission yeast. However, upon investigation, we found it very difficult to determine how Hsp90 modulates RNAi-dependent heterochromatin assembly in the cell. A lack of detectable small interfering RNAs in hsp90 mutant cells prevented us from examining the role of Hsp90 in the siRNA loading in the cell. In addition, deletion of genes encoding co-chaperones for Hsp90 appears not to affect RNAi-dependent pericentromeric silencing. One possible approach for elucidating the role of Hsp90 in RNAi-dependent heterochromatin assembly is the use of forward genetic screens to identify novel factors linking Hsp90 with other known RNAi factors. Here, we discuss the benefits of conducting further screenings and present some technical hints to help identify new factors.
热休克蛋白 90（Hsp90）最近被鉴定为裂殖酵母 Schizosaccharomyces pombe 中 RNA 干扰（RNAi）依赖性异染色质组装所必需的沉默因子。由于已知 Hsp90 有助于形成含有小 RNA 的效应复合物，因此预计 Hsp90 也参与裂殖酵母中的 RNAi 途径。然而，在研究过程中，我们发现很难确定 Hsp90 如何调节细胞中的 RNAi 依赖性异染色质组装。在 hsp90 突变细胞中缺乏可检测到的小干扰 RNA，使我们无法研究 Hsp90 在细胞中 siRNA 加载中的作用。此外，删除编码 Hsp90 共伴侣的基因似乎不会影响 RNAi 依赖性着丝粒周围沉默。阐明 Hsp90 在 RNAi 依赖性异染色质组装中的作用的一种可能方法是利用正向遗传筛选来鉴定将 Hsp90 与其他已知 RNAi 因子联系起来的新因子。在这里，我们讨论了进一步进行筛选的好处，并提供了一些技术提示，以帮助识别新的因子。
