Laboratory of Genome Maintenance, The Rockefeller University, New York, NY 10065, USA.
Cell Rep. 2013 Oct 17;5(1):207-15. doi: 10.1016/j.celrep.2013.08.041. Epub 2013 Sep 27.
Holliday junctions (HJs), the DNA intermediates of homologous recombination, need to be faithfully processed in order to preserve genome integrity. In human cells, the BLM helicase complex promotes nonnucleolytic dissolution of double HJs. In vitro, HJs may be nucleolytically processed by MUS81-EME1, GEN1, and SLX4-SLX1. Here, we exploit human SLX4-null cells to examine the requirements for HJ resolution in vivo. Lack of BLM and SLX4 or GEN1 and SLX4 is synthetically lethal in the absence of exogenous DNA damage, and lethality is a consequence of dysfunctional mitosis proceeding in the presence of unprocessed HJs. Thus, GEN1 activity cannot be substituted for the SLX4-associated nucleases, and one of the HJ resolvase activities, either of those associated with SLX4 or with GEN1, is required for cell viability, even in the presence of BLM. In vivo HJ resolution depends on both SLX4-associated MUS81-EME1 and SLX1, suggesting that they are acting in concert in the context of SLX4.
霍利迪连接点 (HJs) 是同源重组的 DNA 中间体，为了保持基因组完整性，需要对其进行准确处理。在人类细胞中，BLM 解旋酶复合物促进双 HJ 的非核酸酶溶解。在体外，HJ 可能被 MUS81-EME1、GEN1 和 SLX4-SLX1 进行核酸酶处理。在这里，我们利用人类 SLX4 缺陷细胞来研究体内 HJ 分辨率的要求。在没有外源 DNA 损伤的情况下，缺乏 BLM 和 SLX4 或 GEN1 和 SLX4 是合成致死的，并且在存在未处理的 HJ 的情况下，有丝分裂功能障碍是导致致死的原因。因此，GEN1 活性不能替代 SLX4 相关的核酸酶，并且即使存在 BLM，SLX4 相关的 MUS81-EME1 和 SLX1 之一的 HJ 解旋酶活性对于细胞存活也是必需的。体内 HJ 分辨率取决于 SLX4 相关的 MUS81-EME1 和 SLX1，表明它们在 SLX4 的背景下协同作用。
