Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA.
Genetics. 2024 Oct 7;228(2). doi: 10.1093/genetics/iyae128.
Cohesins promote proper chromosome segregation, gene transcription, genomic architecture, DNA condensation, and DNA damage repair. Mutations in either cohesin subunits or regulatory genes can give rise to severe developmental abnormalities (such as Robert Syndrome and Cornelia de Lange Syndrome) and also are highly correlated with cancer. Despite this, little is known about cohesin regulation. Eco1 (ESCO2/EFO2 in humans) and Rad61 (WAPL in humans) represent two such regulators but perform opposing roles. Eco1 acetylation of cohesin during S phase, for instance, stabilizes cohesin-DNA binding to promote sister chromatid cohesion. On the other hand, Rad61 promotes the dissociation of cohesin from DNA. While Eco1 is essential, ECO1 and RAD61 co-deletion results in yeast cell viability, but only within a limited temperature range. Here, we report that eco1rad61 cell lethality is due to reduced levels of the cohesin subunit Mcd1. Results from a suppressor screen further reveals that FDO1 deletion rescues the temperature-sensitive (ts) growth defects exhibited by eco1rad61 double mutant cells by increasing Mcd1 levels. Regulation of MCD1 expression, however, appears more complex. Elevated expression of MBP1, which encodes a subunit of the MBF transcription complex, also rescues eco1rad61 cell growth defects. Elevated expression of SWI6, however, which encodes the Mbp1-binding partner of MBF, exacerbates eco1rad61 cell growth and also abrogates the Mpb1-dependent rescue. Finally, we identify two additional transcription factors, Fkh1 and Fkh2, that impact MCD1 expression. In combination, these findings provide new insights into the nuanced and multi-faceted transcriptional pathways that impact MCD1 expression.
黏连蛋白促进染色体正确分离、基因转录、基因组结构、DNA 凝聚和 DNA 损伤修复。黏连蛋白亚基或调节基因的突变会导致严重的发育异常（如 Robert 综合征和 Cornelia de Lange 综合征），并且与癌症高度相关。尽管如此，人们对黏连蛋白的调节知之甚少。Eco1（人类中的 ESC02/EFO2）和 Rad61（人类中的 WAPL）就是这样的两个调节因子，但它们发挥着相反的作用。例如，Eco1 在 S 期对黏连蛋白进行乙酰化，稳定黏连蛋白-DNA 结合，从而促进姐妹染色单体的黏合。另一方面，Rad61 促进黏连蛋白从 DNA 上解离。虽然 Eco1 是必需的，但 ECO1 和 RAD61 的共同缺失导致酵母细胞存活，但仅在有限的温度范围内。在这里，我们报告 eco1rad61 细胞的致死性是由于黏连蛋白亚基 Mcd1 水平降低所致。抑制剂筛选的结果进一步表明，FDO1 缺失通过增加 Mcd1 水平来挽救 eco1rad61 双突变细胞表现出的温度敏感（ts）生长缺陷。然而，MCD1 表达的调节似乎更为复杂。MBP1 的表达升高，MBP1 编码 MBF 转录复合物的一个亚基，也能挽救 eco1rad61 细胞的生长缺陷。然而，SWI6 的表达升高，SWI6 编码 MBF 的 Mbp1 结合伴侣，加剧了 eco1rad61 细胞的生长，并消除了 Mpb1 依赖的挽救作用。最后，我们确定了另外两个转录因子 Fkh1 和 Fkh2，它们影响 MCD1 的表达。总之，这些发现为影响 MCD1 表达的微妙和多方面的转录途径提供了新的见解。
