From the Department of Medical Genetics, Center for Medical Genetics, Peking University Health Science Center, Beijing 100191.
College of Pharmacy, Henan University, Kaifeng 475001, Henan.
J Biol Chem. 2018 Nov 16;293(46):17769-17779. doi: 10.1074/jbc.RA118.003629. Epub 2018 Oct 3.
The histone transmethylase complex comprising WD repeat domain 77 (WDR77) and protein arginine methyltransferase 5 (PRMT5) catalyzes dimethylation of H4R3 (H4R3me2) and drives cancer cell proliferation and migration, but its regulation is not fully understood. Here, we report that sirtuin 7 (SIRT7) directly deacetylates WDR77 and that this deacetylation interferes with the WDR77-PRMT5 interaction and suppresses proliferation of human colon cancer HCT116 cells. Using co-expression in HEK293T cells and co-immunoprecipitation assays, we observed that SIRT7 deacetylates WDR77 at Lys-3 and Lys-243, which reduced of WDR77's interaction with PRMT5. More importantly, this reduction suppressed the transmethylase activity of the WDR77/PRMT5 complex, resulting in a reduction of the H4R3me2 modification. Rescue of the WDR77-KO HCT116 cells with a WDR77-2KR (K3R and K243R) variant yielded cell migration and proliferation rates that were significantly lower than those of WDR77-KO HCT116 cells rescued with WT WDR77. In summary, SIRT7 is a major deacetylase for WDR77, and SIRT7-mediated deacetylation of WDR77 at Lys-3 and Lys-243 weakens the WDR77-PRMT5 interaction and activity and thereby suppresses growth of cancer cells.
由 WD 重复结构域 77（WDR77）和蛋白质精氨酸甲基转移酶 5（PRMT5）组成的组蛋白转甲基酶复合物催化 H4R3（H4R3me2）的二甲基化，并驱动癌细胞增殖和迁移，但它的调控机制尚不完全清楚。在这里，我们报告说，Sirtuin 7（SIRT7）可直接去乙酰化 WDR77，而去乙酰化作用会干扰 WDR77-PRMT5 相互作用并抑制人结肠癌细胞 HCT116 的增殖。通过在 HEK293T 细胞中的共表达和共免疫沉淀实验，我们观察到 SIRT7 在赖氨酸 3 和赖氨酸 243 处去乙酰化 WDR77，这减少了 WDR77 与 PRMT5 的相互作用。更重要的是，这种减少抑制了 WDR77/PRMT5 复合物的转甲基酶活性，导致 H4R3me2 修饰减少。用 WDR77-2KR（K3R 和 K243R）变体挽救 WDR77-KO HCT116 细胞，得到的细胞迁移和增殖率明显低于用 WT WDR77 挽救的 WDR77-KO HCT116 细胞。总之，SIRT7 是 WDR77 的主要去乙酰化酶，SIRT7 介导的 WDR77 赖氨酸 3 和赖氨酸 243 的去乙酰化作用削弱了 WDR77-PRMT5 相互作用和活性，从而抑制了癌细胞的生长。
