Unidad de Investigación, Hospital Universitario de Canarias, 38320 Santa Cruz de Tenerife, Spain.
Instituto de Tecnologías Biomédicas, Universidad de La Laguna, 38200 Santa Cruz de Tenerife, Spain.
Cells. 2022 Aug 11;11(16):2492. doi: 10.3390/cells11162492.
SETD8 is a histone methyltransferase that plays pivotal roles in several cellular functions, including transcriptional regulation, cell cycle progression, and genome maintenance. SETD8 regulates the recruitment of 53BP1 to sites of DNA damage by controlling histone H4K20 methylation. Moreover, SETD8 levels are tightly regulated in a cell cycle-dependent manner by ubiquitin-dependent proteasomal degradation. Here, we identified ubiquitin-specific peptidase 29, USP29, as a novel regulator of SETD8. Depletion of USP29 leads to decreased SETD8 protein levels, an effect that is independent of the cell cycle. We demonstrate that SETD8 binds to USP29 in vivo, and this interaction is dependent on the catalytic activity of USP29. Wildtype USP29 can deubiquitinate SETD8 in vivo, indicating that USP29 directly regulates SETD8 protein levels. Importantly, USP29 knockdown inhibits the irradiation-induced increase in H4K20 monomethylation, thereby preventing focus formation of 53BP1 in response to DNA damage. Lastly, depletion of USP29 increases the cellular sensitivity to irradiation. These results demonstrate that USP29 is critical for the DNA damage response and cell survival, likely by controlling protein levels of SETD8.
组蛋白甲基转移酶 SETD8 在多个细胞功能中发挥关键作用，包括转录调控、细胞周期进程和基因组维护。SETD8 通过控制组蛋白 H4K20 甲基化来调节 53BP1 到 DNA 损伤部位的募集。此外，SETD8 的水平通过泛素依赖性蛋白酶体降解在细胞周期依赖性方式中受到严格调节。在这里，我们鉴定了泛素特异性肽酶 29（USP29）作为 SETD8 的新型调节剂。USP29 的耗竭导致 SETD8 蛋白水平降低，这种效应独立于细胞周期。我们证明 SETD8 在体内与 USP29 结合，这种相互作用依赖于 USP29 的催化活性。野生型 USP29 可以在体内去泛素化 SETD8，表明 USP29 直接调节 SETD8 蛋白水平。重要的是，USP29 敲低抑制了辐照诱导的 H4K20 单甲基化增加，从而阻止了 53BP1 在 DNA 损伤时形成焦点。最后，USP29 的耗竭增加了细胞对辐照的敏感性。这些结果表明，USP29 对于 DNA 损伤反应和细胞存活至关重要，可能通过控制 SETD8 的蛋白水平。
