Thermo Fisher Scientific, 5781 Van Allen Way, Carlsbad, CA, 92008, USA.
Vesigen Therapeutics, 790 Memorial Drive, Suite 103, Cambridge, MA, 02139, USA.
Nat Commun. 2023 Mar 4;14(1):1233. doi: 10.1038/s41467-023-36968-1.
Deletion of the conserved C-terminus of the Rothmund-Thomson syndrome helicase RECQ4 is highly tumorigenic. However, while the RECQ4 N-terminus is known to facilitate DNA replication initiation, the function of its C-terminus remains unclear. Using an unbiased proteomic approach, we identify an interaction between the RECQ4 N-terminus and the anaphase-promoting complex/cyclosome (APC/C) on human chromatin. We further show that this interaction stabilizes APC/C co-activator CDH1 and enhances APC/C-dependent degradation of the replication inhibitor Geminin, allowing replication factors to accumulate on chromatin. In contrast, the function is blocked by the RECQ4 C-terminus, which binds to protein inhibitors of APC/C. A cancer-prone, C-terminal-deleted RECQ4 mutation increases origin firing frequency, accelerates G/S transition, and supports abnormally high DNA content. Our study reveals a role of the human RECQ4 C-terminus in antagonizing its N-terminus, thereby suppressing replication initiation, and this suppression is impaired by oncogenic mutations.
Rothmund-Thomson 综合征解旋酶 RECQ4 的保守 C 端缺失具有高度致瘤性。然而，尽管已知 RECQ4 N 端有助于 DNA 复制起始，但 C 端的功能仍不清楚。使用无偏蛋白质组学方法，我们在人类染色质上鉴定到 RECQ4 N 端与后期促进复合物/细胞周期蛋白（APC/C）之间的相互作用。我们进一步表明，这种相互作用稳定了 APC/C 共激活因子 CDH1，并增强了 APC/C 依赖性复制抑制剂 Geminin 的降解，从而使复制因子在染色质上积累。相比之下，RECQ4 C 端会阻断这种功能，因为它与 APC/C 的蛋白抑制剂结合。具有致癌倾向的、C 端缺失的 RECQ4 突变会增加起始频率，加速 G1/S 期过渡，并支持异常高的 DNA 含量。我们的研究揭示了人类 RECQ4 C 端在拮抗其 N 端、从而抑制复制起始方面的作用，而这种抑制作用会被致癌突变所破坏。
