Christyani, Grania

Zinc Finger Protein 161 (ZFP161) is a key regulator of Ataxia Telangiectasia and Rad3-related (ATR) signaling, playing a crucial role in maintaining genomic stability. Human ZFP161 activates c-MYC , whereas its murine ortholog, ZF5, serves as a putative transcriptional repressor of c-MYC . In this study, we identified ZFP161 as a direct regulator of c-MYC. We show that ZFP161 binds to the promoter region of c-MYC , modulating its expression and downstream signaling pathways. Additionally, ZFP161 promotes cell proliferation and tumorigenesis through c-MYC regulation and contributes to the malignant transformation of non-cancerous retinal pigment epithelial (RPE-1) cells. Furthermore, high ZFP161 expression is associated with poor survival in patients with mixed colon adenocarcinoma. These findings suggest that the regulation of c-MYC by ZFP161 may represent a potential therapeutic target in c-MYC -driven cancers.

Abstract The TopBP1-ATR axis is critical for maintaining genomic stability during DNA replication stress, yet the precise regulation of TopBP1 in replication stress responses remains poorly understood. In this study, we identified PHD and Ring Finger Domains 1 (PHRF1) as an important ATR activator through its interaction with TopBP1. Our analysis revealed a correlation between PHRF1 and genomic stability in cancer patients. Mechanistically, PHRF1 is recruited to DNA lesions in a manner dependent on its PHD domain and histone methylation. Subsequently, PHRF1 mono-ubiquitinates TopBP1 at lysine 73, which enhances the TopBP1-ATR interaction and activates ATR. Depletion of PHRF1 disrupts ATR activation and sensitizes cells to replication stress-inducing agents. Furthermore, conditional knockout of Phrf1 in mice leads to early lethality and impaired ATR-Chk1 axis signaling. Collectively, our findings establish PHRF1 as a novel E3 ligase for TopBP1, coordinating the replication stress response by enhancing TopBP1-ATR signaling.