Biology subjects

Djerir, B.

Publications and source records attributed to Djerir, B..

3 recordsLinked to original sources

bioRxiv2026

Temporal proximity proteomics reveals ANP32A roles in replication fork progression and end joining

Acidic nuclear phosphoprotein 32 family member A (ANP32A) regulates chromatin and histone homeostasis, but its contribution to DNA replication and repair remains unclear. Time-resolved AirID proximity labeling with data-independent acquisition mass spectrometry revealed phased remodeling of the ANP32A proximal proteome during hydroxyurea-induced replication stress. Early stress enriched DNA replication and repair factors, including FEN1, XRCC5/Ku80, and XRCC6/Ku70, whereas prolonged exposure shifted the network towards checkpoint and cell-cycle regulators. Orthogonal proximity ligation assays revealed sustained ANP32A-FEN1 proximity and transiently increased ANP32A-XRCC5 proximity. ANP32A was dynamically recruited to {gamma}H2AX-marked lesions following laser microirradiation and showed increased proximity to {gamma}H2AX after hydroxyurea treatment. ANP32A loss impaired proliferation and G1/S progression and moderately reduced replication fork velocity. However, it did not promote nascent strand degradation at stalled forks or measurably alter homologous recombination reporter activity. In contrast, ANP32A loss reduced non-homologous end-joining reporter activity, consistent with its stress-induced proximity to Ku proteins. These findings identify ANP32A as a chromatin-associated factor supporting replication fork progression and end joining while dispensable for stalled-fork protection, linking ANP32A-dependent chromatin regulation to genome maintenance.

cell biology↗

bioRxiv2021

POGZ modulates the DNA damage response in a HP1-dependent manner

The heterochromatin protein HP1 plays a central role in the maintenance of genome stability, in particular by promoting homologous recombination (HR)-mediated DNA repair. However, little is still known about how HP1 is controlled during this process. Here, we describe a novel function of the POGO transposable element derived with ZNF domain protein (POGZ) in the regulation of HP1 during the DNA damage response in vitro. POGZ depletion delays the resolution of DNA double-strand breaks (DSBs) and correlates with an increased sensitivity to different DNA damaging agents, including the clinically-relevant Cisplatin and Talazoparib. Mechanistically, POGZ promotes homology-directed DNA repair pathways by retaining the BRCA1/BARD1 complex at DSBs, in a HP1-dependent manner. In vivo CRISPR inactivation of Pogz is embryonically lethal and Pogz haplo-insufficiency (Pogz+/{Delta}) results in a developmental delay, impaired intellectual abilities, a hyperactive behaviour as well as a compromised humoral immune response in mice, recapitulating the main clinical features of the White Sutton syndrome (WHSUS). Importantly, Pogz+/{Delta} mice are radiosensitive and accumulate DSBs in diverse tissues, including the spleen and the brain. Altogether, our findings identify POGZ as an important player in homology-directed DNA repair both in vitro and in vivo, with clinical implications for the WHSUS.

molecular biology↗

bioRxiv2018

FAM35A co-operates with REV7 to coordinate DNA double-strand break repair pathway choice.

DNA double-strand breaks (DSBs) can be repaired by two major pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). DNA repair pathway choice is governed by the opposing activities of 53BP1, in complex with its effectors RIF1 and REV7, and BRCA1. However, it remains unknown how the 53BP1/RIF1/REV7 complex stimulates NHEJ and restricts HR to the S/G2 phases of the cell cycle. Using a mass spectrometry (MS)-based approach, we identify 11 high-confidence REV7 interactors and elucidate the role of a previously undescribed factor, FAM35A/SHDL2, as a novel effector of REV7 in the NHEJ pathway. FAM35A depletion impairs NHEJ-mediated DNA repair and compromises antibody diversification by class switch recombination (CSR) in B-cells. FAM35A accumulates at DSBs in a 53BP1-, RIF1- and REV7-dependent manner and antagonizes HR by limiting DNA end resection. In fact, FAM35A is part of a larger complex composed of REV7 and another previously uncharacterized protein, C20orf196/SHDL1, which promotes NHEJ and limits HR. Together, these results establish FAM35A as a novel effector of REV7 in controlling the decision-making process during DSB repair.

cancer biology↗