Biology subjects

Courtes, M.

Publications and source records attributed to Courtes, M..

3 recordsLinked to original sources

bioRxiv2025

Slx4 and Fun30/SMARCAD1 coordinate S-phase checkpoint regulation and replication fork protection in response to Top1-DNA crosslinks

Replication stress is a major driver of genomic instability and is implicated in the development of diseases such as cancer. It triggers the S-phase checkpoint, a signaling pathway that coordinates the handling of replication obstacles with cell cycle progression. One prominent source of replication stress is the formation of DNA-protein crosslinks on the template, such as those induced by DNA topoisomerase I poisoning by camptothecin (CPT). In this study, we investigated how the S-phase checkpoint responds to CPT-induced replication stress. We show that both activation and timely deactivation of checkpoint signaling are critical for DNA replication completion and cell viability. Using a locus-specific approach, we found that checkpoint signaling is actively dampened at lesion sites. Mechanistically, this attenuation involves the displacement of the checkpoint mediator Rad9 by the DNA repair factors Slx4 and Fun30. This local dampening not only promotes cell cycle progression, but also permits Exo1-dependent resection of replication forks stalled by Top1-DNA crosslinks. Controlled resection, in turn, allows homologous recombination factors to access and stabilize the forks, preventing their degradation. In conclusion, we propose that local checkpoint dampening by Slx4 and Fun30 at replication stress sites is a critical mechanism that promotes replication completion and preserves genome stability. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/667195v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1bdb2eorg.highwire.dtl.DTLVardef@d2d840org.highwire.dtl.DTLVardef@7366b0org.highwire.dtl.DTLVardef@5ac295_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2021

CRISPR Activation/Inhibition Experiments Reveal that Expression of Intronic MicroRNA miR-335 Depends on the Promoter Activity of its Host Gene Mest

MicroRNAs are small non-coding RNAs that act as rheostats to modulate gene expression during development, physiology, and disease. Approximately half of mammalian microRNAs are intronic. It is unknown whether intronic miRNA transcription depends on their host gene or a microRNA-specific promoter. Here, we show that CRISPR inhibition of host gene Mest downregulated hosted miR-335 in mouse embryonic stem cells and brain organoids. Reciprocally, CRISPR transactivation of Mest upregulated miR-335. By contrast, activation of miR-335 predicted promoter had no effect. Thus, intronic miR-335 expression depends on the promoter activity of its host gene. This approach could serve to map microRNA promoters.

genomics↗

bioRxiv2020

ShcA promotes chondrocyte hypertrophic commitment and osteoarthritis in mice through RunX2 nuclear translocation and YAP1 inactivation

Chondrocyte hypertrophic differentiation, a key process in endochondral ossification (EO), is also a feature of osteoarthritis leading to articular cartilage destruction. ShcA (Src homology and Collagen A) is an adaptor protein that binds to the cytoplasmic tail of receptor tyrosine kinases. We found that deletion of ShcA in chondrocytes of mice inhibits hypertrophic differentiation, alters the EO process, and leads to dwarfism. ShcA promotes ERK1/2 activation, nuclear translocation of the master transcription factor for chondrocyte hypertrophy, RunX2, while maintaining the Runx2 inhibitor YAP1 in its cytosolic inactive form. This leads to hypertrophic commitment and expression of markers of hypertrophy, such as Collagen X. In addition, ShcA deletion in chondrocytes protects from age-related osteoarthritis development in mice. Our results reveal that ShcA integrates multiple stimuli which affect the intracellular signaling processes leading to the hypertrophic commitment of chondrocytes and osteoarthritis.

physiology↗