Biology subjects

Miotto, B.

Publications and source records attributed to Miotto, B..

3 recordsLinked to original sources

bioRxiv2022

GNL3 regulates replication origin firing and protects stalled replication forks

DNA replication requires specific proteins that protect replication forks and so prevent the formation of DNA lesions that may damage the genome. Identification of new proteins involved in these processes is essential to understand how cancer cells tolerate DNA lesions. Here we show that human GNL3/nucleostemin, a GTP-binding protein localized mostly in the nucleolus and highly expressed in cancer cells, prevents nuclease-dependent resection of nascent DNA in response to exogenous replication stress. We demonstrate that inhibition of origin firing decreases this resection, indicating that the increased replication origin firing seen upon GNL3 depletion mainly accounts for the observed DNA resection. We show that GNL3 and DNA replication initiation factor ORC2 interact in the nucleolus and that the concentration of GNL3 in the nucleolus is required to limit DNA resection in response to replicative stress. We propose that the accurate control of origin firing by GNL3, possibly through the regulation of ORC2 sub-nuclear localization, is critical to prevent nascent DNA resection in response to replication stress.

molecular biology↗

bioRxiv2020

USP9X deubiquitinase couples the pluripotency network and cell metabolism to regulate ESC differentiation potential

Embryonic stem cells (ESC) have the unique ability to differentiate into all three germ cell layers. ESC transition through different states of pluripotency in response to growth factor signals and environmental cues before becoming terminally differentiated. Here, we demonstrated, by a multi-omic strategy, that the deubiquitinase USP9X regulates the developmental potential of ESC, and their transition from a naive to a more developmentally advance, or primed, state of pluripotency. We show that USP9X facilitates developmental gene expression and induces modifications of the mitochondrial bioenergetics, including decreased routing of pyruvate towards its oxidation and reduced respiration. In addition, USP9X binds to the pluripotency factor ESRRB, regulates its abundance and the transcriptional levels of a subset of its target genes. Finally, under permissive culture conditions, depletion of Usp9X accelerates cell differentiation in all cell lineages. We thus identified a new regulator of naive pluripotency and show that USP9X couples ESRRB pluripotency transcriptional network and cellular metabolism, both of which are important for ESC fate and pluripotency.

cell biology↗

bioRxiv2019

FANCD2 tunes the UPR preventing mitochondrial stress-induced common fragile site instability.

Common fragile sites (CFSs) are genomic regions frequently involved in cancer-associated rearrangements. Most CFSs lie within large genes, and their instability relies on transcription- and replication-dependent mechanisms. Here, we uncover a role for the UBL5-dependent branch of the unfolded protein response pathway (UPR) in the maintenance of CFS stability. We show that genetic or pharmacological UPR activation induces CFS gene expression and concomitant relocalization of FANCD2, a master regulator of CFS stability, to CFSs. Furthermore, a genomic analysis of FANCD2 binding sites identified an enrichment for mitochondrial UPR transcriptional response elements in FANCD2 bound regions. We demonstrated that depletion of FANCD2 increases CFS gene transcription and their instability while also inducing mitochondrial dysfunction and triggering the activation of the UPR pathway. Depletion of UBL5, a mediator of the UPR, but not ATF4, reduces CFS gene expression and breakage in FANCD2-depleted cells. We thus demonstrate that FANCD2 recruitment and function at CFSs depends on transcription and UPR signaling, and in absence of transcription or UBL5, FANCD2 is dispensable for CFS stability. We propose that FANCD2 coordinates nuclear and mitochondrial activities by tuning the UPR to prevent genome instability.

cell biology↗