Biology subjects

Bayona-Feliu, A.

Publications and source records attributed to Bayona-Feliu, A..

3 recordsLinked to original sources

bioRxiv2024

SMARCAD1 Regulates R-Loops at Active Replication Forks Linked to Cancer Mutation Hotspots

DNA replication often encounters obstacles like the stalled transcription machinery and R-loops. While ribonucleases and DNA-RNA helicases can resolve these structures, the role of chromatin remodelers remains understudied. Through a series of in vitro and in vivo experiments, we show that the chromatin remodeler SMARCAD1, which associates with active replication forks, is crucial for resolving nearby R-loops to maintain fork stability. SMARCAD1 directly binds R-loops via its ATPase domain and associates with the replisome through its N-terminus region. Both interactions are critical for resolving R-loops within cells. Genome-wide assays reveal that cells expressing mutant SMARCAD1 accumulate significantly more R-loops than wild-type cells, particularly in regions distinct from known fork blockage-prone sites. These R-loop-enriched regions in SMARCAD1 mutants also exhibit increased mutagenesis in germline tumors, suggesting they are mutation hotspots in cancer. Therefore, SMARCAD1 acts as an R-loop sensor and resolvase at actively progressing forks, maintaining genome stability and preventing tumorigenesis.

genetics↗

bioRxiv2022

Centriolar subdistal appendages promote double strand break repair through homologous recombination

The centrosome is a cytoplasmic organelle with roles in microtubule organization which has also been proposed to act as a hub for cellular signaling. Some centrosomal components are required for full activation of the DNA Damage Response. However, if the centrosome regulates specific DNA repair pathways is not known. Here, we show that centrosomes presence is required to fully activate recombination, specifically to completely license its initial step, the so-called DNA end resection. Furthermore, we identify a centriolar structure, the subdistal appendages, and a specific factor, CEP170, as the critical centrosomal component involved in the regulation of recombination and resection, albeit it does not control end-joining repair. Cells lacking centrosomes or depleted for CEP170 are, consequently, hyper-sensitive to DNA damaging agents. Moreover, low levels of CEP170 in multiple cancer types correlate with an increase of the mutation burden associated with specific mutational signatures and a better prognosis, suggesting that changes in CEP170 can act as a mutation driver but also could be targeted to improve current oncological treatments.

cell biology↗

bioRxiv2020

TDP-43 deficiency links Amyotrophic Lateral Sclerosis with R-loop homeostasis and R loop-mediated DNA damage

TDP-43 is a DNA and RNA binding protein involved in RNA processing and with structural resemblance to heterogeneous ribonucleoproteins (hnRNPs), whose depletion sensitizes neurons to double strand DNA breaks (DSBs). Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disorder, in which 97% of patients are familial and sporadic cases associated with TDP-43 proteinopathies and conditions clearing TDP-43 from the nucleus, but we know little about the molecular basis of the disease. Here, we prove that mislocalization of mutated TDP-43 (A382T) in transfected neuronal SH-SY5Y and lymphoblastoid cell lines (LCLs) from an ALS patient cause R-loop accumulation, and R loop-dependent increased DSBs and Fanconi Anemia repair centers. Similar results were observed in a non-neuronal model of HeLa cells depleted of TDP-43. These results uncover a new role of TDP-43 in the control of co-transcriptional R-loops and the maintenance of genome integrity by preventing harmful R-loop accumulation. Our findings thus link TDP-43 pathology to increased R-loops and R loop-mediated DNA damage opening the possibility that R-loop modulation in TDP-43-defective cells might help develop ALS therapies.

molecular biology↗