Biology subjects

Contreras-Galindo, R.

Publications and source records attributed to Contreras-Galindo, R..

4 recordsLinked to original sources

bioRxiv2026

Centromeric α-satellite DNA is a hotspot of genotoxic damage, incomplete repair, and cytoplasmic mislocalization

Centromeric -satellite DNA constitutes a highly repetitive and structurally specialized component of the human genome, yet the mechanisms underlying its damage susceptibility and repair fidelity under genotoxic stress remain undefined. Here, we demonstrate that genotoxic stress preferentially targets active centromeres, generating DNA double-strand breaks (DSBs) within -satellite arrays. Using bleomycin as a defined genotoxic perturbation, we identify dynamic alterations in centromeric repeat content, manifesting as net copy number losses and gains across multiple chromosome-specific -satellite arrays following damage. Similar centromere-associated damage signatures are observed in fibroblasts from patients with limited cutaneous systemic sclerosis, indicating that these features extend beyond experimental systems. Centromeric DSBs engage ATM-dependent DNA damage signaling and are repaired predominantly through RAD51-associated homologous recombination; however, repair fails to fully restore centromeric integrity. This incomplete repair is associated with defects in kinetochore organization, chromosome missegregation, and the formation of micronuclei containing centromeric DNA. Notably, [~]30% of these structures retain CENP-B but lacks detectable CENP-A, indicating disruption of centromere chromatin organization. Centromeric chromatin is frequently mislocalized to the cytoplasm following nuclear envelope perturbation, where immunofluorescence analysis reveals proximity to MHC class II (HLA-DRB1). Together, these findings establish centromeric -satellite DNA as a vulnerability hotspot under genotoxic stress, with implications for chromosome instability and chromatin antigen exposure in fibrosis-associated autoimmunity.

genetics↗

bioRxiv2025

Centromere instability links genome damage to immune activation in systemic sclerosis

Systemic sclerosis (SSc) is a fibrotic autoimmune disease in which genomic sources of instability and their immunological consequences remain poorly defined. We show that bleomycin, a widely used SSc fibrosis model, induces DNA double-strand breaks (DSBs) at active centromeres. Similar centromeric damage signatures were observed in fibroblasts from patients with limited cutaneous SSc, consistent with prior observations. Quantification of -satellite repeat content revealed dynamic changes in repeat abundance, consistent with deletions and insertions and incomplete restoration following damage. These breaks are repaired primarily ATM-dependent, RAD51-associated homologous recombination, but repair remains incomplete. Incomplete repair is associated with altered kinetochore assembly, chromosome missegregation, and increased formation of micronuclei and cytoplasmic chromatin enriched in centromere proteins. These fragments escape via nuclear envelope rupture and show spatial colocalization with MHC class II molecules. Together, these findings establish bleomycin-induced centromere damage as a tractable model to study active-centromere instability, its incomplete repair, and the resulting chromatin mislocalization in fibroblasts, with features relevant to systemic sclerosis.

genetics↗

bioRxiv2023

Fyn-mediated phosphorylation of Menin disrupts telomere maintenance in stem cells

Telomeres protect chromosome ends and determine the replication potential of dividing cells. The canonical telomere sequence TTAGGG is synthesized by telomerase holoenzyme, which maintains telomere length in proliferative stem cells. Although the core components of telomerase are well-defined, mechanisms of telomerase regulation are still under investigation. We report a novel role for the Src family kinase Fyn, which disrupts telomere maintenance in stem cells by phosphorylating the scaffold protein Menin. We found that Fyn knockdown prevented telomere erosion in human and mouse stem cells, validating the results with four telomere measurement techniques. We show that Fyn phosphorylates Menin at tyrosine 603 (Y603), which increases Menins SUMO1 modification, C-terminal stability, and importantly, its association with the telomerase RNA component (TR). Using mass spectrometry, immunoprecipitation, and immunofluorescence experiments we found that SUMO1-Menin decreases TRs association with telomerase subunit Dyskerin, suggesting that Fyns phosphorylation of Menin induces telomerase subunit mislocalization and may compromise telomerase function at telomeres. Importantly, we find that Fyn inhibition reduces accelerated telomere shortening in human iPSCs harboring mutations for dyskeratosis congenita.

molecular biology↗

bioRxiv2018

The Genomic Landscape of Centromeres in Various Cancers

Centromere genomics remain poorly characterized in cancer, due to technologic limitations in sequencing and bioinformatics methodologies that make high-resolution delineation of centromeric loci difficult to achieve. We here leverage a highly specific and targeted rapid PCR methodology to quantitatively assess the genomic landscape of centromeres in cancer cell lines and primary tissue. PCR-based profiling of centromeres revealed widespread heterogeneity of centromeric and pericentromeric sequences in cancer cells and tissue as compared to healthy counterparts. Quantitative reductions in select centromeric core and pericentromeric markers were observed in neoplastic samples as compared to healthy counterparts. Subsequent phylogenetic analysis of a pericentromeric endogenous retrovirus amplified by PCR revealed possible gene conversion events occurring at numerous pericentromeric loci in the setting of malignancy. Our findings collectively represent the first look into centromere genetics in the setting of malignancy, providing valuable insight into the evolution and reshuffling of centromeric sequences in cancer development and progression.

genomics↗