Biology subjects

Sabatinos, S. A.

Publications and source records attributed to Sabatinos, S. A..

4 recordsLinked to original sources

bioRxiv2025

Fission yeast histone chaperone Rtt106 regulates histone levels, prevents early division, and promotes genome stability

Chromatin packaging influences gene expression and is linked to genome stability through the establishment and maintenance of histone modifications. Histone chaperone proteins regulate chromatin assembly and thus packaging. We tested how loss of the histone chaperone Rtt106 affects genome stability through cell cycle checkpoint stability in response to cellular stress. We tested how double mutants lacking DNA replication or DNA damage checkpoint kinases are impacted by the absence of histone chaperone rtt106. Rtt106 brings histone H3 and histone H4 together into complexes. We found that rtt106{Delta} cells with loss of the DNA replication checkpoint (cds1{Delta}, rad3{Delta}) were more sensitive to hydroxyurea. However, DNA damage kinase chk1{Delta} rtt106{Delta} cells became less sensitive to DNA damaging drugs. The effects of Rtt106 on growth are observed in division timing, where rtt106{Delta} cells show early division in the presence of drug. Coupled to a decrease in histone H3 levels and increased mutation rate, our work shows how non-essential Rtt106 activities contribute to genome stability. By regulating histone levels and use, Rtt106 regulates the cell division and may function in chromatin arm coherence and segregation.

genetics↗

bioRxiv2025

Checkpoint-dependent sensitivities to nucleoside analogues uncover specific patterns of genomic instability

Nucleoside analogues are used as drugs and as labels in lab-based research. However, the effect of different nucleoside analogue mechanism(s) on cell sensitivity or mutagenesis is unclear. This is particularly important in cancer treatments where checkpoint proteins and DNA damage factors are often mutated. We tested 6 nucleoside analogues in the fission yeast, Schizosaccharomyces pombe. We found that the mutations in the DNA replication checkpoint cause unique sensitivity profiles towards chemotherapeutic nucleoside analogues (gemcitabine, 5-fluorouracil, cytarabine) and the non-clinical analogue bromodeoxyuridine. Antiretroviral compounds, zidovudine and lamivudine, did not alter cell growth. We compared half-maximal inhibitory concentration (IC50) doses between checkpoint deficient yeast strains, examining culture growth and DNA mis-segregation. Intriguingly, gemcitabine and bromodeoxyuridine doses above the IC50 promoted better growth. Above each compounds IC50 dose we saw that cells were insensitive to nucleoside analogue re-exposure, particularly in DNA replication checkpoint mutants (cds1{Delta}, rad3{Delta}). Thus, pairing nucleoside analogue use with personal genomics may inform drug choice, dose, and schedule. Finally, these data indicate that resistance may be predictable, informing clinical strategy.

cell biology↗

bioRxiv2024

Modelling DNA replication fork stability and collapse using chromatin fiber analysis and the R-ODD-BLOBS program

We describe the anatomy of replication forks by comparing the lengths of synthesized BrdU-labelled DNA in wild type, mrc1{Delta} and cds1{Delta} Schizoasaccharomyces pombe. We correlated Rad51 and Cdc45 proteins relative to their positions on the fork, replicated tract, or unreplicated regions. We did this by using chromatin fiber images. These fibers track pixel intensity data, which is analyzed using our program: R-ODD-BLOBS. We compared the lengths of BrdU tracts and proteins, as well as the percentage of Rad51 and Cdc45 colocalization, and compared our results with literature findings. We measured average BrdU lengths consistent with current literature; cds1{Delta} was the longest at [~]2.9 kb (8.6 pixels, px), wild type was [~] 2.5 kb (7.5 px), and mrc1{Delta} was the shortest at [~]1.7 kb (5.1 px). Intriguingly, Rad51 was found at 22% more replicated areas in mrc1{Delta} than in wild type. This suggests that homologous recombination repair may be more common at mrc1{Delta} forks. In this study, we summarize the usefulness of a computational modeling tool to assess large datasets of chromatin spread data. In turn, we find patterns of DNA replication length and protein components at replication forks, to describe the anatomy of a fork and how structures change with checkpoint loss. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/621594v2_figa1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@1fd59forg.highwire.dtl.DTLVardef@1f234org.highwire.dtl.DTLVardef@1c46b51org.highwire.dtl.DTLVardef@61ce37_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGRAPHICAL ABSTRACT:C_FLOATNO R-ODD-BLOBS uses chromatin fiber data to rigorously model replication fork structures. DNA replication forks are multi-subunit structures that must pair and regulate DNA copying activity of the polymerases with unwinding activity of helicase. Chromatin fiber data retains proteins, and can be used to detect DNA synthesis (blue) and associated DNA replication fork proteins such as MCM4 helicase (MCM4) and replication protein A (RPA). In our work, we have used homologous recombination protein Rad51 and helicase factor Cdc45 to understand how DNA replication fork structures are destabilized during hydroxyurea treatment, and how they fail to recover because of Cdc45/helicase mis-localization. C_FIG

cell biology↗

bioRxiv2021

Multiscale interactome analysis coupled with off-target drug predictions reveals drug repurposing candidates for human coronavirus disease

The COVID-19 pandemic has led to an urgent need for the identification of new antiviral drug therapies that can be rapidly deployed to treat patients with this disease. COVID-19 is caused by infection with the human coronavirus SARS-CoV-2. We developed a computational approach to identify new antiviral drug targets and repurpose clinically-relevant drug compounds for the treatment of COVID-19. Our approach is based on graph convolutional networks (GCN) and involves multiscale host-virus interactome analysis coupled to off-target drug predictions. Cellbased experimental assessment reveals several clinically-relevant repurposing drug candidates predicted by the in silico analyses to have antiviral activity against human coronavirus infection. In particular, we identify the MET inhibitor capmatinib as having potent and broad antiviral activity against several coronaviruses in a MET-independent manner, as well as novel roles for host cell proteins such as IRAK1/4 in supporting human coronavirus infection, which can inform further drug discovery studies.

cell biology↗