Biology subjects

Ghasemi, H. I.

Publications and source records attributed to Ghasemi, H. I..

3 recordsLinked to original sources

bioRxiv2025

SFPQ Promotes Homologous Recombination via mRNA Stabilization of RAD51 and Its Paralogs

Double-strand break (DSB) repair occurs through non-homologous end joining (NHEJ) or homologous recombination (HR). To identify non-canonical factors that influence DSB repair outcomes, we parsed data from pooled genetic screens. Through this approach, we identified the splicing factor SFPQ, which has been previously reported to associate with DSBs and promote repair. Here, we show that SFPQ depletion alters DSB repair via HR. However, in contrast to other published work, we find that SFPQ does not localize to DSBs but instead stabilizes the expression of RAD51 and its paralogs independently of p53 activation or DNA damage. Our findings suggest that SFPQ contributes to constitutive DSB repair by maintaining RAD51 paralog mRNA stability rather than through direct interaction with DSBs or RAD51 protein and highlight indirect mechanisms by which RNA-binding proteins can influence genome stability.

molecular biology↗

bioRxiv2023

Engineering water exchange is a safe and effective method for magnetic resonance imaging in diverse cell types

Aquaporin-1 (Aqp1), a water channel, has garnered significant interest for cell-based medicine and in vivo synthetic biology due to its ability to be genetically encoded to produce magnetic resonance signals by increasing the rate of water diffusion in cells. However, concerns regarding the effects of Aqp1 overexpression and increased membrane diffusivity on cell physiology have limited its widespread use as a deep-tissue reporter. In this study, we present evidence that Aqp1 generates strong diffusion-based magnetic resonance signals without adversely affecting cell viability or morphology in diverse cell lines derived from mice and humans. Our findings indicate that Aqp1 overexpression does not induce ER stress, which is frequently associated with heterologous expression of membrane proteins. Furthermore, we observed that Aqp1 expression had no detrimental effects on native biological activities, such as phagocytosis, immune response, insulin secretion, and tumor cell migration in the analyzed cell lines. These findings should serve to alleviate any lingering safety concerns regarding the utilization of Aqp1 as a genetic reporter and should foster its broader application as a noninvasive reporter for in vivo studies.

bioengineering↗

bioRxiv2022

Interstrand Crosslinks in Donor DNA Boost Gene Editing in Human Cells

Co-introduction of targeted nucleases and DNA/RNA templates encoding new genomic sequence is the basis for rapid, effective, and iterable gene editing workflows for therapeutic, agricultural, and basic science applications. Extensive optimization of reagent delivery and nuclease activity have improved genome editing workflows, but comparatively few efforts have been made to alter the gene editing activity of template molecules. Here, we report template DNA modified with interstrand crosslinks (ICLs) - xHDRTs - increases editing frequencies in Cas9-directed gene editing workflows by up to five-fold. xHDRTs increase gene editing frequencies independent of DNA template topology, amount of sequence added, or cell type. Gene editing using xHDRTs requires the DNA repair kinase, ATR, and partially requires Fanconi Anemia proteins, including FANCA, but is independent of other ICL-repair pathways. Covalent modification of donor DNA thus presents a compelling opportunity to improve nonviral gene editing workflows.

molecular biology↗