Poster abstracts
Poster number 27 submitted by Ian Mikale Llaneza
BIN1 homologous proteins promote cellular wound repair
Ian Mikale A. Llaneza (Ohio State Biochemistry Program), Davinder Singh (Department of Molecular Genetics, The Ohio State University), Aysha H. Osmani (Department of Molecular Genetics, The Ohio State University), Shuai Huang
Abstract:
Cancer cells frequently incur plasma membrane damage during rapid proliferation, chemotherapy stress, T-cell mediated attacks, and metastasis in confined environments. Cancer cells survive by upregulating plasma membrane repair. Defects in plasma membrane repair also lead to common pathologies such as Alzheimers and muscular dystrophy. However, the molecular mechanisms that enable efficient membrane repair remain poorly understood. Here, we identify N-BAR proteins Hob1 and Hob3 (homologs of human proteins BIN1 and BIN3, respectively) as key components of cellular wound repair machinery in the fission yeast model system. Using live-cell imaging of wounded cells by laser ablation, low doses of SDS, or genetic mutations, we found that Hob1 and Hob3 rapidly form biomolecular condensates interdependently at the sites of plasma membrane damage. The condensates exhibit fusion and fission behavior and dissolve at high temperatures and in 1,6-hexanediol. We confirmed these behaviors by in-vitro reconstitution assays using purified recombinant proteins. Hob1 and Hob3 interact through their BAR domains to promote condensate formation. Loss of the Hob1/3 proteins or their mistargeting led to defective membrane repair and increased cell lysis following damage. Condensate formation is regulated by calcium independently from calmodulin, the actin network, or vesicle-based trafficking pathways. Interestingly, the human Bin1 complements condensate formation in hob1 deletion cells. Together, our findings reveal a condensate-based mechanism for plasma membrane repair and suggest that BAR-domain proteins can function as damage-responsive molecular signals or plugs. These results will provide insights into designing novel therapies against metastasizing cancer cells and other degenerative diseases.
Keywords: Biomolecular condensates, cellular wound repair, N-BAR proteins