Coordinated cytoskeletal and cell adhesion dynamics in vesicant induced skin injury - Project Summary: The continued presence of chemical weapons poses a significant threat to public health and safety. Exposure to skin blister agents, which are most commonly used in chemical warfare, can cause severe skin inflammation and tissue destruction, leading to permanent disfigurement and disability. However, the mechanism of vesicant-induced skin blistering is complex and poorly defined, which hinders the development of effective medical countermeasures. Dynamic remodeling of cell adhesions is essential for many biological processes, such as cell movement, developmental morphogenesis, and tumor metastasis. Disruption of cell adhesion is a critical step during skin chemical injury. Cell adhesions are closely associated with the underlying cytoskeletal networks, which together provide the structural framework for the cells. Turnover of cell adhesion requires coordinated activities of cytoskeleton. Previous work from our group demonstrates that spectraplakin family protein, Actin Crosslinking Factor 7 (ACF7) promotes cell adhesion turnover by targeting microtubule plus ends toward cell adhesions. ACF7 harbors both microtubule and F-actin binding affinity, and the latter is regulated by focal adhesion kinase (FAK). Our recent study shows that tyrosine phosphorylation of ACF7 by FAK plays an indispensable role in coordinated cytoskeletal dynamics and cell adhesion turnover in skin keratinocytes. Interestingly, with ACF7 skin conditional knockout (cKO) model, we found that loss of ACF7 can attenuate skin damage induced by Phenylarsine oxide (PAO), a lewisite analog. With primary mouse keratinocytes, we found that PAO can induce FAK activity and enhance ACF7 phosphorylation, which lead to increased cell adhesion turnover in vitro. Together, our previous research and preliminary results raise the intriguing hypothesis that skin vesicants can regulate cell adhesion turnover through a novel signaling network centering on ACF7. In this proposal, we will employ an integrative approach to explore the basic molecular mechanism underlying skin vesication. We will determine the role of ACF7 and FAK in PAO or NM (nitrogen mustard)-induced skin blistering in vivo with mouse cKO models. We will use quantitative and live cell imaging approach to investigate how skin vesicants regulate cell adhesion and cytoskeletal dynamics through ACF7 and FAK signaling in vitro. Hemidesmosomes play a critical role in maintaining skin tissue integrity and mechanical stability. In this proposal, we will use a unique mouse skin organoid culture and engraftment model to investigate hemidesmosome dynamics and its regulation by ACF7 in response to skin vesicants. Together, by leveraging our extensive expertise in cell adhesion and cytoskeletal dynamics, the proposed study will fulfill a significant gap in our understanding of skin chemical injuries and reveal potential therapeutic targets for treatment.
