An optopharmacological tool for on-demand perturbation of branched actin polymerization

Mandal, S.; Chahal, A.; Chung, S.; Som, A.; Kishore, K.; Shekari, P. A.; Baidya, A.; Babu, K.; Mak, M.; Ditlev, J. A.; Agasti, S. S.; Kumari, S.

doi:10.64898/2026.05.28.728449

bioRxiv · 10.64898/2026.05.28.728449

An optopharmacological tool for on-demand perturbation of branched actin polymerization

Mandal, S.·Chahal, A.·Chung, S.·Som, A.·Kishore, K.·Shekari, P. A.·Baidya, A.·Babu, K.·Mak, M.·Ditlev, J. A.·Agasti, S. S.·Kumari, S.

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Abstract

Regulated actin cytoskeletal organization and dynamics are essential for life-sustaining processes in eukaryotic cells. The spatiotemporal regulation of filamentous actin can generate a staggering variety of higher-order architectures to meet diverse cellular needs. However, connecting a specific actin substructure to the selective cellular function remains challenging because tools to specifically inhibit F-actin in a spatiotemporally controlled manner are currently limited. To address this crucial technical gap, we have synthesized and characterized a photocrosslinkable small molecule inhibitor of a major and evolutionarily conserved actin nucleation factor, Arp2/3 complex. The new inhibitor "AZ" combines the specificity of a preexisting inhibitor CK666 with photosensitive crosslinking by an Azido group, such that a light-induced, instantaneous, on-demand, irreversible inhibition of Arp2/3 complex-dependent actin nucleation is achieved in a spatiotemporally defined manner at a subcellular, supracellular, and organismal scale. Whole cell treatment with AZ, followed by subcellular photoirradiation, revealed a divergent actin nucleation homeostasis in the cortex of different cells. Thus, AZ could be a powerful tool to infer actin polymerization homeostasis and network properties in live cells-processes which otherwise remain obscure.

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Mandal, S., Chahal, A., Chung, S., Som, A., Kishore, K., Shekari, P. A., Baidya, A., Babu, K., Mak, M., Ditlev, J. A., Agasti, S. S., Kumari, S.. 2026-05-29. An optopharmacological tool for on-demand perturbation of branched actin polymerization. https://doi.org/10.64898/2026.05.28.728449

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