Coronin1C SUMOylation modulates filopodia formation, neuritogenesis, and neuronal differentiation

Actin dynamics in the cytosol and at the cell periphery are critical for metabolic processes and the formation of cellular projections. Coronin1C, a versatile cytoskeletal regulator, is an actin-binding protein that associates with actin at the leading edge of a cell. Consequences of Coronin1C interactions on actin dynamics enable actin-mediated filopodia and neurite formation. Here, we report that Coronin1C is SUMOylated at multiple lysine residues in its carboxy-terminus, preferentially by SUMO1. SUMOylation of Coronin1C is critically required for efficient neurite formation and extensive cellular projections during neuronal differentiation. Moreover, SUMOylation-deficient Coronin1C mutant forms cytoplasmic aggregates colocalizing with stress granules, a hallmark of neurodegenerative diseases, under neuronal differentiation conditions. We also demonstrate that Coronin1C SUMOylation works in synergy with Cdc42 GTPase towards actin-polymerization and promotes filopodia formation. In conclusion, we report that Coronin1C SUMOylation by SUMO1 in its carboxy-terminus is critical for cellular projections formation and neuronal differentiation.