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. The effects of Coronin1C interactions on actin dynamics enable actin-mediated filopodia and neurite formation. Here, we report that Coronin1C is SUMOylated, but preferentially by SUMO1 at multiple lysine residues in its carboxy-terminus. SUMOylation of Coronin1C impacts filopodia formation in cells; thus, cellular migration is significantly impaired when all five SUMOylatable residues are mutated. Further, we observe that Coronin1C SUMOylation is critically required for efficient neurite formation and extensive cellular projections during neuronal differentiation. Moreover, the non-SUMOylatable Coronin1C mutant forms cytoplasmic aggregates under neuronal differentiation conditions, a hallmark of neurodegenerative diseases. In conclusion, we report that Coronin1C is SUMOylated in its carboxy-terminus and COR1C SUMOylation is critical for cellular projections formation and neuronal differentiation.