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Biology of the cell

Possible role of cortactin phosphorylation by protein kinase Cα in actin-bundle formation at growth cone.


PMID 26033110

Abstract

Cortactin contributes to growth cone morphogenesis by forming with dynamin, ring-shaped complexes that mechanically bundle and stabilise F-actin. However, the regulatory mechanism of cortactin action is poorly understood. Immunofluorescence microscopy revealed that protein kinase C (PKC) α colocalises with cortactin at growth cone filopodia in SH-SY5Y neuroblastoma cells. PKC activation by phorbol 12-myristate 13-acetate causes cortactin phosphorylation, filopodial retraction and F-actin-bundle loss. Moreover, PKCα directly phosphorylates cortactin in vitro at S135/T145/S172, mitigating both cortactin's actin-binding and actin-crosslinking activity, whereas cellular expression of a phosphorylation-mimetic cortactin mutant hinders filopodial formation with a significant decrease of actin bundles. Our results indicate that PKC-mediated cortactin phosphorylation might be implicated in the maintenance of growth cone.