Thr‐412 of coronin‐1 is phosphorylated by protein kinase C α (802.23)

Abstract

Coronin‐1, a hematopoietic cell‐specific actin‐binding protein, is thought to be involved in phagocytic process through its interaction with actin filaments. The dissociation of coronin‐1 from phagosomes after its transient accumulation on the phagosome surface is associated with lysosomal fusion. We previously reported that 1) coronin‐1 is phosphorylated by protein kinase C (PKC), 2) coronin‐1 has two phosphorylation sites, Ser‐2 and Thr‐412, 3) Thr‐412 of coronin‐1 is phosphorylated during phagocytosis. In this study, we examined which PKC isoforms have influence on phosphorylation of coronin‐1 at Thr‐412 using isotype‐specific PKC inhibitors and short interfering RNAs (siRNAs). The phosphorylation of coronin‐1 at Thr‐412 was blocked by Gö6976, an inhibitor of PKCα/β. This phosphorylation was attenuated by PKCα siRNA, but not by PKCβ siRNA. We next analyzed the intracellular distribution of coronin‐1 in Gö6976‐treated HL60 cells during phagocytosis. The confocal fluorescence microscopic observation showed that coronin‐1 was not dissociated from phagosomes. These results indicate that phosphorylation of coronin‐1 at Thr‐412 by PKCα regulates its interaction with actin filaments and intracellular distribution during phagocytosis.