Coronin-1 is phosphorylated at Thr-412 by protein kinase Cα in human phagocytic cells

Teruaki Oku; Yutaka Kaneko; Rie Ishii; Yuki Hitomi; Makoto Tsuiji; Satoshi Toyoshima; Tsutomu Tsuji

doi:10.1016/j.bbrep.2021.101041

Coronin-1 is phosphorylated at Thr-412 by protein kinase Cα in human phagocytic cells

Biochem Biophys Rep. 2021 Jun 15:27:101041. doi: 10.1016/j.bbrep.2021.101041. eCollection 2021 Sep.

Authors

Teruaki Oku¹, Yutaka Kaneko¹, Rie Ishii¹, Yuki Hitomi¹, Makoto Tsuiji¹, Satoshi Toyoshima², Tsutomu Tsuji¹

Affiliations

¹ Department of Microbiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan.
² Japan Pharmacists Education Center, 1-9-13 Akasaka, Minato-ku, Tokyo, 107-0052, Japan.

Abstract

Coronin-1, a hematopoietic cell-specific actin-binding protein, is thought to be involved in the 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, and 3) Thr-412 of coronin-1 is phosphorylated during phagocytosis. In this study, we examined which PKC isoform is responsible for the phosphorylation of coronin-1 at Thr-412 by using isotype-specific PKC inhibitors and small interfering RNAs (siRNAs). Thr-412 phosphorylation of coronin-1 was suppressed by Gö6976, an inhibitor of PKCα and PKCβI. This phosphorylation was attenuated by siRNA for PKCα, but not by siRNA for PKCβ. Furthermore, Thr-412 of coronin-1 was phosphorylated by recombinant PKCα in vitro, but not by recombinant PKCβ. We next examined the effects of Gö6976 on the intracellular distribution of coronin-1 in HL60 cells during phagocytosis. The confocal fluorescence microscopic observation showed that coronin-1 was not dissociated from phagosomes in Gö6976-treated cells. These results indicate that phosphorylation of coronin-1 at Thr-412 by PKCα regulates intracellular distribution during phagocytosis.

Keywords: ATP, adenosine 5’-triphosphate; Actin-binding protein; Coronin-1; HRP, horseradish peroxidase; OpZ, opsonized zymosan; PBS, phosphate-buffered saline; PKC, protein kinase C; PS, phosphatidylserine; Phagocytosis; Phagosome-lysosome fusion; Protein kinase C; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; siRNA, small interfering RNA.