4 years ago

RhoC regulates actin remodeling to form phagosomes during FcγR-mediated phagocytosis.

Katsuhisa Kawai, Nobukazu Araki, Youhei Egami
Phagosome formation is a complicated process that requires spatiotemporally regulated actin reorganization. We found that RhoC GTPase is a critical regulator of FcγR-mediated phagocytosis in macrophages. Our live-cell imaging revealed that RhoC, but not RhoA, is recruited to phagocytic cups engulfing IgG-opsonized erythrocytes (IgG-Es). RhoC silencing by RNAi, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-mediated RhoC knockout and the expression of dominant-negative or dominant-active RhoC mutants suppressed the phagocytosis of IgG-Es. Moreover, RhoC-GTP pull-down experiments showed that endogenous RhoC is transiently activated during phagosome formation. Notably, actin-driven pseudopod extension to form phagocytic cups was severely impaired in cells expressing dominant-active mutant RhoC-G14V, which induced abnormal F-actin accumulation underneath the plasma membrane. mDia1, a Rho-dependent actin nucleation factor, and RhoC were colocalized at the phagocytic cups. Similarly as for RhoC, mDia1 silencing by RNAi inhibited phagosome formation. Additionally, the coexpression of mDia1 with dominant-active mutant RhoC-G14V or expression of active mutant mDia1-ΔN3 drastically inhibited the uptake of IgG-Es. These data suggest that RhoC modulates phagosome formation by actin cytoskeletal remodeling via mDia1.

Publisher URL: http://doi.org/10.1242/jcs.202739

DOI: 10.1242/jcs.202739

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