Open AccessRhoC regulates actin remodeling to form phagosomes during FcγR-mediated phagocytosis
Author(s) -
Youhei Egami,
Kensuke Kawai,
Nobuhito Araki
Publication year - 2017
Publication title -
journal of cell science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.384
H-Index - 278
eISSN - 1477-9137
pISSN - 0021-9533
DOI - 10.1242/jcs.202739
Subject(s) - rhoc , microbiology and biotechnology , rhoa , biology , mdia1 , phagosome , pseudopodia , phagocytosis , actin , rna interference , actin remodeling , actin cytoskeleton , cytoskeleton , signal transduction , biochemistry , cell , rna , gene
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.