Rho-kinase and myosin-II control phagocytic cup formation during CR, but not FcgammaR, phagocytosis.
Phagocytosis through Fcgamma receptor (FcgammaR) or complement receptor 3 (CR) requires Arp2/3 complex-mediated actin polymerization, although each receptor uses a distinct signaling pathway. Rac and Cdc42 are required for actin and Arp2/3 complex recruitment during FcgammaR phagocytosis, while Rho controls actin assembly at CR phagosomes. To better understand the role of Rho in CR phagocytosis, we tested the idea that a known target of Rho, Rho-kinase (ROK), might control phagocytic cup formation and/or engulfment of particles. Inhibitors of ROK (dominant-negative ROK and Y-27632) and of the downstream target of ROK, myosin-II (ML7, BDM, and dominant-negative myosin-II), were used to test this idea. We found that inhibition of the Rho --> ROK --> myosin-II pathway caused a decreased accumulation of Arp2/3 complex and F-actin around bound particles, which led to a reduction in CR-mediated phagocytic engulfment. FcgammaR-mediated phagocytosis, in contrast, was independent of Rho or ROK activity and was only dependent on myosin-II for particle internalization, not for actin cup formation. While myosins have been previously implicated in FcgammaR phagocytosis, to our knowledge, this is the first demonstration of a role for myosin-II in CR phagocytosis.
School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, Birmingham, United Kingdom.
Isabel M
IM
Olazabal
Emmanuelle
E
Caron
Robin C
RC
May
Kerstin
K
Schilling
David A
DA
Knecht
Laura M
LM
Machesky
D000199:Actins / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D016177:Macrophage-1 Antigen / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D024462:Myosin Type II / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010587:Phagocytosis / Q000502:physiology*; D010588:Phagosomes / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017452:Receptors, IgG / Q000378:metabolism*; D054460:rho-Associated Kinases
D000199:Actins; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D016177:Macrophage-1 Antigen; D017452:Receptors, IgG; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D024462:Myosin Type II