RHOA mediated mechanical force generation through Dectin-1

Abstract

Dectin-1 is an innate immune pattern recognition receptor which recognizes {beta}-glucan on the Candida albicans (C. albicans) cell wall. Recognition of {beta}-glucan by immune cells leads to phagocytosis, oxidative burst, cytokine and chemokine production. We looked for specific mechanisms that coordinate phagocytosis downstream of Dectin-1 leading to actin reorganization and internalization of fungus. We found that stimulation of Dectin-1 by soluble {beta}-glucan leads to mechanical force generation and areal contraction in Dectin-1 transfected HEK-293 cells and M1 macrophages. With inhibitor studies, we found this force generation is a SYK-independent, SFK (SRC Family Kinase)-dependent process mediated through the RHOA-ROCK-MLC pathway. We confirmed activation of RHOA downstream of Dectin-1 using G-LISA and stress fiber formation. Through phagocytosis assays, we found direct evidence for importance of RHOA-ROCK-MLC pathway in process of phagocytosis of C. albicans. In conclusion, we found evidence for RHOA-ROCK-MLC mediated mechanical force generation downstream of Dectin-1 for C. albicans phagocytosis.