Mitofusin 2 regulates neutrophil adhesive migration via suppressing Rac activation

Abstract

Neutrophils rely on glycolysis for energy production. How mitochondria regulate neutrophil function is not fully understood. Here, we report that mitochondrial outer membrane protein Mitofusin 2 (Mfn2) regulates neutrophil homeostasis in vivo. Mfn2-deficient neutrophils are released from the hematopoietic tissue and trapped in the vasculature in zebrafish embryos. Human neutrophil-like cells deficient with MFN2 fail to arrest on activated endothelium under sheer stress or perform chemotaxis. Deletion of Mfn2 results in a significant reduction of neutrophil infiltration to the inflamed peritoneal cavity in mice. Mfn2, but not Mfn1, -null mouse embryonic fibroblast cells have altered actin structure and are impaired in wound closure. MFN2-deficient neutrophil-like cells display heightened intracellular calcium levels and Rac activation after chemokine stimulation. Mechanistically, MFN2 maintains mitochondria-ER interaction. Restoring mitochondria-ER tether rescues the chemotaxis defect and Rac activation resulted from MFN2 depletion. Finally, inhibition of Rac restores chemotaxis in MFN2-deficient neutrophils. Altogether, we identified that MFN2 regulates neutrophil migration via suppressing Rac activation and uncovered a previously unrecognized role of MFN2 in regulating the actin cytoskeleton.