Mitochondrial dysfunction triggers actin polymerization necessary for rapid glycolytic activation

Abstract

Mitochondrial damage represents a dramatic change in cellular homeostasis, necessitating rapid responses. One rapid response is peri-mitochondrial actin polymerization, termed ADA (acute damage-induced actin). The consequences of ADA are not fully understood. Here we show that ADA is necessary for rapid glycolytic activation upon inhibition of mitochondrial ATP production in multiple cells, including mouse embryonic fibroblasts and effector CD8+ T lymphocytes, for which glycolysis is an important source of ATP and biosynthetic molecules. Treatments that induce ADA include CCCP, antimycin A, rotenone, oligomycin, and hypoxia. The Arp2/3 complex inhibitor CK666 or the mitochondrial sodium-calcium exchanger (NCLX) inhibitor CGP37157, applied simultaneously with the ADA stimulus, inhibit both ADA and the glycolytic increase within 5-min, suggesting that ADA is necessary for glycolytic stimulation. Two situations causing chronic reductions in mitochondrial ATP production, ethidium bromide treatment (to deplete mitochondrial DNA) and mutation to the NDUFS4 subunit of complex 1 of the electron transport chain, cause persistent peri-mitochondrial actin filaments of similar morphology to ADA. Both peri-mitochondrial actin loss and a 20% ATP decrease occur within 10 min of CK666 treatment in NDUFS4 knock-out cells. We propose that ADA is necessary for rapid glycolytic activation upon mitochondrial impairment, to re-establish ATP production.