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Parallel kinase pathways stimulate actin polymerization at depolarized mitochondria

ABSTRACT: Mitochondrial damage (MtD) represents a dramatic change in cellular homeostasis, necessitating metabolic changes and stimulating mitophagy. One rapid response to MtD is rapid peri-mitochondrial actin polymerization, termed ADA (acute damage-induced actin). The activation mechanism for ADA is unknown. Here, we use mitochondrial depolarization or the complex I inhibitor metformin to induce ADA. We show that two parallel signaling pathways are required for ADA. In one pathway, increased cytosolic calcium activates in turn PKC-β, Rac, WAVE regulatory complex, and Arp2/3 complex. In the other pathway, a drop in cellular ATP activates in turn AMPK (through LKB1), Cdc42, and FMNL formins. We also identify putative guanine nucleotide exchange factors for Rac and Cdc42, Trio and Fgd1 respectively, whose phosphorylation states increase upon mitochondrial depolarization and whose suppression inhibits ADA. The depolarization-induced calcium increase is dependent on the mitochondrial sodium-calcium exchanger NCLX, suggesting initial mitochondrial calcium efflux. We also show that ADA inhibition results in enhanced mitochondrial shape changes upon mitochondrial depolarization, suggesting that ADA inhibits these shape changes. These depolarization-induced shape changes are not fragmentation but a circularization of the inner mitochondrial membrane, dependent on the inner mitochondrial membrane protease Oma1. ADA inhibition increases proteolytic processing of an Oma1 substrate, the dynamin GTPase Opa1. These results show that ADA requires the combined action of Arp2/3 complex and formin proteins to polymerize a network of actin filaments around mitochondria, and that the ADA network inhibits the rapid mitochondrial shape changes that occur upon mitochondrial depolarization.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Mus Musculus (mouse)

SUBMITTER: Tak Shun Fung

LAB HEAD: Henry N Higgs

PROVIDER: PXD031699 | Pride | 2022-03-15

REPOSITORIES: Pride

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			Action	DRS
	Experiment_Higgs_020421_TMT1_Lysate_from_Higgs_020421_Lysate_SF01__17_others.mzid.gz	Mzid
	Experiment_Higgs_020421_TMT1_Lysate_from_Higgs_020421_Lysate_SF01__17_others.mzid_Experiment_Higgs_020421_TMT1_Lysate_from_Higgs_020421_Lysate_SF01__17_others.MGF	Mzid
	Experiment_Higgs_020421_TMT1_Phos_from_Higgs_020421_Phos_SF01__17_others.mzid.gz	Mzid
	Experiment_Higgs_020421_TMT1_Phos_from_Higgs_020421_Phos_SF01__17_others.mzid_Experiment_Higgs_020421_TMT1_Phos_from_Higgs_020421_Phos_SF01__17_others.MGF	Mzid
	Experiment_MaxQuant_lysate_from_Higgs_lysate_070121_SF01__17_others.mzid.gz	Mzid

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Parallel kinase pathways stimulate actin polymerization at depolarized mitochondria.

Fung Tak Shun TS Chakrabarti Rajarshi R Kollasser Jana J Rottner Klemens K Stradal Theresia E B TEB Kage Frieda F Higgs Henry N HN

Current biology : CB 20220314 7

Mitochondrial damage (MtD) represents a dramatic change in cellular homeostasis, necessitating metabolic changes and stimulating mitophagy. One rapid response to MtD is a rapid peri-mitochondrial actin polymerization termed ADA (acute damage-induced actin). The activation mechanism for ADA is unknown. Here, we use mitochondrial depolarization or the complex I inhibitor metformin to induce ADA. We show that two parallel signaling pathways are required for ADA. In one pathway, increased cytosolic ...[more]

PMID: 35290799

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