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AMPK activation induces mitophagy and promotes mitochondrial fission while activating TBK1 in a PINK1-Parkin independent manner

Abstract

Mitophagy is a key process regulating mitochondrial quality control. Several mechanisms have been proposed to regulate mitophagy, but these have mostly been studied using stably expressed non-native proteins in immortalized cell lines. In skeletal muscle, mitophagy and its molecular mechanisms require more thorough investigation. To measure mitophagy directly, we generated a stable skeletal muscle C2C12 cell line, expressing a mitophagy reporter construct (mCherry-green fluorescence protein-mtFIS1101-152 ). Here, we report that both carbonyl cyanide m-chlorophenyl hydrazone (CCCP) treatment and adenosine monophosphate activated protein kinase (AMPK) activation by 991 promote mitochondrial fission via phosphorylation of MFF and induce mitophagy by ~20%. Upon CCCP treatment, but not 991, ubiquitin phosphorylation, a read-out of PTEN-induced kinase 1 (PINK1) activity, and Parkin E3 ligase activity toward CDGSH iron sulfur domain 1 (CISD1) were increased. Although the PINK1-Parkin signaling pathway is active in response to CCCP treatment, we observed no change in markers of mitochondrial protein content. Interestingly, our data shows that TANK-binding kinase 1 (TBK1) phosphorylation is increased after both CCCP and 991 treatments, suggesting TBK1 activation to be independent of both PINK1 and Parkin. Finally, we confirmed in non-muscle cell lines that TBK1 phosphorylation occurs in the absence of PINK1 and is regulated by AMPK-dependent signaling. Thus, AMPK activation promotes mitophagy by enhancing mitochondrial fission (via MFF phosphorylation) and autophagosomal engulfment (via TBK1 activation) in a PINK1-Parkin independent manner.

Type Journal
ISBN 1530-6860 (Electronic) 0892-6638 (Linking)
Authors Seabright, A. P.; Fine, N. H. F.; Barlow, J. P.; Lord, S. O.; Musa, I.; Gray, A.; Bryant, J. A.; Banzhaf, M.; Lavery, G. G.; Hardie, D. G.; Hodson, D. J.; Philp, A.; Lai, Y. C. EPUB
Responsible Garvan Author Dr Andy Philp
Publisher Name FASEB JOURNAL
Published Date 2020-05-01
Published Volume 34
Published Issue 5
Published Pages 6284-6301
Status Published in-print
DOI 10.1096/fj.201903051R
URL link to publisher's version https://www.ncbi.nlm.nih.gov/pubmed/32201986