title: Deletion of PRKAA triggers mitochondrial fission by inhibiting the autophagy-dependent degradation of DNM1L.
abstract: PRKAA (protein kinase, AMP-activated, α catalytic subunit) regulates mitochondrial biogenesis, function, and turnover. However, the molecular mechanisms by which PRKAA regulates mitochondrial dynamics remain poorly characterized. Here, we report that PRKAA regulated mitochondrial fission via the autophagy-dependent degradation of DNM1L (dynamin 1-like). Deletion of Prkaa1/AMPKα1 or Prkaa2/AMPKα2 resulted in defective autophagy, DNM1L accumulation, and aberrant mitochondrial fragmentation in the mouse aortic endothelium. Furthermore, autophagy inhibition by chloroquine treatment or ATG7 small interfering RNA (siRNA) transfection, upregulated DNM1L expression and triggered DNM1L-mediated mitochondrial fragmentation. In contrast, autophagy activation by overexpression of ATG7 or chronic administration of rapamycin, the MTOR inhibitor, promoted DNM1L degradation and attenuated mitochondrial fragmentation in Prkaa2-deficient (prkaa2-/-) mice, suggesting that defective autophagy contributes to enhanced DNM1L expression and mitochondrial fragmentation. Additionally, the autophagic receptor protein SQSTM1/p62, which bound to DNM1L and led to its translocation into the autophagosome, was involved in DNM1L degradation by the autophagy-lysosome pathway. Gene silencing of SQSTM1 markedly reduced the association between SQSTM1 and DNM1L, impaired the degradation of DNM1L, and enhanced mitochondrial fragmentation in PRKAA-deficient endothelial cells. Finally, the genetic (DNM1L siRNA) or pharmacological (mdivi-1) inhibition of DNMA1L ablated mitochondrial fragmentation in the mouse aortic endothelium and prevented the acetylcholine-induced relaxation of isolated mouse aortas. This suggests that aberrant DNM1L is responsible for enhanced mitochondrial fragmentation and endothelial dysfunction in prkaa knockout mice. Overall, our results show that PRKAA deletion promoted mitochondrial fragmentation in vascular endothelial cells by inhibiting the autophagy-dependent degradation of DNM1L.
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Qilong
authors.initials: Q
authors.lastname: Wang
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Shengnan
authors.initials: S
authors.lastname: Wu
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Huaiping
authors.initials: H
authors.lastname: Zhu
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Ding
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Dai
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Changhan
authors.initials: C
authors.lastname: Ouyang
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Han
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Zhonglin
authors.initials: Z
authors.lastname: Xie
authors.affiliation: a Center for Molecular and Translational Medicine, Georgia State University , Atlanta , GA USA.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zou
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000648:ultrastructure; D001343:Autophagy / Q000187:drug effects; D002469:Cell Separation; D034281:Dynamins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D017353:Gene Deletion; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D063154:Mitochondrial Dynamics / Q000187:drug effects; D024101:Mitochondrial Proteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D000071456:Sequestosome-1 Protein / Q000378:metabolism; D020123:Sirolimus / Q000008:administration & dosage / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects
chemical_list: D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D010768:Phosphoserine; C526181:PRKAA2 protein, human; D055372:AMP-Activated Protein Kinases; C526180:PRKAA1 protein, human; D020558:GTP Phosphohydrolases; C110768:DNM1L protein, human; C486391:Dnm1l protein, mouse; D034281:Dynamins; D020123:Sirolimus
keywords: AMPK; DNM1L; PRKAA/AMPK catalytic subunit α; autophagy; endothelial dysfunction; mitochondrial fission