title: miR-24-mediated knockdown of H2AX damages mitochondria and the insulin signaling pathway.
abstract: Mitochondrial deficits or altered expressions of microRNAs are associated with the pathogenesis of various diseases, and microRNA-operated control of mitochondrial activity has been reported. Using a retrovirus-mediated short-hairpin RNA (shRNA) system, we observed that miR-24-mediated H2AX knockdown (H2AX-KD) impaired both mitochondria and the insulin signaling pathway. The overexpression of miR-24 decreased mitochondrial H2AX and disrupted mitochondrial function, as indicated by the ATP content, membrane potential and oxygen consumption. Similar mitochondrial damage was observed in shH2AX-mediated specific H2AX-KD cells. The H2AX-KD reduced the expression levels of mitochondrial transcription factor A (TFAM) and mitochondrial DNA-dependent transcripts. H2AX-KD mitochondria were swollen, and their cristae were destroyed. H2AX-KD also blocked the import of precursor proteins into mitochondria and the insulin-stimulated phosphorylation of IRS-1 (Y632) and Akt (S473 and T308). The rescue of H2AX, but not the nuclear form of ΔC24-H2AX, restored all features of miR-24- or shH2AX-mediated impairment of mitochondria. Hepatic miR-24 levels were significantly increased in db/db and ob/ob mice. A strong feedback loop may be present among miR-24, H2AX, mitochondria and the insulin signaling pathway. Our findings suggest that H2AX-targeting miR-24 may be a novel negative regulator of mitochondrial function and is implicated in the pathogenesis of insulin resistance.
authors.affiliation: Department of Neuroscience, Graduate School, Seoul, Korea.
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Jeong
authors.affiliation: Department of Neuroscience, Graduate School, Seoul, Korea.
authors.forename: Young
authors.initials: Y
authors.lastname: Cheol Kang
authors.affiliation: Department of Neuroscience, Graduate School, Seoul, Korea.
authors.forename: Ying
authors.initials: Y
authors.lastname: Piao
authors.affiliation: Department of Neuroscience, Graduate School, Seoul, Korea.
authors.forename: Sora
authors.initials: S
authors.lastname: Kang
authors.affiliation: Department of Neuroscience, Graduate School, Seoul, Korea.|Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Youngmi Kim
authors.initials: YK
authors.lastname: Pak
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D045744:Cell Line, Tumor; D019069:Cell Respiration; D020868:Gene Silencing; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: C468783:H2AX protein, human; D006657:Histones; C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; C543845:MIRN24 microRNA, human; D035683:MicroRNAs; D000255:Adenosine Triphosphate