title: Mitochondrial stress-induced p53 attenuates HIF-1α activity by physical association and enhanced ubiquitination.
abstract: Retrograde signaling is a mechanism by which mitochondrial dysfunction is communicated to the nucleus for inducing a metabolic shift essential for cell survival. Previously, we showed that partial mitochondrial DNA (mtDNA) depletion in different cell types induced mitochondrial retrograde signaling pathway (MtRS) involving Ca+2-sensitive Calcineurin (Cn) activation as an immediate upstream event of stress response. In multiple cell types, this stress signaling was shown to induce tumorigenic phenotypes in immortalized cells. In this study we show that MtRS also induces p53 expression, which was abrogated by Ca2+chelators and short hairpin RNA-mediated knockdown of CnAβ mRNA. Mitochondrial dysfunction induced by mitochondrial ionophore, carbonyl cyanide m-chlorophenyl hydrazone and other respiratory inhibitors, which perturb the transmembrane potential, were equally efficient in inducing the expression of p53 and downregulation of MDM2. Stress-induced p53 physically interacted with hypoxia-inducible factor-1α (HIF-1α) and attenuated the latter's binding to promoter DNA motifs. In addition, p53 promoted ubiquitination and degradation of HIF-1α in partial mtDNA-depleted cells. The mtDNA depleted cells, with inhibited HIF-1α, showed upregulation of glycolytic pathway genes, glucose transporter 1-4 (Glut1-4), phosphoglycerate kinase 1 and Glucokinase but not of prolyl hydroxylase isoforms. For the first time we show that p53 is induced as part of MtRS and it renders HIF-1α inactive by physical interaction. In this respect, our results show that MtRS induces tumor growth independent of the HIF-1α pathway.
authors.affiliation: Department of Biomedical Sciences and Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: A Roy
authors.initials: AR
authors.lastname: Chowdhury
authors.affiliation: Division of Gastroenterology, Department of Medicine and Genetics, Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Long
authors.affiliation: Department of Biomedical Sciences and Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: S Y
authors.initials: SY
authors.lastname: Fuchs
authors.affiliation: Division of Gastroenterology, Department of Medicine and Genetics, Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Rustgi
authors.affiliation: Department of Biomedical Sciences and Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: N G
authors.initials: NG
authors.lastname: Avadhani
mesh_terms: D000072283:A549 Cells; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D004272:DNA, Mitochondrial / Q000235:genetics*; D045325:HCT116 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D051379:Mice; D008928:Mitochondria / Q000235:genetics*; D011485:Protein Binding; D051381:Rats; D017384:Sequence Deletion; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D004272:DNA, Mitochondrial; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D019703:Calcineurin; D002118:Calcium