Mitochondrial MDM2 Regulates Respiratory Complex I Activity Independently of p53

Mol Cell. 2018 Feb 15;69(4):594-609.e8. doi: 10.1016/j.molcel.2018.01.023.

Abstract

Accumulating evidence indicates that the MDM2 oncoprotein promotes tumorigenesis beyond its canonical negative effects on the p53 tumor suppressor, but these p53-independent functions remain poorly understood. Here, we show that a fraction of endogenous MDM2 is actively imported in mitochondria to control respiration and mitochondrial dynamics independently of p53. Mitochondrial MDM2 represses the transcription of NADH-dehydrogenase 6 (MT-ND6) in vitro and in vivo, impinging on respiratory complex I activity and enhancing mitochondrial ROS production. Recruitment of MDM2 to mitochondria increases during oxidative stress and hypoxia. Accordingly, mice lacking MDM2 in skeletal muscles exhibit higher MT-ND6 levels, enhanced complex I activity, and increased muscular endurance in mild hypoxic conditions. Furthermore, increased mitochondrial MDM2 levels enhance the migratory and invasive properties of cancer cells. Collectively, these data uncover a previously unsuspected function of the MDM2 oncoprotein in mitochondria that play critical roles in skeletal muscle physiology and may contribute to tumor progression.

Keywords: MDM2; MT-ND6; hypoxia; migration; mitochondria; respiratory complex I.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / genetics
  • Adenocarcinoma / metabolism
  • Adenocarcinoma / pathology
  • Animals
  • Carcinoma, Non-Small-Cell Lung / genetics
  • Carcinoma, Non-Small-Cell Lung / metabolism
  • Carcinoma, Non-Small-Cell Lung / pathology*
  • Cell Movement
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / metabolism
  • Cell Transformation, Neoplastic / pathology*
  • Electron Transport Complex I / genetics
  • Electron Transport Complex I / metabolism*
  • Gene Expression Regulation, Neoplastic*
  • Genome, Mitochondrial
  • Humans
  • Lung Neoplasms / genetics
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitochondria / genetics
  • Mitochondria / metabolism
  • Mitochondria / pathology*
  • Neoplasm Invasiveness
  • Oxidative Stress
  • Proto-Oncogene Proteins c-mdm2 / genetics
  • Proto-Oncogene Proteins c-mdm2 / metabolism*
  • Signal Transduction
  • Transcription, Genetic
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Xenograft Model Antitumor Assays

Substances

  • Tumor Suppressor Protein p53
  • Proto-Oncogene Proteins c-mdm2
  • Electron Transport Complex I