HSP72 is a mitochondrial stress sensor critical for Parkin action, oxidative metabolism, and insulin sensitivity in skeletal muscle

Diabetes. 2014 May;63(5):1488-505. doi: 10.2337/db13-0665. Epub 2013 Dec 30.

Abstract

Increased heat shock protein (HSP) 72 expression in skeletal muscle prevents obesity and glucose intolerance in mice, although the underlying mechanisms of this observation are largely unresolved. Herein we show that HSP72 is a critical regulator of stress-induced mitochondrial triage signaling since Parkin, an E3 ubiquitin ligase known to regulate mitophagy, was unable to ubiquitinate and control its own protein expression or that of its central target mitofusin (Mfn) in the absence of HSP72. In wild-type cells, we show that HSP72 rapidly translocates to depolarized mitochondria prior to Parkin recruitment and immunoprecipitates with both Parkin and Mfn2 only after specific mitochondrial insult. In HSP72 knockout mice, impaired Parkin action was associated with retention of enlarged, dysmorphic mitochondria and paralleled by reduced muscle respiratory capacity, lipid accumulation, and muscle insulin resistance. Reduced oxygen consumption and impaired insulin action were recapitulated in Parkin-null myotubes, confirming a role for the HSP72-Parkin axis in the regulation of muscle insulin sensitivity. These data suggest that strategies to maintain HSP72 may provide therapeutic benefit to enhance mitochondrial quality and insulin action to ameliorate complications associated with metabolic diseases, including type 2 diabetes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Respiration / drug effects
  • Cell Respiration / physiology
  • HEK293 Cells
  • HSP72 Heat-Shock Proteins / genetics
  • HSP72 Heat-Shock Proteins / metabolism*
  • Humans
  • Insulin / metabolism*
  • Insulin / pharmacology
  • Insulin Resistance / physiology
  • Lipid Metabolism / drug effects
  • Lipid Metabolism / physiology
  • Mice
  • Mice, Knockout
  • Mitochondria / drug effects
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism*
  • Oxidative Stress / drug effects
  • Oxidative Stress / physiology*
  • Oxygen Consumption / drug effects
  • Oxygen Consumption / physiology
  • Reactive Oxygen Species / metabolism
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*

Substances

  • HSP72 Heat-Shock Proteins
  • Insulin
  • Reactive Oxygen Species
  • Ubiquitin-Protein Ligases
  • parkin protein