Human ATP synthase beta is phosphorylated at multiple sites and shows abnormal phosphorylation at specific sites in insulin-resistant muscle

K. Højlund, Z. Yi, N. Lefort, P. Langlais, B. Bowen, K. Levin, H. Beck-Nielsen, L. J. Mandarino

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

Aims/hypothesis: Insulin resistance in skeletal muscle is linked to mitochondrial dysfunction in obesity and type 2 diabetes. Emerging evidence indicates that reversible phosphorylation regulates oxidative phosphorylation (OxPhos) proteins. The aim of this study was to identify and quantify site-specific phosphorylation of the catalytic beta subunit of ATP synthase (ATPsyn-β) and determine protein abundance of ATPsyn-β and other OxPhos components in skeletal muscle from healthy and insulin-resistant individuals. Methods: Skeletal muscle biopsies were obtained from lean, healthy, obese, non-diabetic and type 2 diabetic volunteers (each group n = 10) for immunoblotting of proteins, and hypothesis-driven identification and quantification of phosphorylation sites on ATPsyn-β using targeted nanospray tandem mass spectrometry. Volunteers were metabolically characterised by euglycaemic-hyperinsulinaemic clamps. Results: Seven phosphorylation sites were identified on ATPsyn-β purified from human skeletal muscle. Obese individuals with and without type 2 diabetes were characterised by impaired insulin-stimulated glucose disposal rates, and showed a ∼30% higher phosphorylation of ATPsyn-β at Tyr361 and Thr213 (within the nucleotide-binding region of ATP synthase) as well as a coordinated downregulation of ATPsyn-β protein and other OxPhos components. Insulin increased Tyr361 phosphorylation of ATPsyn-β by ∼50% in lean and healthy, but not insulin-resistant, individuals. Conclusions/interpretation: These data demonstrate that ATPsyn-β is phosphorylated at multiple sites in human skeletal muscle, and suggest that abnormal site-specific phosphorylation of ATPsyn-β together with reduced content of OxPhos proteins contributes to mitochondrial dysfunction in insulin resistance. Further characterisation of phosphorylation of ATPsyn-β may offer novel targets of treatment in human diseases with mitochondrial dysfunction, such as diabetes.

Original languageEnglish (US)
Pages (from-to)541-551
Number of pages11
JournalDiabetologia
Volume53
Issue number3
DOIs
StatePublished - Mar 2010
Externally publishedYes

Keywords

  • ATP synthase
  • Insulin resistance
  • Mass spectrometry
  • Mitochondrial oxidative phosphorylation
  • Obesity
  • Proteomics
  • Type 2 diabetes

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

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