A role for ubiquitinylation and the cytosolic proteasome in turnover of mitochondrial uncoupling protein 1 (UCP1)

Kieran J. Clarke, Alison E. Adams, Lars H. Manzke, Terry W. Pearson, Christoph H. Borchers, Richard K. Porter

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

In this study we show that mitochondrial uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) and thymus mitochondria can be ubiquitinylated and degraded by the cytosolic proteasome. Using a ubiquitin conjugating system, we show that UCP1 can be ubiquitinylated in vitro. We demonstrate that UCP1 is ubiquitinylated in vivo using isolated mitochondria from brown adipose tissue, thymus and whole brown adipocytes. Using an in vitro ubiquitin conjugating-proteasome degradation system, we show that the cytosolic proteasome can degrade UCP1 at a rate commensurate with the half-life of UCP1 (i.e. 30-72 h in brown adipocytes and ~ 3 h, in thymocytes). In addition, we demonstrate that the cytoplasmic proteasome is required for UCP1 degradation from mitochondria that the process is inhibited by the proteasome inhibitor MG132 and that dissipation of the mitochondrial membrane potential inhibits degradation of UCP1. There also appears to be a greater amount of ubiquitinylated UCP1 associated with BAT mitochondria from cold-acclimated animals. We have also identified (using immunoprecipitation coupled with mass spectrometry) ubiquitinylated proteins with molecular masses greater than 32 kDa, as being UCP1. We conclude that there is a role for ubiquitinylation and the cytosolic proteasome in turnover of mitochondrial UCP1.

Original languageEnglish
Pages (from-to)1759-1767
Number of pages9
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1817
Issue number10
DOIs
Publication statusPublished - Oct 2012
Externally publishedYes

Keywords

  • Brown adipose tissue
  • Mitochondria
  • Proteosome
  • Thymus
  • Ubiquitinylation
  • UCP1

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