Atrogin-1 and MuRF1 regulate cardiac MyBP-C levels via different mechanisms

Giulia Mearini, Christina Gedicke, Saskia Schlossarek, Christian C. Witt, Elisabeth Krämer, Peirang Cao, Marcelo D. Gomes, Stewart H. Lecker, Siegfried Labeit, Monte S. Willis, Thomas Eschenhagen, Lucie Carrier

Research output: Contribution to journalArticle

63 Scopus citations

Abstract

Aims Familial hypertrophic cardiomyopathy (FHC) is frequently caused by cardiac myosin-binding protein C (cMyBP-C) gene mutations, which should result in C-terminal truncated mutants. However, truncated mutants were not detected in myocardial tissue of FHC patients and were rapidly degraded by the ubiquitin-proteasome system (UPS) after gene transfer in cardiac myocytes. Since the diversity and specificity of UPS regulation lie in E3 ubiquitin ligases, we investigated whether the muscle-specific E3 ligases atrogin-1 or muscle ring finger protein-1 (MuRF1) mediate degradation of truncated cMyBP-C. Methods and resultsHuman wild-type (WT) and truncated (M7t, resulting from a human mutation) cMyBP-C species were co-immunoprecipitated with atrogin-1 after adenoviral overexpression in cardiac myocytes, and WT-cMyBP-C was identified as an interaction partner of MuRF1 by yeast two-hybrid screens. Overexpression of atrogin-1 in cardiac myocytes decreased the protein level of M7t-cMyBP-C by 80 and left WT-cMyBP-C level unaffected. This was rescued by proteasome inhibition. In contrast, overexpression of MuRF1 in cardiac myocytes not only reduced the protein level of WT- and M7t-cMyBP-C by >60, but also the level of myosin heavy chains (MHCs) by >40, which were not rescued by proteasome inhibition. Both exogenous cMyBP-C and endogenous MHC mRNA levels were markedly reduced by MuRF1 overexpression. Similar to cardiac myocytes, MuRF1-overexpressing (TG) mice exhibited 40 lower levels of MHC mRNAs and proteins. Protein levels of cMyBP-C were 29 higher in MuRF1 knockout and 34 lower in TG than in WT, without a corresponding change in mRNA levels. Conclusion These data suggest that atrogin-1 specifically targets truncated M7t-cMyBP-C, but not WT-cMyBP-C, for proteasomal degradation and that MuRF1 indirectly reduces cMyBP-C levels by regulating the transcription of MHC.

Original languageEnglish (US)
Pages (from-to)357-366
Number of pages10
JournalCardiovascular research
Volume85
Issue number2
DOIs
StatePublished - Jan 1 2010
Externally publishedYes

Keywords

  • Atrogin-1
  • E3 ubiquitin ligase
  • MuRF1
  • Myosin-binding protein C
  • Sarcomere

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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    Mearini, G., Gedicke, C., Schlossarek, S., Witt, C. C., Krämer, E., Cao, P., Gomes, M. D., Lecker, S. H., Labeit, S., Willis, M. S., Eschenhagen, T., & Carrier, L. (2010). Atrogin-1 and MuRF1 regulate cardiac MyBP-C levels via different mechanisms. Cardiovascular research, 85(2), 357-366. https://doi.org/10.1093/cvr/cvp348