Atrogin-1 and MuRF1 regulate cardiac MyBP-C levels via different mechanisms
| Autor: | Marcelo D. Gomes, Peirang Cao, Christina Gedicke, Monte S. Willis, Lucie Carrier, Stewart H. Lecker, Saskia Schlossarek, Christian C. Witt, Thomas Eschenhagen, Siegfried Labeit, Giulia Mearini, Elisabeth Krämer |
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| Rok vydání: | 2009 |
| Předmět: |
Proteasome Endopeptidase Complex
Physiology Ubiquitin-Protein Ligases Mutant Muscle Proteins Gene mutation Sarcomere Tripartite Motif Proteins Mice Ubiquitin Physiology (medical) Myosin Animals Humans Myocyte Myocytes Cardiac SKP Cullin F-Box Protein Ligases biology Myocardium Binding protein Original Articles Molecular biology Ubiquitin ligase biology.protein Carrier Proteins Cardiology and Cardiovascular Medicine |
| Zdroj: | Cardiovascular Research. 85:357-366 |
| ISSN: | 1755-3245 0008-6363 |
| DOI: | 10.1093/cvr/cvp348 |
| Popis: | 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 results Human 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. |
| Databáze: | OpenAIRE |
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