Developmental regulation of MURF E3 ubiquitin ligases in skeletal muscle

J Muscle Res Cell Motil. 2012 Jun;33(2):107-22. doi: 10.1007/s10974-012-9288-7. Epub 2012 Mar 17.

Abstract

The striated muscle-specific tripartite motif (TRIM) proteins TRIM63/MURF1, TRIM55/MURF2 and TRIM54/MURF3 can function as E3 ubiquitin ligases in ubiquitin-mediated muscle protein turnover. Despite the well-characterised role of MURF1 in skeletal muscle atrophy, the dynamics of MURF isogene expression in the development and early postnatal adaptation of skeletal muscle is unknown. Here, we show that MURF2 is the isogene most highly expressed in embryonic skeletal muscle at E15.5, with the 50 kDa A isoform predominantly expressed. MURF1 and MURF3 are upregulated only postnatally. Knockdown of MURF2 p50A by isoform-specific siRNA results in delayed myogenic differentiation and myotube formation in vitro, with perturbation of the stable, glutamylated microtubule population. This underscores that MURF2 plays an important role in the earliest stages of skeletal muscle differentiation and myofibrillogenesis. During further development, there is a shift towards the 60 kDa A isoform, which dominates postnatally. Analysis of the fibre-type expression shows that MURF2 A isoforms are predominantly slow-fibre associated, whilst MURF1 is largely excluded from these fibres, and MURF3 is ubiquitously distributed in both type I and II fibres.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation
  • Embryo, Mammalian / cytology
  • Embryo, Mammalian / embryology
  • Embryo, Mammalian / metabolism
  • Embryonic Development
  • Fluorescent Antibody Technique
  • Gene Expression Regulation, Developmental*
  • Gene Knockdown Techniques
  • Mice
  • Mice, Inbred C57BL
  • Microtubules / genetics
  • Microtubules / metabolism
  • Muscle Development
  • Muscle Fibers, Skeletal / cytology
  • Muscle Fibers, Skeletal / metabolism
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / embryology
  • Muscle, Skeletal / metabolism*
  • Myoblasts / cytology
  • Myoblasts / metabolism
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • RNA, Small Interfering
  • Transfection
  • Tripartite Motif Proteins
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • Muscle Proteins
  • Protein Isoforms
  • RNA, Small Interfering
  • Rnf30 protein, mouse
  • Tripartite Motif Proteins
  • muscle RING finger 2 protein, mouse
  • Trim63 protein, mouse
  • Ubiquitin-Protein Ligases