CSN-5, a component of the COP9 signalosome complex, regulates the levels of UNC-96 and UNC-98, two components of M-lines in Caenorhabditis elegans muscle

Mol Biol Cell. 2009 Aug;20(15):3608-16. doi: 10.1091/mbc.e09-03-0208. Epub 2009 Jun 17.

Abstract

In Caenorhabditis elegans two M-line proteins, UNC-98 and UNC-96, are involved in myofibril assembly and/or maintenance, especially myosin thick filaments. We found that CSN-5, a component of the COP9 signalosome complex, binds to UNC-98 and -96 using the yeast two-hybrid method. These interactions were confirmed by biochemical methods. The CSN-5 protein contains a Mov34 domain. Although one other COP9 signalosome component, CSN-6, also has a Mov34 domain, CSN-6 did not interact with UNC-98 or -96. Anti-CSN-5 antibody colocalized with paramyosin at A-bands in wild type and colocalized with abnormal accumulations of paramyosin found in unc-98, -96, and -15 (encodes paramyosin) mutants. Double knockdown of csn-5 and -6 could slightly suppress the unc-96 mutant phenotype. In the double knockdown of csn-5 and -6, the levels of UNC-98 protein were increased and the levels of UNC-96 protein levels were slightly reduced, suggesting that CSN-5 promotes the degradation of UNC-98 and that CSN-5 stabilizes UNC-96. In unc-15 and unc-96 mutants, CSN-5 protein was reduced, implying the existence of feed back regulation from myofibril proteins to CSN-5 protein levels. Taken together, we found that CSN-5 functions in muscle cells to regulate UNC-98 and -96, two M-line proteins.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • COP9 Signalosome Complex
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Fluorescent Antibody Technique
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Muscles / metabolism*
  • Mutation
  • Peptide Hydrolases / genetics
  • Peptide Hydrolases / metabolism
  • Protein Binding
  • RNA Interference
  • Tropomyosin / genetics
  • Tropomyosin / metabolism
  • Two-Hybrid System Techniques

Substances

  • CSN-5 protein, C elegans
  • Caenorhabditis elegans Proteins
  • Carrier Proteins
  • Multiprotein Complexes
  • Muscle Proteins
  • Tropomyosin
  • UNC-15 protein, C elegans
  • UNC-96 protein, C elegans
  • UNC-98 protein, C elegans
  • Peptide Hydrolases
  • COP9 Signalosome Complex