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

• Type of Material: Article
• Authors: Rachel K. Miller, Emory University; Hiroshi Qadota, Emory University; Thomas J. Stark, Emory University; Kristina B. Mercer, Emory University; Tesheka S. Wortham, Emory University; Akwasi Anyanful, Emory University; Guy Benian, Emory University
• Language: English
• Date: 2009-08-01
• Publisher: American Society for Cell Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2009 by The American Society for Cell Biology
• Final Published Version (URL): http://www.molbiolcell.org/content/20/15/3608
• Title of Journal or Parent Work: Molecular Biology of the Cell
• ISSN: 1059-1524
• Volume: 20
• Issue: 15
• Start Page: 3608
• End Page: 3616
• Grant/Funding Information: These studies were supported by Grant AR052133 from the National Institutes of Health to G.M.B. and predoctoral fellowship 0415274B from the American Heart Association Southeast Affiliate to R.K.M.; Some strains used in this work were provided by the Caenorhabditis Genetics Center, which is supported by the National Center for Research Resources of the National Institutes of Health.
• Research Categories: Health Sciences, Pathology; Biology, Molecular; Biology, Cell

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.