Abstract
Mutations in human CLC-1 chloride channel are associated with the skeletal muscle disorder myotonia congenita. The disease-causing mutant A531V manifests enhanced proteasomal degradation of CLC-1. We recently found that CLC-1 degradation is mediated by cullin 4 ubiquitin ligase complex. It is currently unclear how quality control and protein degradation systems coordinate with each other to process the biosynthesis of CLC-1. Herein we aim to ascertain the molecular nature of the protein quality control system for CLC-1. We identified three CLC-1-interacting proteins that are well-known heat shock protein 90 (Hsp90)-associated co-chaperones: FK506-binding protein 8 (FKBP8), activator of Hsp90 ATPase homolog 1 (Aha1), and Hsp70/Hsp90 organizing protein (HOP). These co-chaperones promote both the protein level and the functional expression of CLC-1 wild-type and A531V mutant. CLC-1 biosynthesis is also facilitated by the molecular chaperones Hsc70 and Hsp90β. The protein stability of CLC-1 is notably increased by FKBP8 and the Hsp90β inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) that substantially suppresses cullin 4 expression. We further confirmed that cullin 4 may interact with Hsp90β and FKBP8. Our data are consistent with the idea that FKBP8 and Hsp90β play an essential role in the late phase of CLC-1 quality control by dynamically coordinating protein folding and degradation.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Chloride Channels / antagonists & inhibitors
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Chloride Channels / genetics*
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Chloride Channels / metabolism
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Cullin Proteins / genetics
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Cullin Proteins / metabolism
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Cysteine Proteinase Inhibitors / pharmacology
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Gene Expression Regulation
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Genetic Vectors / chemistry
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Genetic Vectors / metabolism
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HEK293 Cells
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HSP90 Heat-Shock Proteins / genetics*
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HSP90 Heat-Shock Proteins / metabolism
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Homeodomain Proteins / genetics*
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Homeodomain Proteins / metabolism
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Humans
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Lentivirus / genetics
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Lentivirus / metabolism
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Leupeptins / pharmacology
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Models, Biological
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Molecular Chaperones / genetics*
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Molecular Chaperones / metabolism
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Myotonia Congenita / genetics
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Myotonia Congenita / metabolism
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Myotonia Congenita / pathology
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Patch-Clamp Techniques
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Proteasome Endopeptidase Complex / drug effects
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Proteasome Endopeptidase Complex / metabolism
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Proteolysis
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism
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Signal Transduction
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Tacrolimus Binding Proteins / genetics*
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Tacrolimus Binding Proteins / metabolism
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Transfection
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Tumor Suppressor Proteins / genetics*
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Tumor Suppressor Proteins / metabolism
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Ubiquitination / drug effects
Substances
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AHSA1 protein, human
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CLC-1 channel
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CUL4A protein, human
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Chloride Channels
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Cullin Proteins
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Cysteine Proteinase Inhibitors
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FKBP8 protein, human
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HOPX protein, human
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HSP90 Heat-Shock Proteins
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HSP90AB1 protein, human
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Homeodomain Proteins
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Leupeptins
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Molecular Chaperones
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RNA, Small Interfering
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Tumor Suppressor Proteins
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Proteasome Endopeptidase Complex
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Tacrolimus Binding Proteins
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benzyloxycarbonylleucyl-leucyl-leucine aldehyde