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Limiting role of protein disulfide isomerase in the expression of collagen-tailed acetylcholinesterase forms in muscle.

Authors
  • Ruiz, Carlos A
  • Rotundo, Richard L
Type
Published Article
Journal
Journal of Biological Chemistry
Publisher
American Society for Biochemistry and Molecular Biology
Publication Date
Nov 13, 2009
Volume
284
Issue
46
Pages
31753–31763
Identifiers
DOI: 10.1074/jbc.M109.038471
PMID: 19758986
Source
Medline
License
Unknown

Abstract

The expression of acetylcholinesterase (AChE) in skeletal muscle is regulated by muscle activity; however, the underlying molecular mechanisms are incompletely understood. We show here that the expression of the synaptic collagen-tailed AChE form (ColQ-AChE) in quail muscle cultures can be regulated by muscle activity post-translationally. Inhibition of thiol oxidoreductase activity decreases expression of all active AChE forms. Likewise, primary quail myotubes transfected with protein disulfide isomerase (PDI) short hairpin RNAs showed a significant decrease of both the intracellular pool of all collagen-tailed AChE forms and cell surface AChE clusters. Conversely, overexpression of PDI, endoplasmic reticulum protein 72, or calnexin in muscle cells enhanced expression of all collagen-tailed AChE forms. Overexpression of PDI had the most dramatic effect with a 100% increase in the intracellular ColQ-AChE pool and cell surface enzyme activity. Moreover, the levels of PDI are regulated by muscle activity and correlate with the levels of ColQ-AChE and AChE tetramers. Finally, we demonstrate that PDI interacts directly with AChE intracellularly. These results show that collagen-tailed AChE form levels induced by muscle activity can be regulated by molecular chaperones and suggest that newly synthesized exportable proteins may compete for chaperone assistance during the folding process.

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