Limiting role of protein disulfide isomerase in the expression of collagen-tailed acetylcholinesterase forms in muscle.
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.
Ruiz
Carlos A
CA
Department of Cell Biology and Anatomy and the Neuroscience Program, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
Rotundo
Richard L
RL
D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D037281:Calnexin / Q000378:metabolism; D037282:Calreticulin / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D003094:Collagen / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005109:Extracellular Matrix; D005455:Fluorescent Antibody Technique; D015971:Gene Expression Regulation, Enzymologic; D047468:Immunoprecipitation; D008562:Membrane Glycoproteins / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism*; D009132:Muscles / Q000166:cytology / Q000201:enzymology*; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D011784:Quail / Q000196:embryology; D012323:RNA Processing, Post-Transcriptional; D014158:Transcription, Genetic
D037282:Calreticulin; D008562:Membrane Glycoproteins; C062477:endoplasmic reticulum glycoprotein p72; D037281:Calnexin; D003094:Collagen; D000110:Acetylcholinesterase; D019704:Protein Disulfide-Isomerases