A cyclic AMP-dependent pathway regulates the expression of acetylcholinesterase during myogenic differentiation of C2C12 cells.
The expression of acetylcholinesterase (AChE) is markedly increased during myogenic differentiation of C2C12 myoblasts to myotubes; the expression is mediated by intrinsic factor(s) during muscle differentiation. In order to analyze the molecular mechanisms regulating AChE expression during myogenic differentiation, a approximately 2.2-kb human AChE promoter tagged with a luciferase reporter gene, namely pAChE-Luc, was stably transfected into C2C12 cells. The profile of promoter-driven luciferase activity during myogenic differentiation of C2C12 myotubes was found to be similar to that of endogenous expression of AChE catalytic subunit. The increase of AChE expression was reciprocally regulated by a cAMP-dependent signaling pathway. The level of intracellular cAMP, the activity of cAMP-dependent protein kinase, the phosphorylation of cAMP-responsive element binding protein and the activity of cAMP- responsive element (CRE) were down-regulated during the myotube formation. Mutating the CRE site of human AChE promoter altered the original myogenic profile of the promoter activity and its suppressive response to cAMP. In addition, the suppressive effect of the CRE site is dependent on its location on the promoter. Therefore, our results suggest that a cAMP-dependent signaling pathway serves as a suppressive element in regulating the expression of AChE during early myogenesis.
Siow
Nina L
NL
Department of Biology and Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay Road, Hong Kong, China.
Choi
Roy C Y
RC
Cheng
Anthony W M
AW
Jiang
Joy X S
JX
Wan
David C C
DC
Zhu
Shang Q
SQ
Tsim
Karl W K
KW
D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D015152:Blotting, Northern; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D015151:Immunoblotting; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D009132:Muscles / Q000166:cytology*; D009154:Mutation; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D004247:DNA; D000242:Cyclic AMP; D008156:Luciferases; D017868:Cyclic AMP-Dependent Protein Kinases; D000110:Acetylcholinesterase