Abstract |
MYOGENIN is a member of the muscle regulatory factor family that orchestrates an obligatory step in myogenesis, the terminal differentiation of skeletal muscle cells. A paradoxical feature of alveolar rhabdomyosarcoma (ARMS), a prevalent soft tissue sarcoma in children arising from cells with a myogenic phenotype, is the inability of these cells to undergo terminal differentiation despite the expression of MYOGENIN. The chimeric PAX3-FOXO1 fusion protein which results from a chromosomal translocation in ARMS has been implicated in blocking cell cycle arrest, preventing myogenesis from occurring. We report here that PAX3-FOXO1 enhances glycogen synthase kinase 3β (GSK3β) activity which in turn represses MYOGENIN activity. MYOGENIN is a GSK3β substrate in vitro on the basis of in vitro kinase assays and MYOGENIN is phosphorylated in ARMS-derived RH30 cells. Constitutively active GSK3β(S9A) increased the level of a phosphorylated form of MYOGENIN on the basis of western blot analysis and this effect was reversed by neutralization of the single consensus GSK3β phosphoacceptor site by mutation (S160/164A). Congruently, GSK3β inhibited the trans-activation of an E-box reporter gene by wild-type MYOGENIN, but not MYOGENIN with the S160/164A mutations. Functionally, GSK3β repressed muscle creatine kinase (MCK) promoter activity, an effect which was reversed by the S160/164A mutated MYOGENIN. Importantly, GSK3β inhibition or exogenous expression of the S160/164A mutated MYOGENIN in ARMS reduced the anchorage independent growth of RH30 cells in colony-formation assays. Thus, sustained GSK3β activity represses a critical regulatory step in the myogenic cascade, contributing to the undifferentiated, proliferative phenotype in alveolar rhabdomyosarcoma (ARMS).
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Authors | M G Dionyssiou, S Ehyai, E Avrutin, M K Connor, J C McDermott |
Journal | Cell death & disease
(Cell Death Dis)
Vol. 5
Pg. e1094
(Feb 27 2014)
ISSN: 2041-4889 [Electronic] England |
PMID | 24577092
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- MYOG protein, human
- Myogenin
- Oncogene Proteins, Fusion
- PAX3-FOXO1A fusion protein, human
- Paired Box Transcription Factors
- Protein Kinase Inhibitors
- GSK3B protein, human
- Glycogen Synthase Kinase 3 beta
- Gsk3b protein, mouse
- Proto-Oncogene Proteins c-akt
- Glycogen Synthase Kinase 3
- Creatine Kinase, MM Form
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Topics |
- Animals
- COS Cells
- Cell Line, Tumor
- Cell Proliferation
- Chlorocebus aethiops
- Creatine Kinase, MM Form
(genetics, metabolism)
- Electric Stimulation
- Enzyme Activation
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Neoplastic
- Genotype
- Glycogen Synthase Kinase 3
(antagonists & inhibitors, genetics, metabolism)
- Glycogen Synthase Kinase 3 beta
- Mice
- Mutation
- Myogenin
(genetics, metabolism)
- Oncogene Proteins, Fusion
(genetics, metabolism)
- Paired Box Transcription Factors
(genetics, metabolism)
- Phenotype
- Phosphorylation
- Promoter Regions, Genetic
- Protein Kinase Inhibitors
(pharmacology)
- Proto-Oncogene Proteins c-akt
(metabolism)
- Rhabdomyosarcoma, Alveolar
(enzymology, genetics, pathology)
- Time Factors
- Transcription, Genetic
- Transfection
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