title: Dominant negative FTase (DNFTalpha) inhibits ERK5, MEF2C and CREB activation in adipogenesis.
abstract: We recently demonstrated that dominant negative FTase/GGTase I alpha-subunit-inhibited (DNFTalpha-inhibited) insulin-stimulated adipocytes differentiation. DNFTalpha interferes with Ras prenylation whereby ERK1/2, CREB and the differentiation cascade are downregulated. To further investigate prenylation in adipogenesis, we examined DNFTalpha's ability to inhibit activation of ERK5, MEF2C and CREB. DNFTalpha-inhibited insulin-stimulated expression, activation and nuclear translocation of ERK5. Inhibition was associated with decreased activation of MEF2C and CREB by 80 and 78%, respectively. PD98059 did not block activation of ERK5 and MEF2C, but inhibited CREB phosphorylation by 90%. ERK5 siRNA-inhibited MEF2C activation, whereas it reduced CREB phosphorylation only 50%. Pre-adipocytes expressing DNFTalpha or treated with PD98059 were unable to differentiate to mature adipocytes, whereas pre-adipocytes transfected with ERK5 siRNA showed moderate inhibition of insulin-induced adipogenesis. Taken together, these data suggest that prenylation plays a critical role in insulin-stimulated adipogenesis, and that the ERK5 plays an important, but less crucial role in adipogenesis as compared to ERK1/2.
authors.affiliation: The Department of Medicine, University of Colorado, Denver Health Sciences Center, Denver, 80220, USA.
authors.forename: Girish
authors.initials: G
authors.lastname: Sharma
authors.forename: Marc L
authors.initials: ML
authors.lastname: Goalstone
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D050156:Adipogenesis; D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D004789:Enzyme Activation; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation; D007328:Insulin / Q000494:pharmacology / Q000502:physiology; D064326:MEF2 Transcription Factors; D051379:Mice; D048054:Mitogen-Activated Protein Kinase 7 / Q000235:genetics / Q000378:metabolism*; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism*; D047495:PPAR gamma / Q000235:genetics / Q000502:physiology; D034741:RNA, Small Interfering; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D018631:ras Proteins / Q000502:physiology
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D005419:Flavonoids; D007328:Insulin; D064326:MEF2 Transcription Factors; C578041:Mef2c protein, mouse; D018006:Myogenic Regulatory Factors; D047495:PPAR gamma; D034741:RNA, Small Interfering; D019883:Alkyl and Aryl Transferases; C064911:p21(ras) farnesyl-protein transferase; D011972:Receptor, Insulin; D048054:Mitogen-Activated Protein Kinase 7; D018631:ras Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one