Regulation of annexin I in adipogenesis: cAMP-independent action of methylisobutylxanthine.
The differentiation of 3T3-L1 fibroblasts to adipocytes can be accelerated by the addition of 1-methyl-3-isobutylxanthine (MIX), insulin, and dexamethasone to the culture medium. During differentiation, we have demonstrated that the level of both annexin I mRNA and protein decreases. The half-times for this reduction were 2 h and 10 h for annexin I mRNA and protein, respectively. Of the added agents in the differentiation medium, only MIX caused a decline in annexin I expression in 3T3-L1 fibroblasts. The MIX effect in fibroblasts was reversible and required de novo transcription but not protein synthesis. Although MIX could be replaced by high levels of theophylline, neither agonists of the beta-adrenergic receptor nor intracellular second messengers, cAMP and cGMP, were able to reduce annexin I. The potential role of annexin I in cellular differentiation is discussed.
Department of Biochemistry and Molecular Biology, University of Florida, Gainesville 32610.
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Wong
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Nick
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Frost
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology*; D016475:3T3 Cells; D000273:Adipose Tissue / Q000166:cytology / Q000502:physiology*; D000818:Animals; D017302:Annexins; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors
D017302:Annexins; D002135:Calcium-Binding Proteins; D007328:Insulin; D012333:RNA, Messenger; D003907:Dexamethasone; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine