The modulation of STAT5A/GR complexes during fat cell differentiation and in mature adipocytes.
OBJECTIVE
Signal transducer and activator of transcription (STAT) 5A has been shown to interact with the glucocorticoid receptor (GR) in adipocytes. The aim of this study was to investigate the subcellular locations and modulation of STAT5A/GR complexes during adipogenesis and in mature adipocytes.


METHODS
Both 3T3-L1 and 3T3-F442A cells were studied by performing subcellular fractionations, immunoprecipitation, and Western blotting after various treatments.


RESULTS
The formation of nuclear STAT5A/GR complexes was regulated in the cytosol and in the nucleus at distinct times during adipogenesis and in mature adipocytes. STAT5A, but not STAT5B, forms a complex with GR in adipocytes. The STAT5A associated with GR in the nucleus is tyrosine phosphorylated.


CONCLUSIONS
The association of STAT5A with GR in the nucleus of adipocytes is modulated by the tyrosine phosphorylation of STAT5A. Both GR and STAT5A are known to have important roles in adipocyte function. Hence, our data suggest that the association of these two transcription factors may be important in the regulation of adipocyte gene expression.
Baugh
James E
JE
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
Floyd
Z Elizabeth
ZE
Stephens
Jacqueline M
JM
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects; D050156:Adipogenesis / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D013006:Growth Hormone / Q000494:pharmacology; D051379:Mice; D008954:Models, Biological; D011485:Protein Binding; D011965:Receptors, Glucocorticoid / Q000378:metabolism* / Q000502:physiology; D050799:STAT5 Transcription Factor / Q000378:metabolism* / Q000502:physiology
D011965:Receptors, Glucocorticoid; D050799:STAT5 Transcription Factor; C494093:Stat5a protein, mouse; D013006:Growth Hormone