C/EBPalpha-dependent induction of glutathione S-transferase zeta/maleylacetoacetate isomerase (GSTzeta/MAAI) expression during the differentiation of mouse fibroblasts into adipocytes.
Western blot analysis of 3T3-L1 adipocyte proteins using an anti-C/EBPalpha antibody detected a 24kD polypeptide in addition to the expected 42 and 30kD isoforms of C/EBPalpha. Mass spectrometric sequencing of the protein following its purification by HPLC and preparative 2D gel electrophoresis identified it as glutathione S-transferase zeta/maleylacetoacetate isomerase (GSTzeta/MAAI). Expression of GSTzeta/MAAI mRNA and protein was induced during the terminal phase of adipogenesis in 3T3-L1 preadipocytes. Ectopic expression of PPARgamma2 in NIH-3T3 fibroblasts exposed to insulin and troglitazone-induced perilipin production, but was incapable of activating GSTzeta/MAAI unless C/EBPalpha was also expressed. Similarly, ectopic expression of C/EBPalpha in PPARgamma +/- or PPARgamma -/- MEFs demonstrated that the C/EBPalpha-dependent induction of GSTzeta/MAAI production was dependent on expression of endogenous PPARgamma. These data suggest a role for GSTzeta/MAAI in mature adipocytes that may be responsive to the thiazolidinedione class of insulin sensitizing PPARgamma ligands.
Qiang
Li
L
Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
Farmer
Stephen R
SR
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D015153:Blotting, Western; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D018076:DNA, Complementary / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000096:biosynthesis* / Q000378:metabolism; D008024:Ligands; D050356:Lipid Metabolism; D013058:Mass Spectrometry; D051379:Mice; D008822:Mice, Transgenic; D047495:PPAR gamma / Q000378:metabolism; D047492:Peroxisome Proliferator-Activated Receptors / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D019745:cis-trans-Isomerases / Q000378:metabolism*
D000975:Antioxidants; D022763:CCAAT-Enhancer-Binding Protein-alpha; D018076:DNA, Complementary; D008024:Ligands; D047495:PPAR gamma; D047492:Peroxisome Proliferator-Activated Receptors; D020033:Protein Isoforms; D012333:RNA, Messenger; C498694:Gstz1 protein, mouse; D005982:Glutathione Transferase; D019745:cis-trans-Isomerases; C021531:maleylacetoacetate isomerase