Expression of phosphoenolpyruvate carboxykinase gene in human adipose tissue: induction by rosiglitazone and genetic analyses of the adipocyte-specific region of the promoter in type 2 diabetes.
Cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) is the key enzyme in glyceroneogenesis, an important metabolic pathway in adipocytes for reesterification of fatty acids during fasting. Dysregulation of glyceroneogenesis could play a role in the increase in plasma non-esterified fatty acids that accompanies type 2 diabetes. In rodent adipocyte transcription of the PEPCK-C gene is induced by thiazolidinediones (TZDs) through an element, named PCK2, in its promoter. PCK2 binds a peroxisome proliferator activated receptor gamma (PPARgamma), retinoid X receptor alpha (RXRalpha) heterodimer. We demonstrated that in cultured human subcutaneous adipose tissue explants, PEPCK-C specific activity and mRNA were induced by 1 microM of the TZD rosiglitazone, respectively, about twofold in 8 h and fivefold in 5 h. Using gel shift experiments, we show that this effect is likely to involve the human PCK2 (hPCK2) element, which binds a protein complex that contains PPARgamma and RXRalpha. We analyzed hPCK2 (position -1031 to -1015 base pairs) and nearby sequences in the PEPCK-C promoter in 403 subjects with type 2 diabetes and 123 non-diabetic controls. The sequence of hPCK2 was not polymorphic, but we detected two C/T single nucleotide polymorphisms (SNPs), in complete linkage disequilibrium, at positions -1097 and -967 bp. Allele and genotype frequencies were not significantly different in patients and controls. However, our results suggest co-dominant effects of C and T-alleles on fasting plasma glucose and glycosylated hemoglobin A1c levels in obese type 2 diabetic patients.
Duplus
Eric
E
UMR-S 530 Inserm--Université René-Descartes, Centre Universitaire des Saints-Pères, U.F.R. Biomédicale, 45 rue des Saints-Pères, 75006 Paris, France.
Benelli
Chantal
C
Reis
André F
AF
Fouque
Françoise
F
Velho
Gilberto
G
Forest
Claude
C
D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005787:Gene Frequency; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000235:genetics; D006801:Humans; D006943:Hyperglycemia / Q000150:complications / Q000235:genetics; D009928:Organ Specificity; D047495:PPAR gamma / Q000235:genetics; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology*
D047495:PPAR gamma; D012333:RNA, Messenger; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D010729:Phosphoenolpyruvate Carboxykinase (GTP)