An analysis of regulatory elements in the phosphoenolpyruvate carboxykinase (GTP) gene which are responsible for its tissue-specific expression and metabolic control in transgenic mice.
Sequences in the gene for P-enolpyruvate carboxykinase (PEPCK) which are responsible for its complex pattern of transcriptional control were determined using transgenic mice containing a chimeric PEPCK-bovine growth hormone (bGH) gene consisting of a segment of the PEPCK promoter from -460 to +73, with mutations in specific regulatory domains. A mutation in the cAMP response element (CRE) (-87 to -74), which binds CCATT/enhancer-binding protein beta (C/EBP beta) and/or cAMP response element-binding protein (CREB), resulted in a 4- and 20-fold elevation in the level of bGH mRNA in the liver and kidney of transgenic mice, respectively. Expression of the PEPCK-bGH gene in the liver was reduced 60% by a mutation in the P3 (I) region (-248 to -230), whereas expression in the kidney was increased 10-fold by the same mutation. A mutation in the P2 region (-200 to -164) greatly reduced expression of the PEPCK-bGH gene in the kidney but not in the liver. Induction of hepatic PEPCK-bGH gene expression by Bt2cAMP was eliminated by mutations in the CRE, P1, P3(I), or by a double mutation of the CRE and P3(I). Mutations in the CRE or P3(I) regions of the PEPCK promoter did not interfere with the expected induction of the PEPCK-bGH gene in the liver at birth. None of the mutations in the PEPCK promoter interfered with the induction of transcription of the PEPCK-bGH gene in the liver when mice were fed a carbohydrate-free diet or the deinduction of transcription from the PEPCK promoter caused by a diet high in carbohydrate, whereas a mutation in P2 (an HNF-1 binding domain) eliminated dietary regulation of transcription of the transgene in the kidney. A model to explain the role of the various elements in the PEPCK promoter on the control of PEPCK gene transcription in the liver and kidney is presented.
Patel
Y M
YM
Pew Center for Molecular Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4935.
Yun
J S
JS
Liu
J
J
McGrane
M M
MM
Hanson
R W
RW
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D004032:Diet; D015971:Gene Expression Regulation, Enzymologic; D013006:Growth Hormone / Q000235:genetics; D008099:Liver / Q000196:embryology / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic
D013006:Growth Hormone; D000242:Cyclic AMP; D010729:Phosphoenolpyruvate Carboxykinase (GTP)