Exploration of a liver-specific, glucose/insulin-responsive promoter in transgenic mice.
The functional role of the different sites binding transcriptional factors on the tissue-specific, glucose-responsive promoter of the L type pyruvate kinase gene (L-PK) has been investigated in transgenic mice. These sites are able to bind, from 3' to 5', HNF1, NF1, HNF4, and MLTF/USF, respectively. We have compared the level of chloramphenicol acetyltransferase reporter transgene expression when driven by a L-PK promoter fragment of either -96 base pairs (bp) (containing only the HNF1 binding site) or -150 bp (lacking the MLTF/USF binding site) or driven by a -183-bp L-PK promoter fragment with or without the NF1 binding site. Our results demonstrate that: 1) HNF1 alone is not sufficient to promote an efficient L-PK gene transcription in vivo; 2) with only binding sites for HNF1, NF1, and HNF4, though the tissue-specific pattern of expression is respected, the level of the gene transcription is low and the hormonal control is lost; 3) the MLTF/USF binding site is the target of the hormonal control, required for both positive response to carbohydrates and negative response to glucagon; 4) the role of NF1 in the promoter activity could be to negatively modulate the L-PK gene expression in the different tissues, without interfering with the glucose and hormone responsiveness.
Cuif
M H
MH
Laboratoire de Recherches en Génétique et Pathologie Moléculaires, Institut National de la Santé et de la Recherche Médicale Unité 129, Paris, France.
Porteu
A
A
Kahn
A
A
Vaulont
S
S
D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics*; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011770:Pyruvate Kinase / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D007328:Insulin; D014157:Transcription Factors; D015500:Chloramphenicol O-Acetyltransferase; D011770:Pyruvate Kinase; D005947:Glucose