Elements responsible for hormonal control and tissue specificity of L-type pyruvate kinase gene expression in transgenic mice.
L-type pyruvate kinase (L-PK) is a key enzyme of the glycolytic pathway specifically expressed in the liver and, to a lesser degree, in the small intestine and kidney. One important characteristic of L-PK gene expression is its strong activation by glucose and insulin and its complete inhibition by fasting or glucagon treatment. Having previously established that the entire rat L-PK gene plus 3.2 kbp of 5'-flanking region functions in mice in a tissue-specific and hormonally regulated manner, various deletions of these 3.2 kbp of 5'-flanking regions were tested in transgenic animals to map the cis-acting elements involved in transcriptional gene regulation. Our experiments indicate that the proximal region between -183 and +11 confers tissue specificity and contains all the information necessary for dietary and hormonal control of L-PK gene expression in vivo. We found, however, that the transcriptional activity generated by this proximal promoter fragment can be modulated by distal sequences in a tissue-specific manner. (i) Sequences between bp -183 and -392 seem to play a dual role in the liver and small intestine; they induce L-PK expression in the liver but repress it in the small intestine. (ii) Sequences from bp -392 up to -1170 do not seem to have any additional effect on promoter activity. (iii) Between bp -1170 and -2080, we found a putative extinguisher whose transcriptional inhibitory effect is much more marked in the small intestine than in the liver. (iv) Finally, between bp -2080 and -3200, we identified an activating sequence required for full expression of the gene in the liver.
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.
Cognet
M
M
Boquet
D
D
Tremp
G
G
Kahn
A
A
Vaulont
S
S
D000818:Animals; D015139:Blotting, Southern; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic; D005934:Glucagon / Q000502:physiology; D005947:Glucose / Q000502:physiology; D006728:Hormones / Q000502:physiology*; D007328:Insulin / Q000502:physiology; D007421:Intestine, Small / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009928:Organ Specificity / Q000235:genetics; D011770:Pyruvate Kinase / Q000235:genetics* / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid
D006728:Hormones; D007328:Insulin; D005934:Glucagon; D015500:Chloramphenicol O-Acetyltransferase; D011770:Pyruvate Kinase; D005947:Glucose