Hormonal regulation of multiple promoters of the rat mitochondrial glycerol-3-phosphate dehydrogenase gene: identification of a complex hormone-response element in the ubiquitous promoter B.
Rat mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH) is regulated by multiple promoters in a tissue-specific manner. Here, we demonstrate that thyroid hormone (3,5,3'-tri-iodo-L-thyronine) and steroid hormone but not the peroxisome proliferator clofibrate and retinoic acid stimulate the activation of the ubiquitous promoter B in a receptor-dependent manner, whereas the more tissue-restricted promoters A and C are not inducible by these hormones. Thyroid hormone action is mediated by a direct repeat +4 (DR+4) hormone-response element as identified by deletion and mutation analyses of promoter B in transient transfection analyses. The DR+4 element was able to bind to an in vitro translated thyroid hormone receptor in band-shift and supershift experiments. The hormone-response element comaps with a recognition site for the transcription factor Sp1, suggesting complex regulation of this sequence element. Mutation of this Sp1-recognition site reduces the basal promoter B activity dramatically in HepG2 and HEK293 cells in transient transfection and abolishes the binding of Sp1 in band-shift experiments. As demonstrated by Western-blot experiments, administration of tri-iodothyronine to euthyroid rats increases hepatic mGPDH protein concentrations in vivo. As it has recently been reported that human mGPDH promoter B is not regulated by tri-iodothyronine, this is the first example of a differentially tri-iodothyronine-regulated orthologous gene promoter in man and rat.
Weitzel
J M
JM
Institut für Medizinische Biochemie und Molekularbiologie, Universitätsklinikum Hamburg-Eppendorf, Germany. weitzel@uke.uni-hamburg.de
Kutz
S
S
Radtke
C
C
Grott
S
S
Seitz
H J
HJ
D000818:Animals; D001483:Base Sequence; D002994:Clofibrate; D015971:Gene Expression Regulation, Enzymologic; D005993:Glycerolphosphate Dehydrogenase / Q000235:genetics*; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051381:Rats; D011988:Receptors, Thyroid Hormone / Q000378:metabolism; D020218:Response Elements; D013256:Steroids / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology*
D006728:Hormones; D011988:Receptors, Thyroid Hormone; D013256:Steroids; D014284:Triiodothyronine; D014212:Tretinoin; D005993:Glycerolphosphate Dehydrogenase; D002994:Clofibrate