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Cloning and functional characterization of the 5â² regulatory region of the human mitochondrial glycerolâ3âphosphate dehydrogenase gene: Lack of 3,5,3â²âtriiodothyronine responsiveness in adipose tissue
- Urcelay, Elena, JareÃ±o, MarÃa A., Menaya, Juan, Parrilla, Roberto, Ayuso, Matilde S., MartÃnâRequero, Angeles
- European journal of biochemistry 2000 v.267 no.24 pp. 7209-7217
- adipocytes, adipose tissue, genes, glycerol-3-phosphate dehydrogenase, humans, promoter regions, rats, transcription (genetics), transcription factors, transfection
- We report data on the structural and functional characterization of the 5â² flanking region of the human mitochondrial glycerolâ3âphosphate dehydrogenase (mtGPDH) gene. We found two regions upstream of 5â²âuntranslated sequences exhibiting promoter activity in transient transfection assays. Transcription start sites and potential regulatory sites in both promoter regions were defined. The proximal promoter was approximately sevenfold more active than the distal one in most cell lines, but it was only twice as active in a neuroblastoma cell line. These observations seem to indicate that the rate of transcription, as well as the tissueâspecific expression of the human mtGPDH gene, is the result of a combinatorial effect of transcription factors on at least two promoters. 3,5,3â²âTriiodothyronine failed to alter the transcriptional activity of human mtGPDH promoter(s) constructs in transient transfection assays. Although this finding seems to be in conflict with the reported effect of 3,5,3â²âtriiodothyronine in rodents, it is consistent with our observation of 3,5,3â²âtriiodothyronine stimulation of mtGPDH activity in primary cultures of rat adipocytes, but not human cultured adipocytes, suggesting distinct regulation of this gene in both species.