The rat mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme-A-synthase gene contains elements that mediate its multihormonal regulation and tissue specificity.
Mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme-A (HMG-CoA) synthase, a liver-specific enzyme, is a constituent of the HMG-CoA cycle responsible for ketone-body synthesis. We report the isolation and characterization of genomic clones that encompass the gene for rat mitochondrial HMG-CoA synthase. The gene spans at least 24 kbp and contains ten exons and nine introns. The 5' flanking region of the gene has also been cloned and characterized. Exon 1 contains the untranslated sequence of the transcript, extending downstream to enclose the coding region for the putative mitochondrial-targeting signal (35 amino acids). The 1149-bp proximal region of the transcription start point permits transcription of a reporter gene in transfected hepatoma cells but not in an extrahepatic cell line, confirming the function of the promoter. A truncated construct of 142 bp is still able to promote transcription in hepatoma cells, suggesting the presence of liver-specific enhancer elements in the proximal promoter region. The 5' flanking region contains typical promoter elements, including a TATA box and several putative recognition sequences for transcription factors involved in controlling both basal-level and hormone-modulated transcription rates. Furthermore, the presence in the mitochondrial HMG-CoA-synthase promoter of cis-elements, responsible for the multihormonal regulation of transcription, is supported by transient transfection experiments.
Gil-Gómez
G
G
Unitat de Bioquímica, Facultat de Farmàcia, Universitat de Barcelona, Spain.
Ayté
J
J
Hegardt
F G
FG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D005091:Exons; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015698:Genomic Library; D006801:Humans; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000235:genetics* / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007438:Introns; D008930:Mitochondria, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D019301:Oleic Acid; D009829:Oleic Acids / Q000494:pharmacology; D009838:Oligodeoxyribonucleotides; D009928:Organ Specificity; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012326:RNA Splicing; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D007328:Insulin; D009829:Oleic Acids; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D019301:Oleic Acid; D003907:Dexamethasone; D000242:Cyclic AMP; D006904:Hydroxymethylglutaryl-CoA Synthase