Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.99.3 (heme oxygenase)
 4,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human heme oxygenase is induced by its substrate heme, but not induced by heat shock [Yoshida et al. (1988) Eur. J. Biochem. 171, 457-461]. In order to study the molecular mechanisms of heme-mediated induction of human heme oxygenase, we have isolated and characterized the genomic clones for heme oxygenase. The human heme oxygenase gene (HO gene) is about 14 kb long and organized into five exons. The transcription initiation site was identified by S1 nuclease mapping and primer-extension analyses. Using HeLa whole cell extracts, we confirmed that the transcription of the cloned HO gene is initiated accurately at the assigned initiation site. In its 5'-flanking region, a potential heat-shock element (HSE) is present 367 bp upstream from the initiation site, although, in contrast to rat heme oxygenase, human enzyme is not induced by heat shock. We therefore analyzed the effects of heat shock on the transient expression of chimeric fusion genes harboring the promoter of the human HO gene ligated to the Escherichia coli gene gpt in mouse amelanotic melanoma cells. The 5'-flanking region of the human HO gene bearing a potential HSE failed to confer the heat-inducibility of gpt RNA production, suggesting that the HSE of the human HO gene is not functional.
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PMID:Structural organization of the human heme oxygenase gene and the function of its promoter. 253 23

A heat shock element is located in the 5'-flanking region of the rat heme oxygenase gene (HO gene). The incubation of rat glioma cells at 42 degrees C or with hemin at 37 degrees C increased the levels of heme oxygenase mRNA within 1 h and produced a maximum at 3 h (at least a 20-fold increase). In both treatments, the heme oxygenase activity started to increase after a lag period of about 1 h and reached a maximum value at 5 h. There was an apparent additive effect of both treatments on the heme oxygenase induction. Studies with actinomycin D and cycloheximide suggested that both heat shock and hemin acted at the transcriptional level to induce heme oxygenase. Therefore, we analyzed the transient expression of chimeric fusion genes harboring the promoter of the rat HO gene ligated to the Escherichia coli gene gpt in rat glioma cells and in K1735 mouse amelanotic melanoma cells. The 5'-flanking region of the rat HO gene bearing the heat shock element conferred the heat inducibility of gpt RNA production in both cell lines; however, hemin treatment did not induce gpt RNA. These results indicate that rat heme oxygenase is a heat shock protein and that hemin induces heme oxygenase through a different mechanism from heat shock.
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PMID:Transcriptional control of rat heme oxygenase by heat shock. 365 94