Functional analysis of cDNAs for two types of human heme oxygenase and evidence for their separate regulation.
We cloned a cDNA coding for a putative human heme oxygenase isozyme, designated type 2 (HO-2), and analyzed its function by transient expression assays. HeLa cells transfected with either HO-2 cDNAs or a cDNA coding for authentic heme oxygenase (HO-1) expressed the activity of heme oxygenase, although no activity was detected in the mock transfected cells. Using specific anti-HO-1 antibody, we showed that expression of a HO-1 cDNA resulted in the increase in its protein levels, but HO-1 protein was not detectable in the cells expressing HO-2 cDNAs. We thus confirmed the functional identity of HO-1 and HO-2. Then, we analyzed their expression in an erythroid cell line, YN-1-0-A. Treatment with hemin or by heat shock (42 degrees C) led to a remarkable increase in the HO-1 mRNA levels, while HO-2 mRNA expression was not induced at all, suggesting that they are under separate regulation.
Shibahara
S
S
Department of Applied Physiology and Molecular Biology, Tohoku University School of Medicine, Miyagi.
Yoshizawa
M
M
Suzuki
H
H
Takeda
K
K
Meguro
K
K
Endo
K
K
D002460:Cell Line; D004247:DNA; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*
D007527:Isoenzymes; D004247:DNA; D006419:Heme Oxygenase (Decyclizing)