Differential effects of metalloporphyrins on messenger RNA levels of delta-aminolevulinate synthase and heme oxygenase. Studies in cultured chick embryo liver cells
Biochemistry & Molecular Pharmacology
Graduate School of Biomedical Sciences
Medical Subject Headings
5-Aminolevulinate Synthetase; Animals; Cells, Cultured; Chick Embryo; Heme Oxygenase (Decyclizing); Liver; Metalloporphyrins; RNA, Messenger
Life Sciences | Medicine and Health Sciences
The acute porphyrias in relapse are commonly treated with intravenous heme infusion to decrease the activity of delta-aminolevulinic acid synthase, normally the rate-controlling enzyme in heme biosynthesis. The biochemical effects of heme treatment are short-lived, probably due in part to heme-mediated induction of heme oxygenase, the rate-controlling enzyme for heme degradation. In this work, selected nonheme metalloporphyrins were screened for their ability to reduce delta-aminolevulinic acid synthase mRNA and induce heme oxygenase mRNA in chick embryo liver cell cultures. Of the metalloporphyrins tested, only zinc-mesoporphyrin reduced delta-aminolevulinic acid synthase mRNA without increasing heme oxygenase mRNA. The combination of zinc-mesoporphyrin and heme, at nanomolar concentrations, decreased delta-aminolevulinic acid synthase mRNA in a dose-dependent manner. The combination of zinc-mesoporphyrin (50 nM) and heme (200 nM) decreased the half-life of the mRNA for delta-aminolevulinic acid synthase from 5.2 to 2.5 h, while a similar decrease was produced by heme (10 microM) alone (2.2 h). The ability of zinc-mesoporphyrin to supplement the reduction of delta-aminolevulinic acid synthase mRNA by heme, in a process similar to that observed with heme alone, provides a rationale for further investigation of this compound for eventual use as a supplement to heme therapy of the acute porphyrias and perhaps other conditions in which heme may be of benefit.
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Citation: J Clin Invest. 1994 Aug;94(2):649-54. Link to article on publisher's site
The Journal of clinical investigation
Cable, Edward Earl; Pepe, Joyce A.; Karamitsios, Nicholas C.; Lambrecht, Richard W.; and Bonkovsky, Herbert L., "Differential effects of metalloporphyrins on messenger RNA levels of delta-aminolevulinate synthase and heme oxygenase. Studies in cultured chick embryo liver cells" (1994). GSBS Student Publications. 164.