[PMID]: | 16033334 |
[Au] Autor: | Kolluri S; Sadlon TJ; May BK; Bonkovsky HL |
[Ad] Endereço: | Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, Farmington, CT 06030, USA. |
[Ti] Título: | Haem repression of the housekeeping 5-aminolaevulinic acid synthase gene in the hepatoma cell line LMH. |
[So] Source: | Biochem J;392(Pt 1):173-80, 2005 Nov 15. |
[Is] ISSN: | 1470-8728 |
[Cp] País de publicação: | England |
[La] Idioma: | eng |
[Ab] Resumo: | Haem is essential for the health and function of nearly all cells. 5-Aminolaevulinic acid synthase-1 (ALAS-1) catalyses the first and rate-controlling step of haem biosynthesis. ALAS-1 is repressed by haem and is induced strongly by lipophilic drugs that also induce CYP (cytochrome P450) proteins. We investigated the effects on the avian ALAS-1 gene promoter of a phenobarbital-like chemical, Glut (glutethimide), and a haem synthesis inhibitor, DHA (4,6-dioxoheptanoic acid), using a reporter gene assay in transiently transfected LMH (Leghorn male hepatoma) hepatoma cells. A 9.1 kb cALAS-1 (chicken ALAS-1) promoter-luciferase-reporter construct, was poorly induced by Glut and not by DHA alone, but was synergistically induced by the combination. In contrast, a 3.5 kb promoter ALAS-1 construct was induced by Glut alone, without any further effect of DHA. In addition, exogenous haem (20 microM) repressed the basal and Glut- and DHA-induced activity of luciferase reporter constructs containing 9.1 and 6.3 kb of ALAS-1 5'-flanking region but not the construct containing the first 3.5 kb of promoter sequence. This effect of haem was subsequently shown to be dependent on the -6.3 to -3.5 kb region of the 5'-flanking region of cALAS-1 and requires the native orientation of the region. Two deletion constructs of this approx. 2.8 kb haem-repressive region (1.7 and 1.1 kb constructs) retained haem-dependent repression of basal and drug inductions, suggesting that more than one cis-acting elements are responsible for this haem-dependent repression of ALAS-1. These results demonstrate that there are regulatory regions in the 5'-flanking region of the cALAS-1 gene that respond to haem and provide a basis for further investigations of the molecular mechanisms by which haem down-regulates expression of the ALAS-1 gene. |
[Mh] Termos MeSH primário: |
5-Aminolevulinato Sintetase/genética Regulação para Baixo/efeitos dos fármacos Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos Heme/farmacologia
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[Mh] Termos MeSH secundário: |
Animais Linhagem Celular Tumoral Galinhas Sinergismo Farmacológico Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos Glutetimida/farmacologia Heme/antagonistas & inibidores Heme/metabolismo Heptanoatos/farmacologia Regiões Promotoras Genéticas/genética Regulação para Cima/efeitos dos fármacos
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[Pt] Tipo de publicação: | JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, U.S. GOV'T, P.H.S. |
[Nm] Nome de substância:
| 0 (Heptanoates); 42VZT0U6YR (Heme); 51568-18-4 (succinylacetone); C8I4BVN78E (Glutethimide); EC 2.3.1.37 (5-Aminolevulinate Synthetase) |
[Em] Mês de entrada: | 0602 |
[Cu] Atualização por classe: | 161203 |
[Lr] Data última revisão:
| 161203 |
[Sb] Subgrupo de revista: | IM |
[Da] Data de entrada para processamento: | 050722 |
[St] Status: | MEDLINE |
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