Identification of the xenosensors regulating human 5-aminolevulinate synthase

Podvinec, M. and Handschin, C. and Looser, R. and Meyer, U. A.. (2004) Identification of the xenosensors regulating human 5-aminolevulinate synthase. Proceedings of the National Academy of Sciences of the United States of America, 101 (24). pp. 9127-9132.

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Official URL: http://edoc.unibas.ch/dok/A5259309

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Heme is an essential component of numerous hemoproteins with functions including oxygen transport, energy metabolism, and drug biotransformation. In nonerythropoietic cells, 5-aminolevulinate synthase (ALAS1) is the rate-limiting enzyme in heme biosynthesis. Upon exposure to drugs that induce cytochromes P450 and other drug-metabolizing enzymes, ALAS1 is transcriptionally up-regulated, increasing the rate of heme biosynthesis to provide heme for cytochrome P450 hemoproteins. We used a combined in silico-in vitro approach to identify sequences in the ALAS1 gene that mediate direct transcriptional response to xenobiotic challenge. We have characterized two enhancer elements, located 20 and 16 kb upstream of the transcriptional start site. Both elements respond to prototypic inducer drugs and interact with the human pregnane X receptor NR1I2 and the human constitutive androstane receptor NR1I3. Our results suggest that the fundamental mechanism of drug induction is the same for cytochromes P450 and ALAS1. Transcriptional activation of the ALAS1 gene is the first step in the coordinated up-regulation of apoprotein and heme synthesis in response to exogenous and endogenous signals controlling heme levels. Understanding the direct effects of drugs on heme synthesis is of clinical interest, particularly in patients with hepatic porphyrias.
Faculties and Departments:03 Faculty of Medicine > Departement Biomedizin > Associated Research Groups > Pharmakologie (Handschin)
05 Faculty of Science > Departement Biozentrum > Growth & Development > Growth & Development (Handschin)
05 Faculty of Science > Departement Biozentrum > Services Biozentrum > Research IT (Podvinec)
UniBasel Contributors:Handschin, Christoph and Podvinec, Michael
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:National Academy of Sciences
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:03 Oct 2017 09:35
Deposited On:22 Mar 2012 13:22

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