1: J Hypertens. 2003 Nov;21(11):2111-24. 

Comment in:
    J Hypertens. 2003 Nov;21(11):2013-4.

Regulation of the major isoform of human endothelin-converting enzyme-1 by a
strong housekeeping promoter modulated by polymorphic microsatellites.

Funke-Kaiser H, Thomas A, Bremer J, Kovacevic SD, Scheuch K, Bolbrinker J, Theis
S, Lemmer J, Zimmermann A, Zollmann FS, Herrmann SM, Paul M, Orzechowski HD.

Institute of Clinical Pharmacology and Toxicology, Charite - Campus Benjamin
Franklin, Berlin, Germany.

BACKGROUND: Human endothelin-converting enzyme (ECE)-1, the key enzyme in
endothelin biosynthesis, shows broad cell and tissue expression within the
cardiovascular system. Expression of ECE-1c, which represents the major ECE-1
isoform, is directed by an alternative promoter, but the mechanisms of ECE-1c
promoter regulation are largely unknown. As ECE-1c transcription is initiated
from several start sites, we hypothesized that the ECE-1c promoter functions as
a housekeeping promoter. OBJECTIVE: To investigate the putative housekeeping
function of the ECE-1c promoter in vascular endothelial cells, which represent a
main site of its expression. RESULTS: Using promoter reporter assays, gel shift
and supershift assays, we have demonstrated, in human endothelial EA.hy926
cells, functionality of cis-acting elements for binding of the CAAT-box binding
protein NF-YB, GATA-2) E2F-2, and a GC-box binding factor, which are spatially
associated with transcriptional start sites of ECE-1c. In the more upstream
promoter region we have identified three highly polymorphic dinucleotide
repeats, 5'-(CA)n, (CG)n and 3'-(CA)n, which strongly affected promoter function
in endothelial EA.hy926 cells (2.7-fold activation comparing the most active to
the least active allele) and, in a similar manner, in human neuronal KELLY
cells. Finally, by in-vitro methylation, we were able to achieve strong
suppression of the ECE-1c promoter activity in endothelial cells. CONCLUSION:
Our results provide a molecular explanation for constitutive expression of
ECE-1c mRNA. Modulation by genetic and epigenetic mechanisms as revealed in our
study may account for interindividual variation of the constitutive endothelin
system activity in humans and thus influence individual predisposition to
cardiovascular disease.

PMID: 14597855 [PubMed - indexed for MEDLINE]


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