Human dopamine β-hydroxylase promoter variant alters transcription in chromaffin cells, enzyme secretion, and blood pressure.
BACKGROUND
Dopamine β-hydroxylase (DBH) plays an indispensable role in catecholamine synthesis by converting dopamine into norepinephrine. Here, we characterized a DBH promoter polymorphism (C-2073T; rs1989787; minor allele frequency ~16%) that influences not only gene transcription but also enzyme secretion and blood pressure (BP) in vivo.


METHODS
Plasma DBH activity was measured spectrophotometrically. DBH genetic effects on BP were tested in subjects with the most extreme BP values in a large primary care population. Functional effects of promoter variants were studied by site-directed mutagenesis in DBH promoter haplotype/luciferase reporter plasmids transfected into chromaffin cells. Sequence motifs were predicted from position weight matrices, and endogenous transcription factor binding was probed by Chromatin ImmunoPrecipitation (ChIP).


RESULTS
The T-allele of common promoter variant C-2073T was contained in a promoter haplotype that associated with plasma DBH activity, a trait also predicted by that variant itself. Promoter haplotypes including C-2073T predicted BP in the population, and the effect was also referable to C-2073T itself. Computationally, C-2073 disrupted a predicted match for transcription factor c-FOS. Site-directed mutagenesis at C-2073T altered not only basal promoter activity, but also transactivation by c-FOS, as well as the chromaffin cell secretory stimuli nicotine or pituitary adenylate cyclase-activating polypeptide (PACAP). Endogenous c-FOS bound to the motif in chromatin.


CONCLUSIONS
These results suggest that DBH promoter variant C-2073T is functional in vivo: this promoter variant seems to initiate a cascade of transcriptional and biochemical changes including augmented DBH secretion, eventuating in elevation of basal BP, and hence cardiovascular risk. The observations suggest new strategies for probing the pathophysiology, risk, and treatment of hypertension.
Chen
Yuqing
Y
Department of Medicine, University of California at San Diego, La Jolla, USA.
Zhang
Kuixing
K
Wen
Gen
G
Rao
Fangwen
F
Sanchez
Amber P
AP
Wang
Lei
L
Rodriguez-Flores
Juan L
JL
Mahata
Manjula
M
Mahata
Sushil K
SK
Waalen
Jill
J
Ziegler
Michael G
MG
Hamilton
Bruce A
BA
O'Connor
Daniel T
DT
D000818:Animals; D001794:Blood Pressure; D019439:Chromaffin Cells / Q000378:metabolism*; D004299:Dopamine beta-Hydroxylase / Q000097:blood / Q000235:genetics*; D005260:Female; D016762:Genes, fos; D006239:Haplotypes; D006801:Humans; D006973:Hypertension / Q000209:etiology; D008297:Male; D016716:PC12 Cells; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D051381:Rats; D014158:Transcription, Genetic
D004299:Dopamine beta-Hydroxylase
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