Common functional genetic variants in catecholamine storage vesicle protein promoter motifs interact to trigger systemic hypertension.
OBJECTIVE
The purpose of this study is to understand whether naturally occurring genetic variation in the promoter of chromogranin B (CHGB), a major constituent of catecholamine storage vesicles, is functional and confers risk for cardiovascular disease.


BACKGROUND
CHGB plays a necessary (catalytic) role in catecholamine storage vesicle biogenesis. Previously, we found that genetic variation at CHGB influenced autonomic function, with association maximal toward the 5' region.


METHODS
Here we explored transcriptional mechanisms of such effects, characterizing 2 common variants in the proximal promoter, A-296C and A-261T, using transfection/cotransfection, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP). We then tested the effects of promoter variation on cardiovascular traits.


RESULTS
The A-296C disrupted a c-FOS motif, exhibiting differential mobility shifting to chromaffin cell nuclear proteins during EMSA, binding of endogenous c-FOS on ChIP, and differential response to exogenous c-FOS. The A-261T disrupted motifs for SRY and YY1, with similar consequences for EMSA, endogenous factor binding, and responses to exogenous factors. The 2-SNP CHGB promoter haplotypes had a profound (p=3.16E-20) effect on blood pressure (BP) in the European ancestry population, with a rank order of CT<AA<<CA<AT on both systolic blood pressure (SBP) and diastolic blood pressure (DBP), accounting for approximately 2.3% to approximately 3.4% of SBP/DBP variance; the haplotype effects on BP in vivo paralleled those on promoter activity in cella. Site-by-site interactions at A-296C and A-261T yielded highly nonadditive effects on SBP/DBP. The CHGB haplotype effects on BP were also noted in an independent (African ancestry) sample. In normotensive twins, parallel effects were noted for a pre-hypertensive phenotype, BP response to environmental stress.


CONCLUSIONS
The common CHGB promoter variants A-296C and A-261T, and their consequent haplotypes, alter binding of specific transcription factors to influence gene expression in cella as well as BP in vivo. Such variation contributes substantially to risk for human hypertension. Involvement of the sex-specific factor SRY suggests a novel mechanism for development of sexual dimorphism in BP.
Zhang
Kuixing
K
Department of Medicine, University of California at San Diego, San Diego, California, USA.
Rao
Fangwen
F
Wang
Lei
L
Rana
Brinda K
BK
Ghosh
Sajalendu
S
Mahata
Manjula
M
Salem
Rany M
RM
Rodriguez-Flores
Juan L
JL
Fung
Maple M
MM
Waalen
Jill
J
Tayo
Bamidele
B
Taupenot
Laurent
L
Mahata
Sushil K
SK
O'Connor
Daniel T
DT
D000328:Adult; D053378:Chromogranin B / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D006973:Hypertension / Q000235:genetics*; D008297:Male; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012307:Risk Factors
C506134:CHGB protein, human; D053378:Chromogranin B