A Polymorphism in Intron I of the Human Angiotensinogen Gene (hAGT) Affects Binding by HNF3 and hAGT Expression and Increases Blood Pressure in Mice
Angiotensinogen (AGT) is the precursor of one of the most potent vasoconstrictors, peptide angiotensin-II. Genome-wide association studies (GWAS) have shown that two A/G polymorphisms (rs2493134 and rs2004776) located at +507 and +1164 in intron I of human AGT (hAGT) gene are associated with hypertension. Polymorphisms of the AGT gene result in two main haplotypes. Hap-I contains the variants -217A, -6A, +507G, and +1164A and is pro-hypertensive, whereas Hap-II contains the variants -217G, -6G, +507A, and +1164G and does not affect blood pressure. The nucleotide sequence of intron I of the hAGT gene containing the +1164A variant has a stronger homology with hepatocyte nuclear factor 3 (HNF3)-binding site than does +1164G. Here, we found that (a) an oligonucleotide containing +1164A binds HNF3beta more strongly than does +1164G, and (b) Hap I-containing reporter gene constructs have increased basal and HNF3- and glucocorticoid-induced promoter activity in transiently transfected liver and kidney cells. Using a knock-in approach at the HPRT locus, we generated transgenic mouse model containing the human renin (hREN) gene and either Hap-I or Hap-II. We show that transgenic animals containing Hap-I have increased blood pressure compared with those containing Hap-II. Moreover, the transcription factors glucocorticoid receptor (GR), CCAAT enhancer-binding protein beta (C/EBPbeta), and HNF3beta bound more strongly to chromatin obtained from the liver of transgenic animals containing Hap-I than to liver chromatin from Hap-II-containing animals. These findings suggest that unlike Hap-II variants, Hap-I variants of the hAGT gene have increased transcription rates, resulting in elevated blood pressure.
Mopidevi, B., Kaw, M., Sivankutty, I., Jain, S., Perla, S., & Kumar, A. (2019). A Polymorphism in Intron I of the Human Angiotensinogen Gene (hAGT) Affects Binding by HNF3 and hAGT Expression and Increases Blood Pressure in Mice. The Journal of Biological Chemistry, 294 (31), 11829-11839. https://doi.org/10.1074/jbc.RA119.007715