Abstract 154: GWAS Candidate Gene Knockout in Rats Reveals a Role for Erk/mapk Signaling in Hypertension

The data revealed by GWAS studies provide a wealth of candidate human disease genes now requiring functional validation in animal models. In two years, we disrupted a large set of GWAS candidate genes for human hypertension and chronic kidney disease by Zinc Finger Nuclease (ZFN)-mediated gene targeting in the SS (Dahl salt-sensitive) strain background. Phenotyping male rats from gene-disrupted strains revealed five genes ( Sh2b3 , Rasgrp3 , Gpr73 , Ulk3 , and Wdr72 ) significantly altering the salt-induced hypertension in and renal damage phenotypes in this model strain of human hypertension compared to age matched wild type controls. Ingenuity Pathway Analysis revealed a putative connection for four of these genes ( Sh2b3 , Rasgrp3 , Gpr73 , and Ulk3 ) to the ERK/MAPK signaling pathway and suggested that decreased ERK signaling would exacerbate disease in the SS model. To test this hypothesis, we measured the response of SS rats to a 4% salt diet with daily IP injections of the MEK inhibitor PD98059 or vehicle control. Wild type SS animals treated with PD98059 show a significant increase in mean arterial pressure compared to vehicle-injected controls (n=10, 142±7 vs. 126±6 mmHg respectively, P<0.05) suggesting that ERK signaling plays an important role in the pathogenesis of this model. In conclusion, we have used gene knockout in a hypertensive rat model to identify genes and associated pathway mechanisms of BP regulation. The gene disruption phenotype and participation of multiple genes in the ERK/MAPK signaling pathway indicates that regulation of this pathway plays a major role in determining blood pressure.