Mutation of Plekha7 attenuates salt-sensitive hypertension in the rat

Abstract

PLEKHA7 (pleckstrin homology domain containing family A member 7) has been found in multiple studies as a candidate gene for human hypertension, yet functional data supporting this association are lacking. We investigated the contribution of this gene to the pathogenesis of salt-sensitive hypertension by mutating Plekha7 in the Dahl salt-sensitive (SS/JrHsdMcwi) rat using zincfinger nuclease technology. After four weeks on an 8% NaCl diet, homozygous mutant rats had lower mean arterial (149 ± 9 mmHg vs. 178 ± 7 mmHg; P < 0.05) and systolic (180 ± 7 mmHg vs. 213 ± 8 mmHg; P < 0.05) blood pressure compared with WT littermates. Albumin and protein excretion rates were also significantly lower in mutant rats, demonstrating a renoprotective effect of the mutation. Total peripheral resistance and perivascular fibrosis in the heart and kidney were significantly reduced in Plekha7 mutant animals, suggesting a potential role of the vasculature in the attenuation of hypertension. Indeed, both flow-mediated dilation and endothelium-dependent vasodilation in response to acetylcholine were improved in isolated mesenteric resistance arteries of Plekha7 mutant rats compared with WT. These vascular improvements were correlated with changes in intracellular calcium handling, resulting in increased nitric oxide bioavailability in mutant vessels. Collectively, these data provide the first functional evidence that Plekha7 may contribute to blood pressure regulation and cardiovascular function through its effects on the vasculature.H ypertension is a complex disease that is characterized by increased blood pressure, renal damage, and vascular dysfunction which collectively increase risk of atherosclerosis, stroke, heart disease, and renal failure in one-quarter of all adults worldwide (1-3). Because there is strong evidence of heritability in hypertension (2, 4, 5), considerable effort has been put toward identifying novel candidate genes and their molecular mechanisms. Genome-wide association studies (GWAS) have identified many potential hypertension loci, which shed light on the genetic complexity of this disease (5-8) but have provided little mechanistic insight. As such, validation and elucidation of the functional roles and disease mechanisms for these gene candidates are the next important challenges (4).Because hypertension is a complex disease (i.e., multiple variants of small effect sizes contributing to disease risk), we hypothesized candidate gene targeting on a genetically sensitized background would reveal functional role(s) of genetic disease modifiers. The Dahl salt-sensitive (SS) rat is an inbred genetic model of salt-sensitive hypertension that displays hypertensioninduced renal damage, cardiac hypertrophy and vascular dysfunction (9-11). These phenotypes are induced by exposing SS rats to a high-salt diet, which results in rapid induction of hypertensive phenotypes that closely resemble salt-induced hypertension seen in humans (12-15). Knockout of specific genes in this disease model using zinc-finger nuclease (ZFN...

The adherens junctions control susceptibility to Staphylococcus aureus α-toxin

“…Some canonical adherens junctions proteins such as E-cadherin and p120 catenin are essential for junction formation, and systemic knockouts are embryonic lethal (48,49). In contrast, our previously unpublished PLEKHA7 −/− mice and a recently described PLEKHA7 −/− rat model (36) are healthy and fecund, exhibiting no gross developmental or epithelial pathology. From this we infer that PLEKHA7 is not an essential junctional protein in vivo but rather may serve to regulate some previously unidentified aspect of junction function under specific conditions.…”

Essential role of Kir5.1 channels in renal salt handling and blood pressure control

“…Following urine collection, designated rats were anesthetized with 2%-3 % (vol/vol) isoflurane and a blood pressure transmitter (PA-C40; DSI) was surgically implanted subcutaneously, with the catheter tip secured in the abdominal aorta via the femoral artery. After a 3-day recovery period, blood pressure and heart rate were measured with a DSI system in conscious, freely moving male SS and SS Kcnj16-/-rats under different diet protocols, similar to those described previously (55,56). Urine measurements were taken weekly during the high-salt challenge; in this case, Na + , K + , Cl -, and Ca 2+ electrolytes were measured with radiometric assay (ABL800 FLEX, Radiometer America Inc.).…”

2015 Guidelines for Establishing Genetically Modified Rat Models for Cardiovascular Research

“…At the same time, genetically modified inbred strains also hold several significant advantages for modeling CVD traits. Firstly, most inbred rat strains have been selected for genetic susceptibility to complex CVD traits and therefore provide multiple endogenous variants that are required for pathogenesis of complex diseases, such as hypertension [17, 18]. Secondly, gene-targeting on an inbred background enables interstrain comparisons with other genetically modified individuals derived from the same inbred parental strain, because these individuals are genetically homogenous except for the unique genome modifications.…”