Altered nuclear protein binding to the first intron of the renin gene of the spontaneously hypertensive rat

Association of Mbo I-RFLP at the Renin Locus (rs2368564) with Essential Hypertension

Several lines of experimental and clinical evidence have alluded a pivotal role of renin in blood pressure homeostasis and therefore a relevance of molecular variants of the renin gene and essential hypertension have been speculated. This study was designed to evaluate the pattern, alliance and risk of renin Mbo I (10631A>G; rs2368564) polymorphism at the locus intron 9 for a possible role in modulating essential hypertension in adult population from Gujarat (India). A total of 257 consecutively enrolled essential hypertensive patients and 270 controls were genotyped using polymerase chain reaction-restriction fragment length polymorphism method for the selected marker. Suitable descriptive statistics was used for different variables. Genotypic (x(2) 10.43, p 0.0054) and allelic (x(2) 11.46, p 0.0007) distribution of this SNP displayed significant differences between cases and controls with an increased frequency of the A allele (x(2) 6.275; p 0.0122) and A/A geno-type (x(2) 8.247; p 0.0041) in hypertensive individuals. However, it showed no deviation from Hardy-Weinberg equilibrium in either affected or control group. A significant association was found in the A/A variant of rs2368564 with essential hypertension (p 0.0032), along with a statistically significant increase in odds of hypertension (OR 1.69; CI 1.46-2.28; p 0.02), even after confounding factors were adjusted in multiple logistic regression analysis and is substantiated by inter-genotypic variations in the mean systolic and diastolic blood pressure in patients. In conclusion, renin 10631A>G gene mutation at the ninth intron play critical roles in BP (dys)regulation and can be implicated in an individual's susceptibility for hypertension.

High-salt diet and hypertension: focus on the renin-angiotensin system

A high-salt diet is one of the major risk factors in the development and maintenance of hypertension. Numerous experimental and observational studies have confirmed the association of sodium intake with blood pressure levels. The effects of a high-salt diet are related to the function of the renin-angiotensin system, which is normally suppressed by a high-salt diet. Endothelial dysfunction probably plays an important role in the influence of high sodium intake on blood pressure, although the exact mechanisms remain elusive. Genetic factors are known to be very important, and various consomic and congenic rat strains as animal models have proven to be very useful in bringing us a step closer to understanding the interaction between salt intake and hypertension. In this article, experimental data obtained in studies on animals and humans, as well as epidemiological data are reviewed.

Association of the renin gene polymorphism, three angiotensinogen gene polymorphisms and the haplotypes with essential hypertension in the Mongolian population

Renin is a rate-limiting enzyme of the renin-angiotensin system and plays a crucial role in the regulation of blood pressure (BP). Angiotensinogen (AGT) is the precursor of potent vasoactive hormone angiotensin II and the AGT gene has been incriminated as a marker for genetic predisposition to essential hypertension (EH) in some ethnic groups. The purpose of the study is to explore the association of a new genetic marker of renin gene, and AGT gene M235T, A-6G, and A-20C polymorphisms and their haplotypes with EH in the Mongolian population. On the basis of the prevalence survey, 243 hypertensives and 258 normotensives who had no blood relationship with each other were selected as subjects. All the subjects were interviewed with questionnaires and their blood specimens were collected. Renin gene insertion/ deletion (I/D) polymorphism was genotyped by PCR-polyacrylamide gel electrophoresis. AGT gene M235T, A-6G, and A-20C polymorphisms were genotyped by a PCR-restriction fragment length polymorphism and single-strand conformation polymorphism. The frequencies of renin genotype DD and allele D in hypertensives (36.21%, 63.79%, respectively) were significantly higher than those in normotensives (29.84%, 57.17%, respectively, P < 0.05). The odds ratios (OR) of renin genotype ID, DD to renin genotype II on hypertension were 1.98 (OR 95% CI 1.08-3.72) and 2.51 (OR 95% CI 1.33-4.88), respectively. There were no significant differences in the distributions of genotypes and alleles for AGT gene M235T, A-6G, and A-20C polymorphisms and all different haplotypes between the two groups. Renin gene I/D polymorphism is associated with EH, whereas AGT gene M235T, A-6G, and A-20C polymorphisms and the haplotypes are not associated with EH in the Mongolian population.

Association Study Between the Human Renin Gene and Preeclampsia

OBJECTIVE

We recently reported on a missense mutation in exon 9 of the human renin gene (G1051A) that may affect the functioning of this enzyme, and is associated with essential hypertension. The aim of the present study is to assess the association between the genotypes of this missense mutation in the renin gene and preeclampsia (PE) via a case-control study.

METHODS

DNA was extracted from peripheral blood leukocytes, and genotyping of G1051A was performed in 117 PE patients and in 171 non-PE controls.

RESULTS

The frequency of genotypes for G1051A was not significantly different between the two groups. The frequency of the A1051 allele was also not significantly different between PE patients (52.6%) and non-PE controls (50.6%).

CONCLUSIONS

The missense mutation G1051A in the human renin gene is not associated with PE.

Absence of peroxisome proliferator-activated receptor-alpha abolishes hypertension and attenuates atherosclerosis in the Tsukuba hypertensive mouse

Peroxisome proliferator-activated receptor-alpha is widely distributed in the vasculature where it is believed to exert pleiotropic antiatherogenic effects. Its role in the regulation of blood pressure is still unresolved; however, some evidence suggests that it may affect the renin-angiotensin system. We investigated its role in angiotensin II-induced hypertension in the Tsukuba hypertensive mouse (THM). This is a model of hypertension and atherosclerosis because of high angiotensin II and aldosterone levels as a result of the transgenic expression of the entire human renin-angiotensin system. Making the THM animals deficient in Peroxisome proliferator-activated receptor-alpha (THM/PPARKO) totally abolished hypertension and myocardial hypertrophy. This was accompanied by a reduction in plasma human active renin in THM/PPARKO mice compared with THM animals from 3525+/-128 mU/L to 1910+/-750 mU/L (P<0.05) and by a normalization of serum aldosterone (1.6+/-0.29 nmol/L versus 3.4+/-0.69 nmol/L; P=0.003). In the THM/PPARKO mice, the extent of atherosclerosis at the aortic sinus after a 12-week period on an atherogenic diet was decreased by >80%. In addition, the spontaneous formation of foam cells from peritoneal macrophages, a blood pressure-independent event, was reduced by 92% in the THM/PPARKO mice, suggesting protection from the usual oxidative stress in these animals, possibly because of lower prevailing angiotensin II levels. Finally, chronic fenofibrate treatment further elevated blood pressure in THM animals but not in THM/PPARKO animals. Taken together, these data indicate that peroxisome proliferator-activated receptor-alpha may regulate the renin-angiotensin system. They raise the possibility that its activation may aggravate hypertension and hasten atherosclerosis in the context of an activated renin-angiotensin system.

A novel variable number of tandem repeat polymorphism of the renin gene and essential hypertension

The aims of the present study were to find new genetic markers of essential hypertension (EH) and to investigate relationships between EH and polymorphisms of the renin gene. Using single strand conformation polymorphism, we discovered a new variable number of tandem repeat (VNTR) polymorphism in intron 7 that is 18 bp upstream from the boundary with exon 8. Nucleotide sequencing revealed that this VNTR polymorphism is a tandem repeat of the 4-nucleotide sequence TCTG. There were 6 alleles of this VNTR polymorphism, ranging from 7 repeats to 12 repeats. We analyzed the association between EH and this VNTR polymorphism. There was no significant difference in the overall distribution of this VNTR polymorphism between the EH and normotensive subjects. In summary, we discovered a novel VNTR polymorphism in the renin gene, and this polymorphism was not associated with EH.

Haplotype analysis of the human renin gene and essential hypertension

The human renin gene is an attractive candidate for involvement in the underlying cause of essential hypertension (EH). Despite extensive examination, the relation between the renin gene and hypertension remains unclear. The aims of the present study were to discover new genetic markers of EH and to investigate the relations between polymorphisms of the renin gene and EH in the Japanese. Using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method, we isolated 3 novel variants of the renin gene; a single nucleotide polymorphism (SNP) in intron 4 (T+17int4G), a variable number of tandem repeats (VNTR) polymorphism in intron 7, and a missense mutation in exon 9 (G1051A). We performed an association study with these polymorphisms in 212 patients with EH and 209 age-matched normotensive (NT) subjects. The frequency of genotypes VNTR and T+17int4G did not differ significantly between the 2 groups, whereas the overall distribution of G1051A was significantly different between EH and NT. Haplotype analysis revealed that the overall distribution of haplotypes differed significantly between the EH and NT groups. PRA levels in patients with EH with the G/G genotype were significantly higher than in subjects with EH with G/A and A/A genotypes. These data suggest that the missense mutation in exon 9 may affect the enzymatic function of renin and consequently may be involved in the etiology of hypertension.

The role of angiotensin II in cognition and behaviour

Polymorphisms of the renin-angiotensin system are associated with cardiovascular disorders, possibly as a consequence of increased brain angiotensin II activity. Within the brain, angiotensin controls blood pressure, fluid balance and hormone secretion; it also influences behaviour: reduction of central angiotensin function has both antidepressant-like and axiolytic-like actions. Evidence concerning the role of the renin-angiotensin system in learning and memory is contradictory, although more studies support the proposal that angiotensin reduces cognitive function. Studies of renin-angiotensin system genotype and psychological status have suggested an association between the angiotensin-converting enzyme deletion allele and age related cognitive decline, but a greater prevalence of the insertion allele in Alzheimer's disease. The deletion allele has also been associated with depressive illness, as has the M allele of the angiotensinogen gene although other studies have failed to replicate these findings. The role of the brain renin-angiotensin system in human psychopathology remains to be fully explored.

PPARalpha deficiency reduces insulin resistance and atherosclerosis in apoE-null mice

PPARalpha is a ligand-dependent transcription factor expressed at high levels in the liver. Its activation by the drug gemfibrozil reduces clinical events in humans with established atherosclerosis, but the underlying mechanisms are incompletely defined. To clarify the role of PPARalpha in vascular disease, we crossed PPARalpha-null mice with apoE-null mice to determine if the genetic absence of PPARalpha affects vascular disease in a robust atherosclerosis model. On a high-fat diet, concentrations of atherogenic lipoproteins were higher in PPARalpha(-/-)apoE(-/-) than in PPARalpha(+/+)apoE(-/-) mice, due to increased VLDL production. However, en face atherosclerotic lesion areas at the aortic arch, thoracic aorta, and abdominal aorta were less in PPARalpha-null animals of both sexes after 6 and 10 weeks of high-fat feeding. Despite gaining as much or more weight than their PPARalpha(+/+)apoE(-/-) littermates, PPARalpha(-/-)apoE(-/-) mice had lower fasting levels of glucose and insulin. PPARalpha-null animals had greater suppression of endogenous glucose production in hyperinsulinemic clamp experiments, reflecting less insulin resistance in the absence of PPARalpha. PPARalpha(-/-)apoE(-/-) mice also had lower blood pressures than their PPARalpha(+/+)apoE(-/-) littermates after high-fat feeding. These results suggest that PPARalpha may participate in the pathogenesis of diet-induced insulin resistance and atherosclerosis.