Variations of the angiotensin II type 1 receptor gene are associated with extreme human longevity

Abstract

Longevity phenotype in humans results from the influence of environmental and genetic factors. Few gene polymorphisms have been identified so far with a modest effect on lifespan leaving room for the search of other players in the longevity game. It has been recently demonstrated that targeted disruption of the mouse homolog of the human angiotensin II type 1 receptor (AT1R) gene (AGTR1) translates into marked prolongation of animal lifespan (Benigni et al., J Clin Invest 119(3):524-530, 2009). Based on the above study in mice, here we sought to search for AGTR1 variations associated to reduced AT1 receptor protein levels and to prolonged lifespan in humans. AGTR1 was sequenced in 173 Italian centenarians and 376 younger controls. A novel non-synonymous mutation was detected in a centenarian. Two polymorphisms in AGTR1 promoter, rs422858 and rs275653, in complete linkage disequilibrium, were significantly associated with the ability to attain extreme old age. We then replicated the study of rs275653 in a large independent cohort of Japanese origin (598 centenarians and semi-supercentenarians, 422 younger controls) and indeed confirmed its association with exceptional old age. In combined analyses, rs275653 was associated to extreme longevity either at recessive model (P = 0.007, odds ratio (OR) 3.57) or at genotype level (P = 0.015). Significance was maintained after correcting for confounding factors. Fluorescence activated cell sorting analysis revealed that subjects homozygous for the minor allele of rs275653 had less AT1R-positive peripheral blood polymorphonuclear cells. Moreover, rs275653 was associated to lower blood pressure in centenarians. These findings highlight the role of AGTR1 as a possible candidate among longevity-enabling genes.

Fig. 1

Genomic map and LD plot of AGTR1 (not in scale). The filled boxes are exons, numbered 1 to 4; shaded boxes non-coding regions, black box coding region. a Over the genomic AGTR1 map the position of new rare substitutions found in the Italian population is indicated. Below are the known variations, SNP numbers and their location relative to each other. b The LD block structure was calculated using the solid spine method in Haploview. The LD plot on the locus is based on the measure of D’/LOD. SNPs numbered in italic were excluded from analyses because they did not respect the HW distribution

Fig. 2

AT₁R expression in PMNs and in the CD16⁺ fraction of PMNs of subjects according to rs275653 genotype. Evaluation of AT₁R expression in controls was done twice to correct for inter-assay variability, and the means of the two evaluations were considered in the statistical analysis. Centenarians were analysed once. Representative flow cytometry analysis of AT1R expression on total PMN (a) and CD16+ (b) fractions of PMNs in subjects with different genotypes for rs275653 locus: homozygous for minor (GG) and major (AA) alleles and heterozygous (AG). On the left graphs, the fluorescence of negative controls is shown. c Percentage of cells positive for AT₁R surface expression in PMNs. Overall differences were evaluated by ANOVA (P = 0.0036); individuals with GG genotype had significantly lower expression of AT₁R as compared to those with AG (P = 0.0024) and AA (P = 0.0185) genotypes. No statistically significantly difference was observed between AC and AA genotypes. d AT₁R surface expression (percentage of cells positive ) in CD16⁺ fraction of PMNs. Overall there was a statistically significant difference among groups (P _ANOVA = 0.0016). AT₁R expression in the group of subjects homozygous for the minor variant of rs275653 was lower in respect to AG (P = 0.0030) and AA (P = 0.0134) groups. Each column shows the mean ± SEM

Fig. 3

Blood pressure in Italian and Japanese centenarians according to rs275653 genotype. Data are represented as mean ± SEM. a Diastolic blood pressure was significantly lower in centenarians with GG genotype as compared to those AA genotype (additive model, P = 0.031) or to centenarians with AA + AG genotypes (recessive model, P = 0.040). G allele was also associated to reduced DBP (P = 0.037). SBP and MAP (b and c, respectively) were statistically different in centenarians carrying the rs275653 G allele (P = 0.046 and P = 0.042, respectively)