Modulation of human longevity by single nucleotide polymorphisms in the prospective study Treviso Longeva (TRELONG)

Diego Albani, Eleonora Ateri, Stefano Mazzuco, Alice Ghilardi, Serena Rodilossi, Gloria Biella, Fausta Ongaro, Piero Antuono, Paolo Boldrini, Enrico Di Giorgi, Andrea Frigato, Elisabetta Durante, Livio Caberlotto, Andrea Zanardo, Marinella Siculi, Maurizio Gallucci, Gianluigi Forloni

Received: 13 December 2012 / Accepted: 24 June 2013 # American Aging Association 2013

SIRT3 investigates whether variants within the gene are associated with human longevity. We analyzed 549 genomic DNA samples collected during the prospective study Treviso Longeva, including elderly individuals over 70 years of age from the municipality of Treviso, a small city in the northeast of Italy. 

Abstract 

Human sirtuins are a group of seven proteins with deacetylase activity that are emerging as key modulators of basic physiological functions. Some evidence links SIRT3 to longevity in mammals. This study aimed to investigate whether variants within the SIRT3 gene were associated with human longevity.

Electronic supplementary material 

The online version of this article (doi:10.1007/s11357-013-9559-2) contains supplementary material, which is available to authorized users.

D. Albani (*) E. Ateri A. Ghilardi S. Rodilossi: G. Biella G. Forloni Department of Neuroscience, IRCCSIstituto di Ricerche Farmacologiche Mario Negri, via La Masa , Milan, Italy e-mail: diego.albani@marionegri.it e-mail: mazzuco@stat.unipd.it P. Antuono e-mail: elly.a@gmail.com A. Ghilardi e-mail: alice.ghilardi@marionegri.it S. Rodilossi e-mail: serena.rodilossi@marionegri.it G. Biella e-mail: gloria.biella@marionegri.it G. Forloni e-mail: P. Antuono e-mail: PAntuono@mcw.edu Department of Statistics, University of Padova, Via Cesare Battisti, 241, 35121 Padova, Italy e-mail: mgallucci@ulss.tv.it 

Background 

Human sirtuins are a group of seven proteins sharing NAD+-dependent deacetylase activity that seem to be involved in several basic physiological mechanisms and relevant for age-linked diseases (Albani et al. 2010; Polito et al. 2010). Among SIRTs, SIRT3 is a mitochondrial protein involved in defensive mechanisms against oxidative stress (Yu et al. 2012; Bause and Haigis 2012; Iwahara et al. 2012). Considering that oxidative stress is a basic feature of aging, SIRT3 may have a role in modulating longevity, a hypothesis supported by evidence in an animal model where the disruption of the gene coding for angiotensin II receptor type 1A resulted in marked prolongation of lifespan in mice, with an increased number of mitochondria in the kidney and upregulation of prosurvival genes (including SIRT3) (Benigni et al. 2009). Moreover, genetic association studies pointed out a role for SIRT3 in human longevity. The SIRT3 single nucleotide polymorphism (SNP) rs11555236 minor allele (T) increased male survival in an Italian cohort from Calabria and was found in linkage disequilibrium with a putative enhancer located within SIRT3 intron 5 (Bellizzi et al. 2005; Rose et al. 2003). In a different multicentre study that recruited centenarians from Italy and Germany (for a total of 1,321 centenarians and 1,140 younger subjects), some SNPs in SIRT3 showed significant association with longevity in the Italian female and in the German male subgroups, although this result was not supported by a replication enrolling centenarians of French ancestry (Lescai et al. 2009). Moreover, in a study analyzing genetic variants of the oldest old, a list of SIRT3 SNPs was detailed in long-living individuals of Caucasian ancestry (Halaschek-Wiener et al. 2009). Starting from the evidence supporting an involvement of SIRT3 in longevity, we genotyped three SNPs of SIRT3 in an ongoing prospective study enrolling an elderly population (Treviso Longeva (TRELONG) study; GallucciDeparture from Hardy-Weinberg equilibrium was assessed in the considered groups, even after gender stratification (data not shown). Survival curves were estimated using the Kaplan-Meier method. Hazard ratios (HRs) were calculated using the Cox proportional hazard model. The proportional hazard was tested using Schoenfeld's residual test, and it was never rejected, thus confirming the suitability of the model. Multivariate regression analysis was performed considering mortality as the dependent variable. These statistical analyses were computed using the survival package of the R software. After correction for possible confounders (diabetes, cardiovascular diseases, cerebral vasculopathies, cancer, cholesterol level, scholarship, age, and gender), results were considered significant at <0.05, using two-tailed tests of significance.

Prospective analysis of the TRELONG study features a longitudinal follow-up with mortality data. We decided to reanalyze variability considering mortality as a dependent variable and plotting survival curves according to genotype (Fig. 1). As mortality might be influenced by several other variables, we controlled for TRELONG disorders (diabetes, cardiovascular diseases, vasculopathies, and cancer), risk factors (cholesterol level, scholarship), age, and gender. We found an association between rs4980329 and survival, with the allele (A) giving an advantage for longevity. HRs, considering the major allele homozygous genotype as reference, were 1.08 and 0.66 for (GA) and (AA) genotypes, respectively. A second association was found for rs11555236, with the minor allele (T) giving an advantage. For this polymorphism, HRs using the major allele homozygous genotype were 1.18 and 0.58, respectively. No association was found for rs3825075.