Genes in the insulin/IGF1 signaling pathway affect lifespan in yeast, nematodes, fruit flies, and mice (Fontana et al. 2010; Barbieri et al. 2003). Mutation of genes in this signaling pathway confers greater resistance to oxidative stress and phenotypic charac- teristics consistent with delayed and slowed aging. In particular, heterozygous deletion of the IGF1R gene has been shown to causes a modest reduction in size, improves stress resistance and extends life span in mice (Hoizenberger 2003). Furthermore, systemic or neural-specific reduction of the insulin receptor substrate-2 (IRS2) can promote healthy metabolism, attenuate meal-induced oxidative stress, and extend the

Follow-up data

All-cause and cause-specific mortality rates were assessed after a mean follow-up of 6 years. During that time, 227 (31.4%) of the 722 participants had died. Of these, 179 (78.8%) were long-lived subjects, 102 (45%) had died due to cardiovascular diseases (CVD), 34 (15%) due to cancer, and 91 (40%) due to other causes.

Univariate analysis revealed no significant differ- ences in cause-specific mortality risk by Cox regression

Allele combination Frequency Odds ratio (95% CI) p IGF1R IRS2 UCP2 Controls Long-lived G G A 0.27 0.22 1.0 A G A 0.21 0.22 1.286 (0.65–2.54) 0.468 G G V 0.13 0.10 0.932 (0.37–2.32) 0.881 G A A 0.14 0.11 1.084 (0.51–2.27) 0.466 A A A 0.09 0.10 1.226 (0.55–2.72) 0.616 A A V 0.07 0.18 3.185 (1.63–6.19) 0.0006 A G V 0.05 0.04 0.962 (0.36–2.56) 0.938 G A V 0.04 0.02 0.756 (0.26–2.16) 0.601 Polymorphism Allele combination background IGF1R G/A −AV 4.21822 (1.30–13.59) 0.01 IRS2 G/A A–V 3.23002 (1.01–10.33) 0.04 UCP2 A/V AA− 2.49276 (0.95–6.48) 0.06

Allele combination

genetic and/or environmental background may differ- ently modulate the effect of a given gene in different populations.

life span and extend the life span of mice up to 20% (Taguchi et al. 2007). In humans, IGF1R variants have been found associated with susceptibility to metabolic syndrome-related phenotypes, in particular with the risk of having insulin resistance and arterial hyperten- sion (Sookoian et al. 2010). Indeed, we have previously demonstrated that allele A variant at codon 1013 of IGF1R is associated with longevity and with low levels of free plasma IGF-1 (Bonafè et al. 2003) and more recently an overrepresentation of heterozygotes for mutation in IGF1R gene has been found among Jewish female centenarians (Suh et al. 2008). Furthermore, some, but not all, studies have indicated a role for IRS2 gene variants in the pathogenesis of obesity and obesity-associated insulin resistance (Sesti et al. 2001; Stefan et al. 2003). Indeed, we have recently found that subjects with one or two IRS2Asp alleles displayed a greater chance of living between 96 and 104 years of age (Barbieri et al. 2010)

suggested by the ability of UCP2 to reduce ROS and regulate mitochondrial function in a diverse range of tissues (Fridell et al. 2005; Andrews et al. 2009) since mitochondrial dysfunction and ROS production lies at the heart of the aging process. In humans, some, but not all (Klannemark et al. 1998), studies showed that UCP2 gene variants are implicated in diabetes, obesity, and fat metabolism (Zhang et al. 2001) and are strongly linked to resting energy expenditure (Astrup et al. 1999; Buemann et al. 2001; Walder et al. 1998). Interestingly, in our study, AAV haplotype has

Interestingly, in our study, AAV haplotype has been found significantly associated with lower insulin resistance degree and higher energy expenditure parameters.

factor associated with a variety of intermediate pheno- types (hypertension, atherosclerosis, obesity) strongly affecting morbidity, disability and mortality among the elderly (Facchini et al. 2001). By contrast, humans – beyond 85 90 years of age display a preserved insulin — action and centenarians are surprisingly insulin- sensitive. In accordance with previous studies (Barbieri et al. 2008), a remarkably low IR, as well as BMI, WHR, cholesterol, and triglycerides levels was found in our long-lived people, confirming that these individuals are less prone to the metabolic derange- ment normally occurring with aging. Furthermore, as previously demonstrated in a small Italian cohort, despite an age-related decline in energy metabolism parameters, long-lived subjects had greater RQ and RMR compared to aged subjects (Rizzo et al. 2005). It is likely that the overrepresentation of AAV allele combination might help to explain such peculiar phenotype found in long-lived subjects. In fact, through its effect on insulin resistance and energy expenditure parameter AAV allele combination might confer to long-lived subject a better ability to preserve energy metabolism and to delay the age-related metabolic derangement. Indeed, the effect on longevity is supported by the prospective analysis showing AAV allele combination significantly associated with lower all-cause mortality risk. The fact that AAV allele combination has been found associated with a decreased all-cause mortality risk and not with cause-specific mortality risk may suggest that its association with

Recent experimental evidences suggest that the effect of the insulin IGF1 signaling pathway on life span may be partially mediated by regulating the expression of uncoupling protein 2 (UCP2) (Bratic and Trifunovic 2010; Andrews et al. 2005) In flies, over-expressing human UCP2 (hUCP2) to adult neurons resulted in decreased oxidative damage and extended life span without compromising fertility or physical activity (Fridell et al. 2005). Furthermore, a very recent study has demonstrated that the absence of UCP2 shortens life span in wild-type mice, and the level of UCP2 positively correlates with the postnatal survival of superoxide dismutase 2 mutant animals (Andrews and Horvath 2009). Indeed, no difference in relative mortality risk among UCP2 gene variant was observed in a Dutch cohort (van Heemst et al. 2005)