Table 1 Significant SNPs obtained according to test in the stage 2 sample MAX

SNP ID dbSNP RS Variation Position Gene Best model c2 p value best model p valuea MAX 6 rs282070 G/C Intron 1 MAP3K7 Dominant 13,939 5×10−4 0.0011 145 rs2111699 A/G Intron 1 GSTZ1 Recessive 12,511 3×10−4 0.0014 306 rs11066301 A/G Intron 1 SHP2 Dominant 8,444 0.005 0.0111 189 rs1042571 C/T 3′ UTR POMC Recessive 4,413 0.046 0.0874 103 rs3212948 C/G Intron 3 ERCC1 Recessive 4,024 0.048 0.1062

c2 represents the maximum of the three chi-square values MAX ap value was adjusted for multiple testing of different genetic models obtained by the proposed permutational approach

value was adjusted for multiple testing of different genetic models obtained by the proposed permutational approach

Discussion

considered as a crucial factor in the cascade of intra- cellular events initiated by environmental and/or phys- iological stressors that induce cells to survive or to die and therefore may be important for regulating aging. However, although several components of MAPK sig- naling pathways play important roles in the regulation of cellular senescence (Maruyama et al. 2009; Debacq-Chainiaux et al. 2010) and have been also implicated in the pathogenesis of many human dis- eases (Kim and Choi 2010), no data have been docu- mented so far about the influence of MAP3K7 on human aging and longevity. The results of our study provide the first evidence of such an influence with the rs282070-C allele positively affecting longevity in a dominant manner.

In the present study, we investigated possible associa- tions between longevity and 317 SNPs in 104 candi- date genes involved in the regulation of aging-related biological pathways by using a two-stage approach. To improve the efficiency of this study design, we used a robust test that is powerful when the underlying genetic model is unknown and that was successfully applied to genome-wide association studies (Zheng et al. 2007; Sladek et al. 2007). We found that two SNPs, rs282070 on intron 1 of MAP3K7 gene and rs2111699 on intron 1 of GSTZ1 gene, were significantly associ- ’ ated with survival at advanced age after Bonferroni s correction.

Also GSTZ1 is implicated in the cellular response to environmental insults. GSTZ1 is a member of the glutathione S-transferase (GSTs) superfamily of mul- tifunctional enzymes which are involved in the cellu- lar detoxification, via conjugation with glutathione (GSH) of a wide range of endogenous and exogenous toxic compounds, and various reactive products gen- erated under oxidative stress. Diverse cellular func- tions, ranging from apoptosis to cell survival, are also modulated by GSTs (Nebert and Vasiliou 2004; Hayes et al. 2005; Laborde 2010). The GSTs comprise three families of genes designed as cytosolic, mitochondrial, and microsomal transferase. The cytosolic GSTZ class of GSTs is expressed in many eukaryotic species, including fungi, plants, insects, and mammals (Board et al. 1997). Human GSTZ1, which is identical to maleylacetoacetate isomerase, catalyses two distinct α reactions: the biotransformation of a range of - haloacids, including dichloroacetic acid, a drinking water contaminant, and the GSH-dependent isomeri- zation of maleylacetoacetate to fumarylacetoacetate, – the penultimate step in the phenylalanine tyrosine

MAP3K7 (also known as transforming growth β factor- activated kinase-1) is a serine/threonine ki- nase, member of the mitogen-activated protein kinase kinase kinase family, which plays a crucial role in interleukin 1, tumor necrosis factor, and Toll-like re- ceptor signaling pathways. Various stressors and in- flammatory cytokines trigger the activation of MAP3K7 which in turn activates key intracellular kinases such as the p38 MAPK, c-jun N-terminal kinase, and I-kappa B kinase complex. These path- ways ultimately activate transcription factors nuclear factor-kappa B and activator protein-1 which are crit- ical regulators of genes of the immune-inflammatory responses (Ninomiya-Tsuji et al. 1999; Sato et al. 2005; Chen et al. 2006; Landström 2010). Studies have also demonstrated that the oxidative stress caused by reactive oxygen species (ROS) may induce or mediate the activation of the MAPK pathways, including the one mediated by MAP3K (Son et al. 2011 for a review). In particular, Omori et al. (2008) reported that MAP3K7 regulates the levels of ROS and prevent inflammation. Thus, MAP3K7 may be

allelic variants differently affect the transcriptional rate, but linkage disequilibrium of these SNPs with other functional variants is also possible. This is an interesting issue that needs to be investigated in future research. Nevertheless, we believe that our results reinforce the view (synthesized in the oxidation in- flammatory theory of aging, see De la Fuente and Miquel 2009) that the immune, inflammatory, and stress responses, which are essential components of ’ the body s network of defense against external and internal damaging agents, play an essential role in life span and in age-related phenotypes.