of polymorphisms in adiponectin and leptin genes with longevity

1Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, Jordan and 2Department of Clinical Pharmacy, Jordan University of Science and Technology, Irbid, Jordan

(Received 23 November 2009; accepted 12 January 2010)

Abstract

are important for regulation body metabolism and immune response. Many studies have shown that variants in genes play a role in age-associated diseases. In this study, we investigated the contribution of rs266729 rs2241766 (þ45T/G), and rs1501299 (þ276 G/T) SNPs of adiponectin gene (ADIPQO) and rs7799039 SNP of leptin (LEP) gene to human longevity phenotype in Jordanian population. Polymorphisms were in 110 randomly selected elderly subjects (485 years old) with mean age of 90.2 years, and 120 young control (range from 20 to 50 years) with mean age of 32.0 years. No significant differences were detected in the genotype allele frequencies of examined gene variants between the two groups (p 40.05). However, when gender was considered, and alleles frequencies of rs1501299 SNP in ADIPOQ gene and rs7799039 in LEP gene were significantly with longevity in men (p 50.02) but not in women (p4 0.05). Thus, ADIPOQ and LEP genes polymorphisms play a gender-specific role in the pathway to men’s longevity.

Keywords: Adiponectin, leptin, SNP, Jordan, longevity

which alter adiponectin activity, are associated with metabolic phenotype [9,10].

Introduction

Leptin, on the other hand, is increased significantly in individuals suffering from obesity, diabetes melli- tus, hypertension or metabolic syndrome [11]. A common promoter polymorphic site rs7799039 SNP in the leptin (LEP) gene is associated with transcrip- tional activity, leading to reduced circulating leptin concentrations in subjects with AA genotype [11,12]. This polymorphism is also associated with multiple age-related diseases in several populations such as breast cancer among Tunisians [13], and non-small cell lung cancer and prostate cancer among Portu- guese [14,15].

Adiponectin and leptin are adipokines secreted from white adipose tissue and function in a hormone-like manner to regulate body metabolism and immune responses [1]. Adiponectin activates multiple signal- ling pathways, which mediate its anti-diabetic, anti- atherogenic and anti-inflammatory functions, thus, adiponectin has a protective role against age-related diseases [2,3]. Low level of adiponectin has been implicated in several late-onset disease states such as insulin resistance and type-2 diabetes [4], cardiovas- cular disease [5], hypertension [6] and dyslipidemia [7]. Several single nucleotide polymorphisms (SNPs) in ADIPOQ gene (adipocyte-, C1Q and collagen domain containing) that code for adiponectin, have been shown to affect either levels or activity of adiponectin and have been associated with age-related diseases. For example, the promoter rs266729 SNP lowers the circulating levels of adiponectin and has strong association with metabolic syndrome among Spanish and French populations [8]. Furthermore, rs2241766 and rs1501299 SNPs in ADIPOQ gene,

Since adiponectin and leptin play an important role in the body homeostasis and susceptibility to age- related diseases, allelic variants that change the levels and/or activity of adiponectin and leptin might be involved in the pathway of human longevity [16]. Indeed, two allelic variants in ADIPOQ gene, rs17300539 (711391G/A) and þ2019A/7, are associated with longevity in Ashkenazi Jewish popula- tion [17]. In the current study, the contribution of

Correspondence: Dr. Omar Khabour, PhD, Assistant Professor of Molecular Biology, Faculty of Applied Medical Sciences, Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan. Tel: þ962-2-7201000 Ext 23974. Fax: þ962-2-7201087. E-mail: khabour@just.edu.jo ISSN 1368-5538 print/ISSN 1473-0790 online  2010 Informa UK Ltd. DOI: 10.3109/13685531003657800

rs266729, rs2241766, and rs1501299 SNPs in ADI- POQ gene and rs7799039 SNP in LEP gene to longevity phenotype were investigated in Jordanian population. Results showed that rs1501299 SNP in ADIPOQ gene and rs7799039 SNP in promoter region of LEP gene play a gender-specific role in human longevity.

the extracted DNA was measured using Smart- SpectTM3000 (Bio-Rad, Hertfordshire, UK). Three polymorphic sites of ADIPOQ were genotyped according to Li et al. [21] using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Table I summarises the primers sequence, annealing temperature and restriction enzymes (Fermentas. GmbH, St. Leon-Rot, Ger- many) that were used. For each polymorphic site; 20 ml reaction mixtures containing 5 ng of template DNA, 0.75 unit GoTaq polymerase (Promega), and a final concentration of 200 mM of each deoxynu- cleotide and 1X reaction buffer, 1 mM of each forward and reverse primers. PCR products were detected using electrophoresis on 3% agarose, confirming the presence of a product. The restriction enzyme digestion was carried out in 20 ml containing 3 units of enzyme and 10 ml of PCR product and incubated at optimum temperature (see Table I) for 4 h. The LEP rs7799039 SNP was also analysed using PCR-RFLP as described by Stunff et al. [11]. PCR primers, annealing temperature and restriction enzymes are shown in Table I.

Material and methods