Suggestive evidence of associations between liver X receptor [beta] polymorphisms with type 2 diabetes mellitus and obesity in three cohort studies: HUNT2

• Published in: BMC medical genetics 2010-10, Vol.11, p.144
• Main Authors: Solaas, Karianne, Legry, Vanessa, Retterstol, Kjetil, Berg, Paul R, Holven, Kirsten B, Ferrieres, Jean, Amouyel, Philippe, Lien, Sigbjorn, Romeo, Javier, Valtuena, Jara, Widhalm, Kurt, Ruiz, Jonatan R, Dallongeville, Jean, Tonstad, Serena, Rootwelt, Helge, Halvorsen, Bente, Nenseter, Marit S, Birkeland, Kare I, Thorsby, Per M, Meirhaeghe, Aline, Nebb, Hilde I
• Format: Article
• Language: English
• Subjects: Genetic aspects; Genetic polymorphisms; Obesity; Physiological aspects; Risk factors; Transcription factors; Type 2 diabetes
• ISSN: 1471-2350; 1471-2350
• DOI: 10.1186/1471-2350-11-144

The liver X receptors (LXR) [alpha] and [beta] regulate lipid and carbohydrate homeostasis and inflammation. Lxr[beta].sup.-/- .sup.mice are glucose intolerant and at the same time lean. We aimed to assess the associations between single nucleotide polymorphisms (SNPs) in LXR[beta] and risk of type 2 diabetes mellitus (T2DM), obesity and related traits in 3 separate cohort studies. Twenty LXR[beta] SNPs were identified by sequencing and genotyped in the HUNT2 adult nested case-control study for T2DM (n = 835 cases/1986 controls). Five tag-SNPs (rs17373080, rs2695121, rs56151148, rs2303044 and rs3219281), covering 99.3% of the entire common genetic variability of the LXR[beta] gene were identified and genotyped in the French MONICA adult study (n = 2318) and the European adolescent HELENA cross-sectional study (n = 1144). In silico and in vitro functionality studies were performed. We identified suggestive or significant associations between rs17373080 and the risk of (i) T2DM in HUNT2 (OR = 0.82, p = 0.03), (ii) obesity in MONICA (OR = 1.26, p = 0.05) and (iii) overweight/obesity in HELENA (OR = 1.59, p = 0.002). An intron 4 SNP (rs28514894, a perfect proxy for rs17373080) could potentially create binding sites for hepatic nuclear factor 4 alpha (HNF4[alpha]) and nuclear factor 1 (NF1). The C allele of rs28514894 was associated with ~1.25-fold higher human LXR[beta] basal promoter activity in vitro. However, no differences between alleles in terms of DNA binding and reporter gene transactivation by HNF4[alpha] or NF1 were observed. Our results suggest that rs17373080 in LXR[beta] is associated with T2DM and obesity, maybe via altered LXR[beta] expression.