Genetic variation in selenoprotein S influences inflammatory response

Joanne E Curran^1, 6, Jeremy B M Jowett^2, 3, 6, Kate S Elliott^2, 6, Yuan Gao⁴, Kristi Gluschenko², Jianmin Wang², Dalia M Abel Azim⁵, Guowen Cai¹, Michael C Mahaney¹, Anthony G Comuzzie¹, Thomas D Dyer¹, Ken R Walder^3, 4, Paul Zimmet^2, 3, Jean W MacCluer¹, Greg R Collier^3, 4, Ahmed H Kissebah^5, 6 & John Blangero^1, 3, 6

¹  Southwest Foundation for Biomedical Research, San Antonio, Texas 78227, USA.

²  International Diabetes Institute, Caulfield, Victoria, Australia.

³  ChemGenex Pharmaceuticals, Geelong, Victoria, Australia.

⁴  Metabolic Research Unit, School of Health Sciences, Deakin University, Waurn Ponds, Victoria, Australia.

⁵  Take Off Pounds Sensibly Center for Obesity and Metabolic Research, Medical College of Wisconsin, Wisconsin, USA.

⁶  These authors contributed equally to this work.

Chronic inflammation has a pathological role in many common diseases and is influenced by both genetic and environmental factors. Here we assess the role of genetic variation in selenoprotein S (SEPS1, also called SELS or SELENOS), a gene involved in stress response in the endoplasmic reticulum and inflammation control. After resequencing SEPS1, we genotyped 13 SNPs in 522 individuals from 92 families. As inflammation biomarkers, we measured plasma levels of IL-6, IL-1 and TNF-. Bayesian quantitative trait nucleotide analysis identified associations between SEPS1 polymorphisms and all three proinflammatory cytokines. One promoter variant, -105G A, showed strong evidence for an association with each cytokine (multivariate P = 0.0000002). Functional analysis of this polymorphism showed that the A variant significantly impaired SEPS1 expression after exposure to endoplasmic reticulum stress agents (P = 0.00006). Furthermore, suppression of SEPS1 by short interfering RNA in macrophage cells increased the release of IL-6 and TNF-. To investigate further the significance of the observed associations, we genotyped -105G A in 419 Mexican American individuals from 23 families for replication. This analysis confirmed a significant association with both TNF- (P = 0.0049) and IL-1 (P = 0.0101). These results provide a direct mechanistic link between SEPS1 and the production of inflammatory cytokines and suggest that SEPS1 has a role in mediating inflammation.

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