The small GTPase accelerators regulator of G protein signalling (RGS) proteins are important regulators of proximal signalling from G protein coupled receptors. Although natural killer (NK) cells express a number of G-protein coupled receptors, expression of RGS proteins has not been investigated. We analysed the expression of RGS proteins in rat NK cells, and detected mRNA for RGS1, RGS2, RGS5, RGS8, RGS16, and RGS18. Interestingly, when we included a panel of different leucocyte subsets, we found that RGS8 was selectively expressed by NK cells. NK cells are under control of both activating and inhibitory receptors and, utilizing a xenogeneic system where the mouse activating Ly49D or inhibitory Ly49A receptors were transfected into the rat RNK-16 cell line, the potential regulation of RGS proteins by single NK cell receptors was studied. We found that ligation of Ly49D led to a rapid and transient increase in message for RGS2, while Ly49A ligation up-regulated RGS2, RGS16, and RGS18 mRNA. Both receptors also induced a prolonged increase in RGS2 endogenous protein levels. These findings suggest that RGS proteins may be influenced by or involved in NK cell receptor events, suggesting a crosstalk between G-protein coupled receptors and NK cell receptors.

BACKGROUND

Patients with chronic kidney disease manifest an inflammatory state relative to healthy individuals. Inflammation is regulated in part by genes of the interleukin-1 (IL-1) gene cluster. We hypothesized that polymorphisms in this gene cluster may be associated with risk of end-stage renal disease (ESRD).

METHODS

Polymorphisms in the IL-1 gene cluster were examined in a cohort of 239 racially diverse hemodialysis (HD) patients and 252 controls. These individuals were genotyped for 3 single nucleotide polymorphisms (SNPs) in the IL-1alpha and beta genes, and a variable-number-of-tandem-repeats polymorphism in the IL-1 receptor antagonist gene (IL-1RN). Polymorphisms were analyzed by logistic regression for their independent associations with ESRD, and the effect of allele dose of IL-1RN on risk for ESRD was examined. The interaction between race and genotype was also investigated.

RESULTS

A logistic regression model demonstrated that homozygosity for allele 2 of the IL-1RN variable-number-of-tandem-repeats (VNTR) polymorphism was associated with ESRD independent of race (P < 0.0005). The IL-1alpha-889 promoter SNP was associated with ESRD independent of race and of the IL-1RN polymorphism (P= 0.04). The IL-1beta-511 promoter SNP is associated with ESRD, but this is accounted for by race (P= 0.04).

CONCLUSION

Two polymorphisms within the IL-1 gene cluster are associated with ESRD independent of race. This finding is one of the strongest associations between genotype and ESRD reported, and suggests that polymorphisms in the IL-1 gene cluster affect the risk of development of ESRD.