Ozaki et al. have identified a cytokine receptor gene termed novel interleukin receptor (NILR), whose sequence is quite similar to that of the interleukin (IL)-2 receptor beta (IL2Rβ) chain. NILR transcripts are most abundant in thymus and spleen, but are also observed in small intestine and lung. NILR mRNA and protein levels were increased in peripheral blood mononuclear cells (PBMCs) after T cell receptor crosslinking. NILR and Jak1, a tyrosine kinase involved in IL-2 signaling that binds to IL2Rβ, immunoprecipitated together in untransfected PBMCs. Homodimers of chimeric proteins consisting of the erythropoietin (EPO) receptor extracellular domain and the transmembrane and cytoplasmic domains of NILR supported the activation of STAT5 and Jak1 in EPO-treated cells, suggesting that NILR can function to activate cytokine signaling pathways. But which cytokine pathway? An article in press mentioned by Ozaki et al. describes the cloning and characterization of the NILR gene as the receptor for IL-21.
Ozaki, K., Kikly, K., Michalovich, D., Young, P.R., and Leonard, W.J. (2000) Cloning of a type I cytokine receptor most related to the IL-2 receptor chain. Proc. Natl. Acad. Sci. U.S.A. 97: 11439-11444. [Abstract] [Full Text]