Functional Characterization of the Human Interleukin-15 Receptor αChain and Close Linkage of IL15RA and IL2RA Genes

Autor: Jeanette S. Bertles, Linda S. Park, Aaron Loomis, Dirk M. Anderson, Satoru Kumaki, Virginia Valentine, Judith G. Giri, Mark E. Tometsko, Neal G. Copeland, Nancy A. Jenkins, Stephan W. Morris, Debra J. Gilbert, Minoo Ahdieh, David N. Shapiro, David Cosman
Rok vydání: 1995
Předmět:
Zdroj: Journal of Biological Chemistry. 270:29862-29869
ISSN: 0021-9258
DOI: 10.1074/jbc.270.50.29862
Popis: Interleukins-2 and -15 (IL-2 and IL-15) are cytokines with overlapping but distinct biological effects. Their receptors share two subunits (the IL-2R beta and -gamma chains) that are essential for signal transduction. The IL-2 receptor requires an additional IL-2-specific alpha subunit for high affinity IL-2 binding. Recently, a murine IL-15-specific alpha subunit was identified, cloned, and shown to be structurally related to IL-2R alpha. However, the murine IL-15R alpha alone bound IL-15 with a 1000-fold higher affinity than that seen with IL-2R alpha and IL-2. We now extend these studies into the human system with the isolation of three differentially spliced human IL-15R alpha variants that are all capable of high affinity binding of IL-15. The cytoplasmic domain of IL-15R alpha, like that of IL-2R alpha, is dispensable for mitogenic signaling, suggesting that the primary role of the alpha chains is to confer high affinity binding. At high concentrations, IL-15, like IL-2, is able to signal through a complex of IL-2R beta and -gamma in the absence of the alpha subunit. Furthermore, the IL15RA and IL2RA genes have a similar intron-exon organization and are closely linked in both human and murine genomes. However, the distribution of expression of the IL-15R alpha is much wider than that of the IL-2R alpha, suggesting a broader range of cellular targets for IL-15.
Databáze: OpenAIRE