A Membrane-Proximal Region of the Interleukin-2 Receptor γ_c Chain Sufficient for Jak Kinase Activation and Induction of Proliferation in T Cells

Abstract

The interleukin-2 (IL-2) receptor (IL-2R) consists of three distinct subunits (alpha, beta, and gamma c) and regulates proliferation of T lymphocytes. Intracellular signalling results from ligand-mediated heterodimerization of the cytoplasmic domains of the beta and gamma c chains. To identify the residues of gamma c critical to this process, mutations were introduced into the cytoplasmic domain, and the effects on signalling were analyzed in the IL-2-dependent T-cell line CTLL2 and T-helper clone D10, using chimeric IL-2R chains that bind and are activated by granulocyte-macrophage colony-stimulating factor. Whereas previous studies of fibroblasts and transformed T cells have suggested that signalling by gamma c requires both membrane-proximal and C-terminal subdomains, our results for IL-2-dependent T cells demonstrate that the membrane-proximal 52 amino acids are sufficient to mediate a normal proliferative response, including induction of the proto-oncogenes c-myc and c-fos. Although gamma c is phosphorylated on tyrosine upon receptor activation and could potentially interact with downstream molecules containing SH2 domains, cytoplasmic tyrosine residues were dispensable for mitogenic signalling. However, deletion of a membrane-proximal region conserved among other cytokine receptors (cytoplasmic residues 5 to 37) or an adjacent region unique to gamma c (residues 40 to 52) abrogated functional interaction of the receptor chain with the tyrosine kinase Jak3. This correlated with a loss of all signalling events analyzed, including phosphorylation of the IL-2R beta-associated kinase Jak1, expression of c-myc and c-fos, and induction of the proliferative response. Thus, it appears in T cells that Jak3 is a critical mediator of mitogenic signaling by the gamma c chain.

Cloning of the human IL‐13Rα1 chain and reconstitution with the IL‐4Rα of a functional IL‐4/IL‐13 receptor complex

“…The fact that IL-13Ral can replace yc for the reconstitution of an active IL-4 receptor explains, as previously suggested [6], the conflicting reports describing the need for yc for an active IL-4 receptor [9,20], and the description of active IL-4 receptors in the absence of yc [21,22]. Since the cytoplasmic domain of IL-13Ral is 26 amino acids shorter than that of yc we are currently investigating whether IL-13Ral contributes to the recruitment of Jak3, as described for yc [23], and/ or to other signaling events as recently suggested [24]. In this context, it is important to emphasize the presence in the IL13Rod of a proline-rich motif located in the cytoplasmic region near the transmembrane domain suggesting that IL13Ral can associate with some kinases of the Jak family [25].…”

A Permissive Role for Phosphatidylinositol 3-Kinase in the Stat5- mediated Expression of Cyclin D2 by the Interleukin-2 Receptor

“…Western Blots-Cytoplasmic and nuclear extracts of CTLL-2 cells were prepared and immunoblotted as described (33). Antibody to phospho-Jak1 (44-422) was purchased from BIOSOURCE International (Camarillo, CA).…”

Enhanced signaling through the IL-2 receptor in CD8+T cells regulated by antigen recognition results in preferential proliferation and expansion of responding CD8+T cells rather than promotion of cell death

“…Therefore, we examined the effect of enhanced, regulated IL-2R signaling during CD8 ϩ T cell responses by generating Tg mice that express a chimeric GMIL2R under the control of a CD8 enhancer͞ promoter element, as this model mimics the effects of increased availability of IL-2 to trigger the IL-2R selectively in responding CD8 ϩ T cells. In particular, the native GM-CSF receptor and IL-2R have nearly identical K d (Ϸ30 pM) as well as on͞off rates and t 1/2 values of ligand release (29,30), and ligand binding by the GMIL2R transduces a signal that is indistinguishable from the native IL-2R kinetically and functionally (31)(32)(33).…”