Interleukin-4 (IL-4) and IL-13 bind to a shared heterodimeric complex on endothelial cells mediating vascular cell adhesion molecule-1 induction in the absence of the common gamma chain.
Interleukin-4 (IL-4) and IL-13 exert similar, nonadditive effects on endothelial cells, inducing vascular cell adhesion molecule-1 (VCAM-1) expression and subsequent transmigration of eosinophils. The receptor for IL-4 and IL-13 was described as a shared heteromultimeric complex in which the common gamma-chain (gamma c) subunit was essential for activity. Endothelial cell bound both cytokines with high affinity; by flow cytofluorometry and reverse transcription-polymerase chain reaction (RT-PCR), they expressed IL-4 receptor alpha (IL-4R alpha) but did not express the gamma c of the IL-2R. Radioligand cross-linking experiments followed by immunoprecipitation with the monoclonal antibody (MoAb) S697 to the IL-4R alpha showed IL-4-specific binding at 130 kD, the IL-4R alpha, and to a minor extent to a double band coimmunoprecipitated at 65 to 75 kD. [125 I]IL-13 bound predominantly to the 65- to 75- kD band and with a trace amount of binding at 130 kD. However, no ligand-cross-linked receptor was precipitated by the MoAb S697, indicating a cognate novel IL-13-binding subunit. Excess unlabeled IL-4 completely displaced IL-13 binding. Similarly, nonsignaling IL-4 (Y124D)-mutant abolished IL-4- and IL-13-mediated signal transduction. Unlabeled IL-13 competed successfully for IL-4 binding at 65 to 75 kD but was unable to completely displace Il-4 from its binding to the IL-4R alpha. The MoAb TUGh4, specific for the gamma c, failed to precipitate ligand-cross-linked IL-4R and IL-13R. Therefore, the subunit structure of the functional receptors for IL-4 and IL-13 on human endothelial cells does not use or require the common gamma c of the IL-2R.[1]References
- Interleukin-4 (IL-4) and IL-13 bind to a shared heterodimeric complex on endothelial cells mediating vascular cell adhesion molecule-1 induction in the absence of the common gamma chain. Schnyder, B., Lugli, S., Feng, N., Etter, H., Lutz, R.A., Ryffel, B., Sugamura, K., Wunderli-Allenspach, H., Moser, R. Blood (1996) [Pubmed]
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