Proteasomal regulation of βc signaling reveals a novel mechanism for cytokine receptor heterotypic desensitization
Margarita Martinez-Moczygemba, David P. Huston
Margarita Martinez-Moczygemba, David P. Huston
Published December 15, 2001
Citation Information: J Clin Invest. 2001;108(12):1797-1806. https://doi.org/10.1172/JCI13877.
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Article

Proteasomal regulation of βc signaling reveals a novel mechanism for cytokine receptor heterotypic desensitization

Abstract

IL-5, IL-3, and GM-CSF are hematopoietic cytokines that are key mediators of the allergic inflammatory response. The receptors for these three cytokines consist of a cytokine-specific α (Rα) chain and a shared common β (βc) chain. Herein, we demonstrate that agonistic ligation of these receptor subunits rapidly induces proteasomal degradation of the βc, but not the Rα, cytoplasmic domain, resulting in termination of signal transduction and yielding a truncated βc isoform ligated to the Rα subunit. Proteasomal degradation of the βc cytoplasmic domain was also a prerequisite for endocytosis and lysosomal degradation of the ligated receptor subunits. Moreover, proteasome-dependent termination of signaling induced by one βc-engaging cytokine resulted in cellular desensitization to signal transduction by subsequent stimulation with another βc-engaging cytokine. These data provide the first evidence for ligand-dependent proteasomal degradation of the βc cytoplasmic domain, and they establish a novel mechanism for heterotypic desensitization of shared cytokine receptor signaling.

Authors

Margarita Martinez-Moczygemba, David P. Huston

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Figure 1

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IL-5 reduces βc protein expression, while transiently increasing faster-...
IL-5 reduces βc protein expression, while transiently increasing faster-migrating βc bands. (a) TF1 cells that were cytokine-starved for 48 hours were stimulated with 5 ng/ml of either IL-5, GM-CSF, or IL-3 for the indicated times (107 cells/lane). Whole-cell lysates were prepared and immunoprecipitated with anti-βc monoclonal antibody S-16. Immune complexes were resolved on 8% SDS-PAGE gels and immunoblotted with anti-βc polyclonal antibodies. The top arrow in each panel represents full-length βc receptors, and the bottom arrow indicates truncated βc receptors (Δβc). (b) TF1 cells that were cytokine-starved for 48 hours were stimulated with 5 ng/ml of either IL-5, IL-3, or GM-CSF for the indicated times (107 cells/lane). Total RNA was prepared for each timepoint, and 30 μg of RNA/lane was analyzed with a βc probe corresponding to residues 417–530, which includes a piece of the membrane-proximal extracellular domain, the transmembrane domain, and part of the intracytoplasmic domain. (c) Total RNA from the IL-5–stimulated (for 1 hour) TF1 cells was reverse-transcribed using oligo(dT) primers, and amplified by PCR using a 3′ βc primer corresponding to its poly-A+ tail, a 5′ primer to a region flanking the βc transmembrane domain (lane 3), and another 5′ primer located in its transmembrane domain (lane 4). As a negative control, no cDNA was included in lane 2. Lane 1 is a DNA size ladder.