TY - JOUR
T1 - Three lysine residues in the common β chain of the interleukin-5 receptor are required for janus kinase (JAK)-dependent receptor ubiquitination, endocytosis, and signaling
AU - Lei, Jonathan T.
AU - Mazumdar, Tuhina
AU - Martinez-Moczygemba, Margarita
PY - 2011/11/18
Y1 - 2011/11/18
N2 - Eosinophils are multifunctional leukocytes implicated in the pathogenesis of numerous inflammatory diseases including allergic asthma and hypereosinophilic syndrome. Eosinophil physiology is critically dependent on IL-5 and the IL-5 receptor (IL-5R), composed of a ligand binding α chain (IL-5Rα), and a common β chain, βc. Previously, we demonstrated that the βc cytoplasmic tail is ubiquitinated and degraded by proteasomes following IL-5 stimulation. However, a complete understanding of the role of βc ubiquitination in IL-5R biology is currently lacking. By using a well established, stably transduced HEK293 cell model system, we show here that in the absence of ubiquitination, βc subcellular localization, IL-5-induced endocytosis, turnover, and IL-5R signaling were significantly impaired. Whereas ubiquitinated IL-5Rs internalized into trafficking endosomes for their degradation, ubiquitination-deficient IL-5Rs accumulated on the cell surface and displayed blunted signaling even after IL-5 stimulation. Importantly, we identified a cluster of three membrane-proximal βc lysine residues (Lys 457, Lys 461, and Lys 467) whose presence was required for both JAK1/2 binding to βc and receptor ubiquitination. These findings establish that JAK kinase binding to βc requires the presence of three critical βc lysine residues, and this binding event is essential for receptor ubiquitination, endocytosis, and signaling.
AB - Eosinophils are multifunctional leukocytes implicated in the pathogenesis of numerous inflammatory diseases including allergic asthma and hypereosinophilic syndrome. Eosinophil physiology is critically dependent on IL-5 and the IL-5 receptor (IL-5R), composed of a ligand binding α chain (IL-5Rα), and a common β chain, βc. Previously, we demonstrated that the βc cytoplasmic tail is ubiquitinated and degraded by proteasomes following IL-5 stimulation. However, a complete understanding of the role of βc ubiquitination in IL-5R biology is currently lacking. By using a well established, stably transduced HEK293 cell model system, we show here that in the absence of ubiquitination, βc subcellular localization, IL-5-induced endocytosis, turnover, and IL-5R signaling were significantly impaired. Whereas ubiquitinated IL-5Rs internalized into trafficking endosomes for their degradation, ubiquitination-deficient IL-5Rs accumulated on the cell surface and displayed blunted signaling even after IL-5 stimulation. Importantly, we identified a cluster of three membrane-proximal βc lysine residues (Lys 457, Lys 461, and Lys 467) whose presence was required for both JAK1/2 binding to βc and receptor ubiquitination. These findings establish that JAK kinase binding to βc requires the presence of three critical βc lysine residues, and this binding event is essential for receptor ubiquitination, endocytosis, and signaling.
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U2 - 10.1074/jbc.M111.273482
DO - 10.1074/jbc.M111.273482
M3 - Article
C2 - 21965659
AN - SCOPUS:81155132212
SN - 0021-9258
VL - 286
SP - 40091
EP - 40103
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 46
ER -