Level of expression of IL-13Rα2 impacts receptor distribution and IL-13 signaling

MO Daines, Y Tabata, BA Walker, W Chen… - The Journal of …, 2006 - journals.aai.org
MO Daines, Y Tabata, BA Walker, W Chen, MR Warrier, S Basu, GKK Hershey
The Journal of Immunology, 2006journals.aai.org
IL-13, a critical cytokine for allergic inflammation, exerts its effects through a complex
receptor system including IL-4Rα, IL-13Rα1, and IL-13Rα2. IL-4Rα and IL-13Rα1 form a
heterodimeric signaling receptor for IL-13. In contrast, IL-13Rα2 binds IL-13 with high affinity
but does not signal. IL-13Rα2 exists on the cell surface, intracellularly, and in soluble form,
but no information is available regarding the relative distributions of IL-13Rα2 among these
compartments, whether the compartments communicate, and how the relative expression …
Abstract
IL-13, a critical cytokine for allergic inflammation, exerts its effects through a complex receptor system including IL-4Rα, IL-13Rα1, and IL-13Rα2. IL-4Rα and IL-13Rα1 form a heterodimeric signaling receptor for IL-13. In contrast, IL-13Rα2 binds IL-13 with high affinity but does not signal. IL-13Rα2 exists on the cell surface, intracellularly, and in soluble form, but no information is available regarding the relative distributions of IL-13Rα2 among these compartments, whether the compartments communicate, and how the relative expression levels impact IL-13 responses. Herein, we investigated the distribution of IL-13Rα2 in transfected and primary cells, and we evaluated how the total level of IL-13Rα2 expression impacted its distribution. Our results demonstrate that the distribution of IL-13Rα2 is independent of the overall level of expression. The majority of the IL-13Rα2 protein existed in intracellular pools. Surface IL-13Rα2 was continually released into the medium in a soluble form, yet surface expression remained constant supporting receptor trafficking to the cell surface. IL-13Rα2 inhibited IL-13 signaling proportionally to its level of expression, and this inhibition could be overcome with high concentrations of IL-13.
journals.aai.org