Zhao Jing, Wei Jianxin, Bowser Rachel K, Traister Russell S, Fan Ming-Hui, Zhao Yutong
Department of Medicine, Acute Lung Injury Center of Excellence, Vascular Medical Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213.
Department of Medicine, Acute Lung Injury Center of Excellence, Vascular Medical Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
J Immunol. 2015 Jan 15;194(2):795-802. doi: 10.4049/jimmunol.1401414. Epub 2014 Dec 3.
IL-33, a relatively new member of the IL-1 cytokine family, plays a crucial role in allergic inflammation and acute lung injury. Long form ST2 (ST2L), the receptor for IL-33, is expressed on immune effector cells and lung epithelia and plays a critical role in triggering inflammation. We have previously shown that ST2L stability is regulated by the ubiquitin-proteasome system; however, its upstream internalization has not been studied. In this study, we demonstrate that glycogen synthase kinase 3β (GSK3β) regulates ST2L internalization and IL-33 signaling. IL-33 treatment induced ST2L internalization, and an effect was attenuated by inhibition or downregulation of GSK3β. GSK3β was found to interact with ST2L on serine residue 446 in response to IL-33 treatment. GSK3β binding site mutant (ST2L(S446A)) and phosphorylation site mutant (ST2L(S442A)) are resistant to IL-33-induced ST2L internalization. We also found that IL-33 activated focal adhesion kinase (FAK). Inhibition of FAK impaired IL-33-induced GSK3β activation and ST2L internalization. Furthermore, inhibition of ST2L internalization enhanced IL-33-induced cytokine release in lung epithelial cells. These results suggest that modulation of the ST2L internalization by FAK/GSK3β might serve as a unique strategy to lessen pulmonary inflammation.
白细胞介素-33（IL-33）是白细胞介素-1细胞因子家族中一个相对较新的成员，在过敏性炎症和急性肺损伤中起关键作用。IL-33的受体——长链ST2（ST2L）在免疫效应细胞和肺上皮细胞上表达，在引发炎症中起关键作用。我们之前已经表明ST2L的稳定性受泛素-蛋白酶体系统调控；然而，其上游内化过程尚未得到研究。在本研究中，我们证明糖原合酶激酶3β（GSK3β）调节ST2L的内化和IL-33信号传导。IL-33处理诱导ST2L内化，而GSK3β的抑制或下调可减弱这种效应。发现GSK3β在IL-33处理后与ST2L的丝氨酸残基446相互作用。GSK3β结合位点突变体（ST2L(S446A)）和磷酸化位点突变体（ST2L(S442A)）对IL-33诱导的ST2L内化具有抗性。我们还发现IL-33激活了粘着斑激酶（FAK）。抑制FAK会损害IL-33诱导的GSK3β激活和ST2L内化。此外，抑制ST2L内化可增强IL-33诱导的肺上皮细胞细胞因子释放。这些结果表明，FAK/GSK3β对ST2L内化的调节可能是减轻肺部炎症的一种独特策略。
