Evans G A, Goldsmith M A, Johnston J A, Xu W, Weiler S R, Erwin R, Howard O M, Abraham R T, O'Shea J J, Greene W C
Biological Carcinogenesis and Development Program, Scientific Applications International Corporation, Frederick, Maryland 21702-1201, USA.
J Biol Chem. 1995 Dec 1;270(48):28858-63. doi: 10.1074/jbc.270.48.28858.
The interleukin (IL)-2 receptor system has previously been shown to signal through the association and tyrosine phosphorylation of Shc. This study demonstrates that the IL-2 receptor beta (IL-2R beta) chain is the critical receptor component required to mediate this effect. The use of IL-2R beta chain deletion mutants transfected into a Ba/F3 murine cell model describes a requirement for the IL-2R beta "acid-rich" domain between amino acids 315 and 384 for Shc tyrosine phosphorylation and receptor association. COS cell co-transfection studies of IL-2R beta chain constructs containing point mutations of tyrosine to phenylalanine along with the tyrosine kinase Jak-1 and a hemagglutinin-tagged Shc revealed that the motif surrounding phosphorylated tyrosine 338 within the acid-rich domain of the IL-2R beta is a binding site for Shc. Deletion of this domain has previously been shown to abrogate the ability of IL-2 to activate Ras but does not affect IL-2-dependent mitogenesis in the presence of serum. Proliferation assays of Ba/F3 cells containing IL-2R beta chain deletion mutants in serum-free medium with or without insulin shows that deletion of the acid-rich domain does not affect IL-2-driven mitogenesis regardless of the culture conditions. This study thus defines the critical domain within the IL-2R beta chain required to mediate Shc binding and Shc tyrosine phosphorylation and further shows that Shc binding and phosphorylation are not required for IL-2-dependent mitogenesis. Neither serum nor insulin is required to supplement the loss of induction of the Shc adapter or Ras pathways, which therefore suggests a novel mechanism for mitogenic signal transduction mediated by this hematopoietin receptor.
白细胞介素（IL）-2受体系统先前已被证明可通过Shc的缔合和酪氨酸磷酸化来传递信号。本研究表明，IL-2受体β（IL-2Rβ）链是介导此效应所需的关键受体成分。将IL-2Rβ链缺失突变体转染到Ba/F3小鼠细胞模型中进行的研究表明，对于Shc酪氨酸磷酸化和受体缔合，IL-2Rβ在氨基酸315和384之间的“富含酸性”结构域是必需的。对含有酪氨酸突变为苯丙氨酸的点突变的IL-2Rβ链构建体与酪氨酸激酶Jak-1以及血凝素标记的Shc进行的COS细胞共转染研究表明，IL-2Rβ富含酸性结构域内磷酸化酪氨酸338周围的基序是Shc的结合位点。先前已证明缺失该结构域可消除IL-2激活Ras的能力，但在有血清存在的情况下不影响IL-2依赖性有丝分裂。在有或无胰岛素的无血清培养基中对含有IL-2Rβ链缺失突变体的Ba/F3细胞进行的增殖测定表明，无论培养条件如何，富含酸性结构域的缺失均不影响IL-2驱动的有丝分裂。因此，本研究确定了IL-2Rβ链内介导Shc结合和Shc酪氨酸磷酸化所需的关键结构域，并进一步表明IL-2依赖性有丝分裂不需要Shc结合和磷酸化。既不需要血清也不需要胰岛素来补充Shc衔接子或Ras途径诱导缺失的情况，因此提示了由这种造血受体介导的有丝分裂信号转导的新机制。
