Immunoreceptor tyrosine-based inhibitory motif of the IL-4 receptor associates with SH2-containing phosphatases and regulates IL-4-induced proliferation
Immunoreceptor tyrosine-based inhibitory motif of the IL-4 receptor associates with SH2-containing phosphatases and regulates IL-4-induced proliferation
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DOI：
10.4049/jimmunol.167.11.6382
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发表时间：
2001-12-01
影响因子：
4.4
通讯作者：
Rothman, PB
中科院分区：
文献类型：
--
作者：
Kashiwada, M;Giallourakis, CC;Rothman, PB
基于免疫受体酪氨酸的抑制性基序（ITIM）与免疫受体信号通路的负向调节有关。白细胞介素 - 4受体α链（IL - 4Rα）在羧基末端包含一个假定的ITIM。为了确定ITIM在IL - 4信号通路中的作用，我们通过缺失和定点诱变去除了IL - 4Rα的ITIM，并在32D/胰岛素受体底物 - 2（IRS - 2）细胞中稳定表达野生型（WT）和突变型人IL - 4Rα。令人惊讶的是，与表达野生型人IL - 4Rα的细胞相比，表达突变型人（h）IL - 4Rα的32D/IRS - 2细胞在对IL - 4的反应中增殖过度。在表达突变型Y713F的细胞中观察到由hIL - 4诱导的Stat6（但不是IRS - 2）的酪氨酸磷酸化增强。使用与人IL - 4Rα的ITIM相对应的肽段，我们证明酪氨酸磷酸化的肽段（而非其非磷酸化的对应物）可共沉淀含SH2结构域的酪氨酸磷酸酶 - 1、含SH2结构域的酪氨酸磷酸酶 - 2和含SH2结构域的肌醇5'-磷酸酶。通过用抗IL - 4Rα抗体进行免疫共沉淀，验证了含SH2结构域的肌醇5'-磷酸酶与IL - 4Rα在体内的结合。这些结果证明了ITIM在调节IL - 4诱导的增殖中具有功能性作用。
Immunoreceptor tyrosine-based inhibitory motifs (ITIM) have been implicated in the negative modulation of immunoreceptor signaling pathways. The IL-4R alpha -chain (IL-4R alpha) contains a putative ITIM in the carboxyl terminal. To determine the role of ITIM in the IL-4 signaling pathway, we ablated the ITIM of IL-4R alpha by deletion and site-directed mutagenesis and stably expressed the wild-type (WT) and mutant hIL-4R alpha in 32D/insulin receptor substrate-2 (IRS-2) cells. Strikingly, 32D/IRS-2 cells expressing mutant human (h)IL-4R alpha were hyperproliferative in response to IL-4 compared with cells expressing WT hIL-4R alpha. Enhanced tyrosine phosphorylation of Stat6, but not IRS-2, induced by hIL-4 was observed in cells expressing mutant Y713F. Using peptides corresponding to the ITIM of hIL-4R alpha, we demonstrate that tyrosine-phosphorylated peptides, but not their nonphosphorylated counterparts, coprecipitate SH2-containing tyrosine phosphatase-1, SH2-containing tyrosine phosphatase-2, and SH2-containing inositol 5'-phosphatase. The in vivo association of SH2-containing inositol 5'-phosphatase with IL-4R alpha was verified by coimmunoprecipitation with anti-IL-4R alpha Abs. These results demonstrate a functional role for ITIM in the regulation of IL-4-induced proliferation.