A bipartite NLS at the SHP-1 C-terminus mediates cytokine-induced SHP-1 nuclear localization in cell growth control.
A bipartite NLS at the SHP-1 C-terminus mediates cytokine-induced SHP-1 nuclear localization in cell growth control.
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DOI：
10.1006/bcmd.2002.0485
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
Wentian Yang;M. Tabrizi;T. Yi
中科院分区：
文献类型：
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作者：
Wentian Yang;M. Tabrizi;T. Yi
SHP-1蛋白酪氨酸磷酸酶是造血细胞中信号传导的关键调节剂，如SHP-1缺陷小鼠中的致死性造血障碍所示。我们和其他人在以前的研究中已经表明，SHP-1调节膜受体信号传导：它通过其N-末端区域SH 2结构域与酪氨酸磷酸化的膜受体结合，使受体复合物中的关键底物去磷酸化。在这里，我们表明，SHP-1的C-末端区域包含一个二分NLS介导的SHP-1细胞因子的核定位。该NLS位于PTB的氨基酸576-595内，并且当自身与EGFP融合时，将荧光蛋白靶向瞬时转染的NIH 3 T3成纤维细胞和Bac1.2f5巨噬细胞的细胞核中。当定位在SHP-1内时，NSL的活性受到严格调控，如由EGFP/SHP-1融合蛋白在NIH 3 T3转染子中的主要细胞质分布和内源性SHP-1在造血细胞系PBLC-1中的排他性细胞质定位所指示的。在IL-4刺激后4、6和8 h，通过增加NIH 3 T3转染子中EGFP/SHP-1融合蛋白和PBCL-1细胞中内源性SHP-1蛋白的核定位来证明IL-4激活SHP-1中的NLS。SHP-1在PBCL-1细胞中的核定位也被IL-7以类似的方式诱导，这表明它是细胞因子信号传导中的常见事件。与野生型磷酸酶相比，缺乏NLS的SHP-1突变体在抑制NIH 3 T3转染子增殖方面仅显示约一半的活性。这些结果提供了由二分NLS介导的甘氨酸调节的SHP-1核定位的证据，并表明SHP-1在细胞生长控制中调节核信号。
SHP-1 protein tyrosine phosphatase is a critical regulator of signaling in hematopoietic cells as illustrated by the lethal hematopoietic disorders in SHP-1-deficient mice. We and others have shown in previous studies that SHP-1 regulates membrane receptor signaling: it binds via its N-terminal region SH2 domains to tyrosine phosphorylated membrane receptors to dephosphorylate key substrates in the receptor complexes. Here we demonstrate that the SHP-1 C-terminal region contains a bipartite NLS that mediates SHP-1 nuclear localization in response to cytokines. This NLS was located within amino acids 576-595 of the PTPase and, when fused by itself to EGFP, targeted the fluorescent protein into the nuclei of transiently transfected NIH3T3 fibroblasts and Bac1.2f5 macrophage cells. When positioned within SHP-1, the activity of the NSL was under tight regulation as indicated by the predominant cytoplasmic distribution of the EGFP/SHP-1 fusion protein in NIH3T3 transfectants and the exclusive cytoplasmic localization of the endogenous SHP-1 in hematopoietic cell line PBLC-1. Activation of the NLS in SHP-1 by IL-4 was demonstrated by increased nuclear localization of the EGFP/SHP-1 fusion protein in NIH3T3 transfectants and of the endogenous SHP-1 protein in PBCL-1 cells at 4, 6 and 8 h post-IL-4 stimulation. SHP-1 nuclear localization in PBCL-1 cells was also induced by IL-7 in a similar manner, suggesting it as a common event in cytokine signaling. In comparison to that of the wild-type phosphatase, an SHP-1 mutant lacking the NLS showed only approximately half of the activity in inhibiting proliferation of NIH3T3 transfectants. These results provide evidence of cytokine-regulated SHP-1 nuclear localization mediated by a bipartite NLS and suggest that SHP-1 regulates nuclear signaling in cell growth control.