Attenuation of adhesion-dependent signaling and cell spreading in transformed fibroblasts lacking protein tyrosine phosphate-1B
Attenuation of adhesion-dependent signaling and cell spreading in transformed fibroblasts lacking protein tyrosine phosphate-1B
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DOI：
10.1074/jbc.m009734200
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发表时间：
2001-07-13
影响因子：
4.8
通讯作者：
Tremblay, ML
中科院分区：
文献类型：
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作者：
Cheng, A;Bal, GS;Tremblay, ML
先前的生物化学证据已经产生了相互矛盾的模型来解释蛋白酪氨酸磷酸酶1b （PTP-1B）在整合素信号传导调节中的作用，因此，为了建立这种作用的生理相关性，我们采用遗传方法从PTP-1B敲除小鼠中产生胚胎成纤维细胞。原代成纤维细胞及其衍生细胞系均用于本研究。用SV40大T抗原永生化野生型原代细胞导致内源性PTP-1B的表达急剧增加，这表明PTP-1B在转化过程中起作用。此外，与未转化状态相比，转化细胞系中PTP-1B的缺失导致纤维连接蛋白介导的不同信号通路受到更明显的影响。具体来说，与野生型相比，ptp - 1b缺陷细胞的p130（Cas）磷酸化、Erk激活以及细胞扩散被延迟。有趣的是，这种整合素介导事件的衰减与Src缺陷成纤维细胞非常相似。事实上，与野生型成纤维细胞相比，PTP-1B缺陷的转化成纤维细胞在悬浮状态下确实表现出Src抑制位点（tir -527）的过度磷酸化。这些结果表明PTP-1B是转化细胞中整合素信号的积极生理调节因子，作用于Src tyrr -527去磷酸化的上游，导致一些粘附依赖性事件。
Previous biochemical evidence has yielded conflicting models for the role of protein tyrosine phosphatase-1B (PTP-1B) in the regulation of integrin signaling, Thus, to establish the physiological relevance for such a role, we employed a genetic approach by generating embryonic fibroblasts from PTP-1B knockout mice. Both primary fibroblasts and their derived cell lines were used in this study. Immortalization of wild-type primary cells with the SV40 Large T antigen resulted in a dramatic increase in the endogenous expression of PTP-1B, suggesting a role during transformation. Moreover, the absence of PTP-1B in the transformed cell lines led to a more pronounced effect on different pathways of fibronectin-mediated signaling compared with the untransformed state. Specifically, p130(Cas) phosphorylation, Erk activation as well as cell spreading were delayed in PTP-1B-deficient cells, compared with their wild-type counterparts. Interestingly, this attenuation in integrin-mediated events closely resembles that of Src-deficient fibroblasts, Indeed, PTP-1B deficient, transformed fibroblasts held in suspension do exhibit a hyperphosphorylation of the inhibitory site (Tyr-527) of Src, compared with their wild-type counterparts. These results establish PTP-1B as a positive physiological regulator of integrin signaling in transformed cells, acting upstream of Src Tyr-527 dephosphorylation that leads to several adhesion-dependent events.