Pyk2 and Src-family protein-tyrosine kinases compensate for the loss of FAK in fibronectin-stimulated signaling events but Pyk2 does not fully function to enhance FAK- cell migration
Pyk2 and Src-family protein-tyrosine kinases compensate for the loss of FAK in fibronectin-stimulated signaling events but Pyk2 does not fully function to enhance FAK- cell migration
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DOI：
10.1093/emboj/17.20.5933
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发表时间：
1998-10-15
期刊：
影响因子：
11.4
通讯作者：
Schlaepfer, DD
中科院分区：
文献类型：
--
作者：
Sieg, DJ;Ilic, D;Schlaepfer, DD
粘着斑激酶 (FAK) 蛋白酪氨酸激酶 (PTK) 将跨膜整合素受体与细胞内信号通路连接起来。我们发现，与来自 fak(+/+) 胚胎 (FAK(+)) 的细胞相比，从小鼠 fak(-/-) 胚胎 (FAK(-)) 分离的成纤维细胞中，FAK 相关 PTK（Pyk2）的表达升高。 Pyk2 定位于 FAK(+) 和 FAK(-) 细胞的核周区域，纤连蛋白 (FN) 刺激 FAK(-) 细胞可增强 Pyk2 酪氨酸磷酸化，但刺激 FAK(-) 细胞则不会增强。 Pyk2 酪氨酸磷酸化的增加与 FAK(-) 细胞中 Grb2 与 Shc 结合和 ERK2 激活的时间过程平行。 FAK(-) 细胞的 FN 铺板并未增强 Pyk2 体外自磷酸化活性。然而，FN 后 Pyk2 与活性 Src 家族 PTK 相关，但与 FAK(-) 细胞的多聚 L-赖氨酸重新铺板无关，野生型 (WT) 和激酶失活 (Ala457) 过表达，但不与自磷酸化位点突变体 (Phe402) Pyk2 相关，增强 FAK(-) 细胞中内源性 FN 刺激的 c-Src 体外激酶活性，但仅 WT Pyk2 过表达增强FN 刺激共转染 ERK2 的激活，有趣的是，Pyk2 过表达仅微弱增强 FAK(-) 细胞向 FN 的迁移，而与 FAK(+) 细胞相比，瞬时 FAK 表达可有效促进 FAK(-) 细胞向 FN 迁移。显着的是，p50(csk) 过表达抑制内源 Src 家族 PTK 活性抑制 FN 刺激的细胞扩散、Pyk2 酪氨酸磷酸化、Grb2这些研究表明，在 FAK 不存在的情况下，Pyk2 和 Src 家族 PTK 结合促进 FN 刺激的 ERK2 信号传导事件，但这些信号传导事件不足以克服 FAK(-) 细胞迁移缺陷。
The focal adhesion kinase (FAK) protein-tyrosine kinase (PTK) links transmembrane integrin receptors to intracellular signaling pathways, We show that expression of the FAK-related PTK, Pyk2, is elevated in fibroblasts isolated from murine fak(-/-) embryos (FAK(-)) compared with cells from fak(+/+) embryos (FAK(+)). Pyk2 was localized to perinuclear regions in both FAK(+) and FAK(-) cells, Pyk2 tyrosine phosphorylation was enhanced by fibronectin (FN) stimulation of FAK(-) but not FAK(+) cells. Increased Pyk2 tyrosine phosphorylation paralleled the timecourse of Grb2 binding to Shc and activation of ERK2 in FAK(-) cells. Pyk2 in vitro autophosphorylation activity was not enhanced by FN plating of FAK(-) cells. However, Pyk2 associated with active Src-family PTKs after FN but not poly-L-lysine replating of the FAK(-) cells, Overexpression of both wild-type (WT) and kinase-inactive (Ala457), but not the autophosphorylation site mutant (Phe402) Pyk2, enhanced endogenous FN-stimulated c-Src in vitro kinase activity in FAK(-) cells, but only WT Pyk2 overexpression enhanced FN-stimulated activation of co-transfected ERK2, Interestingly, Pyk2 overexpression only weakly augmented FAK(-) cell migration to FN whereas transient FAK expression promoted FAK(-) cell migration to FN efficiently compared with FAK(+) cells, Significantly, repression of endogenous Src-family PTK activity by p50(csk) overexpression inhibited FN-stimulated cell spreading, Pyk2 tyrosine phosphorylation, Grb2 binding to Shc, and ERK2 activation in the FAK(-) but not in FAK(+) cells, These studies show that Pyk2 and Src-family PTKs combine to promote FN-stimulated signaling events to ERK2 in the absence of FAK, but that these signaling events are not sufficient to overcome the FAK(-) cell migration defects.