Mathew Sijo, George Sudeep P, Wang Yaohong, Siddiqui Mohammad Rizwan, Srinivasan Kamalakkannan, Tan Langzhu, Khurana Seema
Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
J Biol Chem. 2008 Aug 15;283(33):22709-22. doi: 10.1074/jbc.M801319200. Epub 2008 May 15.
The ubiquitously expressed Src tyrosine kinases (c-Src, c-Yes, and c-Fyn) regulate intestinal cell growth and differentiation. Src activity is also elevated in the majority of malignant and premalignant tumors of the colon. The development of fibroblasts with the three ubiquitously expressed kinases deleted (SYF cells) has identified the role of Src proteins in the regulation of actin dynamics associated with increased cell migration and invasion. Despite this, unexpectedly nothing is known about the role of the individual Src kinases on intestinal cell cytoskeleton and/or cell migration. We have previously reported that villin, an epithelial cell-specific actin-modifying protein that regulates actin reorganization, cell morphology, cell migration, cell invasion, and apoptosis, is tyrosine-phosphorylated. In this report using the SYF cells reconstituted individually with c-Src, c-Yes, c-Fyn, and wild type or phosphorylation site mutants of villin, we demonstrate for the first time the absolute requirement for c-Src in villin-induced regulation of cell migration. The other major finding of our study is that contrary to previous reports, the nonreceptor tyrosine kinase, Jak3 (Janus kinase 3), does not regulate phosphorylation of villin or villin-induced cell migration and is, in fact, not expressed in intestinal epithelial cells. Further, we identify SHP-2 and PTP-PEST (protein-tyrosine phosphatase proline-, glutamate-, serine-, and threonine-rich sequence) as negative regulators of c-Src kinase and demonstrate a new function for these phosphatases in intestinal cell migration. Together, these data suggest that in colorectal carcinogenesis, elevation of c-Src or down-regulation of SHP-2 and/or PTP-PEST may promote cancer metastases and invasion by regulating villin-induced cell migration and cell invasion.
广泛表达的Src酪氨酸激酶（c-Src、c-Yes和c-Fyn）调节肠道细胞的生长和分化。在大多数结肠恶性和癌前肿瘤中，Src活性也会升高。通过构建缺失三种广泛表达激酶的成纤维细胞（SYF细胞），已确定Src蛋白在调节与细胞迁移和侵袭增加相关的肌动蛋白动力学中的作用。尽管如此，关于单个Src激酶在肠道细胞细胞骨架和/或细胞迁移中的作用却出乎意料地一无所知。我们之前报道过，绒毛蛋白是一种调节肌动蛋白重组、细胞形态、细胞迁移、细胞侵袭和凋亡的上皮细胞特异性肌动蛋白修饰蛋白，它会发生酪氨酸磷酸化。在本报告中，我们使用分别用c-Src、c-Yes、c-Fyn以及野生型或绒毛蛋白磷酸化位点突变体重构的SYF细胞，首次证明了c-Src在绒毛蛋白诱导的细胞迁移调节中是绝对必需的。我们研究的另一个主要发现是，与之前的报道相反，非受体酪氨酸激酶Jak3（Janus激酶3）不调节绒毛蛋白的磷酸化或绒毛蛋白诱导的细胞迁移，实际上它在肠道上皮细胞中并不表达。此外，我们确定SHP-2和PTP-PEST（富含脯氨酸、谷氨酸、丝氨酸和苏氨酸的蛋白酪氨酸磷酸酶）是c-Src激酶的负调节因子，并证明了这些磷酸酶在肠道细胞迁移中的新功能。总之，这些数据表明，在结直肠癌发生过程中，c-Src的升高或SHP-2和/或PTP-PEST的下调可能通过调节绒毛蛋白诱导的细胞迁移和细胞侵袭来促进癌症转移和侵袭。
