Kline J B, Moore D J, Clevenger C V
Department of Pathology and Laboratory Medicine University of Pennsylvania Medical Center Philadelphia, Pennsylvania 19104, USA.
Mol Endocrinol. 2001 May;15(5):832-41. doi: 10.1210/mend.15.5.0631.
Stimulation of the PRL receptor (PRLr) results in the activation of the guanine nucleotide exchange factor (GEF) p95Vav1 with corresponding alterations in cytoarchitecture and cell motility. To better understand the mechanisms involved in the regulation of Vav1 activity, the role of the tyrosine kinase p70Tec was examined. Coimmunoprecipitation and in vitro kinase assays revealed that ligand stimulation of the PRLr resulted in the rapid activation of Tec and its concomitant association with the PRLR: When coexpressed in COS-1 cells, both Vav1 and Tec were found to associate with the PRLr in the presence of ligand. In the absence of receptor, a constitutive complex between Vav1 and Tec was noted. Both Vav1 and Tec, however, were capable of independent engagement of a bipartite intracellular domain of the PRLR: Deletion mapping studies confined this interaction to residues 323 to 527 of the intracellular domain of the PRLR: Furthermore, Tec enhanced the GEF activity of Vav1 as evidenced by an increase in GTP-bound Rac1. These data would suggest a pivotal function for the formation of a Tec/Vav1/PRLr complex during PRL-driven signal transduction, given the role of Vav1 in the control of cell proliferation and the regulation of Rho family-mediated cytoskeletal alterations.
催乳素受体（PRLr）的刺激会导致鸟嘌呤核苷酸交换因子（GEF）p95Vav1的激活，并伴有细胞结构和细胞运动性的相应改变。为了更好地理解参与Vav1活性调节的机制，研究了酪氨酸激酶p70Tec的作用。免疫共沉淀和体外激酶分析表明，PRLr的配体刺激导致Tec的快速激活及其与PRLR的伴随结合：当在COS-1细胞中共表达时，在有配体存在的情况下，发现Vav1和Tec都与PRLr结合。在没有受体的情况下，注意到Vav1和Tec之间存在组成型复合物。然而，Vav1和Tec都能够独立结合PRLR的双组分细胞内结构域：缺失定位研究将这种相互作用局限于PRLR细胞内结构域的323至527位残基：此外，Tec增强了Vav1的GEF活性，这通过结合GTP的Rac1增加得到证明。鉴于Vav1在控制细胞增殖和调节Rho家族介导的细胞骨架改变中的作用，这些数据表明在催乳素驱动的信号转导过程中，Tec/Vav1/PRLr复合物的形成具有关键作用。
