Cabodi Sara, Moro Laura, Baj Germano, Smeriglio Monica, Di Stefano Paola, Gippone Silvana, Surico Nicola, Silengo Lorenzo, Turco Emilia, Tarone Guido, Defilippi Paola
Dipartimento di Genetica, Biologia e Biochimica, Università di Torino, Via Santena 5 bis, 10126 Turin, Italy.
J Cell Sci. 2004 Mar 15;117(Pt 8):1603-11. doi: 10.1242/jcs.01025.
Steroid hormones bind to their receptors and trans-activate target genes. Rapid non-genomic action of steroid hormones has been proposed in addition to the one at the genomic level. Estrogen has been described to activate c-Src kinase and this activation has been shown to be responsible for estrogen-dependent mitogenicity. A major substrate of c-Src kinase activity is the cytoskeletal protein p130Cas, originally identified in v-Src-transformed cells. We show that in the human breast carcinoma T47D cells, upon estrogen treatment, p130Cas rapidly and transiently associates with the estrogen receptor alpha in a multi-molecular complex containing the c-Src kinase and the p85 subunit of PI 3-kinase. Association of p130Cas with the estrogen receptor alpha occurs within 3 minutes of estrogen treatment and is dependent on c-Src kinase activation. Transient overexpression of p130Cas in T47D cells increases estrogen-dependent Src kinase and Erk1/2 MAPKs activities and accelerates their kinetics of stimulation. A similar effect was detected on estrogen-dependent cyclin D1 expression, suggesting a role for p130Cas in regulating estrogen-dependent cell cycle progression. Double-stranded small RNA interference (siRNA) by silencing endogenous p130Cas protein, was sufficient to inhibit estrogen-dependent Erk1/2 MAPKs activity and cyclin D1 induction, demonstrating the requirement of p130Cas in such events. Therefore, our data show that the adaptor protein p130Cas associates with the estrogen receptor transducing complex, regulating estrogen-dependent activation of c-Src kinase and downstream signaling pathways.
类固醇激素与其受体结合并反式激活靶基因。除了在基因组水平上的作用外，还提出了类固醇激素的快速非基因组作用。雌激素已被描述为可激活c-Src激酶，并且这种激活已被证明与雌激素依赖性的促有丝分裂作用有关。c-Src激酶活性的一个主要底物是细胞骨架蛋白p130Cas，最初是在v-Src转化的细胞中鉴定出来的。我们发现，在人乳腺癌T47D细胞中，雌激素处理后，p130Cas会迅速且短暂地与雌激素受体α在一个包含c-Src激酶和PI 3-激酶p85亚基的多分子复合物中结合。p130Cas与雌激素受体α的结合在雌激素处理后3分钟内发生，并且依赖于c-Src激酶的激活。在T47D细胞中瞬时过表达p130Cas会增加雌激素依赖性Src激酶和Erk1/2丝裂原活化蛋白激酶（MAPKs）的活性，并加速它们的刺激动力学。在雌激素依赖性细胞周期蛋白D1的表达上也检测到了类似的效果，这表明p130Cas在调节雌激素依赖性细胞周期进程中发挥作用。通过沉默内源性p130Cas蛋白的双链小RNA干扰（siRNA）足以抑制雌激素依赖性Erk1/2 MAPKs活性和细胞周期蛋白D1的诱导，证明了此类事件中p130Cas的必要性。因此，我们的数据表明衔接蛋白p130Cas与雌激素受体转导复合物结合，调节雌激素依赖性c-Src激酶的激活和下游信号通路。
