Regulation of sertoli-germ cell adherens junction dynamics via changes in protein-protein interactions of the N-cadherin-β-catenin protein complex which are possibly mediated by c-Src and myotubularin-related protein 2:: An in vivo study using an androgen suppression model
Regulation of sertoli-germ cell adherens junction dynamics via changes in protein-protein interactions of the N-cadherin-β-catenin protein complex which are possibly mediated by c-Src and myotubularin-related protein 2:: An in vivo study using an androgen suppression model
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DOI：
10.1210/en.2004-1194
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发表时间：
2005-03-01
期刊：
影响因子：
4.8
通讯作者：
Cheng, CY
中科院分区：
文献类型：
--
作者：
Zhang, JY;Wong, CH;Cheng, CY
通过抑制睾酮雌二醇植入的成年大鼠睾丸内的睾酮水平，我们使用了一个具有良好特征的基于细胞肌动蛋白的粘连连接(AJ)破坏模型，证实了早期的发现，即支持生殖细胞AJ的动力学是通过假定的信号通路激活的激酶来调节的，但有一些意想不到的发现如下。首先，在雄激素抑制期间，生精上皮中生殖细胞的丧失与肌管蛋白相关蛋白2(MTMR2，一种脂质磷酸酶，最近在成年MTMR2(-/-)小鼠中被证明是无精子症，因为生殖细胞和Sertoli细胞之间丧失了细胞黏附功能)的激增有关；和外质特化(ES，一种睾丸特异性细胞-细胞肌动蛋白AJ类型)位点的AJ整合膜蛋白：N-钙粘素、β-连环素、整合素Beta1和Nectin 3。第二，MTMR2不是与磷脂酰肌醇3-激酶(一种蛋白质和脂肪激酶)在结构上相互作用，而是只与非受体蛋白酪氨酸激酶c-Src结合，这一点通过免疫共沉淀和荧光显微镜在ES尖端位置证明，但没有被检测到的激酶、接头和AJ积分蛋白。综上所述，这些结果表明MTMR2/c-Src是睾丸AJ动态过程中重要的磷酸酶/激酶蛋白对。因为c-Src已知与睾丸ES处的钙粘蛋白/连环蛋白复合体有关，所以我们接下来试图研究在雄激素抑制诱导生殖细胞丢失期间该蛋白质复合体的蛋白质-蛋白质相互作用的任何变化。事实上，在生殖细胞从上皮细胞丢失的过程中，伴随着β-连环蛋白酪氨酸磷酸化的激增，N-钙粘附素和β-连环蛋白的关联性丢失。第三，也可能是最重要的一点，当精子细胞重新附着到支持细胞上时，在移除睾酮-雌二醇植入后的上皮自然恢复过程中，检测到N-钙粘附素和β-连环素相关的增加，伴随而来的是β-连环素中增加的Tyr磷酸化的丢失。综上所述，这些结果表明，钙粘蛋白/连接素是调节睾丸AJ动态的重要细胞黏附复合体，其功能可能受MTMR2/c-Src蛋白复合体的调节。
Using a well characterized model of cell-cell actin-based adherens junction (AJ) disruption by suppressing the intratesticular testosterone level in adult rats with testosteroneestradiol implants, we have confirmed earlier findings that Sertoli-germ cell AJ dynamics are regulated by the activation of kinases via putative signaling pathways but with some unexpected findings as follows. First, the loss of germ cells from the seminiferous epithelium during androgen suppression was associated with a surge in myotubularin-related protein 2 (MTMR2, a lipid phosphatase, in which adult MTMR2(-/-) mice were recently shown to be azoospermic because of the loss of cell adhesion function between germ and Sertoli cells); kinases: phosphatidylinositol 3-kinase, c-Src, and C-terminal Src kinase; adaptors: alpha-actinin, vinculin, afadin, and p130 Crk-associated protein; and AJ-integral membrane proteins at the ectoplasmic specialization (ES, a testis-specific cell-cell actin-based AJ type) site: N-cadherin, beta-catenin, integrin beta1, and nectin 3. Second, MTMR2, instead of structurally interacting with phosphatidylinositol 3-kinase, a protein and lipid kinase, was shown to associate only with c-Src, a nonreceptor protein tyrosine kinase, as demonstrated by both coimmunoprecipitation and fluorescent microscopy at the site of apical ES, but none of the kinases, adaptors, and AJ-integral proteins that were examined. Collectively, these results suggest that the MTMR2/c-Src is an important phosphatase/kinase protein pair in AJ dynamics in the testis. Because c-Src is known to associate with the cadherin/catenin protein complex at the ES in the testis, we next sought to investigate any changes in the protein-protein interactions of this protein complex during androgen suppression-induced germ cell loss. Indeed, there was a loss of N-cadherin and beta-catenin association, accompanied by a surge in Tyr phosphorylation of beta-catenin, during germ cell loss from the epithelium. Third, and perhaps the most important of all, during natural recovery of the epithelium after removal of testosterone-estradiol implants when spermatids were reattaching to Sertoli cells, an increase in N-cadherin and beta-catenin association was detected with a concomitant loss in the increased Tyr phosphorylation in beta-catenin. In summary, these results illustrate that the cadherin/catenin is a crucial cell adhesion complex that regulates AJ dynamics in the testis, and its functionality is likely modulated by the MTMR2/c-Src protein complex.