Converse Aubrey, Zhang Chenan, Thomas Peter
Marine Science Institute, The University of Texas at Austin, Port Aransas, Texas 78373.
Endocrinology. 2017 Sep 1;158(9):3015-3029. doi: 10.1210/en.2017-00087.
Recent studies show that androgen-induced apoptosis in Atlantic croaker primary granulosa and theca (G/T) cells and in human breast and prostate cancer cell lines is mediated by the membrane androgen receptor ZIP9, which belongs to the SLC39A zinc transporter family. However, the apoptotic signaling pathways remain unclear because ZIP9 activates an inhibitory G protein in human cancer cells, whereas recombinant croaker ZIP9 activates a stimulatory G protein (Gs) in transfected cancer cells. We investigated androgen-dependent apoptotic pathways to identify the signaling pathways regulated through wild-type croaker ZIP9 in ovarian follicle cells. We show that the ZIP9-mediated apoptotic signaling pathway in croaker G/T cells shares several proapoptotic members with those in human cancer cells, but is activated through a Gsα subunit-dependent pathway. Testosterone treatment of croaker G/T cells increased intracellular zinc levels, mitogen-activated protein (MAP) kinase activity, caspase 3 activity, messenger RNA levels of proapoptotic members Bax, p53, and c-Jun N-terminal kinase, and the incidence of apoptosis, similar to findings in mammalian cancer cells, but also increased cyclic adenosine monophosphate concentrations. Transfection with small interfering RNA targeting croaker ZIP9 blocked testosterone-induced increase in bax, p53, and jnk expression. Testosterone-induced apoptosis and caspase 3 activation depended on the presence of extracellular zinc and were effectively blocked with cotreatment of inhibitors of the Gsα subunit, adenylyl cyclase, protein kinase A, and MAP kinase (Erk1/2) activation. These results indicate that ZIP9-mediated testosterone signaling in croaker G/T cells involves multiple pathways, some of which differ from those activated through ZIP9 in human cancer cells even though a similar apoptotic response is observed.
最近的研究表明，雄激素诱导的大西洋鲱鱼原代颗粒细胞和膜细胞（G/T）以及人乳腺癌和前列腺癌细胞系中的细胞凋亡是由膜雄激素受体ZIP9介导的，ZIP9属于SLC39A锌转运蛋白家族。然而，凋亡信号通路仍不清楚，因为ZIP9在人癌细胞中激活抑制性G蛋白，而重组鲱鱼ZIP9在转染的癌细胞中激活刺激性G蛋白（Gs）。我们研究了雄激素依赖性凋亡途径，以确定通过野生型鲱鱼ZIP9在卵巢卵泡细胞中调节的信号通路。我们发现，鲱鱼G/T细胞中ZIP9介导的凋亡信号通路与人类癌细胞中的凋亡信号通路有几个促凋亡成员相同，但通过Gsα亚基依赖性途径激活。用睾酮处理鲱鱼G/T细胞会增加细胞内锌水平、丝裂原活化蛋白（MAP）激酶活性、半胱天冬酶3活性、促凋亡成员Bax、p53和c-Jun N端激酶的信使核糖核酸水平以及细胞凋亡发生率，这与哺乳动物癌细胞中的发现相似，但也会增加环磷酸腺苷浓度。用靶向鲱鱼ZIP9的小干扰RNA转染可阻断睾酮诱导的bax、p53和jnk表达增加。睾酮诱导的细胞凋亡和半胱天冬酶3激活依赖于细胞外锌的存在，并被Gsα亚基、腺苷酸环化酶、蛋白激酶A和MAP激酶（Erk1/2）激活抑制剂的联合处理有效阻断。这些结果表明，鲱鱼G/T细胞中ZIP9介导的睾酮信号涉及多种途径，其中一些途径与人类癌细胞中通过ZIP9激活的途径不同，尽管观察到类似的凋亡反应。
