Abstract：
ZIP9 is a recently identified membrane-bound androgen receptor of physiological significance that may mediate certain physiological responses to androgens. Using in silico methods, six tetrapeptides with the best docking properties at the testosterone binding site of ZIP9 were synthesized and further investigated. All tetrapeptides displaced T-BSA-FITC, a membrane-impermeable testosterone analog, from the surface of mouse myogenic L6 cells that express ZIP9 but not the classical androgen receptor (AR). Silencing the expression of ZIP9 with siRNA prevented this labeling. All tetrapeptides were found to be pro-androgenic; in L6 cells they stimulated the expression of myogenin, triggered activation of focal adhesion kinase, and prompted the fusion of L6 myocytes to syncytial myotubes. In human osteoblastic SAOS-2 cells that express AR and ZIP9, they reduced the expression of alkaline phosphatase and stimulated mineralization. These latter effects were prevented by silencing ZIP9 expression, indicating that the osteoblast/osteocyte conversion is exclusively mediated through ZIP9. Our results demonstrate that the synthetic tetrapeptides, by acting as ZIP9-specific androgens, have the potential to replace testosterone or testosterone analogs in the treatment of bone- or muscle-related disorders by circumventing the undesirable effects mediated through the classical AR.
摘要：
ZIP9是最近鉴定的具有生理意义的膜结合雄激素受体,其可以介导对雄激素的某些生理反应。使用计算机模拟方法，合成并进一步研究了在ZIP9的睾酮结合位点具有最佳对接特性的六个四肽。所有四肽取代T-BSA-FITC，一种不透膜的睾酮类似物,来自表达ZIP9但不表达经典雄激素受体（AR）的小鼠生肌L6细胞的表面。用siRNA沉默ZIP9的表达阻止了这种标记。发现所有四肽都是促雄激素的；在L6细胞中，它们刺激肌原蛋白的表达，触发了粘着斑激酶的激活，并促使L6肌细胞与合胞肌管融合。在表达AR和ZIP9的人成骨细胞SAOS-2细胞中，它们降低了碱性磷酸酶的表达并刺激了矿化。通过沉默ZIP9表达来防止后者的影响，表明成骨细胞/骨细胞转化是通过ZIP9专门介导的。我们的结果表明，合成四肽，通过充当ZIP9特异性雄激素，通过规避经典AR介导的不良作用，有可能替代睾酮或睾酮类似物治疗骨骼或肌肉相关疾病。
