Estrogen plays an important role in regulating testicular Sertoli cell number. Furthermore, S-phase kinase-associated protein 2 （SKP2） plays a central role in mammalian cell cycle progression. The objective of this study was to determine whether 17β-estradiol can regulate the expression of SKP2, and the Sertoli cell cycle, via estrogen receptor β （ERβ）, the cyclic adenosine monophosphate （cAMP）-protein kinase A （PKA） and extracellular signal-regulated kinase （ERK1/2） pathway. When cultured immature boar Sertoli cells were treated with 17β-estradiol, a time-dependent increase in SKP2 mRNA and protein level was observed by real-time PCR and Western blot, and 17β-estradiol activity peaked at 30 min. Treatment with ICI182780 and ERβ antagonist reduced 17β-estradiol-induced expression of SKP2 and proliferating cell nuclear antigen （PCNA）, while increasing the protein concentration of p27kip1. However, the effect of ERa antagonist on these parameters was lower than that of ICI 182780 and ERβ. Forskolin had a similar effect as 17β-estradiol on the expression of SKP2, PCNA and p27kip1, Rp-cAMP, H-89 and U0126 treatment reduced 17β-estradiol-induced changes, while H-89 also inhibited ERK1/2 activation. Therefore, 17β-estradiol mainly regulates SKP2 mRNA and protein expression via ERβ-cAMP-PKA and ERK1/2 activation. SKP2 and PCNA expression were positively correlated, while increased SKP2 expression likely resulted in p27kip1 degradation.
WANG Xian-zhongZHU Feng-weiWANG YongWANG YiZHANG Jiao-jiaoZHANG Jia-hua
哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,mTOR)是调控蛋白质翻译起始阶段的一种蛋白激酶,与细胞的生长和细胞周期关系十分密切,近年来备受关注。文章就mTOR的结构,mTOR组成的上游信号和下游信号传导通路,mTOR在调节细胞增殖、促进细胞生长、参与免疫抑制和能量代谢及肿瘤发生等方面的作用进行了全面阐述,旨在为全面认识其功能并为相关疾病特别是肿瘤的治疗提供新的思路。
