中文摘要：

本研究旨在证实鞘脂活化蛋白C（saposinC）对雄激素受体（AR）多泛素化降解的影响及其机制．通过将真核表达载体saposinC转染LNCaP细胞，发现saposinC上调AR的蛋白水平和转录激活活性．进一步将野生型和突变型泛素质粒Ubwt和UbK48R分别与saposinC共转染LNCaP细胞发现，saposinC能够促进AR蛋白的单泛素化形式的稳定性，抑制AR的多泛素化修饰及其在蛋白酶体中的降解．其分子机制是saposinC、Ub和AR三者形成复合体，抑制了AR的进一步多泛素化过程．同时还发现，在这一机制中，细胞内低浓度的雄激素（0．1nmol／L）与saposinC具有协同作用．

英文摘要：

In this article we investigated the effect of saposin C on ubiquitination and degradation of androgen receptor （AR） in LNCaP cells. After transient transfections of the eukaryotic expression vectors expressing saposin C, Ubwt or UbK48R into LNCaP cells, Western blot assay was employed to investigate the effect of saposin C on AR protein levels, ubiquitination and degradation. Immunoprecipitation assay was used to investigate the interactions among saposin C, Ub （ubiquitin） and AR. Our results show that saposin C up-regulates the AR protein levels and transactivation activity. Intriguingly, it is found that saposin C strengthens the stability and function of AR protein through the formation of saposin C, Ub and AR complex which restrains the poly- ubiquitination and degradation of the AR in UPS （ubiquitin-proteasome system）. Moreover, saposin C and low concentration androgens cooperatively enhance the inhibition of poly-ubiquitination and degradation of AR.