Lenhart J A, Downey B R, Bagnell C A
Department of Animal Sciences, Rutgers University, New Brunswick, New Jersey 08903, USA.
Biol Reprod. 1998 Feb;58(2):583-90. doi: 10.1095/biolreprod58.2.583.
Connexin 43, a member of the highly conserved connexin family of gap junction proteins, is expressed in the pig ovary. In other species, ovarian connexin 43 expression and phosphorylation are hormonally regulated. We characterized connexin 43 expression and phosphorylation in the ovaries of mature pigs during the estrous cycle and in prepubertal gilts during follicular development induced by eCG (750 IU)/hCG (500 IU; 72 h later). Ovarian connexin 43 protein expression and phosphorylation were examined by immunoblot analysis. Connexin 43 was localized to specific follicular cell types during development by immunofluorescence. While no change in total connexin 43 protein expression was seen during the cycle, connexin 43 phosphorylation was significantly higher (p < 0.05) during the late follicular stage of the cycle than during the early luteal and early to mid-follicular stages. In ovaries of eCG/hCG-primed prepubertal pigs, connexin 43 protein levels remained steady, while phosphorylation of the protein increased significantly at 72 h and 84 h after eCG treatment (p < 0.05), then declined to pretreatment levels by 96 h (24 h post-hCG administration). Immunoreactive connexin 43 was localized predominantly to granulosa cells of cyclic pigs and eCG/hCG-primed prepubertal gilts. Follicular connexin 43 was highest between 60 h and 84 h after eCG and declined after hCG administration. Connexin 43 was not detected in morphologically atretic follicles, stroma, or vascular tissue of the ovary. This is the first evidence that porcine ovarian connexin 43 phosphorylation is differentially regulated during follicular development. The results suggest that hormonally induced changes in connexin 43 phosphorylation may play a coordinating role in porcine follicular development.
连接蛋白43是间隙连接蛋白中高度保守的连接蛋白家族的成员之一，在猪卵巢中表达。在其他物种中，卵巢连接蛋白43的表达和磷酸化受激素调节。我们对发情周期中成熟母猪以及由eCG（750 IU）/hCG（500 IU；72小时后）诱导卵泡发育的青春期前小母猪卵巢中的连接蛋白43表达和磷酸化进行了表征。通过免疫印迹分析检测卵巢连接蛋白43蛋白的表达和磷酸化。通过免疫荧光确定发育过程中连接蛋白43在特定卵泡细胞类型中的定位。虽然在整个周期中连接蛋白43总蛋白表达没有变化，但在周期的卵泡晚期，连接蛋白43的磷酸化显著高于黄体早期和卵泡早期至中期（p<0.05）。在经eCG/hCG预处理的青春期前猪的卵巢中，连接蛋白43蛋白水平保持稳定，而该蛋白的磷酸化在eCG处理后72小时和84小时显著增加（p<0.05），然后在96小时（hCG给药后24小时）降至预处理水平。免疫反应性连接蛋白43主要定位于发情周期母猪和经eCG/hCG预处理的青春期前小母猪的颗粒细胞中。卵泡连接蛋白43在eCG后60小时至84小时之间最高，hCG给药后下降。在卵巢的形态学闭锁卵泡、基质或血管组织中未检测到连接蛋白43。这是首次有证据表明猪卵巢连接蛋白43磷酸化在卵泡发育过程中受到差异调节。结果表明，激素诱导的连接蛋白43磷酸化变化可能在猪卵泡发育中起协调作用。
