LC3 protein expression and localization in mouse follicular granulosa cells / 中国病理生理杂志

ABSTRACT

AIM:To investigate the expression and localization of autophagy related protein microtublule associated protein 1 light chain 3 (LC3) at various stages of follicular development and atresia in the mice.METHODS:On 0,1,2,3,4 and 5 day after intraperitoneal injection of pregnant mare serum gonadotropin (PMSG),expression and positioning situation of autophagy related protein LC3 and apoptosis related protein cleaved caspase-3 were examined by the method of immunohistochemical staining.The protein levels of cleaved caspase-3 and LC3 were determined by Western blot in cultured mouse granulosa cells after incubation under serum-free conditions in the absence or presence of FSH.LC3 subcellular localization in granulosa cells were studied by the method of immunofluorescence.RESULTS:The LC3 protein expressed in granulosa cells during all developmental stages mainly.Granulosa cells of atretic follicles that showed intense staining of cleaved caspase-3 and LC3.The protein levels of cleaved caspase-3 and LC3-Ⅱ in the granulosa cells significantly decreased at 1 d and 2 d after intraperitoneal injection of PMSG (P ＜ 0.05).The protein levels of cleaved caspase3 and LC3-Ⅱ in the granulosa cells increased in turn on 3,4 and 5 day after intraperitoneal injection of PMSG.The positive correlation between LC3-Ⅱ and cleaved caspase-3 protein levels was observed (r2 =0.8299,P ＜ 0.05).The LC3-Ⅱ protein expressed with punctuate structures in granulosa cell cytoplasm cultured under serum-free conditions in the presence of FSH.CONCLUSION:LC3 is expressed in the follicular granulosa cells with cell specificity and regional specificity.Autophagy is induced mainly in granulosa cells during folliculogenesis and shows positive correlation with apoptosis.Ovarian granulosa cell autophagy and apoptosis are gonadotropic hormone dependent.