Changes in cFLIP expression in the corpus luteum throughout the estrous cycle of Shibagoats

Changes in the expression of the anti-apoptotic protein cFLIP (cellular FLICE inhibitory protein) were examined in the caprine corpus luteum (CL), during development and subsequent maintenance. Corpora lutea at four different stages were collected from Shiba goats, to measure the expression of cFLIP mRNA, protein and immunolocalization. Expression of short form cFLIP (cFLIPS) mRNA was highest at the early CL stage, and decreased during late and regressed stages (P < 0.05). In contrast, long form cFLIP (cFLIPL) mRNA expression was high during early, mid and late stages, and only decreased at the regressed stage (P< 0.01). Protein expression of cFLIPS was highest at the late CL stage, and decreased at the regressed stage (P < 0.01). Protein expression of cFLIPL was highest at the early and mid CL stages, and decreased by the late and regressed stages (P < 0.01). Further expression of cFLIPL was higher at the early CL stage than at the mid stage (P < 0.01). cFLIP protein expression was detectable by immunostaining in the early, mid and late CL stages, but not at the regressed CL stage. These results are consistent with the hypothesis that cFLIP acts as a survival factor in the maintenance of CL function in goats.