Abstract
To study the roles of an anti-apoptotic factor, cellular FLICE-like protein (cFLIP), in the regulation of apoptosis in luteal cells of rat ovaries, we revealed that the changes in the expression levels and the localization of cFLIP mRNA and protein in CLs during estrus cycle and pregnancy. cFLIP short form and long form (cFLIPS and cFLIPL, respectively) mRNA and protein levels in the CLs which were categorized in first generation (G1) and second generation (G2) based on their structural and functional regressions and in those prepared from different pregnancy stages [1.0, 7.5, 9.0, 12.0, 13.5, 18.0 and 21.0 days of post coitus (dpc)] were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively, and that the changes in the localization of these proteins were demonstrated by immunohistochemistry. Lower levels of cFLIPS and cFLIPL mRNAs were noted in CLs with proestrus stage of G2, and higher levels were noted in CLs of mid pregnancy stages (12.0 and 13.5 dpc). Higher expression levels of cFLIPS protein were seen in CLs of mid of pregnancy stages and lower levels in CLs with proestrus stage of G2. Strong positive stainings for cFLIPS/L proteins were demonstrated in CLs of mid of pregnancy stages. In the present study, we firstly showed the changes in cFLIP expression levels and the localization in CLs during estrus cycle and pregnancy in rat, and these findings suggest that cFLIP may acts as a dominant survival factor by inhibiting intracellular apoptosis signal transduction in rat CLs.
