Caspase-mediated apoptosis in chicken postovulatory follicle regression

Abstract

Chicken postovulatory follicle (POF) regression occurs via the process of apoptosis. However, the signals and initiator pathways responsible for regression of the POF are unknown. In the current study, we examined gene expression patterns of various caspases (caspase-1, -2 and -3) involved in apoptosis by semi-quantitative RT-PCR. The percentage of apoptotic cells during POF regression was also quantified by flow cytometry. Expression of caspase-3 mRNA was noted in the largest preovulatory follicle (F1). However, the initiator caspases (caspase-1 and -2) were not expressed in F1. During the regression of the POF, caspase-3 was activated during initial stages, whereas the initiator caspases were upregulated at the later stages (POF4 and POF5). The percentage of apoptotic cells was significantly higher during the regression of the POF. It might be possible that levels of caspase-3 mRNA do not necessarily reflect the cell's potential for facilitating apoptosis, as activation of the caspase-3 by initiator caspases is required for its function. We presume that both caspase-1 and caspase-2 were key initiators in the regression of chicken POF and that the apoptosis-mediated regression of POFs might be similar to mammalian corpus luteum involution.

Histology of the Ovary of the Laying Hen (Gallus domesticus)

“…For example, removal of the most recent post-ovulatory follicle before it has completed regression delays oviposition of the egg derived from that follicle [ 24 ]. The post-ovulatory follicle regresses in an orderly fashion via apoptosis [ 50 ] in which caspases and macrophages play an important role [ 25 , 37 , 51 ]. Our observation of macrophages containing hemosiderin within late-stage regressing follicles is consistent with this.…”

“…Our observation of macrophages containing hemosiderin within late-stage regressing follicles is consistent with this. Regression in the laying hen takes about 4–6 days [ 51 ].…”

Dynamic Changes in the Follicular Transcriptome and Promoter DNA Methylation Pattern of Steroidogenic Genes in Chicken Follicles throughout the Ovulation Cycle

“…By comparison, follicles selected to enter the pre-ovulatory hierarchy rarely undergo atresia and the granulosa cells are highly resistant to apoptosis[ 30 , 31 ]. Similar to mammalian corpus luteum, the post-ovulation follicles degenerated mainly through apoptosis process [ 32 , 33 ]. The comparisons of follicle cells from different phases of the ovulation cycle could enable us to identify the cell death or survival factors in the follicles.…”

In vitro Effects of TCDD, PCB126 and PCB153 on Estrogen Receptors, Caspases and Metalloproteinase-2 mRNA Expression in the Chicken Shell Gland

“…Some molecular events involved in programmed cell death are largely mediated by caspases (see review JOHNSON 1996;JOHNSON & BRIDGHAM 2002). The caspase family includes initiator caspase (-1, -2, -8, -9, -10) and effector caspase (-3, -6, -7) and it was found that caspase-1, -2 and -3 play the essential role in the regression of chicken reproductive tissue SUNDARESAN et al 2008). Thus, to ex- amine whether TCDD and PCBs affects cell apoptosis in the chicken shell gland the initiator caspase-1 and executioner caspase-3 mRNA expression was determined.…”