There are no reports of the requirement for caspase activity during luteal regression, but Rueda et al. demonstrated that caspase-1 mRNA is increased in the regressing bovine CL. Cleavage of actin and PARP during follicular atresia and luteal regression was of interest not only because they are both substrates of activated caspase-3 but also because they are both inhibitors of DNase I. buy diabetes drugs
Previous work in our laboratory has identified DNase I as the endonuclease responsible for apoptotic DNA degradation in the ovary. We suggested that one potential mechanism for DNase I activation during apoptosis might be through the degradation of DNase I-inhibitory proteins such as PARP or actin. In the present studies, although both PARP and actin cleavage were evident during luteal regression, degradation of these proteins could not be detected during induced follicular atresia. However, DNA degradation was evident during both atresia and regression, demonstrating that DNase I was activated during both processes. This suggests that although actin and PARP can be degraded during ovarian apoptosis, extensive cleavage of these proteins is not necessary for the activation of DNase I. A variety of substrates for different caspases have been described, and many of these substrates are cleaved by more than one type of caspase.