Mapping and transcription profiling of CASP1, 3, 6, 7 and 8 in relation to caspase activity in the bovine cumulus–oocyte complex

Abstract

So far 12 caspases have been described in mouse and human while only one (CASP13) is known in cattle. The aim of this study was to (1) search for other bovine caspases by reverse transcription and polymerase chain reaction (RT-PCR) and (2) examine the presence of bovine caspase mRNA and active protein in the cumulus-oocyte complex. Five caspases (1, 3, 6, 7 and 8) were identified, partially cloned and sequenced. Four of them were mapped. Differential transcription of the caspase genes was detected, but no active caspase protein was found in diverse bovine oocytes. Cumulus granulosa cells (CGC) contain CASP1, 6, 7 and 8 mRNA and active caspase protein. The presence of caspase mRNA and active caspase proteins in CGCs suggests the occurrence of apoptosis in cumulus-oocyte complex, while caspase activation is blocked in fresh oocytes and therefore caspase transcription cannot be used to predict the oocyte developmental capacity.