DETECTION OF ACTIVATED CASPASE-3 (CPP32) IN THE VERTEBRATE NERVOUS-SYSTEM DURING DEVELOPMENT BY A CLEAVAGE SITE-DIRECTED ANTISERUM

We previously demonstrated that Caspase-3 is highly expressed in dorsa l root ganglia and trigeminal ganglia of mouse embryos [T. Mukasa, K. Urase, Y.M. Momoi, I. Kimura, T. Momoi, Specific expression of CPP32 i n sensory neurons of mouse embryos and activation of CPP32 in the apop tosis induced by a withdrawal of NGF, Biochem. Biophys. Res. Commun., 231 (1997) 770-774.]. Since, however, Caspases are processed into acti ve form during apoptosis, it is difficult to examine the involvement o f activated Caspases in naturally occurring cell death during developm ent by immunohistochemical staining or in situ hybridization method. W e prepared a cleavage site-directed antiserum against Caspase-3 (anti- p20/17). This antiserum reacted with fragment (p20/17) of Caspase-3, b ut not proCaspase-3 (p32), proCaspase-7 (p34) and its cleaved fragment (p24). We examined the relationship between the activation of Caspase -3 and the appearance of the naturally occurring apoptotic cells in th e nervous system during development. In the trigeminal ganglia and dor sal root,ganglia, the expression of Caspase-3 mRNA was maximal before the appearance of p20/17-positive cells and apoptotic cells. In the mo use brain, many p20/17-positive cells and apoptotic cells were observe d in the neuroepithelium in the early developmental stages, but very f ew p20/17-positive cells were detected in postmitotic neurons in the c erebral cortex although Caspase-3 mRNA was expressed highly. Caspase-3 is activated mainly during apoptosis of neuroepithelial cells in the early developmental stages but not of mature neurons at postnatal stag es. (C) 1998 Elsevier Science B.V. All rights reserved.