CYCLIN-DEPENDENT KINASE-5 IS ASSOCIATED WITH APOPTOTIC CELL-DEATH DURING DEVELOPMENT AND TISSUE REMODELING

In a series of studies to more precisely localize the cellular sites o f expression of the cyclin-dependent kinase (Cdk) family members in re productive organs, we observed a striking expression of Cdk5 in atreti c follicles in the ovary, particularly in granulosa cells that appeare d to be dying. We determined that these granulosa cells were undergoin g apoptotic cell death using the in situ DNA fragmentation assay. To e xtend the generality of the association of Cdk5 with apoptotic cells, we examined its expression as it correlated with the detection of apop tosis in a number of developmental paradigms, including regions of the embryonic nervous system, the developing eye, and the developing limb . finally, the association of apoptosis and Cdk5 expression and associ ated kinase activity was examined in the limb and in an induced cell d eath system, that of androgen withdrawal-induced regression of the pro state gland in male mice. These observations provide new insight into the possible function of this novel Cdk during both differentiation an d apoptotic cell death. (C) 1997 Academic Press.