STAUROSPORINE-INDUCED CELL DEATH INTETRAHYMENA THERMOPHILAHAS MIXED CHARACTERISTICS OF BOTH APOPTOTIC AND AUTOPHAGIC DEGENERATION

Staurosporine blocks signal transduction associated with cell survival, proliferation and chemosensory behaviour in the ciliated protozoan,Tetrahymena thermophila. Staurosporine inhibits cell proliferation andin vivoprotein phosphorylation induced by phorbol ester. It also reduces thein vitrophosphorylation of the PKC-specific substrate, myelin basic protein fragment 4-14. Our results show that cell death in the presence of staurosporine is associated with morphological and ultrastructural changes similar to both apoptosis and autophagic degeneration, but these in turn can be postponed or prevented by 8-bromo-cyclic GMP, protoporphyrin IX, hemin or actinomycin D, although phorbol ester and insulin were ineffective. The results support the notion that staurosporine-induced cell death is an active process, associated with and/or requiringde novoRNA synthesis.