Microtubule cytoskeleton perturbation induced by taxol and colchicine affects chaperonin containing TCP-1 (CCT) subunit gene expression in Tetrahymena cells

We report the existence of a CCT epsilon subunit gene that encodes subunit epsilon of the chaperonin CCT (chaperonin containing TCP-1) in Tetrahymena pyriformis. This work focuses on the study of the effects of the microtubul e polymerizing agent taxol and the depolymerizing agent colchicine on micro tubule dynamics and their role in the regulation of tubulin and CCT subunit genes. Under taxol treatment some TpCCT and tubulin genes are distinctly e xpressed until 30 min of treatment. Cytoplasmic TpCCT mRNA levels slightly decrease while tubulin transcripts are increasing. In colchicine treated ce lls TpCCT and tubulin transcripts decrease in the initial 30 min of treatme nt and then start to increase. However, both antimitotic agents induce TpCC T and tubulin gene transcription. This induction does not correlate with in creased steady-state levels of TpCCT proteins and seems to be necessary to replete cytoplasmic TpCCT mRNAs. Moreover, we found that TpCCT epsilon and TpCCT alpha but not TpCCT eta are present in the insoluble fraction after a postmitochondrial fractionation that contains components of the ciliate co rtex structure, basal bodies and cilia. This suggests that some TpCCT subun its may be associated with these structures. The association of TpCCT epsil on subunit is stimulated either by taxol or colchicine treatment. These obs ervations support the idea that CCT subunits could have additional roles in vivo. (C) 2001 Elsevier Science B.V. All rights reserved.