Gene-specific signal transduction between microtubules and tubulin genes in Tetrahymena thermophila

Mol Cell Biol. 1995 Sep;15(9):5173-9. doi: 10.1128/MCB.15.9.5173.


Mammalian cells regulate tubulin mRNA abundance by a posttranscriptional mechanism dependent on the concentration of tubulin monomer. Treatment of mammalian cells with microtubule-depolymerizing drugs and microtubule-polymerizing drugs causes decreases and increases in tubulin mRNA, respectively (D. W. Cleveland, Curr. Opin. Cell Biol. 1:10-14, 1989). In striking contrast to the case with mammalian cells, perturbation of microtubules in Tetrahymena thermophila by microtubule-depolymerizing or -polymerizing drugs increases the level of the single alpha-tubulin gene message by increasing transcription (L. A. Stargell, D. P. Heruth, J. Gaertig, and M. A. Gorovsky, Mol. Cell. Biol. 12:1443-1450, 1992). In this report we show that antimicrotubule drugs preferentially induce the expression of one of two beta-tubulin genes (BTU1) in T. thermophila. In contrast, deciliation induces expression of both beta-tubulin genes. Tubulin gene expression was examined in a mutant strain created by transformation with an in vitro-mutagenized beta-tubulin gene that conferred resistance to microtubule-depolymerizing drugs and sensitivity to the polymerizing drug taxol and in a strain containing a nitrosoguanidine-induced mutation in the single alpha-tubulin gene that conferred the same pattern of drug sensitivities. In both cases the levels of tubulin mRNA expression from the drug-inducible BTU1 gene in the mutant cells paralleled the altered growth sensitivities to microtubule drugs. These studies demonstrate that T. thermophila has distinct, gene-specific mechanisms for modulating tubulin gene expression depending on whether ciliary or cytoplasmic microtubules are involved. They also show that the cytoplasmic microtubule cytoskeleton itself participates in a signal transduction pathway that regulates specific tubulin gene transcription in T. thermophila.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cilia / physiology
  • Dinitrobenzenes / pharmacology
  • Dose-Response Relationship, Drug
  • Gene Expression Regulation
  • Genes, Protozoan / genetics*
  • Microtubules / metabolism*
  • Paclitaxel / pharmacology
  • RNA, Messenger / biosynthesis
  • Signal Transduction*
  • Sulfanilamides*
  • Tetrahymena thermophila / drug effects
  • Tetrahymena thermophila / physiology*
  • Transcription, Genetic
  • Tubulin / genetics*


  • Dinitrobenzenes
  • RNA, Messenger
  • Sulfanilamides
  • Tubulin
  • oryzalin
  • Paclitaxel