Transcriptional and post-transcriptional control of tubulin gene expression in Trypanosoma cruzi

We have shown that tubulin mRNA accumulation is regulated at the transcriptional level during metacyclogenesis of Trypanosoma cruzi, although the contribution of post-transcriptional mechanisms is also indicated. mRNA heterogeneity is not restricted to beta-tubulin, and differential regulation of alpha-tubulin mRNAs is observed during this stage of the parasite's life cycle. Treatment of epimastigotes with the microtubule-depolymerizing agent vinblastine resulted in growth inhibition and morphological alterations. Vinblastine also induced a rise in the pool of free tubulin subunits, concomitant with diminished tubulin synthesis and reduced mRNA levels. Tubulin gene transcription remained unaltered during vinblastine treatment, suggesting post-transcriptional control. These observations are in agreement with the autoregulatory model of tubulin gene expression described for a variety of cell types. We conclude that T. cruzi utilizes transcriptional and post-transcriptional control mechanisms for tubulin gene expression.