Open AccessDestabilization of tubulin mRNA during heat shock in Tetrahymena pyriformis
Author(s) -
CÓIAS Rui,
GALEGO Lisete,
BARAHONA Isabel,
RODRIGUESPOUSADA Claudina
Publication year - 1988
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1988.tb14218.x
Subject(s) - tubulin , polysome , cycloheximide , biology , microbiology and biotechnology , tetrahymena , heat shock protein , tetrahymena pyriformis , protein biosynthesis , transcription (linguistics) , messenger rna , northern blot , microtubule , gene expression , gene , biochemistry , ribosome , rna , linguistics , philosophy
The regulation of tubulin gene expression was studied in Tetrahymena pyriformis cells during heat shock (shift from 28°C to 34°C). Fluorograms of two‐dimensional gels of radiolabelled proteins synthesized during thermal stress revealed that tubulin synthesis is highly repressed when compared with that of exponentially growing cells. The variation in the levels of α and β‐tubulin mRNAs was analyzed by Northern‐blot hybridization using homologous genomic probes (αTT and βTT1). The results obtained show that heat shock induces a drastic and coordinate reduction in the amount of α and β‐tubulin mRNAs isolated from polysomes. This decrease is not due to a shift from the polysomes to the post‐polysomal fraction because it was also observed when total cytoplasmic mRNAs were analyzed. Run‐on transcription experiments were performed in order to examine whether repression of transcription in heat‐shocked cells could explain that reduction. The results obtained show that the apparent rates of tubulin gene transcription are not significantly modified, but on the contrary increase slightly in cells heat‐shocked for 15 min and 30 min. The effects of inhibitors of protein synthesis, cycloheximide and pactamycin, on the destabilization of tubulin mRNAs were tested in heat‐shocked Tetrahymena cells. Our results revealed that in the presence of these inhibitors, tubulin mRNAs become more stable thus suggesting that an induced factor may be involved in the degradation of α and β‐tubulin mRNAs during heat shock.