Drosophila beta-Tubulin 97EF is upregulated at low temperature and stabilizes microtubules

Summary statementEctotherms thrive within an often remarkable temperature range. At low temperature,betaTub97EF, a beta-tubulin paralog stabilizing microtubules, is upregulated in a tissue-specific manner in the flyDrosophila melanogaster.AbstractCells in ectotherms function normally within an often wide temperature range. As temperature dependence is not uniform across all the distinct biological processes, acclimation presumably requires complex regulation. The molecular mechanisms coping with the disruptive effects of temperature variation are still poorly understood. Interestingly, one of five different beta-tubulin paralogs,betaTub97EF, was among the genes up-regulated at low temperature in culturedDrosophilacells. As microtubules are known to be cold-sensitive, we analyzed whetherbetaTub97EFprotects microtubules at low temperatures. During development at the optimal temperature (25°C),betaTub97EFwas expressed in a tissue-specific pattern primarily in the gut. There, as well as in hemocytes, expression was increased at low temperature (14°C). WhilebetaTub97EFmutants were viable and fertile at 25°C, their sensitivity within the well-tolerated range was slightly enhanced during embryogenesis specifically at low temperatures. Changing beta-tubulin isoform ratios in hemocytes demonstrated that beta-Tubulin 97EF has a pronounced microtubule stabilizing effect. Moreover,betaTub97EFis required for normal microtubule stability in the gut. These results suggest thatbetaTub97EFup-regulation at low temperature contributes to acclimation by stabilizing microtubules.