Although mammals have internal mechanisms for regulating body temperature, the vast majority of organisms are ectotherms, meaning that their body temperature is dictated by the external environment. Temperature fluctuations significantly affect cellular homeostasis, but the molecular mechanisms underlying these effects are currently poorly understood. Multiple lines of evidence suggest that microtubules are sensitive to cold, with suboptimal temperatures causing their disassembly. Christian Lehner and colleagues (p. 4573) employed global gene expression analyses of Drosophila S2R+ cells grown over a range of temperatures to identify β-Tubulin 97EF, a previously poorly characterised β-tubulin paralogue, to be among the most temperature-responsive. This upregulation was confirmed in vivo, and exhibited distinct tissue specificity, with expression being most prominent in the gut and the hemocytes. Despite the mild phenotypic consequences of β-Tubulin 97EF inactivation, likely confirming functional redundancy between β-Tubulin paralogues, βTub97EF mutant Drosophila embryos were more sensitive to the cold than their wild-type counterparts. Moreover, although there was no correlation between β-Tubulin 97EF levels and microtubule assembly rates, microtubules containing β-Tubulin 97EF were less prone to destabilisation at lower temperatures. Taken together, these results identify β-Tubulin 97EF as a cold-regulated isoform that promotes microtubule stability, and highlight the importance of mechanisms to allow acclimation to temperature variations.
