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

Abstract

9 3) Author for correspondence (christian.lehner@imls.uzh.ch) 10 11 12 Running title: Drosophila beta-Tubulin 97EF 13 14 KEY WORDS: microtubules, tubulin isoform, boundary cells, low temperature, ectotherm 15 16Summary statement 17 Ectotherms thrive within an often remarkable temperature range. At low temperature, 18 betaTub97EF, a beta-tubulin paralog stabilizing microtubules, is upregulated in a tissue-19 specific manner in the fly Drosophila melanogaster. Abstract 22Cells in ectotherms function normally within an often wide temperature range. As 23 temperature dependence is not uniform across all the distinct biological processes, 24 acclimation presumably requires complex regulation. The molecular mechanisms coping 25 with the disruptive effects of temperature variation are still poorly understood. 26 Interestingly, one of five different beta-tubulin paralogs, betaTub97EF, was among the 27 genes up-regulated at low temperature in cultured Drosophila cells. As microtubules are 28 known to be cold-sensitive, we analyzed whether betaTub97EF protects microtubules at low 29 temperatures. During development at the optimal temperature (25°C), betaTub97EF was 30 expressed in a tissue-specific pattern primarily in the gut. There, as well as in hemocytes, 31 expression was increased at low temperature (14°C). While betaTub97EF mutants were 32 viable and fertile at 25°C, their sensitivity within the well-tolerated range was slightly 33 enhanced during embryogenesis specifically at low temperatures. Changing beta-tubulin 34 isoform ratios in hemocytes demonstrated that beta-Tubulin 97EF has a pronounced 35 microtubule stabilizing effect. Moreover, betaTub97EF is required for normal microtubule 36 stability in the gut. These results suggest that betaTub97EF up-regulation at low 37 temperature contributes to acclimation by stabilizing microtubules. 38 39 45 the environment. But even in endotherms, the exposed peripheral cells need to function 46 over a range of temperatures. 47 77 posttranslational modifications and indirectly via microtubule-associated proteins (MAPs) 78 and motors. Paralogs encoding distinct alpha-and beta-tubulins have evolved in many 79 lineages (Findeisen et al., 2014). Sequence differences are found predominantly in the C-80 terminal tails, where also most posttranslational modifications occur. These modifications 81 are thought to generate a 'tubulin-code' controlling binding and function of many MAPs and 82 motors (Gadadhar et al., 2017;Janke, 2014; Sirajuddin et al., 2014; Yu et al., 2015). 83 In mammals, MAP6 adapts its conformation according to temperature to maintain 84 microtubule networks in cells exposed low temperature (Delphin et al., 2012). Moreover, 85 the recent production of pure tubulin isoforms has definitely established inherent isoform-86 specific differences in microtubule dynamics in vitro (Pamula et al., 2016; Ti et al., 2016; 87 Vemu et al., 2016). 88 Genetic analyses in Drosophila melanogaster have provided the first unequivocal evidence 89 for para...

Temperature gradient affects differentiation of gene expression and SNP allele frequencies in the dominant Lake Baikal zooplankton species

“…Likewise, the finding that several orthologous groups showing differential expression along the thermal gradient contain structural proteins of cytoskeleton is consistent with the previously described thermal adaptation in cytoskeleton proteins of a striking variety of eukaryotes. In particular, α‐ and β‐tubulins in cold‐adapted fish, annelids and ciliates show signatures of adaptation for efficient microtubule assembly at low temperatures (Detrich, Parker, Williams, Nogales, & Downing, ; Pucciarelli et al., ; Tartaglia & Shain, ); differential expression of paralogs of tubulins plays a role in cold acclimation in plants (Christov, Imai, & Blume, ; Farajalla & Gulick, ) and Drosophila (Myachina, Bosshardt, Bischof, Kirschmann, & Lehner, ). The α‐tubulin showing upregulation in the warmer areas of the lake is a copepod‐specific paralog that differs from the ancestral crustacean α‐tubulins by amino acid substitutions in the same areas (M‐loop and adjacent α‐helices) that contain amino acid changes in cold‐adapted fish (Detrich et al., ) and ciliates (Pucciarelli et al., ) and are known to play a role in temperature‐specific microtubule stability (L. Y. Yampolsky, in preparation ).…”

Acis-regulatory element promoting increased transcription at low temperature in cultured ectothermicDrosophilacells

“…However, we definitely also observed examples with an apparent correlation between transcript levels and DNA accessibility. In case of betaTub97EF, which was previously shown to be strongly CoolUp in S2R+ cells (Myachina et al 2017), an increase in DNA accessibility was detected at low temperature within a region just upstream of the transcriptional start site ( Fig. 4D).…”

“…1B). The CoolUp genes of cluster 1 also contained betaTub97EF, one of the limited number of genes with CoolUp regulation in both S2R+ and HB10 cells, encoding a beta tubulin isoform that stabilizes microtubules (Myachina et al 2017). We emphasize that the GO term "response to stress" was not significantly enriched among the 272 gene identified by the de probes in cluster 1.…”

EBV‐miR‐BART12 accelerates migration and invasion in EBV‐associated cancer cells by targeting tubulin polymerization‐promoting protein 1

“…Low temperature promotes the disassembly of microtubes. [36][37][38] After placing TSA-treated cells in a refrigerator at 4°C for 30 minutes, the same experimental procedures described above were performed. By observing cells of the NC group treated with cold + TSA, we determined that the number of microtubules was reduced compared with the NC group treated with TSA and that existing microtubules were completely colocalized with the acetylated microtubules.…”