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Drosophila melanogaster activating transcription factor 4 regulates glycolysis during endoplasmic reticulum stress.

Lee JE, Oney M, Frizzell K, Phadnis N, Hollien J - G3 (Bethesda) (2015)

Bottom Line: The unfolded protein response transcription factor Atf4 was necessary for the up-regulation of glycolytic enzymes and Lactate dehydrogenase (Ldh).Finally, flies up-regulated Ldh and produced more lactate when subjected to ER stress.Together, these results suggest that Atf4 mediates a shift from a metabolism based on oxidative phosphorylation to one more heavily reliant on glycolysis, reminiscent of aerobic glycolysis or the Warburg effect observed in cancer and other proliferative cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112.

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Related in: MedlinePlus

Flies display metabolic changes during ER stress in vivo. (A) We fed male D. melanogaster w1118 with Tm (10 μg/mL, 23 hr) to induce ER stress and measured Ldh mRNA levels by qPCR. (B−C) We crossed UAS-Atf4RNAi to hs-GAL4 to obtain Atf4 knockdown flies. We stressed each strain of flies as in (A) and compared the RNA levels of Atf4 (B), Ldh, and BiP (C) by qPCR. (D) We measured lactate levels in extracts from D. melanogaster fed with or without Tm as in A. Lactate concentrations were normalized using total protein concentrations. For all panels: data are presented as means ± SDs of 3 independent experiments. *P < 0.05; **P < 0.005; ***P < 0.001, Student’s paired t-test. Atf4, activating transcription factor 4; ER, endoplasmic reticulum; Ldh, Lactate dehydrogenase; qPCR, quantitative polymerase chain reaction; Tm, tunicamycin.
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fig7: Flies display metabolic changes during ER stress in vivo. (A) We fed male D. melanogaster w1118 with Tm (10 μg/mL, 23 hr) to induce ER stress and measured Ldh mRNA levels by qPCR. (B−C) We crossed UAS-Atf4RNAi to hs-GAL4 to obtain Atf4 knockdown flies. We stressed each strain of flies as in (A) and compared the RNA levels of Atf4 (B), Ldh, and BiP (C) by qPCR. (D) We measured lactate levels in extracts from D. melanogaster fed with or without Tm as in A. Lactate concentrations were normalized using total protein concentrations. For all panels: data are presented as means ± SDs of 3 independent experiments. *P < 0.05; **P < 0.005; ***P < 0.001, Student’s paired t-test. Atf4, activating transcription factor 4; ER, endoplasmic reticulum; Ldh, Lactate dehydrogenase; qPCR, quantitative polymerase chain reaction; Tm, tunicamycin.

Mentions: To induce ER stress in flies, we fed Drosophila melanogaster strain w1118 media containing Tm (10 μg/mL) for 23 hr. We then isolated RNA from flies and measured the mRNA levels for several genes by qPCR. Consistent with our findings in S2 cells, flies fed Tm showed increased Ldh expression (Figure 7A). Levels of other glycolytic genes, however, were not significantly changed in the presence of Tm. Because Ldh was the most strongly up-regulated metabolic gene in S2 cells (~100 fold), and was regulated to a much lesser extent in flies (~3 fold), it is possible that this regulation occurs only in certain tissues, resulting in expression changes for other genes that were below our detection limit when whole flies were assayed.


Drosophila melanogaster activating transcription factor 4 regulates glycolysis during endoplasmic reticulum stress.

Lee JE, Oney M, Frizzell K, Phadnis N, Hollien J - G3 (Bethesda) (2015)

Flies display metabolic changes during ER stress in vivo. (A) We fed male D. melanogaster w1118 with Tm (10 μg/mL, 23 hr) to induce ER stress and measured Ldh mRNA levels by qPCR. (B−C) We crossed UAS-Atf4RNAi to hs-GAL4 to obtain Atf4 knockdown flies. We stressed each strain of flies as in (A) and compared the RNA levels of Atf4 (B), Ldh, and BiP (C) by qPCR. (D) We measured lactate levels in extracts from D. melanogaster fed with or without Tm as in A. Lactate concentrations were normalized using total protein concentrations. For all panels: data are presented as means ± SDs of 3 independent experiments. *P < 0.05; **P < 0.005; ***P < 0.001, Student’s paired t-test. Atf4, activating transcription factor 4; ER, endoplasmic reticulum; Ldh, Lactate dehydrogenase; qPCR, quantitative polymerase chain reaction; Tm, tunicamycin.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4390581&req=5

fig7: Flies display metabolic changes during ER stress in vivo. (A) We fed male D. melanogaster w1118 with Tm (10 μg/mL, 23 hr) to induce ER stress and measured Ldh mRNA levels by qPCR. (B−C) We crossed UAS-Atf4RNAi to hs-GAL4 to obtain Atf4 knockdown flies. We stressed each strain of flies as in (A) and compared the RNA levels of Atf4 (B), Ldh, and BiP (C) by qPCR. (D) We measured lactate levels in extracts from D. melanogaster fed with or without Tm as in A. Lactate concentrations were normalized using total protein concentrations. For all panels: data are presented as means ± SDs of 3 independent experiments. *P < 0.05; **P < 0.005; ***P < 0.001, Student’s paired t-test. Atf4, activating transcription factor 4; ER, endoplasmic reticulum; Ldh, Lactate dehydrogenase; qPCR, quantitative polymerase chain reaction; Tm, tunicamycin.
Mentions: To induce ER stress in flies, we fed Drosophila melanogaster strain w1118 media containing Tm (10 μg/mL) for 23 hr. We then isolated RNA from flies and measured the mRNA levels for several genes by qPCR. Consistent with our findings in S2 cells, flies fed Tm showed increased Ldh expression (Figure 7A). Levels of other glycolytic genes, however, were not significantly changed in the presence of Tm. Because Ldh was the most strongly up-regulated metabolic gene in S2 cells (~100 fold), and was regulated to a much lesser extent in flies (~3 fold), it is possible that this regulation occurs only in certain tissues, resulting in expression changes for other genes that were below our detection limit when whole flies were assayed.

Bottom Line: The unfolded protein response transcription factor Atf4 was necessary for the up-regulation of glycolytic enzymes and Lactate dehydrogenase (Ldh).Finally, flies up-regulated Ldh and produced more lactate when subjected to ER stress.Together, these results suggest that Atf4 mediates a shift from a metabolism based on oxidative phosphorylation to one more heavily reliant on glycolysis, reminiscent of aerobic glycolysis or the Warburg effect observed in cancer and other proliferative cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112.

Show MeSH
Related in: MedlinePlus