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An investigation of nutrient-dependent mRNA translation in Drosophila larvae.

Nagarajan S, Grewal SS - Biol Open (2014)

Bottom Line: By analyzing individual genes, we observed that nutrient-deprivation led to a general reduction in mRNA translation, regardless of any starvation-mediated changes (increase or decrease) in total transcript levels.Although sugars and amino acids are key regulators of translation in animal cells and are the major macronutrients in the larval diet, we found that they alone were not sufficient to maintain mRNA translation in larvae.However, we found that genetic activation of PI3K and TOR signaling, or regulation of two effectors - 4EBP and S6K - could not prevent the starvation-mediated translation inhibition.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, and Clark H. Smith Brain Tumour Centre, Southern Alberta Cancer Research Institute, University of Calgary, HRIC, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.

No MeSH data available.


Related in: MedlinePlus

TORC1 and insulin regulation of mRNA translation.(A) Representative trace from an experiment comparing polysome profiles in wild-type (left trace, black) versus tor mutant (right trace, red) larvae. Genotypes: wildtype, w1118;;; tor mutant, w1118;torΔP/torΔP. (B–D) Polysome profiles from (B) control, (C) Rheb-overexpressing, (D) dp110-overexpressing larvae. Black traces from fed larvae, red traces from starved larvae. Genotypes – control: ywhsflp122/+; +/+; act>CD2>Gal4, UAS-GFP/+, Rheb overexpression: ywhsflp122/+; UAS-Rheb/+; act>CD2>Gal4, UAS-GFP/+, dp110 overexpression: ywhsflp122/+; UAS-dp110/+; act>CD2>Gal4, UAS-GFP/+. Transgene expression was induced at 48 hr after egg laying. Larvae were then starved (sucrose: PBS) at 72 hr after egg laying.
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f08: TORC1 and insulin regulation of mRNA translation.(A) Representative trace from an experiment comparing polysome profiles in wild-type (left trace, black) versus tor mutant (right trace, red) larvae. Genotypes: wildtype, w1118;;; tor mutant, w1118;torΔP/torΔP. (B–D) Polysome profiles from (B) control, (C) Rheb-overexpressing, (D) dp110-overexpressing larvae. Black traces from fed larvae, red traces from starved larvae. Genotypes – control: ywhsflp122/+; +/+; act>CD2>Gal4, UAS-GFP/+, Rheb overexpression: ywhsflp122/+; UAS-Rheb/+; act>CD2>Gal4, UAS-GFP/+, dp110 overexpression: ywhsflp122/+; UAS-dp110/+; act>CD2>Gal4, UAS-GFP/+. Transgene expression was induced at 48 hr after egg laying. Larvae were then starved (sucrose: PBS) at 72 hr after egg laying.

Mentions: We next explored the signaling requirements for maintaining nutrient-dependent mRNA translation in larvae. The insulin and TORC1 kinase signaling pathways are the major nutrient-dependent regulators of cell, tissue and body growth in Drosophila larvae. Furthermore, an extensive body of work using tissue culture shows that TORC1 signaling is a link between nutrients and mRNA translation in animal cells. We therefore examined if insulin/TORC1 signaling regulates mRNA translation in larvae. We first examined mRNA translation in tor mutants. Using the same polysomal profiling technique described above, we found that compared to wild type larvae, tor larvae had markedly reduced levels of polysomes and an increase in subpolysomal fractions (Fig. 8A). These effects phenocopied the changes in translation seen in starved larvae.


An investigation of nutrient-dependent mRNA translation in Drosophila larvae.

Nagarajan S, Grewal SS - Biol Open (2014)

TORC1 and insulin regulation of mRNA translation.(A) Representative trace from an experiment comparing polysome profiles in wild-type (left trace, black) versus tor mutant (right trace, red) larvae. Genotypes: wildtype, w1118;;; tor mutant, w1118;torΔP/torΔP. (B–D) Polysome profiles from (B) control, (C) Rheb-overexpressing, (D) dp110-overexpressing larvae. Black traces from fed larvae, red traces from starved larvae. Genotypes – control: ywhsflp122/+; +/+; act>CD2>Gal4, UAS-GFP/+, Rheb overexpression: ywhsflp122/+; UAS-Rheb/+; act>CD2>Gal4, UAS-GFP/+, dp110 overexpression: ywhsflp122/+; UAS-dp110/+; act>CD2>Gal4, UAS-GFP/+. Transgene expression was induced at 48 hr after egg laying. Larvae were then starved (sucrose: PBS) at 72 hr after egg laying.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232759&req=5

f08: TORC1 and insulin regulation of mRNA translation.(A) Representative trace from an experiment comparing polysome profiles in wild-type (left trace, black) versus tor mutant (right trace, red) larvae. Genotypes: wildtype, w1118;;; tor mutant, w1118;torΔP/torΔP. (B–D) Polysome profiles from (B) control, (C) Rheb-overexpressing, (D) dp110-overexpressing larvae. Black traces from fed larvae, red traces from starved larvae. Genotypes – control: ywhsflp122/+; +/+; act>CD2>Gal4, UAS-GFP/+, Rheb overexpression: ywhsflp122/+; UAS-Rheb/+; act>CD2>Gal4, UAS-GFP/+, dp110 overexpression: ywhsflp122/+; UAS-dp110/+; act>CD2>Gal4, UAS-GFP/+. Transgene expression was induced at 48 hr after egg laying. Larvae were then starved (sucrose: PBS) at 72 hr after egg laying.
Mentions: We next explored the signaling requirements for maintaining nutrient-dependent mRNA translation in larvae. The insulin and TORC1 kinase signaling pathways are the major nutrient-dependent regulators of cell, tissue and body growth in Drosophila larvae. Furthermore, an extensive body of work using tissue culture shows that TORC1 signaling is a link between nutrients and mRNA translation in animal cells. We therefore examined if insulin/TORC1 signaling regulates mRNA translation in larvae. We first examined mRNA translation in tor mutants. Using the same polysomal profiling technique described above, we found that compared to wild type larvae, tor larvae had markedly reduced levels of polysomes and an increase in subpolysomal fractions (Fig. 8A). These effects phenocopied the changes in translation seen in starved larvae.

Bottom Line: By analyzing individual genes, we observed that nutrient-deprivation led to a general reduction in mRNA translation, regardless of any starvation-mediated changes (increase or decrease) in total transcript levels.Although sugars and amino acids are key regulators of translation in animal cells and are the major macronutrients in the larval diet, we found that they alone were not sufficient to maintain mRNA translation in larvae.However, we found that genetic activation of PI3K and TOR signaling, or regulation of two effectors - 4EBP and S6K - could not prevent the starvation-mediated translation inhibition.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, and Clark H. Smith Brain Tumour Centre, Southern Alberta Cancer Research Institute, University of Calgary, HRIC, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.

No MeSH data available.


Related in: MedlinePlus