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The Regulation of Muscle Structure and Metabolism by Mio/dChREBP in Drosophila.

Polak GL, Pasqualino A, Docherty JE, Beck SJ, DiAngelo JR - PLoS ONE (2015)

Bottom Line: Decreasing Mio levels using RNAi specifically in muscle results in increased thorax glycogen storage.Myofibril size is also decreased in flies just before emerging from their pupal cases, suggesting a role for Mio in myofibril development.Together, these data indicate a novel role for Mio in controlling muscle structure and metabolism and may provide a molecular link between nutrient availability and muscle function.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Hofstra University, Hempstead, NY, 11549, United States of America.

ABSTRACT
All cells require energy to perform their specialized functions. Muscle is particularly sensitive to the availability of nutrients due to the high-energy requirement for muscle contraction. Therefore the ability of muscle cells to obtain, store and utilize energy is essential for the function of these cells. Mio, the Drosophila homolog of carbohydrate response element binding protein (ChREBP), has recently been identified as a nutrient responsive transcription factor important for triglyceride storage in the fly fat body. However, the function of Mio in muscle is unknown. In this study, we characterized the role of Mio in controlling muscle function and metabolism. Decreasing Mio levels using RNAi specifically in muscle results in increased thorax glycogen storage. Adult Mio-RNAi flies also have a flight defect due to altered myofibril shape and size in the indirect flight muscles as shown by electron microscopy. Myofibril size is also decreased in flies just before emerging from their pupal cases, suggesting a role for Mio in myofibril development. Together, these data indicate a novel role for Mio in controlling muscle structure and metabolism and may provide a molecular link between nutrient availability and muscle function.

No MeSH data available.


Related in: MedlinePlus

Mio affects myofibril size in pharate adults.Transmission Electron Microscopy of Indirect Flight Muscles of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls. Panels (A), (B) and (C) show cross sections of the myofibrils. Bars indicate 0.5μm. f, myofibril; c, mitochondrion; g, glycogen granules. (D) Average myofibril area of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls (n = 3–5). Values represent average myofibril area ±SEM. *p<0.05 by One-way ANOVA with post hoc Tukey test.
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pone.0136504.g006: Mio affects myofibril size in pharate adults.Transmission Electron Microscopy of Indirect Flight Muscles of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls. Panels (A), (B) and (C) show cross sections of the myofibrils. Bars indicate 0.5μm. f, myofibril; c, mitochondrion; g, glycogen granules. (D) Average myofibril area of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls (n = 3–5). Values represent average myofibril area ±SEM. *p<0.05 by One-way ANOVA with post hoc Tukey test.

Mentions: To determine whether the altered myofibril phenotype in adult flies was generated by muscle usage or due to a defect in myofibril assembly during development, we visualized the IFMs in pharate adults at the end of the pupal stage of development just before emerging from the pupal case. TEM micrographs of the IFM showed normal assembly of myofibrils in the Mio-RNAi flies with normal crystal lattice formation and round, normally shaped myofibrils (Fig 6A–6C). Although we did not detect any structural problems in myofibrils from Mio-RNAi pharate adults, we did observe smaller cross-sectional areas of myofibrils in animals with decreased Mio levels compared to the GFP controls (Fig 6D), consistent with the smaller myofibrils in Mio-RNAi adults (Fig 4D). These data indicate that Mio might be playing a role in the development and/or assembly of myofibrils in addition to its metabolic function in muscle cells.


The Regulation of Muscle Structure and Metabolism by Mio/dChREBP in Drosophila.

Polak GL, Pasqualino A, Docherty JE, Beck SJ, DiAngelo JR - PLoS ONE (2015)

Mio affects myofibril size in pharate adults.Transmission Electron Microscopy of Indirect Flight Muscles of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls. Panels (A), (B) and (C) show cross sections of the myofibrils. Bars indicate 0.5μm. f, myofibril; c, mitochondrion; g, glycogen granules. (D) Average myofibril area of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls (n = 3–5). Values represent average myofibril area ±SEM. *p<0.05 by One-way ANOVA with post hoc Tukey test.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4549115&req=5

pone.0136504.g006: Mio affects myofibril size in pharate adults.Transmission Electron Microscopy of Indirect Flight Muscles of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls. Panels (A), (B) and (C) show cross sections of the myofibrils. Bars indicate 0.5μm. f, myofibril; c, mitochondrion; g, glycogen granules. (D) Average myofibril area of Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR pharate adults compared to Mef2-Gal4>GFP controls (n = 3–5). Values represent average myofibril area ±SEM. *p<0.05 by One-way ANOVA with post hoc Tukey test.
Mentions: To determine whether the altered myofibril phenotype in adult flies was generated by muscle usage or due to a defect in myofibril assembly during development, we visualized the IFMs in pharate adults at the end of the pupal stage of development just before emerging from the pupal case. TEM micrographs of the IFM showed normal assembly of myofibrils in the Mio-RNAi flies with normal crystal lattice formation and round, normally shaped myofibrils (Fig 6A–6C). Although we did not detect any structural problems in myofibrils from Mio-RNAi pharate adults, we did observe smaller cross-sectional areas of myofibrils in animals with decreased Mio levels compared to the GFP controls (Fig 6D), consistent with the smaller myofibrils in Mio-RNAi adults (Fig 4D). These data indicate that Mio might be playing a role in the development and/or assembly of myofibrils in addition to its metabolic function in muscle cells.

Bottom Line: Decreasing Mio levels using RNAi specifically in muscle results in increased thorax glycogen storage.Myofibril size is also decreased in flies just before emerging from their pupal cases, suggesting a role for Mio in myofibril development.Together, these data indicate a novel role for Mio in controlling muscle structure and metabolism and may provide a molecular link between nutrient availability and muscle function.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Hofstra University, Hempstead, NY, 11549, United States of America.

ABSTRACT
All cells require energy to perform their specialized functions. Muscle is particularly sensitive to the availability of nutrients due to the high-energy requirement for muscle contraction. Therefore the ability of muscle cells to obtain, store and utilize energy is essential for the function of these cells. Mio, the Drosophila homolog of carbohydrate response element binding protein (ChREBP), has recently been identified as a nutrient responsive transcription factor important for triglyceride storage in the fly fat body. However, the function of Mio in muscle is unknown. In this study, we characterized the role of Mio in controlling muscle function and metabolism. Decreasing Mio levels using RNAi specifically in muscle results in increased thorax glycogen storage. Adult Mio-RNAi flies also have a flight defect due to altered myofibril shape and size in the indirect flight muscles as shown by electron microscopy. Myofibril size is also decreased in flies just before emerging from their pupal cases, suggesting a role for Mio in myofibril development. Together, these data indicate a novel role for Mio in controlling muscle structure and metabolism and may provide a molecular link between nutrient availability and muscle function.

No MeSH data available.


Related in: MedlinePlus