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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

Decreasing Mio levels results in abnormal myofibril organization.Scanning Electron Microscopy of longitudinal sections of Indirect Flight Muscles of adult Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR females compared to Mef2-Gal4>GFP controls. f, myofibril; g, glycogen granules. Each arrow points to a single longitudinal myofibril. Scale bar = 20μm.
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pone.0136504.g005: Decreasing Mio levels results in abnormal myofibril organization.Scanning Electron Microscopy of longitudinal sections of Indirect Flight Muscles of adult Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR females compared to Mef2-Gal4>GFP controls. f, myofibril; g, glycogen granules. Each arrow points to a single longitudinal myofibril. Scale bar = 20μm.

Mentions: In order to confirm the small myofibril phenotype observed in the TEM micrographs, Scanning Electron Microscopy (SEM) of IFMs was performed. Cross-sections observed under SEM also showed incorrect assembly of myofibrils where individual myofibrils lacked a defined circular/oval shape as seen in the control flies (Fig 4A–4C), consistent with the TEM data shown above. Quantitation of cross-sectional myofibril area in flies with decreased Mio also showed smaller myofibril size when compared to controls (Fig 4D). In addition to the smaller myofibril phenotype, longitudinal sections of myofibrils from animals where Mio levels were decreased showed irregularly spaced myofibrils filled with glycogen granules (Fig 5B and 5C), which is in contrast to the normal myofibril-mitochondria-myofibril pattern that was observed in the control muscles (Fig 5A). Together, these data suggest that Mio is important for muscle structure.


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)

Decreasing Mio levels results in abnormal myofibril organization.Scanning Electron Microscopy of longitudinal sections of Indirect Flight Muscles of adult Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR females compared to Mef2-Gal4>GFP controls. f, myofibril; g, glycogen granules. Each arrow points to a single longitudinal myofibril. Scale bar = 20μm.
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Related In: Results  -  Collection

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

pone.0136504.g005: Decreasing Mio levels results in abnormal myofibril organization.Scanning Electron Microscopy of longitudinal sections of Indirect Flight Muscles of adult Mef2-Gal4>MiodsRNA and Mef2-Gal4>Mio-IR females compared to Mef2-Gal4>GFP controls. f, myofibril; g, glycogen granules. Each arrow points to a single longitudinal myofibril. Scale bar = 20μm.
Mentions: In order to confirm the small myofibril phenotype observed in the TEM micrographs, Scanning Electron Microscopy (SEM) of IFMs was performed. Cross-sections observed under SEM also showed incorrect assembly of myofibrils where individual myofibrils lacked a defined circular/oval shape as seen in the control flies (Fig 4A–4C), consistent with the TEM data shown above. Quantitation of cross-sectional myofibril area in flies with decreased Mio also showed smaller myofibril size when compared to controls (Fig 4D). In addition to the smaller myofibril phenotype, longitudinal sections of myofibrils from animals where Mio levels were decreased showed irregularly spaced myofibrils filled with glycogen granules (Fig 5B and 5C), which is in contrast to the normal myofibril-mitochondria-myofibril pattern that was observed in the control muscles (Fig 5A). Together, these data suggest that Mio is important for muscle structure.

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