The regulation of muscle function by Mio in Drosophila. Grzegorz Polak, Justin DiAngelo. Department of Biology, Hofstra Univ, Hempstead, NY.

   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 and store nutrients for energy is essential for the function of these cells. Our lab has recently identified Mio, the Drosophila homolog of carbohydrate response element binding protein (ChREBP), as a nutrient responsive transcription factor important for triglyceride storage in the fat body. However, the function of Mio in muscle is unknown. In this study, we characterized the role of Mio, in controlling muscle function in adult flies. Lowering Mio levels using RNAi specifically in muscle leads to a flight defect. This phenotype does not result from a lack of nutrient stores or the inability to utilize those stores as there is little effect on glycogen and triglyceride levels when Mio expression was decreased in muscle. These data raise the possibility that the flight defect observed in muscle-specific Mio knockdown flies may be due to effects on muscle structure and electron microscopy experiments are being performed to test this hypothesis. Together, these data indicate a novel role for Mio in muscle to control flight and may provide a molecular link between nutrient availability and muscle function.