Biology Department, Boston College, Chestnut Hill, MA, 02467, USA.
Skelet Muscle. 2018 Apr 6;8(1):12. doi: 10.1186/s13395-018-0159-9.
A strength of Drosophila as a model system is its utility as a tool to screen for novel regulators of various functional and developmental processes. However, the utility of Drosophila as a screening tool is dependent on the speed and simplicity of the assay used.
Here, we use larval locomotion as an assay to identify novel regulators of skeletal muscle function. We combined this assay with muscle-specific depletion of 82 genes to identify genes that impact muscle function by their expression in muscle cells. The data from the screen were supported with characterization of the muscle pattern in embryos and larvae that had disrupted expression of the strongest hit from the screen.
With this assay, we showed that 12/82 tested genes regulate muscle function. Intriguingly, the disruption of five genes caused an increase in muscle function, illustrating that mechanisms that reduce muscle function exist and that the larval locomotion assay is sufficiently quantitative to identify conditions that both increase and decrease muscle function. We extended the data from this screen and tested the mechanism by which the strongest hit, fascin, impacted muscle function. Compared to controls, animals in which fascin expression was disrupted with either a mutant allele or muscle-specific expression of RNAi had fewer muscles, smaller muscles, muscles with fewer nuclei, and muscles with disrupted myotendinous junctions. However, expression of RNAi against fascin only after the muscle had finished embryonic development did not recapitulate any of these phenotypes.
These data suggest that muscle function is reduced due to impaired myoblast fusion, muscle growth, and muscle attachment. Together, these data demonstrate the utility of Drosophila larval locomotion as an assay for the identification of novel regulators of muscle development and implicate fascin as necessary for embryonic muscle development.
作为一种模式生物，果蝇的优势在于它可作为筛选各种功能和发育过程的新型调节剂的工具。然而，果蝇作为筛选工具的效用取决于所使用的测定方法的速度和简单性。
在这里，我们使用幼虫运动作为一种测定方法来鉴定骨骼肌功能的新型调节剂。我们将该测定法与肌肉特异性的 82 个基因缺失相结合，以鉴定通过在肌肉细胞中表达来影响肌肉功能的基因。该筛选的数据得到了从该筛选中最强的命中的胚胎和幼虫中肌肉模式的特征的支持。
通过该测定，我们发现 12/82 个测试基因调节肌肉功能。有趣的是，五个基因的破坏导致肌肉功能增加，表明存在减少肌肉功能的机制，并且幼虫运动测定法足够定量以鉴定既增加又减少肌肉功能的条件。我们扩展了该筛选的数据，并测试了最强命中物 fascin 影响肌肉功能的机制。与对照相比，用突变等位基因或肌肉特异性 RNAi 破坏 fascin 表达的动物的肌肉数量减少，肌肉较小，肌肉中的细胞核较少，以及肌肉的肌腱结合处受损。然而，仅在肌肉完成胚胎发育后表达 fascin 的 RNAi 并不再现任何这些表型。
这些数据表明，肌肉功能降低是由于成肌细胞融合，肌肉生长和肌肉附着受损所致。这些数据共同证明了果蝇幼虫运动作为鉴定肌肉发育的新型调节剂的测定法的实用性，并暗示 fascin 对于胚胎肌肉发育是必需的。
