Department of Chemical Engineering, Texas Tech University, Lubbock, TX, 79409, USA.
Department of Pathology, Emory University, Atlanta, GA, 30322, USA.
Skelet Muscle. 2021 Aug 13;11(1):20. doi: 10.1186/s13395-021-00275-4.
Caenorhabditis elegans has been widely used as a model to study muscle structure and function. Its body wall muscle is functionally and structurally similar to vertebrate skeletal muscle with conserved molecular pathways contributing to sarcomere structure, and muscle function. However, a systematic investigation of the relationship between muscle force and sarcomere organization is lacking. Here, we investigate the contribution of various sarcomere proteins and membrane attachment components to muscle structure and function to introduce C. elegans as a model organism to study the genetic basis of muscle strength.
We employ two recently developed assays that involve exertion of muscle forces to investigate the correlation of muscle function to sarcomere organization. We utilized a microfluidic pillar-based platform called NemaFlex that quantifies the maximum exertable force and a burrowing assay that challenges the animals to move in three dimensions under a chemical stimulus. We selected 20 mutants with known defects in various substructures of sarcomeres and compared the physiological function of muscle proteins required for force generation and transmission. We also characterized the degree of sarcomere disorganization using immunostaining approaches.
We find that mutants with genetic defects in thin filaments, thick filaments, and M-lines are generally weaker, and our assays are successful in detecting the functional changes in response to each sarcomere location tested. We find that the NemaFlex and burrowing assays are functionally distinct informing on different aspects of muscle physiology. Specifically, the burrowing assay has a larger bandwidth in phenotyping muscle mutants, because it could pick ten additional mutants impaired while exerting normal muscle force in NemaFlex. This enabled us to combine their readouts to develop an integrated muscle function score that was found to correlate with the score for muscle structure disorganization.
Our results highlight the suitability of NemaFlex and burrowing assays for evaluating muscle physiology of C. elegans. Using these approaches, we discuss the importance of the studied sarcomere proteins for muscle function and structure. The scoring methodology we have developed enhances the utility of C. elegans as a genetic model to study muscle function.
秀丽隐杆线虫已被广泛用作研究肌肉结构和功能的模型。其体壁肌肉在功能和结构上与脊椎动物的骨骼肌相似，保守的分子途径有助于肌节结构和肌肉功能。然而，对于肌肉力量与肌节组织之间的关系，还缺乏系统的研究。在这里，我们研究了各种肌节蛋白和膜附着成分对肌肉结构和功能的贡献，将秀丽隐杆线虫引入作为研究肌肉力量遗传基础的模式生物。
我们采用了两种新开发的测试方法，即施加肌肉力的测试，以研究肌肉功能与肌节组织之间的相关性。我们使用了一种名为 NemaFlex 的微流控柱基平台来测量最大可施力，并使用了一个挖掘测试，以在化学刺激下挑战动物在三维空间中移动。我们选择了 20 个具有已知肌节各种亚结构缺陷的突变体，并比较了产生和传递力所需的肌肉蛋白的生理功能。我们还使用免疫染色方法来描述肌节的紊乱程度。
我们发现，具有细丝、粗丝和 M 线遗传缺陷的突变体通常较弱，并且我们的测试成功地检测到了对每个测试肌节位置的功能变化。我们发现，NemaFlex 和挖掘测试在功能上是不同的，可以提供有关肌肉生理学不同方面的信息。具体来说，挖掘测试在表型肌肉突变体方面具有更大的带宽，因为它可以在 NemaFlex 中检测到十个额外的在施加正常肌肉力时受损的突变体。这使我们能够结合它们的读数来开发一个综合的肌肉功能评分，该评分与肌肉结构紊乱的评分相关。
我们的结果强调了 NemaFlex 和挖掘测试用于评估秀丽隐杆线虫肌肉生理学的适用性。使用这些方法，我们讨论了所研究的肌节蛋白对肌肉功能和结构的重要性。我们开发的评分方法提高了秀丽隐杆线虫作为研究肌肉功能的遗传模型的实用性。
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