Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA.
J Exp Biol. 2013 Jul 1;216(Pt 13):2469-77. doi: 10.1242/jeb.082404.
Animals perform a remarkable diversity of movements through the coordinated mechanical contraction of skeletal muscle. This capacity for a wide range of movements is due to the presence of muscle cells with a very plastic phenotype that display many different biochemical, physiological and morphological properties. What factors influence the maintenance and plasticity of differentiated muscle fibers is a fundamental question in muscle biology. We have exploited the remarkable potential of skeletal muscle cells of the gymnotiform electric fish Sternopygus macrurus to trans-differentiate into electrocytes, the non-contractile electrogenic cells of the electric organ (EO), to investigate the mechanisms that regulate the skeletal muscle phenotype. In S. macrurus, mature electrocytes possess a phenotype that is intermediate between muscle and non-muscle cells. How some genes coding for muscle-specific proteins are downregulated while others are maintained, and novel genes are upregulated, is an intriguing problem in the control of skeletal muscle and EO phenotype. To date, the intracellular and extracellular factors that generate and maintain distinct patterns of gene expression in muscle and EO have not been defined. Expression studies in S. macrurus have started to shed light on the role that transcriptional and post-transcriptional events play in regulating specific muscle protein systems and the muscle phenotype of the EO. In addition, these findings also represent an important step toward identifying mechanisms that affect the maintenance and plasticity of the muscle cell phenotype for the evolution of highly specialized non-contractile tissues.
动物通过骨骼肌肉的协调机械收缩来完成多种多样的运动。这种广泛的运动能力源于具有高度可塑性表型的肌肉细胞的存在，这些细胞表现出许多不同的生化、生理和形态特征。哪些因素影响分化的肌肉纤维的维持和可塑性，是肌肉生物学中的一个基本问题。我们利用电鳗 Sternopygus macrurus 的骨骼肌细胞具有显著的转分化潜力，使其分化为电鳗电器官（EO）中的非收缩性发电细胞，以此来研究调节骨骼肌表型的机制。在 S. macrurus 中，成熟的电细胞具有介于肌肉和非肌肉细胞之间的表型。某些编码肌肉特异性蛋白的基因如何下调，而另一些基因被维持，以及新基因被上调，这是控制骨骼肌和 EO 表型的一个有趣问题。迄今为止，尚未确定在肌肉和 EO 中产生和维持特定基因表达模式的细胞内和细胞外因素。在 S. macrurus 中的表达研究已经开始揭示转录和转录后事件在调节特定肌肉蛋白系统和 EO 肌肉表型中的作用。此外，这些发现也代表着确定影响肌肉细胞表型维持和可塑性的机制的重要一步，这些机制与高度专业化的非收缩组织的进化有关。
