Palermo J, Gulick J, Ng W, Grupp I L, Grupp G, Robbins J
Division of Molecular Cardiovascular Biology, Children's Hospital Research Foundation, Cincinnati, OH 45267, USA.
Cell Mol Biol Res. 1995;41(6):501-9.
Our objective was to test the hypothesis that, via transgenesis, one can modify the contractile protein complement of the mouse heart. Using a promoter derived from the mouse myosin heavy chain gene (alpha-MyHC), we attempted to remodel the mouse myocardium by ectopically expressing a ventricular form of the myosin light chain 2 (MLC2v) in the atrium. The ability of the heart to maintain contractile isoform stoichiometry was tested by overexpressing the cDNA in both the atria and ventricle. The promoter drove high levels of transgene expression in both cardiac compartments and was controlled in an appropriate manner during development. The data show that ectopic overexpression of a contractile protein isoform can lead to compartment specific replacement. However, if the transgene encodes the isoform that is normally present (e.g., MLC2v expressed in the ventricle), the protein levels remain unaffected, although the transgenic transcript accumulates to very high levels. The basic function and the physiologic or pathophysiologic significance of differential MLC2 isoform content was examined. Using the whole working heart preparation, we show that an MLC2a --> MLC2v shift in the atrium severely affects contractile function and performance.
通过转基因技术可以改变小鼠心脏收缩蛋白的组成。我们利用从小鼠肌球蛋白重链基因（α - 肌球蛋白重链）衍生而来的启动子，试图通过在心房异位表达心室形式的肌球蛋白轻链2（MLC2v）来重塑小鼠心肌。通过在心房和心室中过表达cDNA来测试心脏维持收缩同工型化学计量的能力。该启动子在两个心脏腔室中驱动高水平的转基因表达，并在发育过程中以适当的方式受到调控。数据表明，收缩蛋白同工型的异位过表达可导致特定腔室的替代。然而，如果转基因编码的是正常存在的同工型（例如，在心室中表达的MLC2v），尽管转基因转录本积累到非常高的水平，但蛋白质水平仍不受影响。我们研究了不同MLC2同工型含量的基本功能及其生理或病理生理意义。使用完整的工作心脏标本，我们发现心房中MLC2a向MLC2v的转变严重影响收缩功能和性能。
