Vincent C K, Gualberto A, Patel C V, Walsh K
Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
Mol Cell Biol. 1993 Feb;13(2):1264-72. doi: 10.1128/mcb.13.2.1264-1272.1993.
Regulatory sequences of the M isozyme of the creatine kinase (MCK) gene have been extensively mapped in skeletal muscle, but little is known about the sequences that control cardiac-specific expression. The promoter and enhancer sequences required for MCK gene expression were assayed by the direct injection of plasmid DNA constructs into adult rat cardiac and skeletal muscle. A 700-nucleotide fragment containing the enhancer and promoter of the rabbit MCK gene activated the expression of a downstream reporter gene in both muscle tissues. Deletion of the enhancer significantly decreased expression in skeletal muscle but had no detectable effect on expression in cardiac muscle. Further deletions revealed a CArG sequence motif at position -179 within the promoter that was essential for cardiac-specific expression. The CArG element of the MCK promoter bound to the recombinant serum response factor and YY1, transcription factors which control expression from structurally similar elements in the skeletal actin and c-fos promoters. MCK-CArG-binding activities that were similar or identical to serum response factor and YY1 were also detected in extracts from adult cardiac muscle. These data suggest that the MCK gene is controlled by different regulatory programs in adult cardiac and skeletal muscle.
肌酸激酶（MCK）基因M同工酶的调控序列已在骨骼肌中得到广泛定位，但对于控制心脏特异性表达的序列却知之甚少。通过将质粒DNA构建体直接注射到成年大鼠的心脏和骨骼肌中，检测了MCK基因表达所需的启动子和增强子序列。一个包含兔MCK基因增强子和启动子的700个核苷酸的片段激活了两个肌肉组织中一个下游报告基因的表达。增强子的缺失显著降低了骨骼肌中的表达，但对心肌中的表达没有可检测到的影响。进一步的缺失揭示了启动子中位于-179位置的一个CArG序列基序，它对于心脏特异性表达至关重要。MCK启动子的CArG元件与重组血清反应因子和YY1结合，这两种转录因子控制骨骼肌肌动蛋白和c-fos启动子中结构相似元件的表达。在成年心肌提取物中也检测到了与血清反应因子和YY1相似或相同的MCK-CArG结合活性。这些数据表明，MCK基因在成年心脏和骨骼肌中受不同的调控程序控制。
