Herring B P, Dixon S, Gallagher P J
Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Am J Physiol Cell Physiol. 2000 Nov;279(5):C1656-64. doi: 10.1152/ajpcell.2000.279.5.C1656.
The purpose of this study was to characterize myosin light chain kinase (MLCK) expression in cardiac and skeletal muscle. The only classic MLCK detected in cardiac tissue, purified cardiac myocytes, and in a cardiac myocyte cell line (AT1) was identical to the 130-kDa smooth muscle MLCK (smMLCK). A complex pattern of MLCK expression was observed during differentiation of skeletal muscle in which the 220-kDa-long or "nonmuscle" form of MLCK is expressed in undifferentiated myoblasts. Subsequently, during myoblast differentiation, expression of the 220-kDa MLCK declines and expression of this form is replaced by the 130-kDa smMLCK and a skeletal muscle-specific isoform, skMLCK in adult skeletal muscle. These results demonstrate that the skMLCK is the only tissue-specific MLCK, being expressed in adult skeletal muscle but not in cardiac, smooth, or nonmuscle tissues. In contrast, the 130-kDa smMLCK is ubiquitous in all adult tissues, including skeletal and cardiac muscle, demonstrating that, although the 130-kDa smMLCK is expressed at highest levels in smooth muscle tissues, it is not a smooth muscle-specific protein.
本研究的目的是描述肌球蛋白轻链激酶（MLCK）在心肌和骨骼肌中的表达特征。在心脏组织、纯化的心肌细胞以及心肌细胞系（AT1）中检测到的唯一经典MLCK与130 kDa的平滑肌MLCK（smMLCK）相同。在骨骼肌分化过程中观察到了复杂的MLCK表达模式，其中220 kDa长的或“非肌肉”形式的MLCK在未分化的成肌细胞中表达。随后，在成肌细胞分化过程中，220 kDa MLCK的表达下降，这种形式的表达被130 kDa的smMLCK和成年骨骼肌中的一种骨骼肌特异性同工型skMLCK所取代。这些结果表明，skMLCK是唯一的组织特异性MLCK，在成年骨骼肌中表达，但在心脏、平滑肌或非肌肉组织中不表达。相比之下，130 kDa的smMLCK在所有成年组织中普遍存在，包括骨骼肌和心肌，这表明，尽管130 kDa的smMLCK在平滑肌组织中表达水平最高，但它不是平滑肌特异性蛋白。
