Kim S O, Katz S, Pelech S L
Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada.
J Cell Biochem. 1998 Jun 15;69(4):506-21. doi: 10.1002/(sici)1097-4644(19980615)69:4<506::aid-jcb11>3.0.co;2-6.
During early postnatal development, cardiomyocytes, which comprise about 80% of ventricular mass and volume, become phenotypically developed to facilitate their contractile functions and terminally differentiated to grow only in size but not in cell number. These changes are due to the expression of contractile proteins as well as the regulation of intracellular signal transduction proteins. In this study, the expression patterns of several protein kinases involved in various cardiac functions and cell-cycle control were analyzed by Western blotting of ventricular extracts from 1-, 10-, 20-, 50-, and 365-day-old rats. The expression level of cAMP-dependent protein kinase was slightly decreased (20%) over the first year, whereas no change was detected in cGMP-dependent protein kinase I. Calmodulin-dependent protein kinase II, which is involved in Ca2+ uptake into the sarcoplasmic reticulum, was increased as much as ten-fold. To the contrary, the expressions of protein kinase C-alpha and iota declined 77% with age. Cyclin-dependent protein kinases (CDKs) such as CDK1, CDK2, CDK4, and CDK5, which are required for cell-cycle progression, abruptly declined to almost undetectable levels after 10-20 days of age. In contrast, other CDK-related kinases, such as CDK8 or Kkialre, did not change significantly or increased up to 50% with age, respectively. Protein kinases implicated in CDK regulation such as CDK7 and Wee1 were either slightly increased in expression or did not change significantly. All of the proteins that were detected in ventricular extracts were also identified in isolated cardiac myocytes in equivalent amounts and analyzed for their relative expression in ten other adult rat tissues.
在出生后的早期发育过程中，心肌细胞约占心室质量和体积的80%，其表型逐渐发育以促进收缩功能，并最终分化为仅体积增大而细胞数量不再增加。这些变化是由于收缩蛋白的表达以及细胞内信号转导蛋白的调节所致。在本研究中，通过对1日龄、10日龄、20日龄、50日龄和365日龄大鼠心室提取物进行蛋白质免疫印迹分析，研究了几种参与各种心脏功能和细胞周期调控的蛋白激酶的表达模式。在出生后的第一年，环磷酸腺苷（cAMP）依赖性蛋白激酶的表达水平略有下降（20%），而环磷酸鸟苷（cGMP）依赖性蛋白激酶I未检测到变化。参与钙离子摄取到肌浆网的钙调蛋白依赖性蛋白激酶II增加了多达10倍。相反，蛋白激酶C-α和蛋白激酶C-ι的表达随年龄增长下降了77%。细胞周期蛋白依赖性蛋白激酶（CDK），如细胞周期进展所需的CDK1、CDK2、CDK4和CDK5，在10 - 20日龄后急剧下降至几乎检测不到的水平。相比之下，其他与CDK相关的激酶，如CDK8或Kkialre，分别没有显著变化或随年龄增长增加了50%。参与CDK调节的蛋白激酶，如CDK7和Wee1，其表达要么略有增加，要么没有显著变化。在心室提取物中检测到的所有蛋白质在分离的心肌细胞中也以等量被鉴定，并分析了它们在其他十种成年大鼠组织中的相对表达。
