Developmental expression and differential cellular localization of obscurin and obscurin-associated kinase in cardiac muscle cells
Developmental expression and differential cellular localization of obscurin and obscurin-associated kinase in cardiac muscle cells
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DOI：
10.1002/jcb.21551
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发表时间：
2008-04-01
影响因子：
4
通讯作者：
Russell, Mark W.
中科院分区：
文献类型：
--
作者：
Borisov, Andrei B.;Raeker, Maide Oe.;Russell, Mark W.
暗蛋白和暗蛋白相关激酶是暗蛋白转录单位的两种产物，编码最近发现的巨大肌肉特异性蛋白暗蛋白。在这项研究中，我们表征了心肌细胞中暗蛋白和暗蛋白相关激酶的发育表达和细胞定位。我们克隆了鼠类暗蛋白相关激酶，发现它在心脏中大量表达为由 2.2 和 4.9 kb 序列编码的两种同种型。激酶的 2.2 kb 同种型比 4.9 kb 同种型的表达更为显着。自心脏发育的早期阶段以来，暗蛋白和激酶样结构域都逐渐上调。在心肌发生的早期阶段，Oscurin 相关激酶的表达水平高于 Obscurin。发育中的心脏中暗蛋白表达强度的增加与细胞分化的进展呈正相关，并且与心房相比，心室中的表达强度更高。这些数据得到了原代心肌细胞培养物实验结果的支持。在肌原纤维收缩装置组装过程中，暗蛋白定位从低分化细胞中的弱免疫阳性弥散模式转变为中 A 带和 Z 盘水平的强烈免疫标记的十字纹分布。在分裂的肌细胞中，与间期细胞不同，暗蛋白从分解的肌原纤维转位成与α-辅肌动蛋白免疫阳性聚集体分开的弥漫性颗粒状模式。暗蛋白相关激酶主要定位于细胞核，并在分化过程中逐渐掺入 Z 盘中。我们的结果表明，这两种新蛋白参与心脏发育高级阶段过渡期间心肌生成的进展。
Obscurin and obscurin-associated kinase are two products of the obscurin transcriptional unit that encodes a recently identified giant muscle-specific protein obscurin. in this study, we characterized the developmental expression and cellular localization of obscurin and obscurin-associated kinase in cardiac muscle cells. We cloned murine obscurin-associated kinase and found that it is abundantly expressed in the heart as two isotypes encoded by 2.2 and 4.9 kb sequences. The 2.2 kb isotype of the kinase was more prominently expressed than the 4.9 kb isotype. Both obscurin and the kinase-like domains were progressively upregulated since the early stages of cardiac development. Obscurin-associated kinase was expressed at higher levels than obscurin at early stages of cardiomyogenesis. Increasing intensity of obscurin expression in the developing heart positively correlated with progressive cell differentiation and was higher in the ventricles compared to the atria. These data were supported by the results of experiments with primary cardiac cell cultures. Obscurin localization changed from a weakly immunopositive diffuse pattern in poorly differentiated cells to an intensely immunolabeled cross-striated distribution at the level of mid-A-bands and Z-disks during the assembly of the myofibrillar contractile apparatus. In dividing myocytes, unlike the interphase cells, obscurin translocated from disassembling myofibrils into a diffuse granulated pattern segregated separately from alpha-actinin-immunopositive aggregates. Obscurin-associated kinase was localized mainly to cell nuclei with increasing incorporation into the Z-disks during differentiation. Our results suggest that these two novel proteins are involved in the progression of cardiac myogenesis during the transition to advanced stages of heart development.