HETEROKARYONS OF CARDIAC MYOCYTES AND FIBROBLASTS REVEAL THE LACK OF DOMINANCE OF THE CARDIAC-MUSCLE PHENOTYPE
HETEROKARYONS OF CARDIAC MYOCYTES AND FIBROBLASTS REVEAL THE LACK OF DOMINANCE OF THE CARDIAC-MUSCLE PHENOTYPE
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DOI：
10.1128/mcb.14.6.4269
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发表时间：
1994-06-01
影响因子：
5.3
通讯作者：
CHIEN, KR
中科院分区：
文献类型：
--
作者：
EVANS, SM;TAI, LJ;CHIEN, KR
在过去的几年里，心脏决定基因的分子特征一直是一个难以捉摸的目标。在克隆骨骼肌决定因子MyoD之前，已经从骨骼肌表型在骨骼肌成纤维细胞异核体中占优势的观察推断出存在显性作用的骨骼肌决定因子（H. M.布劳湾K. Pavlath，E. C.哈德曼角，丘湖西伯利亚，S. G.韦伯斯特，S. C.米勒和D.韦伯斯特，科学230：758-766，1985）。在这些实验中，我们检查了心脏成纤维细胞异核体，以研究是否存在占主导地位的心脏决定因子。我们采用了一种新的实验方法，使用转基因小鼠的原代胚胎成纤维细胞作为测定成纤维细胞核内心脏启动子荧光素酶报告基因激活的手段。这种方法提供了一种潜在的遗传选择的一个显性积极因素，并可以推广到其他系统。我们已经研究了心脏谱系的三个标志物的表达：肌原纤维蛋白启动子（MLC 2），分泌蛋白（ANF）和转录因子（MEF 2）。MEF 2对心肌和骨骼肌细胞都具有特异性。我们的研究结果表明，在大多数异核体与心脏成纤维细胞核的比例相等，没有这些心脏标志物的表达，表明心脏表型是不占主导地位的胚胎成纤维细胞表型。与以前的结果与骨骼肌的区别是强调我们的结果与MEF 2，这是主要表达在骨骼肌成纤维细胞，但不是心脏成纤维细胞异核体，支持其在两种细胞类型的分歧调节。
The molecular characterization of a cardiac determination gene has been an elusive goal for the past several years. Prior to cloning of the skeletal muscle determination factor MyoD, the presence of a dominantly acting skeletal muscle determination factor had been inferred from the observation that the skeletal muscle phenotype was dominant in skeletal muscle-fibroblast heterokaryons (H. M. Blau, G. K. Pavlath, E. C. Hardeman, C.-P. Chiu, L. Siberstein, S. G. Webster, S. C. Miller, and D. Webster, Science 230:758-766, 1985). In these experiments, we have examined cardiac-fibroblast heterokaryons to investigate the existence of a dominantly acting cardiac determination factor. We have employed a novel experimental approach using primary embryonic fibroblasts from transgenic mice as a means of assaying for the activation of a cardiac promoter-luciferase reporter transgene within fibroblast nuclei. This approach provides a potential means of genetic selection for a dominantly acting positive factor and can be generalized to other systems. We have examined the expression of three markers of the cardiac lineage: a myofibrillar protein promoter (MLC2), a secreted protein (ANF), and a transcription factor (MEF2). MEF2 is specific to both cardiac and skeletal muscle cells. Our results indicate that in a majority of heterokaryons with an equal ratio of cardiac to fibroblast nuclei, none of these cardiac markers are expressed, indicating that the cardiac phenotype is not dominant over the embryonic fibroblast phenotype. The distinction from previous results with skeletal muscle is emphasized by our results with MEF2, which is dominantly expressed in skeletal muscle-fibroblast but not cardiac-fibroblast heterokaryons, supporting its divergent regulation in the two cell types.