The area composita of adhering junctions connecting heart muscle cells of vertebrates. VII. The different types of lateral junctions between the special cardiomyocytes of the conduction system of ovine and bovine hearts
The area composita of adhering junctions connecting heart muscle cells of vertebrates. VII. The different types of lateral junctions between the special cardiomyocytes of the conduction system of ovine and bovine hearts
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DOI：
10.1016/j.ejcb.2009.11.025
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发表时间：
2010-05-01
影响因子：
6.6
通讯作者：
Franke, Werner W.
中科院分区：
文献类型：
--
作者：
Pieperhoff, Sebastian;Borrmann, Carola;Franke, Werner W.
哺乳动物心肌细胞出生后在工作心肌中的发育特征是两种黏附连接(AJ)，即桥粒和筋膜粘连(FA)，几乎完全移位到极间间盘(ID)区域，在那里它们聚集、融合和分子融合，形成扩展的杂交细胞间连接结构，区域组成(复合连接；AC)。利用免疫荧光和免疫电子显微镜，我们现在报道，传导系统的AJ结构，特别是牛和绵羊的浦肯野纤维细胞的结构是根本不同的。在这里，许多AJ保持与其他导电细胞的侧向连接。桥粒或桥粒样结仍可与FA连接区分开来，并可识别出第三种类型的AJs，它显示桥粒和FA蛋白的共存，即AC特征。这些结果，再加上其他细胞类型的细胞骨架标记物，如a-心脏肌动蛋白和结蛋白，支持传导细胞来自胚胎心肌细胞的概念，并在分化的早期被阻止。我们还发现，传导细胞具有扩展的质膜区域，其特征是具有桥粒特征的连接和蛋白质的比例特别高，达到50%或更多，导致迄今为止在非上皮细胞中描述的最高的桥粒蛋白堆积。讨论了这些连接与传导系统的形成、维持和功能的相关性，以及传导细胞的桥粒丰富区域是桥粒蛋白突变引起的功能障碍的最脆弱部位的结论。(C)2010年爱思唯尔股份有限公司。版权所有。
Postnatal development of mammalian cardiomyocytes in the working myocardium is characterized by a near-complete translocation of both kinds of adhering junctions (AJs), i.e. desmosomes and fasciae adhaerentes (FAs), to the polar intercalated disk (ID) regions where they cluster, fuse and molecularly amalgamate to extended hybrid intercellular junction structures, the area composita (composite junction; AC). Using immunofluorescence and immunoelectron microscopy we now report that the AJ structures of the conduction system, in particular those of the Purkinje fiber cells of cows and sheep are fundamentally different. Here the numerous AJs remain in lateral connections with other conductive cells. Desmosomal or desmosome-like junctions can still be distinguished from FA junctions, and a third type of AJs can be identified which shows colocalization of desmosomal and FA proteins, i.e. an AC character. These results, together with demonstrations of other cell type cytoskeletal markers such as a-cardiac actin and desmin, support the concept that conductive cells are derived from embryonal cardiomyocytes and are arrested at an early stage of differentiation. We also show that the conductive cells have extended plasma membrane regions characterized by an exceptionally high proportion of junctions with desmosomal character and proteins, amounting to 50% and more, resulting in the highest desmosome protein packing so far described in non-epithelial cells. The relevance of these junctions for the formation, maintenance and functions of the conductive system is discussed, together with the conclusion that the desmosome-rich regions of conductive cells are among the most vulnerable sites for functional disorders caused by desmosomal protein mutations. (c) 2010 Elsevier GmbH. All rights reserved.