DEVELOPMENT OF THE EXCITATION-CONTRACTION COUPLING APPARATUS IN SKELETAL-MUSCLE - ASSOCIATION OF SARCOPLASMIC-RETICULUM AND TRANSVERSE TUBULES WITH MYOFIBRILS
DEVELOPMENT OF THE EXCITATION-CONTRACTION COUPLING APPARATUS IN SKELETAL-MUSCLE - ASSOCIATION OF SARCOPLASMIC-RETICULUM AND TRANSVERSE TUBULES WITH MYOFIBRILS
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DOI：
10.1006/dbio.1993.1292
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发表时间：
1993-11-01
影响因子：
2.7
通讯作者：
FRANZINIARMSTRONG, C
中科院分区：
文献类型：
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作者：
FLUCHER, BE;TAKEKURA, H;FRANZINIARMSTRONG, C
横纹肌中高度规则的膜系统和蛋白质组织的形成和维持需要特定的膜-膜和膜-细胞骨架相互作用。观察了孵化12天(E12天)至21天(E21天)鸡胚胎腓肠肌纤维中T管和肌浆网(SR)的发育，特别注意了T管和肌浆网之间的关系以及与肌原纤维的关系。用荧光脂质类似物DiIC16[3]标记活体和固定肌肉的外膜(质膜和横管)或内部SR。E14时纤维内可见短膜内陷，E15时纤维外周出现纵向T管。在胚胎16岁时，充满整个纤维直径的复杂的T管网络突然发育起来。相反，SR在最早的观测阶段(E12)很丰富，并在I-Z-I带形成规则间隔的交叉条纹。这与电子显微镜下看到的Z盘周围有一层特殊的光滑膜堆积相对应。虽然SR与纤维周围新形成的肌原纤维特异性地相关，但早期T管的分布与SR或肌原纤维几乎没有特定的关系。然而，电子显微镜显示T管和SR之间的连接是在这一时期形成的(Takekura和Franzini-Armstrong，提交发表)。直到孵化前后，三联体开始重组到它们成熟的位置，即A-I交界处，连接才与肌原纤维获得特定的关系。这些发现表明，在肌节中T管和SR的组织中有三个关键事件：(1)早期的SR/Z线相互作用独立于T管；(2)SR/T管相互作用形成三联体连接，独立于肌纤维；以及(3)连接复合体与A-I交界处的肌纤维的晚期结合。
The formation and maintenance of the highly regular organization of membrane systems and proteins in striated muscle require specific membrane-membrane and membrane-cytoskeleton interactions. The development of T-tubules and sarcoplasmic reticulum (SR) was followed in gastrocnemius muscle fibers from chicken embryos between 12 days (E12) and 21 days (E21) of incubation, with particular attention to their relationship with one another and with the myofibrils. The fluorescent lipid analog DiIC16[3] was used to label either the external membranes (plasmalemma and transverse (T)-tubules) or the internal SR in living and fixed muscle. Short membrane invaginations can first be seen in fibers at E14, and at E15 longitudinal T-tubules appear in the periphery of the fibers. A complex network of T-tubules filling the whole fiber diameter develops suddenly at E16. In contrast, SR is abundant at the earliest observed stage (E12) and forms regularly spaced cross striations located at the I-Z-I bands. These correspond to a specific accumulation of smooth membranes around the Z-discs seen in electron micrographs. While SR is specifically associated with the newly formed myofibrils in the periphery of the fibers, the disposition of early T-tubules shows little specific relationship to either SR or the myofibrils. However, electron microscopy shows that junctions between T-tubules and SR are formed during this period (Takekura and Franzini-Armstrong, submitted for publication). Junctions do not acquire a specific relation to the myofibrils until around hatching when triads begin to reorganize into their mature location, the A-I junction. These findings indicate three key events in the organization of T-tubules and SR in the sarcomeres: (1) early SR/Z-line interactions independent of T-tubules; (2) SR/T-tubule interactions to form the triad junctions, independent from the myofibrils; and (3) the late association of the junctional complexes with the myofibrils at the A-I border.