Fibre-type specific concentration of focal adhesion kinase at the sarcolemma: influence of fibre innervation and regeneration.
Fibre-type specific concentration of focal adhesion kinase at the sarcolemma: influence of fibre innervation and regeneration.
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发表时间：
2002-08
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通讯作者：
M. Flück;A. Ziemiecki;R. Billeter;M. Müntener
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作者：
M. Flück;A. Ziemiecki;R. Billeter;M. Müntener
在骨骼肌中，局灶黏附复合物（FACs）构成了肋隔的一部分，肋隔是一种肌膜蛋白复合物，能够实现力的横向转移并确保肌膜的稳定性。目前的研究测试了FACs的主要组装因子，局灶黏附激酶（FAK）在肌膜上的定位是否与已知的纤维类型（神经支配模式）和纤维再生对FACs的调节相似。免疫组化实验表明，FAK优先与正常大鼠比罗鱼肌（N-SOL）的I型（慢抽搐）和IIA型（快抽搐）纤维以及指长伸肌（N-EDL）的IIA型纤维的高比例（约74%）肌膜相关。相比之下，N-EDL中快速收缩的IIB型和I型纤维的比例较低（< 15%），表现出肌上皮FAK免疫反应性。慢抽搐大鼠SOL肌与快速EDL神经交叉再神经移植诱导纤维从慢到快转化，并导致I型和IIA型纤维的肌上皮FAK免疫反应性显著降低。将快速EDL移植到缓慢SOL床中，并通过SOL神经（T-EDL）对肌肉进行再生和再神经支配，导致新型I型和杂交I/II型纤维的肌层FAK免疫反应性显著增加，而“正常”IIA和IIB纤维的肌层FAK免疫反应性相应降低。相反，T-EDL肌小IIB纤维的肌上皮FAK免疫反应性增加。相应地，移植和再生的SOL（由快速EDL神经再神经支配）在（再生的）I型和IIA型纤维中保持了fak阳性肌膜的百分比。因此，FAK与肌膜的表达和关联受到(i)决定纤维类型的因素和（ii）纤维再生过程中的调节。我们的数据表明，肌上皮纤维的完整性取决于纤维类型，在肌纤维再生过程中，纤维纤维的周转量增加。
In skeletal muscles, focal adhesion complexes (FACs) form part of the costamere, a sarcolemmal protein complex that enables lateral transfer of forces and ensures the stability of the sarcolemma. The present investigation tested whether localisation of a major assembly factor of FACs, focal adhesion kinase (FAK), to the sarcolemma parallels the known modulation of FACs by fibre type (innervation pattern) and fibre regeneration. Immunohistochemical experiments indicated that FAK is preferentially associated with the sarcolemma in a high proportion (>74 %) of the (slow-twitch) type I and (fast-twitch) type IIA fibres in normal rat soleus (N-SOL) muscle and of the type IIA fibres in extensor digitorum longus (N-EDL) muscle. In contrast, a low proportion (<15 %) of fast-twitch type IIB and type I fibres in N-EDL showed sarcolemmal FAK immunoreactivity. Cross-reinnervation of slow-twitch rat SOL muscle with the fast EDL nerve induced slow-to-fast fibre transformation and led to a significant reduction in sarcolemmal FAK immunoreactivity in type I and type IIA fibres. Transplantation of the fast EDL into the slow SOL bed with regeneration and reinnervation of the muscle by the SOL nerve (T-EDL) caused a significant increase in sarcolemmal FAK immunoreactivity in new type I and hybrid I/II fibres and a corresponding reduction in sarcolemmal FAK immunoreactivity in 'normal' IIA and IIB fibres. Conversely, sarcolemmal FAK immunoreactivity in small IIB fibres of T-EDL muscle was increased. Correspondingly, the transplanted and regenerated SOL (reinnervated by the fast EDL nerve) maintained the percentage of FAK-positive sarcolemma in the (regenerated) type I and IIA fibres. Thus, the expression and association of FAK with the sarcolemma are regulated (i) by factors that determine the fibre type and (ii) during fibre regeneration. Our data suggest that the integrity of sarcolemmal FACs is dependent on the fibre type and that FAC turnover is increased during regeneration of muscle fibres.