Fiber type-specific immunostaining of the Na+,K+-ATPase subunit isoforms in skeletal muscle: age-associated differential changes.
Fiber type-specific immunostaining of the Na+,K+-ATPase subunit isoforms in skeletal muscle: age-associated differential changes.
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骨骼肌中 Na,K-ATP 酶亚基亚型的纤维类型特异性免疫染色：年龄相关的差异变化。
DOI：
10.1016/j.bbadis.2006.08.006
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Ng,Yuk-Chow
中科院分区：
文献类型：
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作者：
Zhang,Lianqin;Morris,KeithJ;Ng,Yuk-Chow
Na+，K+- atp酶α和β亚基亚型在大鼠骨骼肌中的表达及其与年龄相关的变化已被证明是肌肉类型依赖性的。这些发现背后的细胞基础尚不完全清楚。在这项研究中，我们检测了Na+，K+- atp酶异构体在不同纤维类型中的表达，并验证了随着年龄的增长，不同纤维中异构体表达变化的假设。我们利用免疫组织化学技术来检测亚基异构体在单个纤维水平上的表达。对白色腓肠肌（GW）和红色腓肠肌（GR）的亚基异构体进行免疫荧光染色，发现在肌层膜上染色占优势。与6月龄大鼠骨骼肌相比，α1、β1和β3亚基异构体水平明显升高，α2和β2水平明显降低。此外，我们发现在幼龄和老年大鼠组织切片中α1、α2、β1和β2亚型的染色模式不同。进行肌纤维分型以将染色模式与特定纤维类型相关联。幼龄大鼠骨骼肌中α1和α2异构体的染色基本均匀分布在GW和GR的纤维中，但GR的慢缩氧化型I型纤维中α1的染色水平较高，而在主要氧化纤维和主要糖酵解纤维中β1和β2异构体的染色几乎是相互排斥的。随着年龄的增长，白色腓肠肌IIB型纤维中α2和β2的纤维型选择性质的减少，IIB型纤维中β1和IID型纤维中β2的纤维型选择性质的增加。这些结果在单个纤维水平上为肌群中Na+，K+- atp酶亚基异构体的差异表达提供了细胞基础。数据进一步表明，与年龄相关的亚基亚型表达变化既发生在特定纤维类型中，也发生在跨纤维类型中。由于亚基异构体的不同生化特性，这些变化为我们理解骨骼肌中na泵随年龄增长的适应性增加了另一层复杂性。
The expression of the Na+,K+-ATPase α and β subunit isoforms in rat skeletal muscle and its age-associated changes have been shown to be muscle-type dependent. The cellular basis underlying these findings is not completely understood. In this study, we examined the expression of Na+,K+-ATPase isoforms in individual fiber types and tested the hypothesis that, with age, the changes in the expression of the isoforms differ among individual fibers. We utilized immunohistochemical techniques to examine the expression of the subunit isoforms at the individual fiber levels. Immunofluorescence staining of the subunit isoforms in both white gastrocnemius (GW) and red gastrocnemius (GR) revealed a predominance of staining on the sarcolemmal membrane. Compared to the skeletal muscle of 6-month-old rats, there were substantial increases in the levels of α1, β1, and β3 subunit isoforms, and decreases in the levels of α2 and β2 in 30-month-old rats. In addition, we found distinct patterns of staining for the α1, α2, β1, and β2 isoforms in tissue sections from young and aged rats. Muscle fiber-typing was performed to correlate the pattern of staining with specific fiber types. Staining for α1 and α2 isoforms in the skeletal muscle of young rats was generally evenly distributed among the fibers of GW and GR, with the exception of higher α1 levels in slow-twitch oxidative Type I fibers of GR. By contrast, staining for the β1 and β2 isoforms in the mostly oxidative fibers and the mostly glycolytic fibers, respectively, was almost mutually exclusive. With age, there was a fiber-type selective qualitative decrease of α2 and β2 in Type IIB fibers, and increase of β1 in Type IIB fibers and β2 in Type IID fibers of white gastrocnemius. These results provide, at the individual fiber level, a cellular basis for the differential expression of the Na+,K+-ATPase subunit isoforms in the muscle groups. The data further indicate that the aged-associated changes in expression of the subunit isoforms occur in both a fiber-type specific as well as an across fiber-type manner. Because of the differing biochemical properties of the subunit isoforms, these changes add another layer of complexity in our understanding of the adaptation of the Na-pump in skeletal muscle with advancing age.