Abundant expression of myosin heavy-chain IIB RNA in a subset of human masseter muscle fibres
Abundant expression of myosin heavy-chain IIB RNA in a subset of human masseter muscle fibres
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DOI：
10.1016/s0003-9969(01)00066-8
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发表时间：
2001-11-01
影响因子：
3
通讯作者：
Sciote, JJ
中科院分区：
文献类型：
--
作者：
Horton, MJ;Brandon, CA;Sciote, JJ
通过肌球蛋白重链（MyHC）亚型的ATP酶活性的组织化学染色，在人类骨骼肌中典型地证明了IIB型快纤维。然而，对哺乳动物IIB亚型特异性的单克隆抗体不能检测到人类的MyHC IIB蛋白，并且在组织化学鉴定的IIB纤维中发现了MyHC IIX RNA，这表明IIB蛋白亚型可能不存在于人类中;如果不是这样，表达多种亚型的下颌闭合肌可能是它们存在的候选者。ATP酶组织化学、免疫组化聚丙烯酰胺凝胶电泳和原位杂交。包括MyHC IIB特异性mRNA核糖核酸探针，用于比较人下颌闭合肌咬肌中MyHC同种型的组成和RNA表达。上肢肌肉三头肌、腹肌外斜肌和下肢肌肉腓肠肌。外斜肌含有混合物的组织化学定义的I型，IIA型和IIB型纤维分布在马赛克图案，而三头肌和腓肠肌只含有I型和IIA型纤维。典型的肢体肌纤维，MyHC I特异性mRNA探针与组织化学定义的I型纤维杂交，IIA特异性探针与IIA型纤维杂交，IIX特异性探针与IIB型纤维杂交。MyHC IIB mRNA探针仅与外斜肌样本中少数组织化学定义的I型纤维杂交：除了IIB信息外，这些纤维还表达MyHC I，IIA和IIX的RNA。MyHC IIB RNA在咬肌的组织化学和免疫组织化学IIA型纤维中大量表达，连同IIA和在某些情况下IIX的转录本，通过免疫组织化学、免疫印迹和电泳在外斜肌或咬肌的纤维和提取物中未检测到MyHC IIB蛋白。因此，在两种不同的人类骨骼肌纤维中发现了IIB RNA，而不是蛋白质。据信，这是第一次报告的大量表达的IIB mRNA在人的咬肌纤维的子集，但很少在肢体肌肉中证明。仅在外斜肌的a、e、v纤维中。这些发现为肌球蛋白基因表达的复杂性提供了进一步的证据，特别是在下颌闭合肌中。(C)2001爱思唯尔科技有限公司版权所有。
Type IIB fast fibres are typically demonstrated in human skeletal muscle by histochemical staining for the ATPase activity of myosin heavy-chain (MyHC) isoforms. However, the monoclonal antibody specific for the mammalian IIB isoform does not detect MyHC IIB protein in man and MyHC IIX RNA is found in histochemically identified IIB fibres, suggesting that the IIB protein isoform may not be present in man; if this is not so, jaw-closing muscles, which express a diversity of isoforms, are likely candidates for their presence. ATPase histochemistry, immunohistochemistry polyacrylamide gel electrophoresis and in situ hybridization. which included a MyHC IIB-specific mRNA riboprobe, were used to compare the composition and RNA expression of MyHC isoforms in a human jaw-closing muscle, the masseter. an upper limb muscle, the triceps, an abdominal muscle, the external oblique, and a lower limb muscle, the gastrocnemius. The external oblique contained a mixture of histochemically defined type I, IIA and IIB fibres distributed in a mosaic pattern, while the triceps and gastrocnemius contained only type I and IIA fibres. Typical of limb muscle fibres, the MyHC I-specific mRNA probes hybridized with histochemically defined type I fibres, the IIA-specific probes with type IIA fibres and the IIX-specific probes with type IIB fibres. The MyHC IIB mRNA probe hybridized only with a few histochemically defined type I fibres in the sample from the external oblique: in addition to this IIB message, these fibres also expressed RNAs for MyHC I, IIA and IIX. MyHC IIB RNA was abundantly expressed in histochemical and immunohistochemical type IIA fibres of the masseter, together with transcripts for IIA and in some cases IIX, No MyHC IIB protein was detected in fibres and extracts of either the external oblique or masseter by immunohistochemistry, immunoblotting and electrophoresis. Thus, IIB RNA, but not protein, was found in the fibres of two different human skeletal muscles. It is believed this is the first report of the substantial expression of IIB mRNA in man as demonstrated in a subset of masseter fibres, but rarely in limb muscle. and in only a fe,,v fibres of the external oblique. These findings provide further evidence for the complexity of myosin gene expression, especially in jaw-closing muscles. (C) 2001 Elsevier Science Ltd. All rights reserved.