Li Zhao-Bo, Lehar Mohamed, Nakagawa Hideki, Hoh Joseph Foon Yoong, Flint Paul W
Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
Otolaryngol Head Neck Surg. 2004 Feb;130(2):217-22. doi: 10.1016/j.otohns.2003.09.009.
This study examines the differential expression of myosin heavy chain (MyHC) components in human laryngeal muscle groups.
A battery of monospecific monoclonal antibodies in Western blots was used to determine expression of IIX, extraocular-specific (EOM), and IIB MyHCs for the thyroarytenoid (TA), vocalis (VOC), lateral cricoarytenoid (LCA), cricothyroid (CT), and posterior cricoarytenoid (PCA) muscles obtained from fresh cadaver specimens.
Fast IIX MyHC was only expressed in the TA, VOC, and LCA muscles. Fast IIA and slow MyHCs were expressed in all laryngeal muscles including the CT and PCA. The CT with mixed phonatory and respiratory function and the PCA with respiratory function did not express IIX MyHC. The 2 MyHC isoforms associated with the highest speeds of contraction in rat laryngeal muscle, namely, the EOM MyHC and IIB MyHC, were not detected in human laryngeal muscles. Novel MyHC bands were not detected in SDS-PAGE gels or Western blots using a broad specificity MyHC antibody.
The profile of MyHC expression in human laryngeal muscles differs from that observed in human extraocular and masticator muscles, and other mammalian species. Our data demonstrate that IIX MyHC expression is associated primarily with muscles affecting glottic closure and is absent in CT and PCA.
A higher percentage of IIX MyHC is expected to impart a high speed of shortening to the TA and LCA muscles. The absence of IIX MyHC in muscles with respiratory (PCA) and mixed respiratory/phonatory function (CT) further supports the inference that the physiologic difference between laryngeal muscles is reflected in the molecular composition of contractile protein.
本研究检测人喉肌群中肌球蛋白重链（MyHC）成分的差异表达。
采用一系列单特异性单克隆抗体进行蛋白质免疫印迹分析，以确定从新鲜尸体标本获取的甲杓肌（TA）、声带肌（VOC）、环杓侧肌（LCA）、环甲肌（CT）和环杓后肌（PCA）中IIX、眼外肌特异性（EOM）和IIB MyHC的表达情况。
快速IIX MyHC仅在TA、VOC和LCA肌肉中表达。快速IIA和慢速MyHC在包括CT和PCA在内的所有喉肌中均有表达。具有发声和呼吸混合功能的CT以及具有呼吸功能的PCA均未表达IIX MyHC。在人喉肌中未检测到与大鼠喉肌收缩速度最快相关的两种MyHC亚型，即EOM MyHC和IIB MyHC。在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）凝胶或使用广谱特异性MyHC抗体的蛋白质免疫印迹分析中均未检测到新的MyHC条带。
人喉肌中MyHC的表达模式不同于人眼外肌和咀嚼肌以及其他哺乳动物。我们的数据表明，IIX MyHC的表达主要与影响声门关闭的肌肉有关，在CT和PCA中不存在。
预计较高比例的IIX MyHC会使TA和LCA肌肉具有较高的缩短速度。具有呼吸功能（PCA）和呼吸/发声混合功能（CT）的肌肉中不存在IIX MyHC，这进一步支持了喉肌之间的生理差异反映在收缩蛋白分子组成中的推断。
