Evidence for changes in beta- and gamma-actin proportions during inner ear hair cell life.
Evidence for changes in beta- and gamma-actin proportions during inner ear hair cell life.
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DOI：
10.1002/cm.21227
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发表时间：
2015-06
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影响因子：
--
通讯作者：
Andrade LR
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文献类型：
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作者：
Andrade LR
细胞质肌动蛋白亚型β（β-）和γ（γ-）在内耳毛细胞（HC）中发挥重要的生理作用。静纤毛由两种亚型的平行肌动蛋白丝构成，是对机械刺激如声音、重力和头部运动的反应细胞器。如先前在突变小鼠的遗传研究中所示，同种型比例的修饰影响静纤毛的功能。在此，小鼠的免疫金标记TEM研究表明，早在胚胎期16.5，β-和γ-肌动蛋白亚型就在静纤毛肌动蛋白丝、粘附连接和表皮板中共定位。金颗粒定量表明，在E16.5，γ-肌动蛋白比β-肌动蛋白多40%。相反，β-和γ-actin在耳蜗和前庭HC的静纤毛中同样集中。有趣的是，在22个月大的小鼠中，所有基于肌动蛋白的结构呈现的β-肌动蛋白几乎是γ-肌动蛋白的五倍，这表明γ-肌动蛋白在衰老过程中可能表达不足。这些数据提供了证据的动态修改的肌动蛋白异构体在静纤毛，表皮板和细胞连接在整个HC的生活。
Cytoplasmic actin isoforms beta (β-) and gamma (γ-) perform crucial physiological roles in inner ear hair cells (HC). The stereocilium, which is structured by parallel actin filaments composed of both isoforms, is the responsive organelle to mechanical stimuli such as sound, gravity and head movements. Modifications in isoform proportions affect the function of the stereocilia as previously shown in genetic studies of mutant mice. Here, immunogold labeling TEM studies in mice showed that both β- and γ-actin isoforms colocalize throughout stereocilia actin filaments, adherens junctions and cuticular plates as early as embryonic stage 16.5. Gold-particle quantification indicated that there was 40% more γ- actin than β-actin at E16.5. In contrast, β- and γ-actin were equally concentrated in adult stereocilia of cochlear and vestibular HC. Interestingly, all actin-based structures presented almost five-fold more β-actin than γ-actin in 22 month- old mice, suggesting that γ-actin is probably under-expressed during the aging process. These data provide evidence of dynamic modifications of the actin isoforms in stereocilia, cuticular plates and cell junctions during the whole HC life.