小鼠和人类前庭椭圆囊斑中肌动蛋白环、肌动蛋白缆和异位毛细胞的神秘存在

文献信息

中文摘要

目的： 先前的研究表明，小鼠的椭圆囊包含一群肌动蛋白环，它们位于感觉上皮的下层，嵌入支持细胞的细胞核之间。尽管这些结构显示出与吞噬体的结构相似性，但其功能尚不清楚。本研究表征了正常、发育中和耳毒性损伤的小鼠椭圆囊以及成人人类椭圆囊感觉上皮中的肌动蛋白环、肌动蛋白缆和异位毛细胞。
方法： 用鬼笔环肽标记小鼠椭圆囊中的丝状肌动蛋白结构。对发育中、成熟和损伤的椭圆囊中的肌动蛋白环进行了表征和定量。还检查了正常和发育中椭圆囊中的上皮内肌动蛋白缆和异位毛细胞。对从成人人类获得的椭圆囊进行了类似的研究。
结果： 所有小鼠椭圆囊都含有肌动蛋白环，其数量不受毛细胞损伤的影响。耳毒性损伤的椭圆囊中存在的肌动蛋白环并未明显参与毛细胞碎片的吞噬作用。感觉上皮的下层还含有肌动蛋白缆，它们与“异位”毛细胞相关。尽管许多异位毛细胞似乎被肌动蛋白缆“刺穿”，但这些毛细胞没有明显的病理或变性迹象。肌动蛋白环、肌动蛋白缆和异位毛细胞也存在于新生小鼠的椭圆囊中，远在完整毛细胞群体产生之前。在成熟人类（2名男性，年龄30和67岁；两名女性，年龄27和75岁）的椭圆囊中也观察到了肌动蛋白环和缆。
结论： 肌动蛋白环存在于小鼠椭圆囊中，但不受毛细胞损伤的影响。发育数据表明，如果肌动蛋白环和缆与自发性毛细胞死亡有关，那么这些过程可能在椭圆囊完全成熟之前就开始了。目前，这些结构的起源和功能仍不清楚。

英文摘要

PURPOSE: Prior studies have shown that the utricles of mice contain a population of actin rings that reside in the lower stratum of the sensory epithelium, embedded among the nuclei of supporting cells. Although these structures display structural similarities with phagosomes, their function is not clear. The present study characterized actin rings, as well as actin cables and ectopic hair cells, in the sensory epithelia of normal, developing, and ototoxically-lesioned utricles of mice, and in utricles of adult humans.
METHODS: Filamentous actin structures in the utricles of mice were labeled with phalloidin. Actin rings in developing, mature and lesioned utricles were characterized and quantified. Intraepithelial actin cables and ectopic hair cells in normal and developing utricles were also examined. Similar studies were conducted on utricles obtained from adult humans.
RESULTS: All mouse utricles contained actin rings, whose number was unaffected by hair cell injury. Actin rings present in ototoxically-lesioned utricles did not clearly engage in the phagocytosis of hair cell debris. The lower stratum of the sensory epithelium also contained actin cables, which were associated with 'ectopic' hair cells. Although many ectopic hair cells appeared to be 'impaled' by the actin cables, those hair cells showed no clear signs of pathology or degeneration. Actin rings, actin cables and ectopic hair cells were also present in the utricles of neonatal mice, well before the full population of hair cells had been generated. Actin rings and cables were also observed in utricles of mature humans (2 males, ages 30 and 67; two females, ages 27 and 75).
CONCLUSIONS: Actin rings were present in mouse utricles, but were not affected by hair cell damage. Developmental data suggest that, if actin rings and cables are associated with spontaneous hair cell death, then such processes are likely to begin before the utricle has fully matured. At present, the origin and function of these structures remain unclear.