Diphtheria Toxin-Induced Cell Death Triggers Wnt-Dependent Hair Cell Regeneration in Neonatal Mice
Diphtheria Toxin-Induced Cell Death Triggers Wnt-Dependent Hair Cell Regeneration in Neonatal Mice
复制标题
DOI：
10.1523/jneurosci.2447-15.2016
复制
发表时间：
2016-09-07
影响因子：
5.3
通讯作者：
Shi, Fuxin
中科院分区：
文献类型：
--
作者：
Hu, Lingxiang;Lu, Jingrong;Shi, Fuxin
耳蜗毛细胞（HC）是对声音做出反应的感觉细胞，在成年哺乳动物中受损后不会再生，它们的损失是耳聋的主要原因。在这里，我们表明，HC再生在新生小鼠耳自发发生时，原始细胞被消融与白喉毒素（DT）的耳朵，已被改造为过表达DT受体的治疗，但不能检测到当HC被消融在体内的氨基糖苷类抗生素新霉素。DT损伤后，多种Wnt（Wnt 1、Wnt 2、Wnt 2b、Wnt 4、Wnt 5a、Wnt 7 b、Wnt 9a、Wnt 9 b和Wnt 11）和Wnt通路组分Krm 2均上调。DT损伤耳蜗的毛细胞和支持细胞的核β-连环蛋白上调。Wnt的药理学抑制降低了自发再生，证实了Wnt信号传导在HC再生中的作用。Notch信号传导的抑制进一步增强了自发发生的支持细胞增殖和HC分化。在新霉素耳中新HC的缺乏与较不稳健的Wnt途径活化相关，但是经受新霉素处理的耳在随后的β-连环蛋白的强制上调之后仍然显示增加的细胞分裂和HC分化。这些研究表明，首先，Wnt信号在再生中起着关键作用，其次，新生儿耳蜗损伤的再生反应的结果是通过达到Wnt信号的阈值水平而不是完全缺失或存在来确定的。
Cochlear hair cells (HCs), the sensory cells that respond to sound, do not regenerate after damage in adult mammals, and their loss is a major cause of deafness. Here we show that HC regeneration in newborn mouse ears occurred spontaneously when the original cells were ablated by treatment with diphtheria toxin (DT) in ears that had been engineered to overexpress the DT receptor, but was not detectable when HCs were ablated in vivo by the aminoglycoside antibiotic neomycin. A variety of Wnts (Wnt1, Wnt2, Wnt2b, Wnt4, Wnt5a, Wnt7b, Wnt9a, Wnt9b, and Wnt11) and Wnt pathway component Krm2 were upregulated after DT damage. Nuclear beta-catenin was upregulated in HCs and supporting cells of the DT-damaged cochlea. Pharmacological inhibition of Wnt decreased spontaneous regeneration, confirming a role of Wnt signaling in HC regeneration. Inhibition of Notch signaling further potentiated supporting cell proliferation and HC differentiation that occurred spontaneously. The absence of new HCs in the neomycin ears was correlated to less robust Wnt pathway activation, but the ears subjected to neomycin treatment nonetheless showed increased cell division and HC differentiation after subsequent forced upregulation of beta-catenin. These studies suggest, first, that Wnt signaling plays a key role in regeneration, and, second, that the outcome of a regenerative response to damage in the newborn cochlea is determined by reaching a threshold level of Wnt signaling rather than its complete absence or presence.