In Vivo Cochlear Hair Cell Generation and Survival by Coactivation of β-Catenin and Atoh1
In Vivo Cochlear Hair Cell Generation and Survival by Coactivation of β-Catenin and Atoh1
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DOI：
10.1523/jneurosci.0967-15.2015
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发表时间：
2015-07-29
影响因子：
5.3
通讯作者：
Zuo, Jian
中科院分区：
文献类型：
--
作者：
Kuo, Bryan R.;Baldwin, Emily M.;Zuo, Jian
哺乳动物耳蜗表现出最小的自发再生，感觉毛细胞（HC）的损失导致永久性听力损失。在非哺乳类脊椎动物中，通过周围支持细胞（SC）的增殖和分化发生自发HC再生。在出生后的哺乳动物耳蜗在体内的HC再生仍然受到小HC数量和随后的再生HC死亡的限制。在这里，我们描述了在小鼠耳蜗中比以前报道的多10倍的新HC的体内生成，其中大部分存活到成年。我们通过在新生儿Lgr 5（+）细胞（出生后小鼠耳蜗的假定SC和HC祖细胞）中结合β-连环蛋白（一种典型的Wnt激活剂）的组成型活性形式的表达和Atoh 1（一种HC命运决定因子）的异位表达来实现这一点，并发现增殖和分化的协同增加。新的HC主要位于内源性内部HC附近，表达早期HC分化标志物，尽管突触前和突触后标志物不完全对齐，但仍受神经支配。令人惊讶的是，遗传追踪显示，只有位于内部HC内侧的Lgr 5（+）细胞亚群对这种组合做出反应，突出了Lgr 5（+）细胞之间存在的先前未知的异质性。总之，我们的数据表明，β-连环蛋白和Atoh 1介导的新生儿耳蜗Lgr 5（+）细胞的一个子集的增殖和分化的协同效应，从而克服了主要的限制，HC再生在出生后的小鼠耳蜗在体内。这些结果为听力恢复的组合疗法提供了基础。
The mammalian cochlea exhibit minimal spontaneous regeneration, and loss of sensory hair cells (HCs) results in permanent hearing loss. In nonmammalian vertebrates, spontaneous HC regeneration occurs through both proliferation and differentiation of surrounding supporting cells (SCs). HC regeneration in postnatal mammalian cochleae in vivo remains limited by the small HC number and subsequent death of regenerated HCs. Here, we describe in vivo generation of 10-fold more new HCs in the mouse cochlea than previously reported, most of which survive to adulthood. We achieved this by combining the expression of a constitutively active form of beta-catenin (a canonical Wnt activator) with ectopic expression of Atoh1 (a HC fate determination factor) in neonatal Lgr5(+) cells (the presumed SC and HC progenitors of the postnatal mouse cochlea), and discovered synergistic increases in proliferation and differentiation. The new HCs were predominantly located near the endogenous inner HCs, expressed early HC differentiation markers, and were innervated despite incomplete alignment of presynaptic and postsynaptic markers. Surprisingly, genetic tracing revealed that only a subset of Lgr5(+) cells that lie medial to the inner HCs respond to this combination, highlighting a previously unknown heterogeneity that exists among Lgr5(+) cells. Together, our data indicate that beta-catenin and Atoh1 mediate synergistic effects on both proliferation and differentiation of a subset of neonatal cochlear Lgr5(+) cells, thus overcoming major limitations of HC regeneration in postnatal mouse cochleae in vivo. These results provide a basis for combinatorial therapeutics for hearing restoration.