Genetic control of cellular conversion in the mature cochlea

 描述（由申请人提供）：成熟耳蜗中感觉毛细胞的再生是一个主要的治疗挑战。Atoh 1是毛细胞发育的重要转录因子，能够诱导出生后小鼠耳蜗周围支持细胞形成毛细胞。然而，由Atoh 1再生的毛细胞太少，不完全成熟，最重要的是，在出生后的耳蜗中表现出年龄依赖性下降。目前尚不清楚哪些分子和信号通路调节Atoh 1介导的支持细胞转化为毛细胞在体内成熟的耳蜗。我们的初步研究结果表明，在支持细胞中，对其他因子的遗传操作与Atoh 1激活相结合，可以将其转化为体内成熟耳蜗中的毛细胞。值得注意的是，我们还发现，这三个因素之一本身可以在体内将成熟耳蜗中的支持细胞转化为毛细胞。此外，我们已经建立了新再生的毛细胞的RNA谱，确定转录因子和信号分子，可能参与调控Atoh 1介导的毛细胞再生在成熟的耳蜗。这些新的和令人兴奋的发现使我们测试这些分子的组合遗传操作是否会增加体内成熟耳蜗中支持细胞向毛细胞转化的效率，并确定这种转化的分子机制。支持细胞直接转化为毛细胞是毛细胞再生和听力功能恢复的关键初始步骤。我们的方法在体内产生新的毛细胞方面非常富有成效-以前在出生后的耳蜗中，现在在成熟的耳蜗中。例如，我们已经实现了支持细胞向毛细胞的转化率高达20%，与其他再生系统（如成人胰腺、心脏和CNS）中的转化率相当。我们提出的研究将揭示1）成熟哺乳动物耳蜗毛细胞再生的新机制和2）未来临床听力恢复的新治疗靶点。

 DESCRIPTION (provided by applicant): Regeneration of sensory hair cells in the mature cochlea is a major therapeutic challenge. Atoh1, a transcription factor important for hair cell development, can induce hair cell formation from surrounding supporting cells in postnatal murine cochleae. However, hair cells regenerated by Atoh1 are too few, are incompletely mature, and most importantly, exhibit age-dependent decline in the postnatal cochlea. It remains unclear which molecules and signaling pathways modulate Atoh1-mediated conversion of supporting cells to hair cells in the mature cochlea in vivo. Our preliminary results demonstrate that genetic manipulation of additional factors, in conjunction with Atoh1 activation, in supporting cells can convert them to hair cells in the mature cochlea in vivo. Remarkably, we also showed that one of the three factors by itself can convert supporting cells to hair cells in te mature cochlea in vivo. Moreover, we have established RNA profiles of newly regenerated hair cells that identify transcription factors and signaling molecules that are likely involved in regulation of Atoh1-mediated hair cell regeneration in the mature cochlea. These novel and exciting findings led us to test whether combined genetic manipulation of these molecules would increase the efficiency of conversion of supporting cells to hair cells in the mature cochlea in vivo and determine the molecular mechanisms of such conversion. Direct conversion of supporting cells to hair cells is a key initial step toward hair cell regeneration and functional restoration of hearing. Our approach has been highly fruitful in generating new hair cells in vivo―both previously, in the postnatal cochlea, and now in the mature cochlea. For example, we have achieved a conversion rate of supporting cells to hair cells as high as 20% in vivo, a rate comparable to those in other regenerative systems such as adult pancreas, heart, and CNS. Our proposed studies will reveal 1) novel mechanisms of hair cell regeneration in the mature mammalian cochlea and 2) novel therapeutic targets for future clinical restoration of hearing.