Genetic control of cellular conversion in the mature cochlea

 描述(由申请人提供)：在成熟的耳蜗内再生感觉毛细胞是一个主要的治疗挑战。Atoh1是一种毛细胞发育的重要转录因子，可在出生后的小鼠耳蜗内诱导周围支持细胞形成毛细胞。然而，Atoh1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相关性的下降。目前还不清楚哪些分子和信号通路在体内调节了Atoh1介导的支持细胞向毛细胞的转化。我们的初步结果表明，在支持细胞中，通过对其他因素的遗传操作，结合Atoh1的激活，可以在体内将它们转化为成熟耳蜗中的毛细胞。值得注意的是，我们还发现，这三个因素中的一个因素本身就可以在体内将TE成熟耳蜗中的支持细胞转化为毛细胞。此外，我们还建立了新再生毛细胞的RNA图谱，确定了可能参与调控Atoh1介导的成熟耳蜗毛细胞再生的转录因子和信号分子。这些新的和令人兴奋的发现引导我们测试这些分子的联合遗传操作是否会提高体内成熟耳蜗内支持细胞转化为毛细胞的效率，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第一步。我们的方法在体内产生新的毛细胞方面取得了非常丰硕的成果--无论是以前在出生后的耳蜗处，还是现在在成熟的耳蜗处。例如，我们在体内实现了支持细胞到毛细胞的转化率高达20%，这一比率可与成人胰腺、心脏和中枢神经系统等其他再生系统的转化率相媲美。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，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.