Epigenetic regulation in the postnatal mammalian inner ear

描述（由申请人提供）：细胞重编程为治疗、疾病研究和发育过程提供了巨大的潜力。然而，通过特定转录因子的异位表达直接重编程是一个缓慢且低效的过程，大多数细胞不能重编程。在听觉领域，异位表达 转录因子如Atoh 1已被用于将哺乳动物支持细胞转化为表达许多内源性毛细胞标志物的细胞。然而，将支持细胞转化为毛细胞的重编程过程可能不仅仅是遗传转化，还有表观遗传转化。使用诱导多能干细胞（iPSC）的研究表明，它们保留了其体细胞起源的表观遗传记忆。iPSC保留的表观遗传记忆可以干扰它们分化成其他细胞类型的潜力。此外，与来自幼年小鼠的iPSC相比，来自老年小鼠的iPSC具有降低的重编程潜力。虽然转录因子（Atoh 1）的异位表达可以将新生儿支持细胞转化为毛细胞样细胞，但出生后后期细胞可塑性的丧失可能会在很大程度上影响该方法的临床应用。据推测，支持细胞到毛细胞的最佳重编程将需要完整的表观遗传重编程到内源性毛细胞的表观遗传重编程，但目前的技术尚未开发用于发生完整的表观遗传重编程。然而，表观遗传疗法如组蛋白脱乙酰酶抑制剂、组蛋白甲基转移酶抑制剂和DNA甲基化抑制剂已用于iPSC以提高重编程效率。需要进一步分析以更好地了解哺乳动物毛细胞再生是否需要表观遗传重编程，以及表观遗传疗法是否可能在毛细胞再生中发挥作用。这项研究的长期目标是更好地了解出生后内耳发育过程中发生的表观遗传修饰，并最终帮助增加成熟哺乳动物内耳的细胞可塑性。因此，我们提出了以下中心假设：在哺乳动物内耳新生儿发育过程中的表观遗传修饰导致细胞可塑性丧失，使用表观遗传疗法将增加支持细胞成为毛细胞的转分化潜力。为了验证这一假设，我们提出了以下具体目标：目标1。测试表观遗传因素是否在小鼠内耳新生儿发育过程中差异表达;目的2。测试DNA甲基化是否在出生后发育过程中或响应于异位Atoh 1表达而在小鼠内耳中被修饰;以及目的3。测试表观遗传疗法是否影响小鼠内耳毛细胞再生

DESCRIPTION (provided by applicant): Cellular reprogramming offers tremendous potential for therapeutics, disease studies, and developmental processes. However, direct reprogramming through ectopic expression of defined transcription factors is a slow and inefficient process with most cells failing to reprogram. In the auditory field, ectopic expression of transcription factors such as Atoh1 has been used to convert mammalian supporting cells into cells that express many endogenous hair cell markers. However, the reprogramming process of transforming supporting cells into hair cells may not be solely about genetic transformation, but also epigenetic transformation. Studies using induced pluripotent stem cells (iPSCs) have shown that they retain the epigenetic memory of their somatic cell of origin. The epigenetic memory retained by iPSCs can interfere with their potential for differentiation into other cell types. Additionally, iPSCs derived from aged mice have a decreased potential for reprograming compared to iPSCs derived from juvenile mice. Although, ectopic expression of transcription factors (Atoh1) can convert neonatal supporting cells into hair cell-like cells, loss of cellular plasticity at later postnatal ages could largely impact clinical application of this method. Presumably, the optimal reprogramming of supporting cells to hair cells would require complete epigenetic reprogramming to that of an endogenous hair cell, but current techniques have not yet been developed for complete epigenetic reprogramming to occur. However, epigenetic therapeutics such as histone deacetylase inhibitors, histone methyltransferase inhibitors, and DNA methylation inhibitors have been used on iPSCs to increase reprogramming efficiency. Further analysis is needed to better understand whether epigenetic reprogramming is required for mammalian hair cell regeneration and whether epigenetic therapeutics may have a role in hair cell regeneration. The long term goal of this research is to better understand the epigenetic modifications that occur during postnatal inner ear development, and ultimately to help increase cellular plasticity in the mature mammalian inner ear. Thus, we propose the following central hypothesis: Epigenetic modifications during neonatal development in the mammalian inner ear cause a loss in cellular plasticity and use of epigenetic therapeutics will increase the trans-differentiation potential of supporting cells to become hair cells. To test this hypothesis, we propose the following specific aims: Aim 1. Test whether epigenetic factors are differentially expressed during neonatal development in the mouse inner ear; Aim 2. Test whether DNA methylation is modified in the mouse inner ear during postnatal development or in response to ectopic Atoh1 expression; and Aim 3. Test whether epigenetic therapeutics affect hair cell regeneration in the mouse inner ear