Heterochromatin as a barrier to regeneration in the mouse cochlea

项目总结/摘要 听力损失的主要原因是内耳内耳蜗感觉毛细胞的损伤。长期 Segil实验室的目标是通过再生失去的感觉毛细胞来治疗人类耳聋。 Corti器官毛细胞再生的一个潜在策略是诱导存活的支持细胞在长时间内， 使内耳转分化成新的功能性毛细胞。 在围产期早期小鼠中，毛细胞特异性转录因子ATOH 1的上调或Notch的破坏， 支持细胞中的侧向抑制足以诱导转分化。然而，支持细胞迅速 在出生后一周内失去转分化的潜力。这种可塑性的丧失可能是由于 表观遗传成熟，其中异染色质在围产期支持细胞中的扩散抑制毛细胞， 转分化所需的特定基因调控网络。异染色质高度浓缩 与基因沉默相关的核DNA区域，并且它具有细胞类型特异性特征， 在发展过程中。异染色质的表观遗传学标记包括DNA甲基化、H3 K9甲基化和DNA甲基化。 H3 K27甲基化。 我的初步数据表明，阻断DNA甲基化足以延长肿瘤的窗口期。 转分化潜力的出生后成熟的支持细胞。此外，我已经表明，SC 随着它们从P1到P21的成熟，逐渐获得DNA甲基化。 本项目假设，出生后成熟的支持细胞获得异染色质相关的DNA 甲基化和H3 K9甲基化以抑制转分化所需的毛细胞基因调控网络。 目的1将描述出生后1天和6周龄之间DNA甲基化的变化， 细胞的Corti器官，以及测试DAPT诱导的转分化反应后，阻断DNA 甲基化增益。目的2将检测出生后第1天和6周龄之间H3 K9甲基化的变化 支持细胞，并测试阻断H3 K9甲基化后DAPT诱导的转分化反应 增益这两个目标将阐明异染色质特征在出生后成熟期的传播 支持细胞可能导致转分化潜能的丧失，这将指导未来的研究。 努力再生毛细胞和恢复听力。

PROJECT SUMMARY/ABSTRACT The main cause of hearing loss is damage of cochlear sensory hair cells within the inner ear. The long-term objective of the Segil lab is to treat human deafness through the regeneration of lost sensory hair cells within the organ of Corti. A potential strategy for hair cell regeneration is to induce surviving supporting cells in long- deafened inner ears to transdifferentiate into new functional hair cells. In early perinatal mice, upregulation of the hair-cell specific transcription factor ATOH1, or disruption of Notch lateral inhibition in supporting cells, is sufficient to induce transdifferentiation. However, supporting cells quickly lose the potential to transdifferentiate within one week after birth. The loss of this plasticity may be due to epigenetic maturation, wherein the spread of heterochromatin in perinatal supporting cells represses hair cell- specific gene regulatory networks required for transdifferentiation. Heterochromatin are highly condensed regions of nuclear DNA associated with gene silencing, and it has cell-type specific characteristics that acquires during development. Epigenetic marks of heterochromatin include DNA methylation, H3K9 methylation, and H3K27 methylation. My preliminary data shows that blocking DNA methylation is sufficient to prolong the window of transdifferentiation potential in postnatally maturing supporting cells. Additionally, I have shown that SCs gradually gain DNA methylation as they mature from P1 to P21. This project hypothesizes that postnatally maturing supporting cells gain heterochromatin-associated DNA methylation and H3K9 methylation to repress hair cell gene regulatory networks required for transdifferentiation. Aim 1 will characterize the changes in DNA methylation between postnatal day 1 and 6-week old supporting cells of the organ of Corti, as well as test the DAPT-induced transdifferentiation response after blocking DNA methylation gain. Aim 2 will examine the changes in H3K9 methylation between postnatal day 1 and 6-week old supporting cells, as well as test the DAPT-induced transdifferentiation response after blocking H3K9 methylation gain. These two aims will elucidate how the spread of heterochromatic features in postnatally maturing supporting cells may contribute to the loss of transdifferentiation potential, which will which will guide future endeavors to regenerate hair cells and restore hearing.