Heterochromatin as a barrier to regeneration in the mouse cochlea

项目摘要/摘要 听力损失的主要原因是内耳内耳蜗感毛细胞的损伤。长期的 Segil实验室的目标是通过在体内再生丢失的感觉毛细胞来治疗人类耳聋 科尔蒂风琴。毛细胞再生的一个潜在策略是诱导长时间存活的支持细胞。 耳聋的内耳可以转化为新的功能毛细胞。 在围产期早期的小鼠中，毛细胞特异性转录因子Atoh1上调或Notch基因中断 支持细胞的侧向抑制，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，它具有细胞类型的特定特征，获得 在开发过程中。异染色质的表观遗传标记包括DNA甲基化、H3K9甲基化和 H3K27甲基化。 我的初步数据显示，阻止DNA甲基化足以延长 出生后成熟支持细胞的转分化潜能。此外，我已经证明了SC 随着它们从P1到P21的成熟，逐渐获得DNA甲基化。 该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H3K9甲基化抑制转分化所需的毛细胞基因调控网络。 目标1将描述出生后第1天和6周支持期间DNA甲基化的变化 细胞，以及检测DAPT阻断DNA后诱导的转分化反应 甲基化增加。目标2将检测出生后第1天和6周龄之间H3K9甲基化的变化 支持细胞，以及检测DAPT在阻断H3K9甲基化后诱导的转分化反应 收获。这两个目标将阐明异色特征是如何在后天成熟中传播的 支持细胞可能导致转分化潜能的丧失，这将引导未来 努力再生毛细胞，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.