Notch signaling pathways in auditory support cell differentiation and maintenance

Notch信号通路在听觉支持细胞分化和维持中的作用

• 批准号: 8233258
• 负责人: ANGELIKA DOETZLHOFER
• 金额: $ 41万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8233258
• 关键词: Ablation; Address; Adopted; Adult; Aminoglycosides; Auditory; Birds; Cell Communication; Cell Differentiation process; Cell Lineage; Cell Maintenance; Cell division; Cells; Cochlea; Cues; Data; Development; Diuretics; Epithelial Cells; Future; Gene Expression; Genetic Recombination; Global Change; Goals; Hair Cells; Health; Human; In Situ Hybridization; Injection of therapeutic agent; Knowledge; Label; Lead; Light; Maintenance; Mammals; Mediating; Molecular; Mus; Mutant Strains Mice; Natural regeneration; Neuraxis; Neuroglia; Notch Signaling Pathway; Null Lymphocytes; Organ; Organ of Corti; Pathway interactions; Peripheral; Phenotype; Play; Replacement Therapy; Reporter; Role; Sensory; Sensory Hair; Signal Pathway; Signal Transduction; Staining method; Stains; Supporting Cell; Tamoxifen; Testing; Time; Vertebrates; Work; base; cell injury; cell type; deafness; equilibration disorder; hair cell regeneration; high throughput analysis; improved; inhibitor/antagonist; insight; notch protein; novel; prevent; progenitor; programs; public health relevance; receptor; research study; response; secretase

DESCRIPTION (provided by applicant): In humans and other mammalian species, damage to mechano-sensory hair cells is irreversible, leading to deafness and balance disorders. Remarkably, non-mammalian vertebrates regenerate lost hair cells. In birds, supporting cells have been shown to replace lost hair cells by mechanisms involving either cell division or direct trans-differentiation. In the mammalian auditory sensory organ, supporting cells do not regenerate lost hair cells. Strikingly, our findings suggest that mammalian supporting cells retain the intrinsic ability to function as hair cell progenitors, but their plasticity to regenerate hair cells is actively suppressed by external inhibitory cues. Our long-term goal is to utilize the latent plasticity of supporting cells to develop supporting cell based hair cell replacement strategies. To attain this goal, it is vital to improve our knowledge of the molecular programs active in developing and in mature supporting cells. We reason that to "reprogram" and induce de- differentiation of supporting cells and consequently trans-differentiation of supporting cells into hair cells, we first have to understand the signals that control differentiation and maintenance in the supporting cell lineage. The goal of this proposal is to determine if the Notch signaling pathway, an evolutionary ancient and highly conserved cell-to-cell communication mechanism, functions in supporting cell differentiation and cell maintenance. In Specific Aim 1 of our proposal, we will test if Notch signaling plays an instructive role in supporting cell differentiation. We will test if induction of an activated form of the Notch1 receptor is sufficient to induce supporting cell fate and whether inhibition of Notch signaling with 3-secretase inhibitors effects the onset and progression of supporting cell differentiation. In Specific Aim 2 of our proposal, we will ablate Rbpj, a core component of the canonical Notch signaling pathway, in supporting cells to address if Notch signaling is required for supporting cell maintenance in the intact and hair cell damaged cochlea. To do so we will employ Rbpj conditional mouse mutants in combination with tamoxifen inducible CreERT lines. We anticipate that this analysis will provide valuable insight into the molecular mechanisms that drive supporting cell differentiation and elucidate the function of Notch signaling in supporting cell maintenance in the adult cochlea. In parallel, we will address a longstanding question-"does persistence of Notch signaling in the hair cell damaged cochlea underlie the lack of hair cell regeneration in mammals?" Addressing this question is relevant to human health as inhibiting Notch signaling using 3-secretase inhibitors in mature cochlea could provide a means for restoring a latent capacity to regenerate hair cells. PUBLIC HEALTH RELEVANCE: It is believed that lack of hair cell regeneration in mammals is due to an inability of neighboring supporting cells to regenerate damaged hair cells. In our proposal, we will characterize the molecular mechanisms instructing supporting cell differentiation and maintenance to elucidate why supporting cells fail to de-differentiate and regenerate lost hair cells. We believe that our findings will shed light on the molecular machinery that restrict hair cell regeneration and could provide new targets for future hair cell replacement therapies.

描述(申请人提供)：在人类和其他哺乳动物物种中，机械感觉毛细胞的损伤是不可逆的，会导致耳聋和平衡障碍。值得注意的是，非哺乳动物脊椎动物会再生丢失的毛细胞。在鸟类中，支持细胞已被证明通过涉及细胞分裂或直接转分化的机制来取代丢失的毛细胞。在哺乳动物的听觉感觉器官中，支持细胞不会再生丢失的毛细胞。值得注意的是，我们的发现表明，哺乳动物的支持细胞保留了作为毛细胞前体细胞的内在能力，但它们再生毛细胞的可塑性受到外部抑制信号的积极抑制。我们的长期目标是利用支持细胞的潜在可塑性来开发基于支持细胞的毛细胞替代策略。为了实现这一目标，提高我们对活跃在发育和成熟支持细胞中的分子程序的了解是至关重要的。我们认为，要“重新编程”并诱导支持细胞去分化，从而将支持细胞转分化为毛细胞，我们首先必须了解控制支持细胞谱系分化和维持的信号。这项建议的目的是确定Notch信号通路是否在支持细胞分化和细胞维持方面发挥作用。Notch信号通路是一种进化的古老且高度保守的细胞间通讯机制。在我们建议的具体目标1中，我们将测试Notch信号在支持细胞分化方面是否起到指导作用。我们将测试诱导激活形式的Notch1受体是否足以诱导支持细胞的命运，以及用3-分泌酶抑制剂抑制Notch信号是否影响支持细胞分化的开始和进展。在我们提案的具体目标2中，我们将去除规范的Notch信号通路的核心组件Rbpj，以支持细胞，以解决是否需要Notch信号来支持完整和毛细胞受损的耳蜗中的细胞维持。为此，我们将使用Rbpj条件突变小鼠与他莫昔芬诱导的CRERT系相结合。我们期待这一分析将为推动支持细胞分化的分子机制提供有价值的见解，并阐明Notch信号在支持成年耳蜗细胞维持中的作用。同时，我们将解决一个长期存在的问题--“在毛细胞受损的耳蜗中，Notch信号的持续存在是哺乳动物毛细胞再生不足的原因吗？”解决这个问题与人类健康有关，因为在成熟的耳蜗中使用3-分泌酶抑制剂抑制Notch信号可以提供一种恢复再生毛细胞的潜在能力的方法。 与公共卫生相关：据认为，哺乳动物毛细胞再生的缺乏是由于邻近的支持细胞无法再生受损的毛细胞。在我们的提案中，我们将描述指导支持细胞分化和维持的分子机制，以阐明为什么支持细胞无法去分化和再生丢失的毛细胞。我们相信，我们的发现将阐明限制毛细胞再生的分子机制，并可能为未来的毛细胞替代疗法提供新的靶点。