Hedgehog signaling in taste cell maintenance and regeneration

 描述(由申请人提供)：味觉有助于区分那些摄取维持我们生存的物质和其他损害我们健康的物质。因此，味觉是人类基本生存的关键组成部分。即使在现代，在我们周围都有安全和丰富的营养来源的情况下，当味觉的丧失--通常与神经元损伤或癌症治疗中使用的细胞毒治疗和放射治疗相关--导致不必要的体重减轻和生活质量显著下降时，味觉就会成为一个重大的临床问题。这一问题的一个特别严重的表现出现在接受Hedgehog(HH)途径拮抗剂治疗的癌症患者，他们由于味觉丧失而被迫或选择停止治疗，味觉丧失是这种基于机制的癌症治疗剂引起的一种特殊生物效应。我们的建议集中在HH信号在味觉受体细胞(TrCs)维持和再生中的作用，TrCs被安置在由舌上皮(味蕾)内陷形成的杯状结构中。我们计划确定Hedgehog信号的细胞来源及其影响的性质，特别重要的是，我们将讨论由支配TRCs的感觉神经元提供的Shh配体的作用。这些神经元产生的HH信号可能代表了一种细胞记忆，它指定了味蕾中TRC的再生，而不是舌头上皮的其他部分。这种记忆可能作为一种基本机制，协调再生信号的位置与神经的存在，从而能够接收和处理感觉输入，并可能与其他感觉器官的动态平衡和再生有关。此外，由于HH途径操作提供了一个强大的工具来导致TRCs的丢失或获得，我们将能够比较退化和再生状态以确定其他可能起作用的分泌因子。这些进展将扩大我们对感觉器官的动态平衡和再生的生物学理解，并将提高我们在接受癌症治疗时防止味觉丧失或促进其恢复的能力。我们的实验目标是：目标1：确定HH信号的细胞来源及其在维持TRCs中的作用。将使用条件遗传方法来确定Shh信号如何在TRC维持中发挥作用。目的2：明确味觉感觉神经元Shh在TRCs再生中的作用。手术去神经，条件遗传学和药理学方法，以及器官培养将被用来评估神经元Shh在TRC再生中的作用。目的3.确定维持和再生TRCs所需的HH依赖因子。FACS分选细胞的基因表达谱将用于识别有助于TRC维持和再生的HH依赖因子。候选人将在体外进行有机物培养和体内测试。

 DESCRIPTION (provided by applicant): The sensation of taste contributes centrally to discrimination of substances whose ingestion sustains us and others that are detrimental to our well-being. Taste sensation is thus a critical component of basic human survival. Even in modern times, with safe and abundant sources of nutrients all around us, taste sensation becomes a significant clinical issue when its loss, often associated with neuronal damage or the cytotoxic treatments and radiation employed in cancer therapy, causes unwanted weight reduction and a significant decrement in quality of life. A particularly acute manifestation of thi problem occurs in cancer patients treated with a Hedgehog (Hh) pathway antagonist who are forced or choose to discontinue therapy due to loss of taste sensation, a specific biological effect caused by this class of mechanism-based cancer therapeutic agent. Our proposal focuses on the role of Hh signaling in maintenance and regeneration of taste receptor cells (TRCs), which are housed within cup-shaped structures formed by invagination of the lingual epithelium (taste buds). We plan to determine the cellular source of the Hedgehog signal and the nature of its effects and, of particular significance; we will address the role of Shh ligand provided by sensory neurons that innervate TRCs. The Hh signal produced by these neurons may represent a cellular memory that specifies TRC regeneration within taste buds, as opposed to other parts of the lingual epithelium. Such memory may serve as a fundamental mechanism that coordinates the location of regenerative signaling with the presence of innervation that is able to receive and process sensory input, and may be relevant to the homeostasis and regeneration of other sensory organs. In addition, because Hh pathway manipulation provides a powerful tool to cause loss or gain of TRCs, we will be able to compare degenerating and regenerating states to identify other secreted factors that may play a role. These advances will expand our biological understanding of homeostasis and regeneration of sensory organs generally, and will improve our ability to prevent loss of taste or facilitate its recovery in patints undergoing cancer therapy. Our experimental aims are: Aim 1: Determine the cellular source of the Hh signal and its role in maintenance of TRCs. Conditional genetic approaches will be used to determine how Shh signaling functions in TRC maintenance. Aim 2: Define the role of Shh from gustatory sensory neurons in regeneration of TRCs. Surgical denervation, conditional genetic and pharmacological approaches, and organoid culture will be used to assess the role of neuronal Shh in TRC regeneration. Aim 3. Identify Hh-dependent factors required for maintenance and regeneration of TRCs. Gene expression profiling of FACS-sorted cells will be used to identify Hh-dependent factors that contribute to TRC maintenance and regeneration. Candidates will be tested in vitro in organoid culture and in vivo.