Salivary gland response to Desert hedgehog signaling as an antidote to damage from therapeutic radiation

项目摘要/摘要 流口水是一种重要的生理活动，有助于消化，维持口腔健康，并支持以下功能 如言语、吞咽和味觉。唾液腺功能障碍是由年龄增长引起的，疾病如 Sjögren综合征和头颈部癌症的放射治疗。治疗性照射导致永久性 唾液腺受损，突显其再生能力较差。恢复的一个潜在障碍 唾液分泌可能是损伤，特别是在放射治疗期间，不仅对唾液的产生造成损害。 上皮细胞，也有支持间充质细胞。事实上，间充质的保存或修复 细胞功能可能构成理想的治疗靶点，因为优化的间充质微环境可能 增强残留唾液腺上皮细胞及其前体细胞的功能和再生能力。 了解间充质细胞如何在动态平衡中发挥作用并促进损伤后的再生 因此，可能提供一种新的方法来激活保护唾液腺并增强其修复的机制。 在许多器官中，向上皮提供再生反馈的信号的间质表达 在动态平衡和损伤修复过程中，Hedgehog(HH)蛋白信号的表达诱导了修复 上皮组织。利用小鼠遗传模型、细胞谱系追踪和单细胞转录，我们有 发现沙漠刺猬(DHH)是三种哺乳动物HH家族成员中研究最少的，它驱使 成人主要唾液腺的上皮-间充质反馈(EMF)回路及其活性 回路对于唾液腺的维持和辐射损伤后的再生至关重要。重要的是，尽管 DHH在唾液腺上皮细胞中的表达对再生是必不可少的，我们的发现也强调了 对于再生程序的执行，间充质对这一信号的反应起着至关重要的作用。 在这里，我们建议阐明HH信号在唾液腺动态平衡和再生中的作用。 在单个细胞水平上表征电动势电路活动的转录和表观遗传后果，以及 目的：评估脱氢表雄酮(DHH)在人唾液腺中驱动电动势回路的保守性。其目的是操纵 HH途径的活性用于保护或促进辐射损伤后的组织修复，我们已经开发出 针对HH受体Patched1的构象特异性纳米体，激活HH途径反应。这 纳米体可以针对特定类型的细胞和组织，从而减轻由 全身性HH途径激活。有了这种试剂，我们将测试精确的组织靶向激活的可能性 HH途径可有效增强唾液腺保护的内源性修复机制 放射损伤后的恢复和恢复，就像头颈部癌症治疗中所用的那样。

PROJECT SUMMARY/ABSTRACT Salivation is a critical physiological activity that aids digestion, maintains oral health, and supports functions such as speech, swallowing and taste sensation. Salivary gland dysfunction results from ageing, diseases such as Sjögren syndrome and from radiotherapy for head and neck cancers. Therapeutic irradiation causes permanent damage to salivary glands, highlighting their poor regenerative ability. One potential obstacle to recovery of salivation may be that damage, particularly during radiation therapy, is inflicted not only on saliva-generating epithelial cells but also on supporting mesenchymal cells. Indeed, preservation or restoration of mesenchymal cell function may constitute an ideal therapeutic target, as an optimized mesenchymal microenvironment may augment the function and regenerative capacity of residual salivary gland epithelial cells and their progenitors. A knowledge of how mesenchymal cells function during homeostasis and contribute to regeneration after injury thus may provide a new approach to activate mechanisms that protect salivary glands and enhance their repair. In many organs the mesenchymal expression of signals that provide regenerative feedback to the epithelium during homeostasis and injury repair is induced by expression of a Hedgehog (Hh) protein signal from the epithelium. Using mouse genetic models, cell lineage tracing, and single-cell transcriptomics, we have discovered that Desert hedgehog (DHH), the least studied of the three mammalian Hh family members, drives an epithelial-mesenchymal feedback (EMF) circuit in the major adult salivary glands, and that activity of this circuit is crucial for salivary gland maintenance and for regeneration after radiation injury. Importantly, although DHH expression in cells of the salivary gland epithelium is essential for regeneration, our findings also highlight a vital role for mesenchymal response to this signal for execution of the regenerative program. Here we propose to elucidate the role of Hh signaling in salivary gland homeostasis and regeneration by characterizing at a single cell level the transcriptomic and epigenetic consequences of EMF circuit activity, and to assess the conservation of DHH-driven EMF circuitry in human salivary glands. With the goal of manipulating Hh pathway activity for protection from or enhancement of tissue repair after radiation injury, we have developed a conformation-specific nanobody against the Hh receptor Patched1 that activates Hh pathway response. This nanobody can be targeted to specific cell and tissue types, thus mitigating potential adverse effects arising from systemic Hh pathway activation. With this agent, we will test the possibility that precise, tissue-targeted activation of the Hh pathway can effectively enhance endogenous reparative mechanisms for salivary gland protection from and restoration after injury from irradiation like that administered in head and neck cancer therapy.