Modulating Wnt and Hedgehog Pathways for Functional Restoration of Salivary Gland

描述（由申请人提供）：该申请涉及广泛的挑战领域（15）：转化科学，以及特定的挑战主题15- de -104：唾液腺的功能恢复。涎腺功能减退是格林综合征患者或头颈癌放疗患者常见的病理状况。目前的治疗只能暂时缓解症状，而基于成人唾液腺干细胞的再生疗法在动物模型中显示出恢复唾液腺功能的潜力。为了提高这些再生疗法的效率，需要探索唾液腺干细胞自我更新、增殖和分化的分子调控。Wnt/¿-catenin和Hedgehog细胞间信号通路调节多种成体干细胞的活动，与许多可再生组织的稳态和再生密切相关，但它们是否也参与唾液腺的这些过程尚不清楚。我们通过小鼠遗传模型的初步数据首次证实Wnt/¿-catenin信号在成人唾液腺中具有活性，并调节Hedgehog通路上游唾液腺干细胞的分化和增殖。为了探索操纵Wnt和Hedgehog通路恢复唾液腺功能的潜力，我们将：(1)利用相应的遗传报告小鼠模型识别响应Wnt和Hedgehog信号的细胞群，并追踪它们在唾液腺稳态和再生过程中的命运；(2)确定Wnt信号的瞬间激活是否促进了照射后涎腺功能的恢复，在多西环素诱导下，基底上皮中过表达Wnt1的双转基因小鼠或重组R-Spondin蛋白可以实现Wnt的瞬间激活，从而减轻内源性Wnt的抑制；3)用多西环素诱导下基底上皮过表达Sonic Hedgehog基因的双转基因小鼠局部照射后，观察瞬时激活Sonic Hedgehog信号是否能促进唾液腺功能恢复。鉴于Wnt和Hedgehog信号在各种再生过程中的重要作用，以及我们对其在唾液腺干细胞调控中的作用的初步数据，该项目将揭示恢复唾液腺功能的新再生策略。本申请涉及广泛的挑战领域（15）：转化科学和特定的挑战主题，15- de -104唾液腺功能恢复。我们将通过诱导遗传小鼠模型和重组Wnt去抑制蛋白来探索操纵Wnt和Hedgehog通路恢复唾液腺功能的潜力。

DESCRIPTION (provided by applicant): This application addresses broad challenge area (15): Translational Science, and specific Challenge Topic 15-DE-104: Functional Restoration of Salivary Glands. Hypofunction of salivary gland is a common pathological condition in patients with Sj"gren's syndrome or treated with radiotherapy for head and neck cancer. Current treatments can only temporarily relieve the symptoms, while regenerative therapies based on adult salivary gland stem cells have shown potential to restore salivary gland function in animal models. To improve the efficiency of these regenerative therapies, the molecular control of self-renewal, proliferation and differentiation of salivary gland stem cells need to be explored. Wnt/¿-catenin and Hedgehog intercellular signal pathways regulate activities of various adult stem cells, and are close related to homeostasis and regeneration of many renewable tissues, but whether they are also involved in these processes in salivary gland is unknown. For the first time, our preliminary data from genetic mouse models demonstrated that Wnt/¿-catenin signaling is active in adult salivary gland, and regulates differentiation and proliferation of salivary gland stem cells upstream of Hedgehog pathway. To explore the potential of manipulating Wnt and Hedgehog pathways for restoration of salivary gland function, we will: (1) Identify cell populations responding to Wnt and Hedgehog signals and trace their fate during homeostasis and regeneration of salivary gland with corresponding genetic reporter mouse models; (2) Determine whether transient activation of Wnt signaling promotes functional restoration of salivary gland after irradiation, transient Wnt activation will be achieved either in bi-transgenic mice over-expressing Wnt1 in basal epithelia upon doxycycline induction, or with recombinant R-Spondin protein which relieves endogenous Wnt inhibition; 3) Determine whether transient activation of Sonic Hedgehog signaling promotes salivary gland functional restoration after local irradiation with bi-transgenic mice over-expressing Sonic Hedgehog in basal epithelia upon doxycycline induction. Given the essential roles of Wnt and Hedgehog signaling in various regenerative processes and our preliminary data on their roles in regulation of salivary gland stem cells, the proposed project will shed light on new regenerative strategies to restore the function of salivary gland. This application addresses broad challenge area (15): Translational Science, and specific Challenge Topic, 15-DE-104 Functional Restoration of Salivary Glands. We will explore the potential of manipulating Wnt and Hedgehog pathways for restoration of salivary gland function with inducible genetic mouse models and recombinant Wnt derepressor protein.