The role of Hippo and YAP/TAZ in dental renewal

 描述(申请人提供)：利用成体干细胞进行器官更新和修复是再生医学的一个重要目标。牙齿生物工程引起了人们的极大兴趣，因为龋齿和牙齿脱落是一个重要的公共卫生问题。此外，牙齿异常在许多颅面综合征中很常见，口腔的易达性使牙齿成为器官置换的极佳测试案例。彻底了解驱动牙齿更新和再生的分子和细胞过程将对建造和修复牙齿至关重要。我们正在使用小鼠切牙作为一个模型，以了解干细胞促进牙齿组织更新的机制，因为由于成体干细胞的存在，这颗非凡的牙齿持续生长。我们的初步数据表明，河马途径通过其两个效应器，是相关蛋白(YAP)和带有PDZ结合基序的转录共激活因子(TAZ)，调节切牙干细胞的生态位。重要的是，我们的初步研究表明，切牙中的YAP/TAZ受机械信号调节；这一重要的调节相互作用在成人干细胞生物学中尚未得到充分研究。因此，啮齿动物切牙提供了一个独特的体内平台来研究物理环境如何调节YAP/TAZ，这不仅将推动河马信号转导领域的向前发展，也将为开发基于干细胞的治疗牙科疾病的方法奠定基础。在这个应用中，我们建议检验这样一个假设，即由小的Rho GTP酶介导的机械信号可以调节YAP/TAZ的活性，进而控制干细胞生物学中的关键过程。在第一个目标中，我们将确定YAP/Taz和Lats1/2功能丧失在小鼠切牙中的作用。目标2将阐述机械力和小Rho GTP酶如何调节YAP/TAZ活性。还将进行RNAi试验筛选，以确定YAP/TAZ的新型上游机械调节因子。目标3将阐述YAP/TAZ下游的mTOR通路在切牙干细胞中的作用。总之，这些实验将阐明一条线性机制路径，这将有助于我们了解河马信号和YAP/TAZ是如何介导机械信号来调节小鼠成年门牙干细胞的，它们将产生牙科研究人员以及干细胞和再生医学界普遍感兴趣的发现。这些研究的结果将增进我们对自然界如何在牙齿再生中正常使用干细胞的理解，并增强我们调节物理和生物化学环境以产生用于翻译目的的牙齿干细胞的能力。

 DESCRIPTION (provided by applicant): The utilization of adult stem cells for organ renewal and repair is an important goal in regenerative medicine. Tooth bioengineering is of great interest, because dental decay and tooth loss constitute an important public health issue. Additionally, tooth anomalies are common in many craniofacial syndromes, and the easy accessibility of the oral cavity makes teeth an excellent test case for organ replacement. A thorough understanding of the molecular and cellular processes that drive tooth renewal and regeneration will be crucial to efforts to build and repair teeth. We are using the mouse incisor as a model for understanding the mechanisms that underlie the ability of stem cells to contribute to renewal of dental tissues, because this remarkable tooth grows continuously due to the presence of adult stem cells. Our preliminary data indicate that the Hippo pathway, via its two effectors, Yes-associated Protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), regulates the incisor stem cell niche. Importantly, our initial studies suggest that YAP/TAZ in the incisor are regulated by mechanical cues; this important regulatory interaction has been understudied in adult stem cell biology. Thus, the rodent incisor provides a unique in vivo platform to study how the physical environment regulates YAP/TAZ, which will not only move the field of Hippo signaling forward but also lay the foundation for developing stem cell-based therapies in the treatment of dental diseases. In this application, we propose to test the hypothesis that mechanical signals, mediated by small Rho GTPases, can modulate YAP/TAZ activity, which in turn control key processes in stem cell biology. In the first Aim, we will determine the effect of Yap/Taz and Lats1/2 loss-of-function in the mouse incisor. Aim 2 will address how mechanical forces and small Rho GTPases regulate YAP/TAZ activity. A pilot RNAi screen will also be carried out to identify novel upstream mechano-regulators of YAP/TAZ. Aim 3 will address the role of the mTor pathway downstream of YAP/TAZ in the incisor stem cells. Together, these experiments will elucidate a linear mechanistic pathway that will help us to understand how Hippo signaling and YAP/TAZ mediate mechanical signals to regulate adult incisor stem cells in mice, and they will yield findings that will be of general interest to both dental researchers and to the stem cell and regenerative medicine communities. The results of these studies will advance our understanding of how nature normally uses stem cells in dental regeneration and enhance our ability to modulate both the physical and biochemical environments in order to generate dental stem cells for translational purposes.