Defining the Pancreatic Progenitor Mesenchymal Niche

描述（由申请人提供）：最近对成体组织特异性祖细胞的兴趣激增，这加强了祖细胞从不自主发挥功能的原理;它们的行为总是由从其独特的空间小生境发出的信号控制。将这一原则翻译到胰腺，我们提出胰腺干/祖细胞的成功治疗靶向将需要有效表征和操纵其相应的间充质生态位。因此，我们提出了一个创新的和高度集成的研究计划，以确定，表征和操纵胰腺祖细胞间充质生态位在成人和胚胎胰腺。该建议是基于我们最近鉴定的低丰度，自我更新，多谱系上皮祖细胞群体在成年小鼠胰腺，和相应的间充质小生境细胞能够促进祖细胞扩增。基于这些令人兴奋的发现，我们提出了以下中心假设：第一，胚胎和成年小鼠胰腺中存在独特的间充质小生境细胞群。第二，小生境标识符由特定可溶性形态发生素的产生和分泌来定义。第三，小生境细胞“分泌组”的特征将允许鉴定特定的形态发生素 负责调节胚胎和成人胰腺祖细胞的增殖、分化和自我更新。为了验证这些假设，我们提出了三个具体目标。具体目标1和2共享应用于目标1中的胚胎胰腺和目标2中的正常和再生成人胰腺的平行方法。对于这两个目标，我们将表征和量化不同胰腺间充质细胞亚群的相对丰度，测试它们调节胰腺上皮祖细胞增殖扩增、分化和自我更新的能力，并鉴定负责这些效应的小生境“分泌组”的相关组分。已经鉴定了特定的小生境细胞群体和负责小生境功能的相关分泌形态发生素，目的3中的实验将寻求遗传操纵成年胰腺间充质小生境细胞，使用Cre/lox和rtTA/TRE技术的组合用于激活素A和其他分泌形态发生素的间充质特异性、多西环素诱导型表达。总之，这些目标将提供胰腺间充质发育和胰腺生态位生物学的全新和综合观点，为成人胰腺祖细胞间充质生态位的最终治疗操作奠定基础。

DESCRIPTION (provided by applicant): The recent explosion of interest in adult tissue-specific progenitor cells has reinforced the principle that progenitor cells never function autonomously; their behavior is always governed by signals emanating from their unique spatial niche. Translating this principle to the pancreas, we propose that successful therapeutic targeting of pancreatic stem/progenitor cells will require effective characterization and manipulation of their corresponding mesenchymal niche. We are therefore proposing an innovative and highly integrated research program to identify, characterize and manipulate the pancreatic progenitor mesenchymal niche in adult and embryonic pancreas. The proposal is based on our recent identification of both a low-abundance, self-renewing, multi-lineage epithelial progenitor cell population in adult mouse pancreas, and a corresponding mesenchymal niche cell capable of promoting progenitor expansion. Based on these exciting findings, we are proposing the following central hypotheses: First, that unique population of mesenchymal niche cells exist embryonic and adult mouse pancreas. Second, that niche identify is defined by the production and secretion of specific soluble morphogens. Third, that characterization of the niche cell "secretome" will allow the identification of specific morphogens responsible for regulating the proliferation, differentiation and self-renewal of embryonic and adult pancreatic progenitor cells. To test these hypotheses, we are proposing three Specific Aims. Specific Aims 1 and 2 share parallel approaches applied to the embryonic pancreas in Aim 1 and to normal and regenerating adult pancreas in Aim 2. For both of these Aims, we will characterize and quantify the relative abundance of different pancreatic mesenchymal cell subpopulations, test their ability to regulate the proliferative expansion, differentiation and sel-renewal of pancreatic epithelial progenitor cells, and identify relevant components of the niche "secretome" responsible for these effects. Having identified specific niche cell populations and associated secreted morphogens responsible for niche function, experiments in Aim 3 will seek to genetically manipulate adult pancreatic mesenchymal niche cells, using a combination of Cre/lox and rtTA/TRE technology for mesenchyme-specific, doxycycline-inducible expression of ActivinA and other secreted morphogens. Together, these Aims will provide an entirely novel and integrated view of pancreatic mesenchymal development and pancreatic niche biology, setting the stage for eventual therapeutic manipulation of the adult pancreatic progenitor mesenchymal niche.