HORMONAL REGULATION OF LUNG DEVELOPMENT; PTHrP BIOLOGY

描述（由申请人提供）：甲状旁腺激素相关蛋白（PTHrP）缺失小鼠肺不能肺泡化。我们假设PTHrP的表达和扩增是肺发育、稳定和修复所必需的。我们的长期目标是确定肺形态发生的细胞/分子基础。机制上，在肺发育的肺泡前假腺期，上皮细胞PTHrP上调成纤维细胞FGF-10，刺激上皮细胞Shh扩增PTHrP。PTHrP信号因此下调成纤维细胞Wnt信号（通过刺激蛋白激酶A），上调脂肪成纤维细胞（LIF）的分化，特别是PTHrP受体的表达，进一步放大PTHrP信号对II型细胞分化的作用。在Aim 1中，我们假设删除PTHrP表达会阻止LIF促进肺泡发育所需的FGF-10和Shh的上调。我们进一步假设，决定LIF表型的PTHrP的条件性再表达将“挽救”空小鼠的肺泡化。在Aim 2中，我们假设在成年小鼠肺中删除PTHrP信号会诱导肌成纤维细胞（MYF）分化，导致间质纤维化。我们将确定PTHrP的条件性再表达是否可以阻止MYF分化和间质性肺纤维化。我们将使用分层方法来检验这些假设，包括免疫组织学、原位杂交、实时RT-PCR和全肺Western Blotting；肺切片形态测量结合激光捕获显微解剖/实时RT-PCR分离肺细胞mRNA转染、微阵列和稳定同位素代谢组学。这种系统的方法将确定PTHrP是否通过Wnt或PKA途径的细胞间信号传导决定肺泡发育和病理。这些研究将为新生儿和成人慢性肺部疾病的病理生理学和治疗提供重要的见解。

DESCRIPTION (provided by applicant): The Parathyroid Hormone-related Protein (PTHrP)-null mouse lung fails to alveolize. We hypothesize that PTHrP expression and amplification are necessary for lung development, stability and repair. Our long-term goal is to determine the cell/molecular basis of lung morphogenesis. Mechanistically, during the pre-alveolar pseudoglandular phase of lung development epithelial PTHrP up-regulates flbroblast FGF-10, stimulating epithelial Sonic Hedgehog (Shh) amplification of PTHrP. PTHrP signaling consequently down-regulates fibroblast Wnt signaling (by stimulating Protein Kinase A), up-regulating lipofibroblast (LIF) differentiation particularly PTHrP receptor expression, further amplifying PTHrP signaling for type II cell differentiation. In Aim 1 we hypothesize that deleting PTHrP expression will prevent the up-regulation of FGF-10 and Shh needed for LIF promotion of alveolar development. We further hypothesize that conditional re-expression of PTHrP, which determines the LIF phenotype, will 'rescue' alveolization in the null mouse. In Aim 2 we hypothesize that deleting PTHrP signaling in the null adult mouse lung will induce myofibroblast (MYF) differentiation, causing interstitial fibrosis. We will determine if conditional re-expression of PTHrP can prevent MYF differentiation and interstitial lung fibrosis. We will use a hierarchical approach to test these hypotheses, including immunohistology, in situ hybridization, Real Time RT-PCR and Western Blotting of whole lung; morphometry combined with Laser Capture Microdissection/Real Time RT-PCR of sectioned lung; and isolated lung cell mRNA transfection, microarray and stable isotope metabolomics. This systematic approach will determine if PTHrP determines lung alveolar development and pathology through intercellular signaling via the Wnt or PKA pathway. These studies will provide important insights to the pathophysiology and treatment of chronic lung diseases of the newborn and adult alike.