A novel telomerase expressing lung fibroblast phenotype

描述（由申请方提供）：成纤维细胞数量增加是肺纤维化的一个关键特征，其在密集细胞形成中的聚结（称为成纤维细胞灶）是特发性肺纤维化（IPF）的诊断性组织病理学特征。增殖增加是成纤维细胞增加的可能机制，成纤维细胞的表型与从正常肺分离的细胞不同。有趣的是，在肺损伤和纤维化的动物模型中发现了一种新的成纤维细胞表型，其特征在于端粒酶活性的表达。虽然端粒酶活性与某些细胞在早期发育过程中和许多肿瘤细胞中增殖能力和寿命的增加有关，但其在肺纤维化发病机制中的意义尚不清楚。在这个项目中，它是假设出现从头端粒酶表达成纤维细胞表型是由某些因素引起的细胞增殖和/或生存增加。这将增加作为中间分化群体的增殖细胞的池大小，所述中间分化群体可以终末分化为肌成纤维细胞表型。提出了四个具体目标来检验这一假设。首先，将在肺成纤维细胞中研究端粒酶诱导的机制。将克隆端粒酶基因及其5 '-侧翼序列用于转录调控分析。其次，通过分析端粒酶和β-平滑肌肌动蛋白基因表达之间的关系，以及两种基因的转录调控机制是否在细胞分化方面以某种有意义的功能方式相关，来检查端粒酶表达和肌成纤维细胞表型之间的关系。第三，端粒酶表达的功能意义将通过比较端粒长度与体内和体外端粒酶表达，以及端粒酶表达是否赋予细胞对生长因子和/或凋亡信号应答的差异特征来分析。最后，将通过使用端粒酶（端粒酶逆转录酶或端粒酶RNA组分）敲除小鼠以及特异性端粒酶抑制剂在博莱霉素模型中体内检查端粒酶在肺纤维化中的作用。通过使用这些组合的方法，这种端粒酶表达表型的潜在作用和意义的新见解将被揭示，这可能被证明是有用的设计未来的新的治疗方法。

DESCRIPTION (provided by applicant): Increased numbers of fibroblasts are a key feature of pulmonary fibrosis, and their coalescence in densely populated cell formations, termed fibroblastic foci, is a diagnostic histopathological feature of idiopathic pulmonary fibrosis (IPF). Increased proliferation is a likely mechanism for this increase in fibroblasts whose phenotype is distinct from cells isolated from normal lung. Interestingly a new fibroblast phenotype is found to emerge in animal models of lung injury and fibrosis characterized by the expression of telomerase activity. While telomerase activity is associated with increased proliferative capacity and life span in certain cells during early development and many tumor cells, its significance in the pathogenesis of pulmonary fibrosis is unknown. In this project it is hypothesized that emergence de novo of a telomerase-expressing fibroblast phenotype is induced by certain factors resulting in increased cell proliferation and/or survival. This would increase the pool size of proliferative cells serving as an intermediate differentiated population that can terminally differentiate to the myofibroblast phenotype. Four specific aims are proposed to test this hypothesis. First, the mechanism of telomerase induction will be studied in lung fibroblasts. The telomerase gene and its 5'-flanking sequences will be cloned for analysis of transcriptional regulation. Second, the relationship between the telomerase expressing and myofibroblast phenotypes will be examined by analyzing the relationship between telomerase and (-smooth muscle actin gene expression, and whether the transcriptional regulatory mechanisms for both genes are somehow related in a functionally meaningful way in terms of cellular differentiation. Third, the functional significance of telomerase expression will be analyzed by comparing telomere length with telomerase expression in vivo and in vitro, and whether telomerase expression endow cells with differential characteristics with respect to response to growth factors and/or apoptotic signals. Finally, the role of telomerase in pulmonary fibrosis will be examined in vivo in the bleomycin model by use of telomerase (either telomerase reverse transcriptase or telomerase RNA component) knockout mice as well as specific telomerase inhibitors. By using these combined approaches, new insights into the potential role and significance of this telomerase expressing phenotype will be uncovered, which may prove to be useful for devising future novel therapeutic approaches.