Regulation of TGF-B1 Production and Signaling by Pin-1

除了间歇性、可逆性阻塞外，一些哮喘患者还发生已知的固定性气道阻塞， 重塑。越来越多的文献表明，活化和长寿命的气道产生的TGF β 1和TGF β 2可能与气道炎症有关。 实质嗜酸性粒细胞（EOS）诱导细支气管成纤维细胞、平滑肌和 肌上皮细胞最终产生胶原和细胞外基质蛋白。 当嗜酸性粒细胞从气道中被清除时，重塑减少，这表明抑制气道炎症是可能的。 EOS衍生的TGF β 1或其在细胞靶点中的促纤维化信号传导的阻断可具有治疗益处。 最近，我们已经鉴定了Pin 1，一种肽基脯氨酰异构酶（PPIase），作为TGF β 1产生的参与者 和信号。Pin 1与亲环素A和FKBP相关，并且是唯一已知的结合亲环素A和FKBP的真核酶。 并催化磷酸丝氨酸-脯氨酸或磷酸苏氨酸-脯氨酸肽的顺反异构化 债券靶蛋白的异构化改变了它们的构象、功能或稳定性。pin 1最近 与GM-CSF mRNA代谢有关，表明在细胞因子的调节中具有更广泛的作用。 通过激活的EOS进行生物合成。我们现在提供的证据表明Pin 1通过EOS调节TGF β 1的表达， 成纤维细胞中的TGF β 1信号传导。特异性阻断EOS中PinVs PPIase活性降低TGF β 1 mRNA 稳定性，导致稳态mRNA水平和蛋白质表达显著下降。 免疫沉淀研究表明，Pint与多种蛋白质结合，这些蛋白质与免疫抑制剂的作用有关。 TGF β 1 mRNA衰减或基因表达的调节。Pin 1抑制减少胶原mRNA积累 在体外暴露于TGF β 1的支气管气道衍生的成纤维细胞中以及在气道中，支气管肺泡 灌洗液（BAL）细胞和肺实质的哮喘过敏大鼠模型在体内治疗。所以我们 假设Pin 1是一种关键的信号中间体，在以下物质的产生和作用中起关键作用： 哮喘肺中的TGF β 1。因此，我们建议：确定Pin 1异构酶活性是如何调节的 嗜酸性粒细胞活化后，2.确定Pin 1蛋白如何靶向HuR和AUF 1控制TGF β 1 mRNA decay，3.确定Pin 1如何调节成纤维细胞中的TGF β 1信号传导和4，确定Pin 1阻断是否 可以改变慢性过敏原暴露动物模型的气道重塑。这些研究将 阐明Pin 1在哮喘发病机制和气道重塑中的作用和功能。

In addition to intermittent, reversible obstruction, some asthmatics, develop fixed airway obstruction known as remodeling. A growing literature suggests thatTGFpt produced by activated and long-lived airway and parenchymal eosinophils (EOS) induces hyperplasia of bronchiolar fibroblasts, smooth muscle and myoepithelial cells culminating with enhanced production of collagens and extracellular matrix proteins. Remodeling is reduced when eosinophils are eliminated from the airways suggesting that suppression of EOS derived TGFpl or blockade of its profibrotic signaling in cellular targets could have therapeutic benefits. Recently, we have identified Pin1, a peptidyl-prolyl isomerase (PPIase) as a participant in TGF(31 production and signaling. Pin1 is related to cyclophilin A and FKBP and is the only known eukaryotic enzyme that binds to and catalyzes the cis-trans isomerization of phosphoserine-proline or phosphothreonine-proline peptide bonds. The isomerization of target proteins alters their conformation, function or stability. Pin1 has recently been implicated in GM-CSF mRNA metabolism, suggesting a broader role in the regulation of cytokine biogenesis by activated EOS. We now present evidence that Pin1 regulates TGFpl expression by EOS and TGFpl signaling in fibroblasts. Specific blockade of PinVs PPIase activity in EOS reduced TGFpl mRNA stability, causing steady state mRNA levels and protein expression to significantly decline. Immunoprecipitation studies revealed that Pint binds to multiple proteins that have been implicated in the regulation of TGFpl mRNA decay or gene expression. Pin1 inhibition reduced collagen mRNA accumulation in bronchial airway derived fibroblasts exposed to TGFpl in vitro as well as in the airways, bronchoalveolar lavage (BAL) cells and lung parenchyma of allergic rat models of asthma treated in vivo. Therefore, we hypothesize that Pin1 is a critical, signaling intermediate that plays a key role in the production and action of TGFpl in the asthmatic lung. We therefore propose to: 1. Identify how Pin1 isomerase activity is regulated after eosinophil activation, 2. Determine how Pin1 protein targets HuR and AUF1 control TGFpl mRNA decay, 3. Determine how Pin1 regulates TGFpl signaling in fibroblasts and 4, Determine if Pin1 blockade can alter airway remodeling in animal models of chronic allergen exposure. In aggregate these studies will clarify the role and function of Pin1 in asthma pathogenesis and airway remodeling.