Pin1 regulation of prosurvival signalling in eosinophils

描述(申请人提供)：嗜酸性肺部炎症是哮喘的主要特征。一旦进入肺部，嗜酸性粒细胞(Eos)就会表现出活化的表型，并在暴露于GM-CSF等生存细胞因子后对凋亡产生抵抗力。长时间存活的Eos会造成组织损伤，促进粘膜下、支气管纤维化和呼吸道重塑的发展。因此，抑制GM-CSF的产生或其生存信号可以减少肺嗜酸性粒细胞增多症和哮喘的长期发病率。活化的Eos释放的GM-CSF与异源二聚体细胞表面受体结合，激活PI-3K、MAPK和Syk等多个生存级联反应。这些途径如何调节Eos的存活在很大程度上是未知的。最近，我们发现PPIase(PPIase)在Eos的GM-CSF mRNA代谢以及随后的生存信号中起着重要的作用。Pin1结合并催化磷酸丝氨酸-脯氨酸或磷酸苏氨酸-Pro(Ser/Thr-Pro)多肽键的顺反异构化。靶蛋白的异构化会改变它们的构象、功能或稳定性。我们现在证明，Pin1‘S异构酶活性是EOS生存所必需的至少两种方式。首先，Pin1通过调节GM-CSF mRNA的稳定性来控制Eos的生存细胞因子的产生。Pin1结合并直接控制细胞中GM-CSF mRNA和RNA衰变机制的关键mRNA结合蛋白的亲和力。其次，Pin1通过直接与Bax、PKC和proaspase 8等多种凋亡效应因子相互作用，对GM-CSF的存活效应起着至关重要的作用。因此，我们假设Pin1是一个关键的信号中间体，通过调节GM-CSF的产生和GM-CSF的存活信号来控制嗜酸性粒细胞的存活。因此，我们建议：1.确定PIN1活性如何受GM-CSF介导的信号调节。2.确定Pin1如何调节GM-CSF mRNA结合蛋白AUF1的功能。3.研究Pin1如何调控GM-CSF的生存效应。4.在哮喘动物模型中，确定Pin1受体阻滞剂能否与吸入糖皮质激素协同作用，减轻嗜酸性炎症，保护肺功能。总而言之，这些研究将加深我们对哮喘Eos生物学的理解。与公共卫生相关。拟议研究的完成将有助于了解当生长因子被移除时嗜酸性粒细胞是如何死亡的，并可能为加速这一过程的药物的开发铺平道路。这些药物可能对治疗慢性哮喘有用。

DESCRIPTION (provided by applicant): Eosinophilic pulmonary inflammation is a cardinal feature of asthma. Once in the lung, eosinophils (Eos) show an activated phenotype and become resistant to apoptosis after exposure to prosurvival cytokines such as GM-CSF. Long lived Eos contribute to tissue damage and facilitate the development of submucosal, bronchial fibrosis and airway remodeling. Therefore, suppression of GM-CSF production or its prosurvival signaling could reduce pulmonary eosinophilia and the long-term morbidity of asthma. GM-CSF released by activated Eos binds to a heterodimeric, cell surface receptor which activates multiple prosurvival cascades involving PI-3K, MAPK and Syk. How these pathways modulate Eos survival are largely unknown. Recently, we identified the peptidyl-prolyl isomerase (PPIase), Pin1, as a critical participant in GM-CSF mRNA metabolism as well as subsequent prosurvival signaling in Eos. Pin1 binds to and catalyzes the cis-trans isomerization of phosphoserine-proline or phosphothreonine-proline (Ser/Thr-Pro) peptide bonds. Isomerization of target proteins alters their conformation, function or stability. We now show that Pin1's isomerase activity is required for Eos survival in at least 2 ways. First, Pin1 controls the production of prosurvival cytokines by Eos by regulating the stability of GM-CSF mRNA. Pin1 binds to and directly controls the affinity of critical mRNA binding proteins for both GM-CSF mRNA and the RNA decay machinery in cells. Secondly, Pin1 is essential for the prosurvival effects of GM-CSF by directly interacting with multiple apoptotic effectors including Bax, PKC and procaspase 8. Therefore, we hypothesize that Pin1 is a critical, signaling intermediate which controls eosinophil survival through the regulation of GM-CSF production and GM-CSF prosurvival signaling. We therefore propose to: 1. Identify how Pin1 activity is regulated by GM-CSF mediated signaling. 2. Determine how Pin1 regulates the function of the GM-CSF mRNA binding protein, AUF1. 3. Characterize how Pin1 modulates the prosurvival effects of GM-CSF. 4. Determine if Pin1 blockade can reduce eosinophilic inflammation and preserve lung function in synergy with inhaled corticosteroids in animal models of asthma. In aggregate these studies will further our understanding of Eos biology in asthma. PUBLIC HEALTH RELEVANCE. Completion of the proposed studies will help understand how eosinophils die when growth factors are removed and potentially pave the way for the development of drugs which can accelerate that process. Such drugs could be useful for the treatment of chronic asthma.