REGULATION OF MUCOUS CELL METAPLASIA IN ASTHMA

描述（由申请人提供）：在哮喘患者中，粘液细胞出现在通常没有这些细胞的气道中。这种表型称为粘液细胞化生（MCM）。MCM造成严重的风险，因为急性分泌的粘液会减少气流，有时会完全阻塞气道，导致哮喘患者死亡。此外，流行病学研究表明，慢性MCM患者患肺癌的风险更高。我们的研究表明，干扰素？和STAT 1信号传导通过诱导气道上皮细胞（AECs）中的细胞死亡对于MCM的解决至关重要。因此，这一更新申请的重点是描绘的分子机制，干扰素？诱导AEC中的细胞死亡。干扰素？激活ERK 1/2并将Bax易位至内质网（ER）并减少MCM。我们发现，Bik，一个Bcl-2家族成员，定位于ER，在从哮喘患者支气管刷取的AEC中与对照组相比显著减少。来自bik-/-小鼠的AEC不受IFN？影响，Bik过表达可激活ERK 1/2并诱导AECs杀伤。Noxa是Bcl-2家族的另一个成员，由IFN？并增强Bik诱导的细胞凋亡。Noxa与磷酸化HSP 27相互作用，降低I？B水平与NF-？B，降低Bcl-2 mRNA表达。这些发现使我们得出以下假设：IFN？诱导的细胞死亡是由Bik诱导的ERK 1/2激活介导的，其导致Bax易位到ER以启动凋亡。此外，Bik介导的细胞凋亡是增强Noxa通过其相互作用与磷酸热休克蛋白27降解I？B1，但抑制活化的NF-？B能降低Bcl-2的表达。我们将通过以下方式检验这一假设：（1）调查Bik是否是IFN？通过激活ERK 1/2和将Bax易位到ER来诱导细胞死亡和MCM的消退。(2)确定Noxa交联磷酸化HSP 27是否促进NF-？B激活，但抑制NF-？B，从而降低Bcl-2 mRNA表达，以增强Bik诱导的细胞死亡并鉴定Noxa-HSP 27相互作用的结构域。(3)确定Bik诱导的ER应激是否需要Bax和巴克在长时间暴露于过敏原期间解析MCM。了解这些蛋白质在MCM的分解过程中的作用，可以使我们减少增生的上皮细胞，可以分泌过多的粘液在哮喘不损害休息的上皮细胞，因此上皮的屏障功能。开发减少MCM的靶向方法也可能有助于消除患肺癌风险增加的患者的肿瘤前细胞。公共卫生相关性。气道中粘液细胞数量的增加会带来严重的风险，因为急性分泌的粘液会减少气流，有时会完全阻塞气道，导致哮喘患者死亡。拟议的研究将剖析事件的分子序列，这些事件是正常小鼠长期暴露于过敏原期间这些粘液细胞正常分辨过程的基础。了解这些分子过程可能会提供新的策略，减少粘液分泌，消除增生的粘液细胞。

DESCRIPTION (provided by applicant): In patients with asthma mucous cells appear in airways that are normally devoid of these cells. This phenotype is called mucous cell metaplasia (MCM). MCM poses a serious risk because acutely secreted mucus can reduce airflow or can sometimes completely obstruct the airways and lead to death of asthmatics. In addition, epidemiological studies suggest that patients with chronic MCM are at a higher risk of developing lung cancer. Our studies demonstrated that IFN? and STAT1 signaling are crucial for the resolution of MCM by inducing cell death in airway epithelial cells (AECs). Therefore, this renewal application is focused on delineating the molecular mechanisms by which IFN? induces cell death in AECs. IFN? activates ERK1/2 and translocates Bax to the endoplasmic reticulum (ER) and reduces MCM. We found that Bik, a Bcl-2 family member that localizes to the ER, was significantly reduced in AECs obtained by bronchial brushings from asthmatics compared to controls. AECs from bik-/- mice were unaffected by IFN?, and Bik overexpression caused activation of ERK1/2 and induced killing in AECs. Noxa, another Bcl-2 family member, is induced by IFN? and enhances Bik-induced apoptosis. Noxa interacts with phosphorylated HSP27, reduces I?B levels, co-localizes with NF-?B, and reduces Bcl-2 mRNA expression. These findings led us to the following hypothesis: IFN?-induced cell death is mediated by Bik-induced activation of ERK1/2 that results in the translocation of Bax to the ER to initiate apoptosis. Furthermore, the Bik-mediated apoptosis is enhanced by Noxa through its interaction with phopho-HSP27 to degrade I?B1 but inhibit nuclear translocation of activated NF-?B and decrease Bcl-2 expression. We will test this hypothesis by: (1) Investigating whether Bik is central for the IFN?-induced cell death and resolution of MCM by activating ERK1/2 and translocating Bax to the ER. (2) Determining whether Noxa cross-linked to phosphorylated HSP27 facilitates NF-?B activation but inhibits nuclear translocation of NF-?B and thereby decreases Bcl-2 mRNA expression to enhance Bik-induced cell death and to identify the domain of Noxa-HSP27 interaction. (3) Determining whether Bik-induced ER stress requires Bax and Bak for the resolution of MCM during prolonged exposure to allergen. Understanding the role of these proteins in the resolution process of MCM may allow us to reduce hyperplastic epithelial cells that can secrete excessive mucus in asthmatics without compromising the resting epithelial cells and therefore the barrier functions of the epithelium. Development of targeted approaches to reduce MCM may also be useful for eliminating pre-neoplastic cells in patients with an increased risk of developing lung cancer. PUBLIC HEALTH RELEVANCE. Increased number of mucous cells in the airways poses a serious risk because acutely secreted mucus can reduce airflow or can sometimes completely obstruct the airways and lead to death of asthmatics. The proposed studies will dissect the molecular sequence of events that underlies the normal resolution process for these mucous cells during prolonged exposure to allergen in normal mice. Understanding these molecular processes may provide new strategies for reducing mucous secretions by eliminating hyperplastic mucous cells.