REGULATION OF MUCOUS CELL METAPLASIA IN ASTHMA

描述（由申请人提供）：哮喘患者在气道中出现粘液细胞，而气道通常缺乏这些细胞。这种表型被称为粘液细胞化生（MCM）。MCM具有严重的风险，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IFN？和STAT1信号是通过诱导气道上皮细胞（AECs）细胞死亡来解决MCM的关键。因此，这一更新应用的重点是描述IFN？诱导aec细胞死亡。干扰素吗?激活ERK1/2并将Bax转运到内质网（ER）并减少MCM。我们发现，与对照组相比，哮喘患者通过支气管刷洗获得的aec中，Bcl-2家族成员Bik（定位于内质网）显著降低。来自bik-/-小鼠的aec不受IFN？Bik过表达可激活ERK1/2，诱导AECs死亡。Noxa是另一个Bcl-2家族成员，由IFN诱导。并增强bik诱导的细胞凋亡。Noxa与磷酸化的HSP27相互作用，减少I？B水平与NF-？B，降低Bcl-2 mRNA的表达。这些发现使我们提出以下假设：IFN？-诱导的细胞死亡是通过bik诱导的ERK1/2激活介导的，ERK1/2导致Bax易位到内质网，从而启动细胞凋亡。此外，Noxa通过与phop - hsp27相互作用降解I？而抑制活化的NF-？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是否对IFN起核心作用？通过激活ERK1/2和将Bax转运到内质网，诱导细胞死亡和MCM的解决。(2)确定Noxa与磷酸化HSP27交联是否促进NF-？B活化但抑制NF-？从而降低Bcl-2 mRNA的表达，从而增强bik诱导的细胞死亡，并鉴定Noxa-HSP27相互作用的结构域。(3)确定bik诱导的内质网应激是否需要Bax和Bak来解决长时间暴露于过敏原时的MCM。了解这些蛋白在MCM溶解过程中的作用，可以使我们减少哮喘患者体内分泌过多粘液的增生上皮细胞，而不损害静息上皮细胞，从而不损害上皮的屏障功能。减少MCM的靶向方法的发展也可能有助于消除肺癌发展风险增加的患者的肿瘤前细胞。公共卫生相关性。气道中黏液细胞数量的增加会带来严重的风险，因为急性分泌的黏液会减少气流，有时甚至会完全阻塞气道，导致哮喘患者死亡。拟议的研究将剖析在正常小鼠长时间暴露于过敏原时这些黏液细胞正常分解过程的分子序列。了解这些分子过程可能为通过消除增生性黏液细胞来减少黏液分泌提供新的策略。

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.