Role of Cul4A in Governing Th2-Type Tolerance

项目摘要/摘要 过敏性疾病的特点是炎症部位Th2细胞的渗透/聚集； 然而，控制不受欢迎的Th2驱动的呼吸道疾病发展的机制很差。 明白了。因此，今天，了解Th2型免疫反应和方式变得越来越明显 控制它们对于治疗过敏性炎症可能被证明是无价的。 最近，我们和其他人一样，已经证明了E3泛素连接酶在T细胞耐受中的作用。 Cullin4A(Cul4A)属于进化上保守的E3连接酶家族，被认为是 参与了造血细胞的激活和染色质的调节；然而，Cul4A在T细胞中的作用 淋巴细胞还没有被解决。有趣的是，在耐受性T中，Cul4A的表达上调 细胞。此外，在耐受条件下，Cul4A基因敲除(KO)的CD4+T细胞在体外和体内都被激活 与野生型细胞相比，表现出更高的增殖水平以及IL-2和IL-4的产生， 提示Cul4A在调节T细胞耐受中起重要作用。令人惊讶的是，我们发现Cul4A KO 效应T细胞和Treg细胞表达更高水平的Th2，但不表达Th1和Th17细胞因子，这与 随着Cul4A KO小鼠血清中IgG1和IgE水平的升高，表明Cul4A在KO小鼠中具有选择性作用 控制炎症性Th2型反应。重要的是，我们检测到在CD4+T细胞中Cul4A的表达减少 哮喘患者的细胞与健康献血者的CD4+T细胞的比较，进一步表明Cul4A 可能有助于诱导呼吸道免疫耐受。此外，Cul4A的shRNA敲除 人类CD4+T细胞可上调Th2特异性细胞因子的表达。基于这些发现，我们 假设Cul4A对Th2型免疫反应的调节可能是一个重要的检查点 在呼吸道耐受诱导中，这对预防过敏性疾病的发展至关重要。 在目标1中，我们建议确定Cul4A通过利用 基因敲除方法和体内外Th2耐受诱导模型。在目标2中，我们将 确定Cul4A在Th2细胞编程中的作用及其潜在机制。我们将聘用 尖端技术，包括双杂交筛选和基因表达微阵列分析，以 确定Cul4A的确切靶点(S)，以确定其在Th2发育中的功能。此外，我们还将评估 Cul4A控制Th2型过敏性哮喘的细胞机制。在目标3中，我们将确定 Cul4A调节Treg功能的机制，特别是在控制Th2炎症方面 回应。这一发现的生理意义将在不同的活体模型中进行分析。 拟议的研究将为描述机制的特征提供新的重要见解 潜在的Cul4A介导的Th2型耐受可能具有治疗意义 过敏性疾病。

PROJECT SUMMARY/ABSTRACT The hallmark of allergic diseases is the infiltration/accumulation of Th2 cells at the sites of inflammation; however the mechanisms governing the development of unwanted Th2-driven airway diseases are poorly understood. Thus, today it is becoming clear that understanding the Th2-type immune responses and ways to control them may prove to be invaluable for the treatment of allergic inflammation. Recently, we as well as others, have demonstrated the role of E3 ubiquitin ligases in T cell tolerance. Cullin4A (Cul4A) belongs to the evolutionally conserved E3 ligase family and has been suggested to be involved in hematopoietic cell activation and in chromatin regulation; however, the role of Cul4A in T lymphocytes has not been addressed yet. Interestingly, expression of Cul4A was upregulated in tolerant T cells. Moreover, Cul4A knockout (KO) CD4+ T cells activated in vitro and in vivo under tolerogenic conditions exhibited an enhanced level of proliferation along with IL-2 and IL-4 production compared to wild-type cells, suggesting an important role of Cul4A in regulation of T cell tolerance. Strikingly, we found that Cul4A KO effector T cells and Treg cells expressed higher levels of Th2 but not Th1 and Th17 cytokines, which correlates with increased levels of IgG1 and IgE in the sera of Cul4A KO mice, indicating the selective role of Cul4A in controlling inflammatory Th2-type responses. Importantly, we detected reduced Cul4A expression in CD4+ T cells from asthmatic patients compared to CD4+ T cells from healthy donors, further indicating that Cul4A potentially contributes to airway immune tolerance induction. In addition, shRNA knockdown of Cul4A in human CD4+ T cells resulted in upregulated expression of Th2-specific cytokines. Based on these findings, we hypothesize that regulation of Th2-type immune responses by Cul4A may be an important checkpoint in airway tolerance induction, which is crucial to prevent development of allergic diseases. In Aim 1, we propose to determine the mechanisms whereby Cul4A controls T cell activation by utilizing gene knockdown approaches and in vitro and in vivo Th2 tolerance induction models. In Aim 2, we will determine the role of Cul4A in Th2 cell programming and its underlying mechanisms as well. We will employ cutting edge technologies, including two-hybrid screening and microarray analysis of gene expression, to identify the exact target(s) of Cul4A to determine its function in Th2 development. In addition, we will assess the cellular mechanisms whereby Cul4A controls Th2 type-driven allergic asthma. In Aim 3, we will determine the mechanism by which Cul4A regulates Treg function, particularly in controlling Th2 inflammatory responses. The physiological significance of this finding will be analyzed in different in vivo models. The proposed research will provide new significant insight into characterization of mechanisms underlying Cul4A-mediated Th2-type tolerance that may potentially have therapeutic implications for allergic diseases.