MAST CELL-SPECIFIC REGULATION OF IL-4 GENE EXPRESSION

白介素4(IL-4)是一种强大的免疫调节细胞因子，具有 对多个靶细胞的影响极为不同。IL-4扮演着一个 在造血细胞生长和发育中的重要生理作用 分化、肿瘤监视与局部保护性炎症 回应。然而，失调的IL-4产生已被证明具有 极其有害的影响。病理情况，如特应性 疾病和无法解决某些寄生虫感染 显然与IL-4的过度生产有关。IL-4最初是 被定义为T细胞因子，但现在很清楚，肥大细胞是 也是产生IL-4的重要细胞。肥大细胞分布广泛 在许多IL-4靶细胞附近的血管组织中。 这个位置为肥大细胞来源的IL-4提供了机会 轻松访问这样的细胞并有效地调制广泛的局部 炎症反应。由于其独特的组织分布 肥大细胞，因此肥大细胞衍生的潜在不同功能 IL-4对局部炎症反应的作用机制被预测 在肥大细胞中调节IL-4基因表达的哪种方式与 T细胞中的那些。 最近的研究证实了这一预测。事实证明， 存在调节IL-4基因的独特顺式作用序列 T细胞和肥大细胞的转录。组织特异性的主要成分 肥大细胞中的转录活性似乎包含在一个 IL-4基因第二内含子的序列。这个序列展示了 肥大细胞系中的原型增强子活性及其活性 依赖于正向和负向调控的相互作用 元素。这项建议的具体目标是：1.确定 构成IL-4的基本正负作用序列 内含子增强剂。2.鉴定DNA结合蛋白 具体管理IL-4内含子增强子的功能和 确定它们在肥大细胞和细胞中的表达和结合动力学 其他血统的人。3.检查新隔离的桅杆种群 细胞在刺激下表达IL-4的能力，并分析 肥大细胞特异性转录因子在这些细胞中的表达。 4.确定IL-4内含子增强子如何与其他IL-4相互作用 调节肥大细胞中IL-4表达的调控序列。DNA- 蛋白质结合分析和反应元件-报告基因构建 将使用与瞬时转染分析相结合的方法来完成 这些目标。了解组织特异性的分子基础 对肥大细胞的调节是最终实现 设计有选择地限制或增强的治疗策略 过敏性疾病中肥大细胞或T细胞来源的IL-4活性 黑色素瘤等肿瘤的免疫治疗。

Interleukin 4 (IL-4) is a potent immunoregulatory cytokine with extremely diverse effects on a number of target cells. IL-4 plays an important physiologic role in hematopoietic cell growth and differentiation, tumor surveillance and local protective inflammatory responses. However, dysregulated IL-4 production has been shown to have extremely detrimental effects. Pathological conditions such as atopic disease and inability to resolve certain parasitic infections are clearly associated with overproduction of IL-4. IL-4 was originally defined as a T cell cytokine, but it is now clear that mast cells are also important IL-4 producing cells. Mast cells are widely distributed in vascularized tissues in the proximity of many IL-4 target cells. This location provides the opportunity for mast cell-derived IL-4 to easily access such cells and effectively modulate a wide range of local inflammatory responses. Because of the unique tissue distribution of mast cells and thus potentially distinct functions of mast cell-derived IL-4 on local inflammatory responses, it was predicted that mechanisms which regulate IL-4 gene expression in mast cells would differ from those in T cells. Recent studies have confirmed this prediction. It was demonstrated that there are unique cis acting sequences which regulate IL-4 gene transcription in T and mast cells. A major component of tissue-specific transcriptional activity in mast cells appears to be contained in a sequence in the second intron of the IL-4 gene. This sequence exhibits prototypic enhancer activity in mast cell lines and its activity is dependent on the interaction of both positive and negative regulatory elements. The specific aims of this proposal are: 1. To identify essential positive and negative acting-sequences that comprise the IL-4 intronic enhancer. 2. To identify DNA binding proteins which specifically govern the function of the IL-4 intronic enhancer and determine their expression and binding dynamics in mast cells and cells of other lineages. 3. To examine populations of freshly isolated mast cells for their ability to express IL-4 upon stimulation and analyze the expression of mast cell specific transcription factors in these cells. 4. To determine how the IL-4 intronic enhancer interacts with other IL-4 regulatory sequences to modulate IL-4 expression in mast cells. DNA- protein binding assays and response element-reporter gene constructs in concert with transient transfection assays will be used to accomplish these aims. Understanding the molecular basis for tissue specific regulation in mast cells is an important first step in ultimately devising therapeutic strategies for selectively limiting or augmenting mast cell or T cell-derived IL-4 activity in allergic disease or immunotherapy of tumors such as melanoma.