The Role of Src Family Kinase Lck in Th2 Differentiation

描述(申请人提供)：控制T辅助细胞分化为Th1和Th2谱系的机制尚不完全清楚。这些研究探讨了SRC家族激酶Lck在Th2分化中的作用。Th2细胞分泌抗炎细胞因子IL-4、IL-5、IL-10和IL-13，并介导对细胞外病原体的保护。已知Th1细胞产生促炎细胞因子干扰素-γ和肿瘤坏死因子-α，并介导对细胞内病原体的保护。必须保持Th1和Th2谱系之间的平衡，因为TM或Th2效应器谱系发育不当可能导致疾病。Th2细胞因子分为两个遗传位点。细胞因子IL-5、IL-13和IL-4被连接在被称为Th2细胞因子的区域，而IL-10在基因组的其他地方被发现。GATA-3控制这些细胞因子的表达，尽管其作用机制因基因座不同而不同。过去的研究表明LCK在Th2分化和/或功能中起作用，但这些研究并没有确定LCK的作用机制。LCK缺陷的Th2细胞有少量或不表达Th2细胞因子IL-4，正常表达IL-10，并合成Th1细胞因子干扰素-γ。初步研究表明，LCK缺陷的Th2偏斜细胞不适当地表达Th1特异性转录因子T-bet，并降低了Th2特异性转录因子GATA-3的表达。因为IL-10的产生在突变体中是正常的，这种缺陷可能是Th2细胞因子基因所特有的。我们推测，Lck通过维持GATA-3的表达来介导完整的Th2谱系承诺，而在缺乏Lck的情况下，GATA-3通过T-bet的异位表达而受到抑制，导致Th2效应功能的缺陷，这是由于Th2细胞因子基因座上发现的细胞因子表达缺陷所致。这些研究将集中在两个领域。第一个目标将确定是否需要LCK来表达与Th2细胞因子基因相关的所有细胞因子，还是只需要IL-4。第二个目的将确定在缺乏Lck的情况下，异位T-bet是否抑制GATA-3的表达。已有研究表明，T-bet过表达时可抑制GATA-3的表达和功能。这些研究将为控制T辅助细胞分化的机制提供洞察力。与公共卫生相关：在过去的几十年里，Th2介导的疾病，如哮喘和过敏的比率迅速上升。需要更多地了解控制Th1和Th2分化的因素，如LCK。这些研究将有助于阐明Th2分化的机制，并有可能导致Th2介导性疾病的治疗，如过敏和哮喘。

DESCRIPTION (provided by applicant): The mechanisms controlling T helper differentiation into the Th1 and Th2 lineages are not fully understood. These studies investigate the role of the SRC-family kinase Lck in Th2 differentiation. Th2 cells secrete anti-inflammatory cytokines IL-4, IL-5, IL-10, and IL-13 and mediate protection against extracellular pathogens. Th1 cells are known to produce pro-inflammatory cytokines IFN-y and TNF-a and mediate protection against intracellular pathogens. The balance between the Th1 and Th2 lineages must be maintained, because improper development of TM or Th2 effector lineages can lead to disease. Th2 cytokines are grouped into two genetic loci. The cytokines IL-5, IL-13, and IL-4 are linked in what is referred to as the Th2 cytokine locus, while IL-10 is found elsewhere in the genome. GATA-3 controls the expression of these cytokines, although the mechanism differs depending on the locus. Past studies have suggested that Lck plays a role in Th2 differentiation and/or function, but these studies did not determine the mechanism by which Lck functions. Lck deficient Th2 skewed cells have little to no expression of the Th2 cytokine IL-4, normal IL-10 expression, and synthesize the Th1 cytokine IFN-y. Preliminary studies indicate that Lck deficient Th2 skewed cells inappropriately express Th1 specific transcription factor T-bet, and have reduced expression of Th2 specific transcription factor GATA-3. Because IL-10 production is normal in the mutants, the defect may be specific for the Th2 cytokine locus. We hypothesize that Lck mediates full Th2 lineage commitment via maintenance of GATA-3 expression, and in the absence of Lck, GATA-3 is inhibited through ectopic expression of T-bet, resulting in a defect in Th2 effector functions due to defective expression of cytokines found at theTh2 cytokine locus. These studies will focus on two areas. The first aim will determine if Lck is required for expression of all cytokines associated with the Th2 cytokine locus or only IL-4. The second aim will determine if ectopic T-bet inhibits GATA-3 expression in the absence of Lck. T-bet has been shown to inhibit GATA-3 expression and function when overexpressed. These studies will provide insight into the mechanisms that control T helper differentiation. PUBLIC HEALTH RELEVANCE: The rates of Th2 mediated disorders, such as asthma and allergy, have increased rapidly in past decades. A greater understanding of the factors that control Th1 and Th2 differentiation, such as Lck, is needed. These studies will help elucidate the mechanisms that mediate Th2 differentiation and potentially lead to treatments of Th2 mediate diseases, such as allergy and asthma.