IDENTIFICATION & CHARACTERIZATION OF IL-10 RELATED GENES

鉴别

• 批准号: 6436327
• 负责人: R. P DONNELLY
• 金额: --
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6436327
• 关键词: biological signal transduction; cytokine receptors; endotoxins; gene induction /repression; interferon gamma; interleukin 1; interleukin 10; interleukin 4; leukocyte activation /transformation; monocyte; protein biosynthesis; tissue /cell culture; tumor necrosis factor alpha

Activation of human monocytes by bacterial endotoxin, lipopolysaccharide (LPS), induces expression of many cytokines, including tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6 and IL-10. IL-10 expression is delayed relative to that of TNF, IL-1 and IL-6. Furthermore, IL-10 feedback inhibits expression of TNF, IL-1 and IL-6, thus providing an efficient autocrine mechanism for controlling proinflammatory cytokine production in monocytes. In this project, we are examining the mechanism by which IL-10 down-regulates production of cytokines such as TNF and IL-1 in endotoxin-stimulated monocytes. We are also evaluating the effects of IL-10 on signal transduction events that are activated by cytokines such as IFN-gamma (IFN-g) and IL-4. We have found that IL-10 inhibits activation and gene expression induced by IL-4 and IFN-gamma. We have also determined that the ability of IL-10 to inhibit IL-4-inducible gene expression is a consequence of decreased tyrosine phosphorylation and nuclear translocation of the IL-4-inducible transcription factor, STAT6. We are now examining the role of a novel family of JAK/STAT inhibitory genes, the Suppressors of Cytokine Signaling (SOCS) genes, in mediating these IL-10-inducible inhibitory effects. We have found that IL-10 selectively induces expression of one member of this newly identified gene family, SOCS-3. Forced expression of SOCS-3 in a macrophage cell line markedly inhibits induction of STAT activity by several cytokines, including IFN-gamma, GM-CSF and IL-4. Therefore, the ability of IL-10 to antagonize cytokine-inducible gene expression appears to be associated with its ability to induce rapid expression of the SOCS-3 gene. In related studies, we are also examining the biological activities of several newly identified IL-10 homologues. One of these, IL-19, shares approximately 21% amino acid homology with IL-10, and may utilize at least one of the two receptor chains that form the functional IL-10 receptor complex. We have found that expression of the IL-19 gene is upregulated by many of the same agents that induce IL-10 gene expression in monocytes. However, unlike the IL-10 gene, IL-19 is not expressed in activated T cells. Another IL-10 homologue, IL-TIF (IL-10-related T cell-derived inducible factor), has also recently been described. Together with scientists at the University of Medicine & Dentistry of New Jersey (UMDNJ), we have identified and characterized the gene encoding the ligand-binding chain of the receptor for this novel IL-10-related cytokine, IL-TIF. This receptor chain heterodimerizes with the IL-10R-beta chain (IL-10R2) to form a functional IL-TIF receptor complex. Therefore, IL-10R2 is component of both the IL-10 and IL-TIF receptors. We have recently found that the IL-TIF receptor is expressed at high levels in liver and kidney, but not in hematopoietic tissues such as the spleen and thymus. This suggests a possible functional role for this receptor in regulating gene expression in these tissues.

细菌内毒素脂多糖 (LPS) 激活人类单核细胞，诱导许多细胞因子的表达，包括肿瘤坏死因子 (TNF)、白介素-1 (IL-1)、IL-6 和 IL-10。 IL-10 的表达相对于 TNF、IL-1 和 IL-6 延迟。 此外，IL-10反馈抑制TNF、IL-1和IL-6的表达，从而为控制单核细胞中促炎细胞因子的产生提供有效的自分泌机制。 在这个项目中，我们正在研究 IL-10 下调内毒素刺激的单核细胞中细胞因子（例如 TNF 和 IL-1）产生的机制。 我们还在评估 IL-10 对 IFN-gamma (IFN-g) 和 IL-4 等细胞因子激活的信号转导事件的影响。 我们发现 IL-10 抑制 IL-4 和 IFN-γ 诱导的激活和基因表达。 我们还确定，IL-10 抑制 IL-4 诱导型基因表达的能力是酪氨酸磷酸化减少和 IL-4 诱导型转录因子 STAT6 核易位的结果。 我们现在正在研究一个新的 JAK/STAT 抑制基因家族，即细胞因子信号传导抑制因子 (SOCS) 基因，在介导这些 IL-10 诱导的抑制作用中的作用。 我们发现 IL-10 选择性诱导这一新鉴定的基因家族成员 SOCS-3 的表达。 SOCS-3 在巨噬细胞系中的强制表达可显着抑制多种细胞因子（包括 IFN-γ、GM-CSF 和 IL-4）诱导的 STAT 活性。 因此，IL-10拮抗细胞因子诱导基因表达的能力似乎与其诱导SOCS-3基因快速表达的能力相关。 在相关研究中，我们还研究了几种新鉴定的IL-10同系物的生物活性。 其中之一，IL-19，与 IL-10 具有大约 21% 的氨基酸同源性，并且可以利用形成功能性 IL-10 受体复合物的两条受体链中的至少一条。 我们发现，许多诱导单核细胞中 IL-10 基因表达的相同试剂上调了 IL-19 基因的表达。 然而，与 IL-10 基因不同，IL-19 在活化的 T 细胞中不表达。 最近还描述了另一种 IL-10 同源物 IL-TIF（IL-10 相关 T 细胞衍生诱导因子）。 我们与新泽西医学与牙科大学 (UMDNJ) 的科学家一起，鉴定并表征了编码这种新型 IL-10 相关细胞因子 IL-TIF 受体配体结合链的基因。 该受体链与 IL-10R-β 链 (IL-10R2) 异二聚化，形成功能性 IL-TIF 受体复合物。 因此，IL-10R2 是 IL-10 和 IL-TIF 受体的组成部分。 我们最近发现IL-TIF受体在肝脏和肾脏中高水平表达，但在脾脏和胸腺等造血组织中不表达。 这表明该受体在调节这些组织中的基因表达中可能发挥功能作用。