Pathways that Regulate Antigrowth Effects of Interferons

1型干扰素是天然免疫和抗病毒反应的关键调节剂。施展他们的行动 它们通常也会抑制细胞生长。干扰素抑制细胞增殖的机制各不相同 许多情况还没有得到很好的理解。在某些细胞中，1型干扰素(干扰素/13)可诱导细胞凋亡； 其他细胞系IFNod_在不诱导细胞凋亡的情况下抑制细胞生长，在某些情况下 细胞因子实际上通过其他刺激来阻止细胞凋亡。在体内和在细胞培养中，干扰素_T3刺激细胞凋亡 未成熟的B细胞。基因敲除小鼠依赖BLL-7 B细胞的初步结果 STAT1、STAT1、STAT5a/b或TYK2表达表明干扰素激活了受调控早期反应基因 转录因子STAT1和STAT2对IFNcdl3的促凋亡作用不是必需的。然而， 酪氨酸激酶TYK2的表达是IFNodl3刺激ProB细胞死亡所必需的，以及 这些细胞因子激活STAT3。这些体外结果在体内也可以看到，TYK2基因缺失的小鼠 抵抗巨细胞病毒刺激的B细胞从骨髓和脾的损失。我们假设干扰素_ 介导的细胞凋亡需要TYK2的激酶活性，导致酪氨酸磷酸化。 STAT3及其转录因子对导致ProB细胞程序性死亡的基因调控 细胞。 具体目标是： 1.确定干扰素诱导IL-7依赖的骨细胞凋亡所需的TYK2结构域 骨髓来源的B细胞。 2.确定磷酸化STAT3在IFNI刺激的B细胞PCD中的作用 3.确定依赖IL-7的原代B细胞中需要TYK2表达的蛋白质 激活STAT3，引起IFNI刺激的细胞凋亡。

Type 1 interferons are critical regulators of innate immunity and antiviral responses. To exert their actions they often also inhibit cell growth. The mechanisms by which interferons inhibit cell proliferation vary and in many circumstances are not well understood. In some cells type 1 interferons (IFN_/13) induce apoptosis; in other cell lines IFNod_ inhibit cell growth without induction of apoptosis, and in certain circumstances these cytokines actually prevent apoptosis by other stimuli. In vivo and in cell culture, IFN_t3 stimulates apoptosis of immature B cells. Preliminary results using bll-7-dependent B cells from knock out mice that do not express Statl, Statl, Stat5a/b, or Tyk2 indicate that interferon activation of early response genes regulated by the Statl and Stat2 transcription factors is not necessary for the apoptotic actions of IFNcdl3. However, expression of the tyrosine kinase Tyk2 is required for IFNodl3 stimulated death of pro B cells as well as activation of Stat3 by these cytokines. These in vitro results are also seen in vivo where Tyk2-null mice are resistant to LCMV stimulated loss of B cells from bone marrow and spleen. We hypothesize that IFN_ mediated apoptosis requires the kinase activity of Tyk2, resulting in tyrosine phosphorylation of Stat3 and regulation of genes by this transcription factor that lead to programmed cell death of pro B cells. The Specific Aims are: 1. Determine the domains in Tyk2 required for IFN_ stimulated apoptosis of IL-7-dependent bone marrow-derived B cells. 2. Determine the role of phosphorylated Stat3 in IFNI_ stimulated PCD of B cells 3. Identify proteins in primary IL-7 dependent B cells that require the expression of Tyk2 to activate Stat3 and cause IFNI_ stimulated apoptosis.