Pathways that Regulate Antigrowth Effects of Interferons

描述(申请人提供)：1型干扰素是天然免疫和抗病毒反应的关键调节器。为了发挥它们的作用，它们通常还会抑制细胞生长。干扰素抑制细胞增殖的机制各不相同，在许多情况下还不清楚。在某些细胞中，1型干扰素(IFNα/β)可诱导细胞凋亡；在其他细胞系中，IFNα/β可抑制细胞生长而不诱导细胞凋亡，在某些情况下，这些细胞因子实际上可通过其他刺激来阻止细胞凋亡。在体内和细胞培养中，IFNα/β刺激未成熟B细胞的凋亡。用不表达STAT1、STAT1、Stat5a/b或TYK2的敲除小鼠的依赖于bll-7的B细胞的初步结果表明，受STAT1和Stat2转录因子调控的早期反应基因的干扰素激活对于IFNA/a的凋亡作用并不是必需的。然而，酪氨酸激酶TYK2的表达是IFNalkpha/beta刺激的ProB细胞死亡以及这些细胞因子激活STAT3所必需的。这些体外结果在体内也可以看到，TYK2基因缺失的小鼠对LCMV刺激的骨髓和脾B细胞损失具有抵抗力。我们假设，IFNα/β介导的细胞凋亡需要TYK2的活性，导致Stat3的酪氨酸磷酸化，并由该转录因子调节基因，从而导致ProB细胞的程序性死亡。 具体目标是： 1.确定TYK2中的哪些结构域是IFNBeta刺激依赖IL-7的骨髓源性B细胞凋亡所必需的。 2.确定磷酸化STAT3在IFNBeta刺激的B细胞PCD中的作用 3.鉴定依赖IL-7的原代B细胞中需要TYK2表达以激活STAT3并导致IFNBeta刺激的细胞凋亡的蛋白质。

DESCRIPTION (provided by applicant): 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 (IFNalpha/beta) induce apoptosis; in other cell lines IFNalpha/beta 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, IFNalpha/beta stimulates apoptosis of immature B cells. Preliminary results using bll-7-dependent B cells from knock out mice that do not express Stat1, Stat1, Stat5a/b, or Tyk2 indicate that interferon activation of early response genes regulated by the Stat1 and Stat2 transcription factors is not necessary for the apoptotic actions of IFNa/a. However, expression of the tyrosine kinase Tyk2 is required for IFNalkpha/beta 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 IFNalpha/beta mediated apoptosis requires the kinase activity of Tyk2, resulting in tyrosine phosphorylation ofStat3 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 IFNBeta stimulated apoptosis of IL-7-dependent bone marrow-derived B cells. 2. Determine the role of phosphorylated Stat3 in IFNBeta 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 IFNBeta stimulated apoptosis.