T-cell Transformation by Oncoviruses

我们工作的主旨是使用人类病毒转化T细胞的体外模型来了解病毒和细胞蛋白在T细胞转化中的作用。在HTLV-I的情况下，我们关注的是一种12kD的病毒蛋白(P12I)，它是一个小的癌基因，与IL-2Rβ和伽马-c链结合。我们已经发现这种相互作用导致STAT5激活的增加(Nicot等人，布拉德，2001)，并假设这种效应在体内可能是重要的。此外，我们已经证明了p12I在自然界中存在于两个等位基因中(在患者样本中发现)：一个在第88位携带赖氨酸，并且是泛素化的，半衰期为半小时；而另一个自然等位基因在第88位携带精氨酸，非常稳定。HTLV-I感染细胞血清中的抗体也能识别p12I。一项新的发现是，p12I与游离的MHC I重链结合，并干扰其与β-2微球蛋白的关联(Johnson等人，J.Virol，2001)。生化研究正在进行中，以了解在p12I存在下MHC I的成熟和运输的变化以及STAT5的激活机制。 此外，最近我们还鉴定了另一种HTLV-I小蛋白p30II的功能。这种蛋白质干扰P53的S功能，与Tax一起可能帮助病毒绕过细胞生长的检查点。我们已经发现，p30II是病毒表达的负调控因子，与p12I一起可能允许感染细胞的扩张。因此，靶向p30II的努力可能被证明是值得进行可能的治疗干预的。 在这一年里，我们还在一只患有塞萨里综合征的猪尾猕猴身上发现了一种新的病毒(HVMNE)。这种病毒和人类EBV一样，在系统发育上属于淋巴病毒。HVMNE是从淋巴瘤CD8+T细胞系中分离出来的，该细胞系从这种疾病动物的血液和皮肤中产生。在兔身上接种HVMNE后，HVMNE会导致高频率的淋巴瘤(Ferrari等人，布拉德，2001)，从而提供了一种淋巴瘤的小动物模型，从而评估治疗方法和T细胞转化所涉及的遗传决定因素，这可能有助于人类淋巴瘤的治疗。

The main thrust of our work is to use in vitro models of transformation of T-cells by human viruses to understand the role of viral and cellular proteins in T-cell transformation. In the case of HTLV-I, we have focused on a viral protein (p12I) of 12 kD, which is a small oncogene and binds to the IL-2R beta and gamma-c chains. We have found that this interaction results in an increase of STAT5 activation (Nicot et al., Blood, 2001) and hypothesized that this effect may be important in vivo. In addition, we have demonstrated that p12I exists in two alleles in nature (found in patient samples): one carries in position 88 a Lysine and is ubiquitinated and has a half-life of a half of an hour whereas the other natural allele carries an Arginine in position 88 and is very stable. p12I also is recognized by antibodies in sera of HTLV-I infected cells. A new finding is that p12I binds to the free MHC I heavy chain and interferes with its association with the beta-2 microglobulin (Johnson et al., J. Virol., 2001). Biochemical studies are in progress to understand the alteration in maturation and trafficking of MHC I in the presence of p12I and the mechanism of STAT5 activation. In addition, very recently we have identified the function of another HTLV-I small protein, p30II. This protein interferes with p53's function and together with Tax may help the virus to circumvent checkpoints of cell growth. We have discovered that p30II is a negative regulator of viral expression and in concert with p12I may allow expansion of infected cells. Thus, efforts to target p30II may prove worthwhile for possible therapeutic intervention. During this year, we also discovered a new virus (HVMNE) in a pig-tailed macaque with Sezary syndrome. This virus, like the human EBV, phylogenetically belongs to the lymphocryptoviruses. HVMNE was isolated from lymphomatous CD8+ T-cell lines, generated from the blood and skin of this diseased animal. Upon inoculation in rabbits, HVMNE causes lymphomas with high frequency (Ferrari et al., Blood, 2001), thus providing a small-animal model for lymphoma whereby to assess therapeutic approaches and the genetic determinants involved in T-cell transformation that may help in the treatment of human lymphoma.