Expression and Function of Tob in T Lymphocytes

细胞静止是以细胞大小和代谢活性降低为特征的状态。幼稚淋巴细胞的静止减少了维持大量T和B细胞所需的资源、能量和空间。静止也可能保护细胞免受可能导致恶性肿瘤的累积代谢损伤。最近的研究表明，淋巴细胞的静止是一种积极维持的状态，而不是在没有信号的情况下的默认状态。迄今为止鉴定的静止因子代表潜在的肿瘤抑制基因，因为它们的表达或功能的改变有助于淋巴结转移的进展。 恶性肿瘤。因此，了解和加强淋巴细胞静止的策略可能有助于控制白血病和淋巴瘤。最近，我们确定了Tob作为一个基因，介导T淋巴细胞的静止。我们的研究表明Tob mRNA在无反应性细胞中高度表达。Tob mRNA也在未刺激的原代外周血T淋巴细胞中组成型表达，并且在共刺激存在下通过TCR/CD 3在活化期间下调。Tob的强制表达抑制细胞因子和细胞周期蛋白的转录以及T细胞增殖。相反，用反义寡核苷酸抑制Tob可增强CDS介导的反应，并消除最大增殖和细胞因子分泌所需的共刺激。为了了解Tob在完整宿主的免疫应答中的功能作用，我们已经产生了转基因小鼠，其在其T细胞中组成型表达Tob。在体外，Tob-Tg T细胞表现出降低的增殖和增殖抑制。 细胞因子产生。在体内免疫后，Tob-transgenic小鼠表现出降低的初级应答和废除的回忆T细胞应答抗原的挑战。这些结果提供了证据表明，T细胞静止不是一种默认状态，而是一种积极维持的基因程序，必须抑制T细胞活化才能发生。我们的研究结果表明，Tob在维持T细胞静止方面具有关键作用。因此，了解控制Tob表达的整合过程背后的生物化学和逻辑将阐明药物靶标和方法，以更好地调节T细胞免疫应答，用于自身免疫，移植和过敏中的免疫抑制或用于疫苗，慢性感染和癌症中的增强。由于Tob代表了一种潜在的肿瘤抑制因子，而Tob缺陷小鼠会发生恶性淋巴瘤，因此此类研究也可能为淋巴恶性肿瘤的病理生理学提供见解。因此，策略来调节Tob表达可能是有用的控制白血病和淋巴瘤。为了实现这些目标，我提出了三个具体的目标：1）确定调节Tob mRNA表达的机制; 2）确定Tob转录和翻译后调节中涉及的生化信号通路; 3）确定Tob在调节完整宿主中T细胞免疫应答中的作用， 使用转基因小鼠进行Tob.

Cellular quiescence is a state characterized by decreased cell size and metabolic activity. Quiescence in naive lymphocytes acts to reduce the resources, energy and space, required to maintain a vast repertoire of T and B cells. Quiescence might also protect cells from accumulating metabolic damage that could result in malignancy. Recent studies have shown that quiescence in lymphocytes is an actively maintained rather than a default state in the absence of a signal. Quiescence factors identified to date, represent potential tumor suppressor genes because alterations in their expression or function contributes to progression of lymphoid malignancies. Thus, strategies to understand and enforce lymphocyte quiescence might be useful in controlling leukemia and lymphoma. Recently, we identified Tob as a gene that mediates quiescence in T lymphocytes. Our studies showed that Tob mRNA is highly expressed in anergic cells. Tob mRNA is also constitutively expressed in unstimulated, primary, peripheral blood T lymphocytes and is downregulated during activation via TCR/CD3 in the presence of costimulation. Forced expression of Tob inhibits transcription of cytokines and cyclins and T cell proliferation. In contrast, suppression of Tob with antisense oligonucleotide augments CDS-mediated responses and abrogates the requirement of costimulation for maximal proliferation and cytokine secretion. In order to understand the functional role of Tob in the immune response of the intact host, we have generated transgenic mice, which constitutively express Tob in their T cells. In vitro, Tob-Tg T cells display reduced proliferation and cytokine production. After in vivo immunization, Tob-transgenic mice display reduced primary responses and abrogated recall T cells responses to antigenic challenge. These results provide evidence that T cell quiescence is not a default state, but an actively maintained gene program that must be suppressed for T cell activation to occur. Our findings indicate that Tob has a critical role in maintaining T cell quiescence. Thus, understanding the biochemistry and logic behind the integrative processes that control Tob expression will illuminate drug targets and approaches to better regulate T cell immune responses either for immunosuppression in autoimmunity, transplantation and allergy or for augmentation in vaccines, chronic infections and cancer. Because Tob represents a potential tumor suppressor and Tob deficient mice develop malignant lymphomas, such studies might also provide insights to the pathophysiology of lymphoid malignancies. Thus, strategies to regulate Tob expression might be useful in controlling leukemia and lymphoma. To achieve these objectives I propose three specific aims to: 1) Determine the mechanisms that regulate Tob mRNA expression; 2) Determine the biochemical signaling pathways involved in transcriptional and post-translational regulation of Tob; 3) Determine the role of Tob in regulating T cell immune responses in the intact host, by using transgenic mice for Tob.