Transcriptional control of IL-7 receptor (IL-7R) in T cells

描述（由申请人提供）：本FIRCA申请代表了美国耶鲁大学Susan Kaech博士和土耳其伊斯坦布尔萨班奇大学Batu Erman博士的合作。具体目标源于授予Kaech博士（AI066232）的父母NIH R01赠款，题为“记忆CD8 T细胞发育的调节”。有效预防传染病是我们今天面临的最关键的全球卫生问题之一，随着世界人口增长到90亿以上，这一问题将继续存在。对许多发展中国家来说，传染病控制或治疗不足是大多数社会经济问题的根源。土耳其国家统计局的网站显示，2004年，4.2%的住院人数和2.5%的死亡人数是由传染病或寄生虫病造成的（www.turkstat.gov.tr）。此外，来自世界卫生组织统计信息系统的最新统计数据表明，土耳其因传染病而损失的寿命年数为44%，而美国为9% （www.who.int/whosis/database）。通过产生长期免疫，疫苗接种为减少传染病的负面影响提供了最大的希望，这种免疫主要基于记忆T细胞和B细胞以及抗体分泌浆细胞的形成。在过去的十年里，我们对这些细胞是如何通过疫苗接种和感染产生的理解以惊人的速度增长，但显然还有很多有待发现。特别地，这个FIRCA提案侧重于通过细胞因子白细胞介素-7 （IL-7）增强我们对幼稚和记忆T细胞发育和稳态的基本理解。幼稚和记忆T细胞的存活依赖于它们通过IL-7受体（IL-7R）“看到”IL-7的能力，而IL-7:IL-7R信号的缺陷会导致严重的免疫缺陷。此外，产生长寿的保护性记忆T细胞需要IL-7R信号传导，在许多慢性病毒感染（如HIV、HCV、EBV）中，抗病毒T细胞通常表达低水平的IL-7R，这可能导致它们的适应性、寿命和抵御感染的能力降低。然而，关于IL-7R在T细胞上表达的转录调控知之甚少。在这里，我们提出表征IL-7R的表观遗传调控，并确定在病毒感染小鼠胸腺T细胞和记忆T细胞发育过程中控制IL-7R表达的关键调控区域和特异性转录因子（tf）。具体来说，我们将描述组蛋白修饰和三个关键tf （GABP1， Gfi-1和NF:B）在Il7ra的三个进化保守区域的结合。此外，我们将使用IL-7R:GFP报告器tg系统测试这些与Il7ra结合的tf在体内激活和抑制转录的需求。长期目标是确定结合这些区域调节IL-7R表达的转录因子。更深入地了解IL-7R表达的分子机制可能会导致操纵T细胞上IL-7R表达的治疗方法，并可能改善感染或疫苗接种期间的免疫功能。公共卫生相关性：有效的传染病疫苗，甚至癌症疫苗依赖于产生强有力的T细胞和B细胞反应，从而产生长期记忆T细胞和B细胞，而IL-7是这些细胞必不可少的存活因子。这项提议的总体目标是了解T细胞如何调节其细胞表面的生存信号IL-7受体（IL-7R）的表达，以便正常发育并持续很长一段时间。我们建议使用一种新的工具，IL-7R:GFP转基因小鼠，来测试在重要发育阶段（当它们从胸腺细胞转移到“激活”记忆T细胞时），体内T细胞中IL-7R的适当表达和抑制对特定基因组元件和转录因子结合位点的需求。这项工作将提供关于T细胞存活和稳态机制的基本信息，并可能导致改进疫苗和T细胞导向疗法，从而增强全世界人类对传染病和癌症的健康。

DESCRIPTION (provided by applicant): This FIRCA application represents a collaboration between Dr. Susan Kaech at Yale University in the US and Dr. Batu Erman at Sabanci University in Istanbul, Turkey. The Specific Aims stem from those of a parent NIH R01 grant awarded to Dr. Kaech (AI066232) entitled "Regulation of Memory CD8 T cell development." Effective protection against infectious disease is one of the most critical global health problems facing us today, and will continue to as the world population grows to more than 9 billion. For many developing countries, inadequate control or treatment of infectious disease is the root of most socio- economic problems. The website of the Turkish State Institute of Statistics indicates that in 2004, 4.2% of all hospitalizations and 2.5% of all mortality resulted from infectious or parasitic diseases (www.turkstat.gov.tr). Moreover, most recent statistics from the World Health Organization Statistical Information Systems indicate that the years of life lost to communicable diseases is 44% in Turkey whereas it is 9% for the U.S. (www.who.int/whosis/database). Vaccination offers the greatest hope for reducing the negative impact of infectious disease by generating long-lived immunity, which is based primarily on the formation of memory T and B cells and antibody-secreting plasma cells. Over the past decade, our understanding of how these cells are generated by vaccination and infection has increased at a profound rate, but clearly much remains to be discovered. In particular, this FIRCA proposal focuses on enhancing our basic understanding of naove and memory T cell development and homeostasis via the cytokine interleukin-7 (IL-7). Naove and memory T cell survival relies on their ability to "see" IL-7 via the IL-7 receptor (IL-7R), and defects in IL-7:IL-7R signaling cause severe immunodeficiency. In addition, generation of long-lived protective memory T cells requires IL-7R signaling and in many chronic viral infections (such as HIV, HCV, EBV) the antiviral T cells often express low levels of IL-7R and this may contribute to their reduced fitness, longevity and ability to stave off the infection. However, little is known about the transcriptional regulation of IL-7R expression on T cells. Here, we propose to characterize the epigenetic regulation of IL-7R and to identify key regulatory regions and specific transcription factors (TFs) that control IL-7R expression during the development of T cells in the thymus and of memory T cells during viral infection in mice. Specifically, we will characterize histone modifications and the binding of three critical TFs (GABP1, Gfi-1 and NF:B) at three evolutionarily conserved regions of Il7ra. Moreover, we will test the requirement of these TFs bound to Il7ra to activate and repress transcription in vivo using an IL-7R:GFP reporter tg system. The long-term goal is to identify the transcription factors that bind to these regions to regulate IL-7R expression. Deeper insight into the molecular mechanism of IL-7R expression could lead to therapies in which IL-7R expression on T cells could be manipulated, and possibly, improve immune function during infection or vaccination. PUBLIC HEALTH RELEVANCE: Effective vaccines against infectious disease, and perhaps, even cancer depend on generating potent T and B cell responses that create long-lived memory T and B cells and IL-7 is an essential survival factor for these cells. The broad goal of this proposal is to understand how T cells regulate the expression of the survival signaling IL-7 receptor (IL-7R) on their cell surfaces in order to properly develop and persist for long periods of time, and here, we propose to test the requirement of specific genomic elements and transcription factor binding sites for proper expression and repression of IL-7R in T cells in vivo during important developmental stages (as they transit from thymocytes`naove`activated`memory T cells) using a novel tool, an IL-7R:GFP reporter transgenic mouse. This work will provide basic information on the mechanisms of T cell survival and homeostasis and could lead to improved vaccines and T cell-oriented therapies that enhance human health worldwide against infectious disease and cancer.