Control of T Lymphopoiesis and Growth by Mad Genes

抗原激活的淋巴细胞，或白血病中的转化淋巴细胞，必须加倍其大小， 在它们可以分裂成相等大小的子细胞之前，它们的内容物（称为细胞生长）。尽管重要性 在正常细胞增殖和癌症中，控制细胞生长的分子事件 淋巴细胞或其它哺乳动物细胞仍然是个谜。我们对小鼠的初步研究表明， Mad碱性螺旋-环-螺旋转录因子家族（Mad 1、Mxil、Mad 3、Mad 4），被认为是 Myc癌蛋白的拮抗剂，部分通过抑制T细胞增殖和发育， 增长此外，人mad 1和mxil基因各自定位于不同的染色体区域 与淋巴细胞白血病、霍奇金病和前列腺癌相关， mad基因在淋巴细胞生物学和癌症中重要性。这项建议的主要目标是 确定Mad家族成员在发育中的正常作用和作用机制， 具体而言，我们打算：（1）检验Mad家族成员 调节T淋巴细胞的成熟。我们将研究疯狂的家庭成员在T 淋巴细胞的发育，采用选定的Mad的靶向缺失和转基因过表达， 老鼠的家庭成员(2)检验Mad家族成员控制细胞增殖和细胞凋亡的假设。 在T细胞活化期间T淋巴细胞的生长（细胞大小、蛋白质合成）。我们将研究功能 Mad过表达或缺失对细胞分裂、细胞大小、RNA加工和蛋白质合成的影响 活化后立即在原代淋巴细胞中合成。(3)检验一下假设， 结合并调节参与细胞生长控制的必需基因的表达。我们将确定是否 Mad 1抑制参与细胞生长控制的几个必需基因的表达。然后我们将使用 染色质免疫沉淀试验，以确定这些基因的调控区是否直接 被疯狂的蛋白质所束缚总之，这些目标将测试总体假设，疯狂麦克斯复杂 正常情况下，通过控制生长因子的表达来部分调节淋巴细胞增殖和发育。 regulatina aenes.这些研究的结果将确定可以操纵的靶基因， Myc和Mad之间的平衡，以抑制淋巴瘤或自身免疫中的淋巴细胞增殖 疾病，或在初次免疫应答中增强抗原特异性淋巴细胞的克隆扩增，或 9例接受骨髓移植。

Antigen-activated lymphocytes, or transformed lymphocytes in leukemias, must double their size and contents (termed cell growth) before they can divide into equal sized daughter cells. Despite the importance of cell growth in normal cell proliferation and cancer, the molecular events that control cell growth in dividing lymphocytes or other mammalian cells remain an enigma. Our preliminary studies in mice suggest that the Mad family of basic helix-loop-helix transcription factors (Mad1, Mxil, Mad3, Mad4), considered to be antagonists of the Myc oncoprotein, inhibit T cell proliferation and development in part by inhibiting cell growth. Furthermore, human mad1 and mxil genes each localize to separate chromosome regions associated with lymphocytic leukemias, Hodgkin's disease, and prostatic carcinomas suggesting the importance of mad genes in lymphocyte biology and cancer. The broad objective of this proposal is to determine the normal roles and mechanism of action of Mad family members in the development and expansion of T Iymphocytes Specifically, we intend to: (1) Test the hypothesis that Mad family members modulate the maturation of T lymphocytes. We will examine the role(s) of Mad family members in T lymphocyte development by employing targeted deletion, and transgenic overexpression, of selected Mad family members in mice. (2) Test the hypothesis that Mad family members control the proliferation and cell growth (cell size, protein synthesis) of T Iymphocytes during T cell activation. We will examine the functional consequences of Mad overexpression or loss on cell division, cell size, RNA processing, and protein synthesis in primary lymphocytes immediately following activation. (3) Test the hypothesis that Mad directly binds and modulates the expression of essential genes involved in cell growth control. We will determine if Mad1 inhibits the expression of several essential genes involved in cell growth control. We will then use chromatin immunoprecipitation assays to determine if the regulatory regions of these genes are directly bound by Mad proteins. Together, these aims will test the overall hypothesis that Mad-Max complexes normally modulate lymphocyte proliferation and development in part by controllinq the expression of .qrowth- regulatina aenes. Results of these studies will identify target genes that could be manipulated to regulate the balance between Myc and Mad in order to inhibit lymphocyte proliferation in lymphomas or autoimmune disease, or to enhance clonal expansion of antigen-specific lymphocytes in a primary immune response, or followin 9 bone marrow transplantation.