FUNCTIONAL STUDIES OF HTM4, A CD20/FCE RIB HOMOLOGUE

CD20/FCE RIB 同源物 HTM4 的功能研究

• 批准号: 6170580
• 负责人: CHAKAR N ADRA
• 金额: $ 12.18万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6170580
• 关键词: CD antigens; antibody receptor; antisense nucleic acid; apoptosis; asthma; atopy; biological signal transduction; cell communication molecule; cell cycle; cell differentiation; cyclin dependent kinase; cytogenetics; cytokine receptors; gene deletion mutation; gene expression; hematopoiesis; hematopoietic stem cells; human tissue; immunoglobulin E; immunoprecipitation; membrane proteins; phosphoprotein phosphatase; protein structure function; tissue /cell culture; tumor necrosis factor alpha; yeast two hybrid system

DESCRIPTION (Adapted from Investigator's abstract): HTm4 is a newly discovered hematopoietic cell-specific gene encoding a 4-transmembrane protein homologous to the B cell-specific antigen CD20, and the beta-subunit of the high affinity IgE Fc receptor, FcecRIB. Protein structural similarities and the localization of all three genes to the same chromosomal region in II qI2-13.1 provide the first substantial evidence for a distinct family of 4-transmembrane proteins. There are data to suggest that CD20 is a Ca2+ channel. It seems likely that CD20 and HTm4 are associated with membrane proteins since the FceRIB is one chain of the complex which forms the high affinity receptor far IgE on mast cells and functions as an amplifier of signals transduced by the FceRI. These three leucocyte proteins are highly relevant for both basic research and clinical applications: Anti-CD20 antibody is used in clinical trials in the treatment of non-Hodgkin's B-cell lymphoma and genetic and biological data suggest that variants of FceRIB, including HTm4, are one cause of IgE responsiveness. We are conducting genetic association studies, in collaboration with the University of Oxford, to see if HTm4 has a major impact on atopy and asthma. This is a proposal to study the cellular and molecular function of this novel hematopoietic-specific gene identified in our laboratory named HTm4. The gene has the distinctive feature of being expressed in primitive G0 hematopoietic stem cells but is shut off in non-quiescent stem cells that are in the proliferating and differentiating phase. HTm4 codes for a cell surface membrane protein that interacts with molecules (TRAF proteins and KAP) essential to two important cellular pathways, apoptosis/transcriptional activation and cell cycle. HTm4 activates NF-kB. All these evidence indicate that HTm4 is a novel putative receptor that mediates important signaling in hematopoietic stem cells. The role of HTm4 may be different in cycling cells than in GO hematopoietic progenitors. Our aims are to determine if HTm4 is involved in stem cell cycling and differentiation by (i) inhibiting the expression of HTm4 in G0 cells with antisense and dominant negative strategies, using functionally isolated G0 stem cells; (ii) over-expressing wild type or dominant-negative HTm4 in actively cycling CD34+ hematopoietic stem cells. We will further investigate to see if HTm4 has any role in (iii) atopy and asthma and in modulation of the apoptotic program; and (iv) elucidate the nature of its interaction with KAP and other TRAF-related proteins in mammalian cells by coimmunoprecipitation technique. This proposal will not only lead to new findings about HTm4 but also to a better understanding of a novel signaling pathway of emerging importance and likely to fresh insights into mechanisms of immune diseases and their treatment.

描述（改编自研究者的摘要）：HTm4 是一种新的 发现编码4次跨膜的造血细胞特异性基因 与 B 细胞特异性抗原 CD20 和 β 亚基同源的蛋白质 高亲和力 IgE Fc 受体 FcecRIB。 蛋白质结构 所有三个基因在同一染色体上的相似性和定位 II qI2-13.1 中的区域为独特的 4次跨膜蛋白家族。 有数据表明CD20 Ca2+ 通道。 CD20 和 HTm4 似乎可能与 膜蛋白，因为 FceRIB 是形成复合物的一条链 肥大细胞上的高亲和力受体远 IgE 并充当 FceRI 转换信号的放大器。 这三个白细胞 蛋白质与基础研究和临床高度相关 应用：抗CD20抗体用于临床试验 非霍奇金 B 细胞淋巴瘤的治疗以及遗传和生物学数据 表明 FceRIB 的变体（包括 HTm4）是 IgE 的原因之一 反应能力。 我们正在进行遗传关联研究， 与牛津大学合作，看看HTm4是否有专业 对特应性和哮喘的影响。 这是一项研究该细胞和分子功能的提案 我们实验室鉴定出一种新的造血特异性基因，名为 HTm4。 该基因具有在原始G0中表达的显着特征 造血干细胞，但在非静止干细胞中被关闭 正处于增殖和分化阶段。 单元格的 HTm4 代码 与分子相互作用的表面膜蛋白（TRAF 蛋白和 KAP）对于细胞凋亡/转录这两个重要的细胞途径至关重要 激活和细胞周期。 HTm4 激活 NF-kB。 所有这些证据 表明 HTm4 是一种新的假定受体，介导重要的 造血干细胞中的信号传导。 HTm4 的作用可能有所不同 循环细胞比 GO 造血祖细胞。 我们的目标是 确定 HTm4 是否参与干细胞循环和分化 (i)用反义和抑制G0细胞中HTm4的表达 显性失活策略，使用功能分离的 G0 干细胞； (ii) 在活跃循环中过度表达野生型或显性失活 HTm4 CD34+ 造血干细胞。 我们将进一步调查HTm4是否 在 (iii) 特应性和哮喘以及细胞凋亡的调节中具有任何作用 程序; (iv) 阐明其与 KAP 和其他机构相互作用的性质 通过免疫共沉淀技术检测哺乳动物细胞中的 TRAF 相关蛋白。 该提案不仅将带来关于 HTm4 的新发现，而且还将带来 更好地理解具有新兴重要性的新型信号通路 可能对免疫疾病及其机制有新的见解 治疗。