FUNCTIONAL STUDIES OF HTM4, A CD20/FCE RIB HOMOLOGUE

描述（改编自研究者摘要）：HTm 4是一种新的 发现了造血细胞特异性基因编码4-跨膜 与B细胞特异性抗原CD 20同源的蛋白质，和β亚基 高亲和力IgE Fc受体，FcecRIB。 蛋白质结构 相似性和所有三个基因定位于同一染色体 II qI 2 -13.1区域提供了第一个明显的证据， 4-跨膜蛋白家族。 有数据表明，CD 20是 a Ca 2+通道。 CD 20和HTm 4似乎与 由于FceRIB是形成膜蛋白的复合物的一条链， 肥大细胞上IgE的高亲和力受体， FceRI是由FceRI转导的信号的放大器。 这三个白细胞 蛋白质与基础研究和临床研究高度相关， 应用：抗CD 20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学和生物学数据 表明FceRIB的变体，包括HTm 4，是IgE的一个原因， 响应能力。 我们正在进行遗传关联研究， 与牛津大学的合作，看看HTm 4是否有一个主要的 对特应性和哮喘的影响。 这是一个研究细胞和分子功能的建议， 我们实验室发现了一种新的造血特异性基因，命名为HTm 4。 该基因具有在原始G 0期表达的显著特征， 但在非静止干细胞中被关闭， 处于增殖和分化阶段 HTm 4代码用于一个单元格 与分子相互作用的表面膜蛋白（TRAF蛋白和 KAP）对于两个重要的细胞途径（细胞凋亡/转录）至关重要 激活和细胞周期。 HTm 4激活NF-κ B。 所有这些证据 表明HTm 4是一种新推定受体，其介导重要的 造血干细胞中的信号传导。 HTm 4的作用可能不同， 比在GO造血祖细胞中的细胞周期更长。 我们的目标是 确定HTm 4是否参与干细胞循环和分化， (i)反义寡核苷酸抑制HTm 4在G 0细胞中的表达， 显性阴性策略，使用功能分离的G 0干细胞; (ii)过表达野生型或显性负性HTm 4， CD 34+造血干细胞 我们将进一步调查，看看HTm 4 在（iii）特应性和哮喘中以及在调节细胞凋亡中具有任何作用 计划;及（iv）阐明其与KAP和其他 应用免疫共沉淀技术研究哺乳动物细胞中TRAF相关蛋白。 这一提议不仅将导致关于HTm 4的新发现， 更好地了解一种新的信号通路的新兴重要性， 可能会对免疫疾病的机制及其 治疗

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.