Formins (FHOS) in CD21-mediated signaling & virus entry

CD21 介导的信号传导中的福尔明 (FHOS)

• 批准号: 6870631
• 负责人: JOYCE DIANE FINGEROTH
• 金额: $ 38.25万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6870631
• 关键词: CD19 molecule; Epstein Barr virus; actin binding protein; aminoacid; autoimmune disorder; binding proteins; biological signal transduction; human tissue; immunologic receptors; immunoregulation; infection; intermolecular interaction; laboratory rabbit; neoplasm /cancer; polymerization; protein structure function; receptor binding; receptor expression; virus infection mechanism

DESCRIPTION (provided by applicant): Human CD21 is an innate immune system receptor (C3dg receptor or complement receptor type 2, CR2) and is a key modulator of the acquired immune response. CD21 is also the high affinity receptor for EBV. CD21 plays a direct role in the pathogenesis of a broad spectrum of human disease, including autoimmune disease, infectious disease (EBV and HIV) and cancer. On B cells, CD21 complexes with the major signal transduction regulator CD19, and it is controversial whether CD21 can signal independently of CD19. Although CD21 was identified more than 20 years ago and distinct roles as an attachment protein for C3dg, CD23 and EBV have been discovered, the precise mechanisms enabling CD21 to directly relay information between the exterior and the interior of the cell are unresolved. In Preliminary Studies, FHOS/FHQD a member of the formin family, was found to bind the cytoplasmic domain of human CD21 both in vitro and in vivo. When expressed in epithelial cells (CD19 negative), EGFP-FHOS localized to the cytoplasm and accumulated with actin in membrane protrusions. Remarkably, when CD21 on epithelial cells was ligated with either EBV or anti-CD21, FHOS translocated to the plasma membrane, where it co-localized in aggregates with CD21. Formins are scaffolding proteins that regulate cell polarity and morphogenesis by linking signal transduction to cytoskeletal rearrangement and gene transcription. Recently, formins were discovered to directly nucleate actin by a pathway distinct from the classic Arp 2,3 complex. Based on these observations it is proposed that ligand stimulation of CD21-FHOS interaction transduces intracellular signals through a pathway directed by formin (FHOSV-mediated cytoskeletal reorganization). The goals of Aim I are to identify the amino acid residues that mediate interaction between CD21 and FHOS and to screen for novel FHOS/CD21-binding proteins as potential downstream effectors of this pathway. Aim II is focused on determining whether FHOS directly nucleates actin, and assessing the role of CD21 in FHOS activation, actin polymerization, and signaling. The goals of Aim III are to isolate and characterize the splenic littoral cell, a specialized cell abundant in human red pulp that highly expresses FHOS, CD21 and is believed to function in antigen filtration. Achievement of these Aims will provide important new knowledge about how CD21 signals and will elucidate the role(s) of the recently discovered formin protein, FHOS, in the immune system. These investigations may lead to identification of novel targets for treatment of autoimmune disease and cancer, for development of vaccines and for eradication of persistent viral and bacterial pathogens that are sequestered by CD21.

描述（由申请人提供）：人CD21是先天免疫系统受体（C3DG受体或补体受体2型，CR2），是获得的免疫反应的关键调节剂。 CD21也是EBV的高亲和力受体。 CD21在广泛的人类疾病的发病机理中起着直接的作用，包括自身免疫性疾病，传染病（EBV和HIV）和癌症。 在B细胞上，具有主要信号转导调节剂CD19的CD21复合物，CD21是否可以独立于CD19发出信号是有争议的。 尽管已经发现了CD21，并且已经发现了C3DG，CD23和EBV的附着蛋白的独特作用，但可以在细胞内部和内部之间直接中继CD21直接中继信息的精确机制。在初步研究中，发现FHOS/FHQD是formin家族的成员，可以在体外和体内结合人CD21的细胞质结构域。 当在上皮细胞（CD19阴性）中表达时，EGFP-FHOS局部局部在细胞质中，并用肌动蛋白在膜突起中积聚。值得注意的是，当将上皮细胞上的CD21与EBV或抗CD21连接时，FHOS转移到质膜上，在该质膜中，它与CD21共定位在聚集体中。 造型是脚手架蛋白，通过将信号转导与细胞骨架重排和基因转录联系起来来调节细胞极性和形态发生。 最近，发现formins是通过与经典ARP 2,3复合物不同的途径直接核定肌动蛋白的。 基于这些观察结果，提出配体刺激CD21-FHOS相互作用通过fomin（FHOSV介导的细胞骨架重组）指导的途径传递细胞内信号。目标I的目标是确定介导CD21与FHO之间相互作用的氨基酸残基，并筛选出新型FHOS/CD21结合蛋白作为该途径的潜在下游效应子。 AIM II的重点是确定FHOS是否直接核定肌动蛋白，并评估CD21在FHOS激活，肌动蛋白聚合和信号传导中的作用。 AIM III的目标是隔离和表征脾沿岸细胞，脾斜线细胞有足够的人类红色纸浆，高表达FHOS CD21，并被认为在抗原过滤中起作用。这些目标的实现将提供有关CD21信号的重要新知识，并将如何阐明最近发现的folly蛋白FHOS在免疫系统中的作用。这些研究可能导致鉴定出用于治疗自身免疫性疾病和癌症的新靶标，用于开发疫苗以及消除被CD21隔离的持续性病毒和细菌病原体。