Genetic and Immunological Impact of the HRES-1/Rab4 Locus in SLE

HRES-1/Rab4 位点对 SLE 的遗传和免疫学影响

• 批准号: 7741046
• 负责人: Andras Perl
• 金额: $ 31.4万
• 依托单位: UPSTATE MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7741046
• 关键词: 1q41; 1q42; 1q43; Alleles; Appearance; Autoantibodies; Autoimmunity; B-Lymphocytes; Binding; Biological Assay; CD3 Antigens; CD4 Antigens; Candidate Disease Gene; Case-Control Studies; Caucasians; Caucasoid Race; Cell surface; Chimeric Proteins; Chloroquine; Chromosomes, Human, Pair 1; Chronic; Complex; Confocal Microscopy; DNA Binding; Data; Databases; Dendritic Cells; Development; Disease; Dominant-Negative Mutation; Endogenous Retroviruses; Endosomes; Enhancers; Enterotoxins; Environmental Risk Factor; Family; Flare; Frequencies; Functional disorder; GTP Binding; Gene Expression; Genes; Genetic; Genetic Polymorphism; Genetic Transcription; Genetic Variation; Genus staphylococcus; Guanosine Triphosphate Phosphohydrolases; HERVs; Haplotypes; Human; Human Genetics; IRF1 gene; Immune system; Immunoprecipitation; Inflammatory; Inherited; Jurkat Cells; Lead; Life; Link; Long Terminal Repeats; Lupus; MHC Class II Genes; Maps; Membrane; Membrane Microdomains; Microsatellite Repeats; Monomeric GTP-Binding Proteins; Nucleotides; Onset of illness; Organelles; Other Genetics; Patients; Peptides; Peripheral Blood Lymphocyte; Play; Polymorphism Analysis; Predisposition; Production; Proteins; Recycling; Rheumatoid Arthritis; Role; Single Nucleotide Polymorphism; Site; Small Interfering RNA; Superantigens; Surface; Synapses; Systemic Lupus Erythematosus; T-Cell Activation; T-Lymphocyte; Testing; Time; Toxic Shock Syndrome Toxin-1; Transcript; Transcriptional Activation; Transducers; Transfection; Transferrin Receptor; Variant; Virus; Western Blotting; ZAP-70 Gene; abstracting; base; chromatin immunoprecipitation; functional outcomes; immunological synapse; immunological synapse formation; inhibitor/antagonist; peripheral blood; promoter; public health relevance; rab4A Protein; receptor; research study; response; segregation; trafficking; transcription factor

DESCRIPTION (provided by applicant): ABSTRACT Systemic lupus erythematosus (SLE) is a chronic inflammatory disease characterized by circulating antinuclear autoantibodies and the dysfunction of T and B lymphocytes. Both genetic and environmental factors are believed to influence the development of the disease. We detected and cloned the HRES-1 human endogenous retrovirus, mapped it to chromosome 1 at q42, newly identified six haplotypes in the long terminal repeat (LTR), and revealed an association of polymorphic HindIII653C-containing alleles with SLE. A newly discovered 2,986-base antisense transcript encodes a 24 kD protein, HRES-1/Rab4, that regulates surface expression of CD4, and, to a lesser extent, expression of the transferrin receptor (TFR) through endosome recycling. The HRES-1 LTR serves as an enhancer of Rab4 expression and the lupus-associated HindIII653/rs451401 polymorhism influences transcription factor binding to the LTR. Thus, the HRES-1 locus may influence autoimmunity in SLE through expression of HRES-1/Rab4. Over-expression of HRES-1/Rab4 reduces surface expression of CD4 by inhibition of endocytic recycling and targets CD4 for lysosomal degradation, while dominant-negative HRES-1/Rab4S27N has the opposite effect both in Jurkat cells and peripheral blood T cells. HRES-1/Rab4 and CD4 protein levels inversely correlate both in healthy and lupus peripheral blood lymphocytes (PBL). CD4 protein levels are reduced, while HRES-1/Rab4 expression is increased in lupus T cells having at least one HindIII653C in the HRES-1 LTR. CD4 plays essential roles in formation of the immunological synapse (IS) during normal T-cell activation by a cognate MHC class II peptide complex. The key intracellular transducer of T-cell activation, Lck, is brought to the IS via binding to CD4. TCR6 chain binds to the TFR. Abnormal T-cell responses in SLE have been associated with reduced TCR6 chain and Lck levels in the lipid rafts of the IS. Although the regulatory roles of Rab GTP-ases in endosome trafficking are well recognized, their involvement in T-cell activation is largely unknown. Under Specific Aim 1, we will test the hypothesis that HRES1/Rab4 regulates the composition of lipid rafts, the assembly of the T-cell synapse, and the functional outcomes of T-cell activation in peripheral blood T cells and Jurkat cells when stimulated with CD3 or superantigen. Under Specific Aim 2 we will determine the role of increased HRES- 1/Rab4 expression in the altered lipid raft composition of lupus T cells. Under Specific Aim 3, we will test the hypothesis that the HindIIIG653C allele, alone or in combination with other genetic factors of lupus-associated haplotypes, enhances the expression of HRES-1/Rab4. The proposed studies will establish the role the small GTPase HRES-1/Rab4 in the formation of the IS and, through integrating the genetic factors and mechanisms regulating its expression and activity, advance our understanding of T-cell dysfunction in SLE. PUBLIC HEALTH RELEVANCE: Systemic lupus erythematosus (SLE) is a chronic inflammatory disease that often has debilitating and potentially life-threatening consequences. While the cause of SLE is unknown, both genetic and environmental factors are thought to be involved in the development of the disease. The genetic factors confer susceptibility, while the environmental factors, such as viruses, have been implicated in triggering disease onset or flares. We previously identified the HRES-1 endogenous retrovirus that may have originated from an infectious virus, however, it is now part of the human genetic make-up. Our preliminary results show that a protein product of HRES-1, called HRES- 1/Rab4, regulates the expression and cell surface appearance of an important receptor, CD4, on T lymphocytes. Gene sequence variations, so called polymorphisms, of HRES-1 have been associated with SLE and increased production of the HRES-1/Rab4 protein in patients with SLE. The proposed experiments will test the hypothesis that HRES-1/Rab4 regulates normal functioning of the immune system and will investigate whether the inherited genetic variations of HRES-1 underlie abnormal functioning of the immune system in SLE.

描述（申请人提供）： 摘要系统性红斑狼疮（SLE）是一种慢性炎症性疾病，其特征是循环抗核自身抗体以及 T 和 B 淋巴细胞功能障碍。据信遗传和环境因素都会影响该疾病的发展。我们检测并克隆了 HRES-1 人内源性逆转录病毒，将其定位到 1 号染色体 q42，新鉴定了长末端重复序列 (LTR) 中的 6 个单倍型，并揭示了含有 HindIII653C 的多态性等位基因与 SLE 的关联。新发现的 2,986 个碱基反义转录物编码 24 kD 蛋白 HRES-1/Rab4，可调节 CD4 的表面表达，并在较小程度上通过内体循环调节转铁蛋白受体 (TFR) 的表达。 HRES-1 LTR 充当 Rab4 表达的增强子，狼疮相关的 HindIII653/rs451401 多态性影响转录因子与 LTR 的结合。因此，HRES-1 基因座可能通过 HRES-1/Rab4 的表达影响 SLE 中的自身免疫。 HRES-1/Rab4 的过表达通过抑制内吞循环来降低 CD4 的表面表达，并靶向 CD4 进行溶酶体降解，而显性失活的 HRES-1/Rab4S27N 在 Jurkat 细胞和外周血 T 细胞中具有相反的作用。在健康和狼疮外周血淋巴细胞 (PBL) 中，HRES-1/Rab4 和 CD4 蛋白水平呈负相关。在 HRES-1 LTR 中至少有一个 HindIII653C 的狼疮 T 细胞中，CD4 蛋白水平降低，而 HRES-1/Rab4 表达增加。在正常 T 细胞被同源 MHC II 类肽复合物激活期间，CD4 在免疫突触 (IS) 的形成中发挥重要作用。 T 细胞激活的关键细胞内转导器 Lck 通过与 CD4 结合而被带到 IS。 TCR6 链与 TFR 结合。 SLE 中 T 细胞反应异常与 IS 脂筏中 TCR6 链和 Lck 水平降低有关。尽管 Rab GTP 酶在内体运输中的调节作用已得到广泛认可，但其在 T 细胞激活中的参与却很大程度上未知。在具体目标 1 下，我们将测试以下假设：HRES1/Rab4 在 CD3 或超抗原刺激下调节脂筏的组成、T 细胞突触的组装以及外周血 T 细胞和 Jurkat 细胞中 T 细胞激活的功能结果。在具体目标 2 下，我们将确定 HRES-1/Rab4 表达增加在狼疮 T 细胞脂筏组成改变中的作用。在具体目标 3 下，我们将检验这样的假设：HindIIIG653C 等位基因单独或与狼疮相关单倍型的其他遗传因素组合可增强 HRES-1/Rab4 的表达。拟议的研究将确定小 GTP 酶 HRES-1/Rab4 在 IS 形成中的作用，并通过整合调节其表达和活性的遗传因素和机制，加深我们对 SLE 中 T 细胞功能障碍的理解。公众健康相关性：系统性红斑狼疮 (SLE) 是一种慢性炎症性疾病，通常会导致患者衰弱并可能危及生命。虽然系统性红斑狼疮的病因尚不清楚，但遗传和环境因素被认为与该疾病的发展有关。遗传因素赋予易感性，而病毒等环境因素则与引发疾病发作或发作有关。我们之前鉴定出 HRES-1 内源性逆转录病毒可能起源于传染性病毒，然而，它现在是人类基因组成的一部分。我们的初步结果表明，HRES-1 的一种蛋白质产物，称为 HRES-1/Rab4，调节 T 淋巴细胞上重要受体 CD4 的表达和细胞表面外观。 HRES-1 的基因序列变异（即所谓的多态性）与 SLE 以及 SLE 患者中 HRES-1/Rab4 蛋白的产生增加有关。拟议的实验将检验 HRES-1/Rab4 调节免疫系统正常功能的假设，并将研究 HRES-1 的遗传性基因变异是否是 SLE 免疫系统功能异常的基础。