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: 8132412
• 负责人: Andras Perl
• 金额: $ 30.78万
• 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/8132412
• 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; Guanosine Triphosphate Phosphohydrolases; HERVs; Haplotypes; Health; 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 response; 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; base; chromatin immunoprecipitation; functional outcomes; immunological synapse; immunological synapse formation; inhibitor/antagonist; peripheral blood; promoter; rab4A Protein; receptor; research study; 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.

系统性红斑狼疮（SLE）是一种慢性炎症性疾病，其特征是循环中的抗核自身抗体以及T和B淋巴细胞功能障碍。遗传和环境因素都被认为会影响疾病的发展。我们检测并克隆了HRES-1人内源性逆转录病毒，将其定位于1号染色体q42，新发现的长末端重复序列（LTR）中的6种单倍型，并揭示了多态性HindIII 653 C等位基因与SLE的关联。新发现的2，986个碱基的反义转录物编码24 kD的蛋白质HRES-1/Rab 4，其调节CD 4的表面表达，并且在较小程度上通过内体再循环调节转铁蛋白受体（TFR）的表达。HRES-1 LTR作为Rab 4表达的增强子，狼疮相关的HindIII 653/rs 451401多态性影响转录因子与LTR的结合。因此，HRES-1基因座可能通过表达HRES-1/Rab 4影响SLE的自身免疫。HRES-1/Rab 4的过表达通过抑制内吞再循环降低了CD 4的表面表达，并靶向CD 4用于溶酶体降解，而显性阴性HRES-1/Rab 4S 27 N在Jurkat细胞和外周血T细胞中具有相反的作用。HRES-1/Rab 4和CD 4蛋白水平在健康和狼疮外周血淋巴细胞（PBL）中均呈负相关。在HRES-1 LTR中具有至少一个HindIII 653 C的狼疮T细胞中，CD 4蛋白水平降低，而HRES-1/Rab 4表达增加。在正常T细胞被同源MHC II类肽复合物激活期间，CD 4在免疫突触（IS）的形成中起重要作用。T细胞活化的关键细胞内转导子Lck通过与CD 4结合被带到IS。TCR 6链与TFR结合。SLE中的异常T细胞应答与IS脂筏中TCR 6链和Lck水平降低相关。虽然Rab GTP酶在内体运输中的调节作用是公认的，但它们参与T细胞活化在很大程度上是未知的。在特定目标1下，我们将检验HRES 1/Rab 4调节脂筏的组成、T细胞突触的组装以及当用CD 3或超抗原刺激时外周血T细胞和Jurkat细胞中T细胞活化的功能结果的假设。在特定目标2下，我们将确定HRES- 1/Rab 4表达增加在狼疮T细胞脂筏组成改变中的作用。在特定目标3下，我们将检验HindIIIG 653 C等位基因单独或与狼疮相关单倍型的其他遗传因子组合增强HRES-1/Rab 4表达的假设。这些研究将建立小GTHRES-1/Rab 4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，促进我们对SLE中T细胞功能障碍的理解。公共卫生关系：系统性红斑狼疮（SLE）是一种慢性炎症性疾病，通常具有衰弱和潜在的危及生命的后果。虽然SLE的病因尚不清楚，但遗传和环境因素都被认为与疾病的发展有关。遗传因素赋予易感性，而环境因素，如病毒，涉及触发疾病发作或爆发。我们先前鉴定出HRES-1内源性逆转录病毒可能起源于感染性病毒，然而，它现在是人类遗传组成的一部分。我们的初步研究结果表明，HRES-1的蛋白质产物，称为HRES- 1/Rab 4，调节T淋巴细胞上一种重要受体CD 4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和SLE患者中HRES-1/Rab 4蛋白的产生增加有关。拟议的实验将测试HRES-1/Rab 4调节免疫系统正常功能的假设，并将调查HRES-1的遗传遗传变异是否是SLE免疫系统功能异常的基础。