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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

基本信息

批准号：
8500100
负责人：
Andras Perl
金额：
$ 28.93万
依托单位：
UPSTATE MEDICAL UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2000
资助国家：
美国
起止时间：
2000-07-01 至 2015-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8500100
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

项目摘要

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）是一种以循环抗核自身抗体和T淋巴细胞和B淋巴细胞功能障碍为特征的慢性炎症性疾病。遗传和环境因素都被认为会影响这种疾病的发展。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，在长末端重复序列（LTR）中新鉴定出6个单倍型，揭示了多态含hindiii655c等位基因与SLE的关联。一个新发现的2,986个碱基的反义转录物编码一个24 kD的蛋白HRES-1/Rab4，该蛋白调节CD4的表面表达，并在较小程度上通过核内体循环调节转铁蛋白受体（TFR）的表达。HRES-1 LTR是Rab4表达的增强子，狼疮相关的HindIII653/rs451401多态性影响与LTR结合的转录因子，因此，HRES-1位点可能通过HRES-1/Rab4的表达影响SLE自身免疫。过表达HRES-1/Rab4通过抑制内噬循环降低CD4的表面表达，靶向CD4进行溶酶体降解，而显性阴性的HRES-1/Rab4S27N在Jurkat细胞和外周血T细胞中均具有相反的作用。HRES-1/Rab4和CD4蛋白水平在健康和狼疮外周血淋巴细胞（PBL）中呈负相关。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。CD4在正常T细胞被同源MHC II类肽复合物激活时，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换能器Lck通过与CD4结合被带到is。TCR6链与TFR结合。SLE患者的异常t细胞反应与IS脂筏中TCR6链和Lck水平的降低有关。虽然Rab gtp酶在核内体运输中的调节作用已经得到了很好的认识，但它们在t细胞活化中的作用在很大程度上是未知的。在Specific Aim 1中，我们将验证HRES1/Rab4在CD3或超抗原刺激下调节外周血T细胞和Jurkat细胞中脂筏的组成、T细胞突触的组装以及T细胞活化的功能结果的假设。在Specific Aim 2下，我们将确定HRES- 1/Rab4表达增加在狼疮T细胞脂质筏组成改变中的作用。在Specific Aim 3下，我们将验证HindIIIG653C等位基因单独或与狼疮相关单倍型的其他遗传因素联合增强HRES-1/Rab4表达的假设。拟开展的研究将确立小GTPase 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，推进我们对SLE中t细胞功能障碍的认识。公共卫生相关性：系统性红斑狼疮（SLE）是一种慢性炎症性疾病，通常具有使人衰弱和潜在威胁生命的后果。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，则与引发疾病发作或发作有关。我们以前鉴定的HRES-1内源性逆转录病毒可能起源于一种传染性病毒，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的蛋白产物，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基因序列变异，即所谓的多态性，与SLE和SLE患者HRES-1/Rab4蛋白产生增加有关。本实验将验证HRES-1/Rab4调节免疫系统正常功能的假说，并将研究HRES-1的遗传变异是否为SLE免疫系统异常功能的基础。