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: 7882527
• 负责人: Andras Perl
• 金额: $ 31.09万
• 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/7882527
• 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 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; abstracting; base; chromatin immunoprecipitation; functional outcomes; immunological synapse; immunological synapse formation; inhibitor/antagonist; peripheral blood; promoter; public health relevance; 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.

描述(申请人提供)：系统性红斑狼疮(SLE)是一种慢性炎症性疾病，以循环中的抗核自身抗体和T、B淋巴细胞功能障碍为特征。遗传和环境因素都被认为是影响疾病发展的因素。我们检测并克隆了人内源性逆转录病毒HRES-1，将其定位于第1染色体上的q42，在长末端重复序列中新发现了6种单倍型，揭示了含有HindIII653C的多态等位基因与SLE的关联。新发现的2,986个碱基的反义转录本编码一个24kD的蛋白质HRES-1/Rab4，它通过内体循环调节CD4的表面表达，并在较小程度上调节转铁蛋白受体(TFR)的表达。HRES-1 LTR是Rab4表达的增强子，狼疮相关的HindIII653/rs451401基因多态性影响转录因子与LTR的结合。因此，HRES-1基因可能通过HRES-1/Rab4的表达影响SLE患者的自身免疫。HRES-1/Rab4的过表达通过抑制细胞内循环而减少了CD4的表面表达，并靶向CD4进行溶酶体的降解，而显性阴性的HRES-1/Rab4S27N在Jurkat细胞和外周血T细胞中的作用相反。健康人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。在正常的T细胞活化过程中，CD4在免疫突触(IS)的形成中起着至关重要的作用，这种作用是由同源的MHC II类多肽复合体引起的。T细胞激活的关键细胞内转导分子Lck通过与CD4结合而被带到IS。TCR6链与TFR结合。系统性红斑狼疮患者T细胞反应异常与其脂质筏中TCR6链和LCK水平降低有关。虽然Rab GTP酶在内体运输中的调节作用已得到很好的认识，但它们在T细胞激活中的参与在很大程度上是未知的。在特定目标1下，我们将测试假设，即HRES1/Rab4调节脂筏的组成，T细胞突触的组装，以及在CD3或超抗原刺激下外周血T细胞和Jurkat细胞中T细胞激活的功能结果。在特定目标2下，我们将确定HRES-1/Rab4表达增加在狼疮T细胞脂筏成分改变中的作用。在特定目标3下，我们将检验这样的假设，即HindIIIG653C等位基因单独或与狼疮相关单倍型的其他遗传因素结合，增强HRES-1/Rab4的表达。这些研究将确定小GTP酶HRES-1/Rab4在IS形成中的作用，并通过整合其表达和活性调节的遗传因素和机制，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，通常会导致虚弱并可能危及生命的后果。虽然SLE的病因尚不清楚，但遗传和环境因素都被认为参与了疾病的发展。遗传因素赋予了易感性，而环境因素，如病毒，已被牵连到引发疾病发作或耀斑。我们以前发现了HRES-1内源性逆转录病毒，它可能起源于一种传染性病毒，然而，它现在是人类基因构成的一部分。我们的初步结果表明，HRES-1的一个蛋白产物，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。在SLE患者中，HRES-1的基因序列变异，即所谓的多态性，与SLE和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，并将调查HRES-1的遗传变异是否导致SLE免疫系统功能异常。