Endocytic Control of Autophagosome Formation in Lupus T cells

狼疮 T 细胞中自噬体形成的内吞控制

• 批准号: 9221987
• 负责人: Andras Perl
• 金额: $ 40.5万
• 依托单位: UPSTATE MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-15 至 2021-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9221987
• 关键词: Address; Adverse effects; Affect; Age; Amino Acids; Appearance; Autoimmune Diseases; Autoimmunity; Autophagocytosis; Autophagosome; Back; Biogenesis; Biological Response Modifiers; CD4 Positive T Lymphocytes; Cell Differentiation process; Cell Survival; Cells; Clinical; Complex; Data; Degradation Pathway; Dependence; Development; Disease; Endosomes; Etiology; Exhibits; FOXP3 gene; FRAP1 gene; Family; Feedback; Female of child bearing age; Flare; Functional disorder; Generations; Genes; Genetic Polymorphism; Goals; Guanosine Triphosphate Phosphohydrolases; Hydroxychloroquine; Immune response; Immune system; In Vitro; Inbred MRL lpr Mice; Inflammatory; Knock-in Mouse; Knowledge; LIGHT protein; Light; Link; Longitudinal Studies; Lupus; Lysosomes; Mediating; Medical; Microtubule-Associated Proteins; Modeling; Monomeric GTP-Binding Proteins; Mus; Nephritis; Onset of illness; Organelles; Pathogenesis; Pathway interactions; Patients; Pharmacology; Play; Population; Prevention; Production; Public Health; Recycling; Regulatory T-Lymphocyte; Research; Role; Secondary to; Sirolimus; Site; Splenocyte; Surface; Systemic Lupus Erythematosus; T-Cell Activation; T-Cell Development; T-Lymphocyte; TFRC gene; Testing; Therapeutic; Work; adaptive immune response; base; chronic autoimmune disease; clinical efficacy; cohort; effective therapy; experimental study; gene therapy; in vivo; inhibitor/antagonist; innovation; lupus prone mice; member; mortality; novel therapeutics; overexpression; protein degradation; public health relevance; rab GTP-Binding Proteins; thymocyte; transdifferentiation

 DESCRIPTION (provided by applicant): Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology. The pathogenesis is at least partly attributed to T-cell dysfunction. Therefore, the proposed studies will focus on a critical gap in knowledge - how autophagy pathways that regulate normal T-cell development cause pro-inflammatory population skewing and dysfunction in SLE. The central hypothesis of this project has been based on recent evidence for the contribution of endosomes to the formation of autophagosomes and the role of Rab4A in increased autophagy in lupus T cells. Rab4A is a small GTPase that regulates endosome recycling. It is markedly overexpressed in SLE patients and, even prior to disease onset, in lupus-prone mice. Although autophagy genes, in particular ATG5, have been genetically linked to SLE, their role in pathogenesis is undefined. Notably, ATG5 is transported by CD71+ endosomes which are recycled by Rab4A. Newly developed mice carrying constitutively active Rab4AQ72L show increased expression of CD71 and depletion of ATG5. Splenocytes and thymocytes of these mice show activation of mTORC1 and depletion of FoxP3. While mTORC1 is generally regarded as an inhibitor of autophagy, it is activated on the surface of lysosomes. Thus, based on compelling preliminary data, the Specific Aims will test the working hypothesis that Rab4A overexpression is responsible for accelerated autophagy and, through promoting the traffic of mTORC1 to lysosomes, for abnormal T-cell development in SLE. Given that the GTPase inhibitor 3-PEHPC inactivates Rab4A in vitro and blocks lupus pathogenesis in vivo, the proposed experiments will determine whether 1) Rab4A promotes CD71/ATG5-dependent autophagosome formation in SLE patients; 2) mTORC1 activation and FoxP3 depletion occur through endocytic traffic to lysosomes; and 3) inactivation of Rab4A blocks pathogenesis in lupus-prone mice. Under Aim 1, Rab4A overexpression will be assessed in longitudinal studies of SLE patients as the cause of enhanced autophagosome biogenesis via the retention of CD71. Under Aim 2, Rab4A-initiated traffic of mTOR from inhibitory Rab5+ endosomes to Rheb+ lysosomes will be evaluated as the mechanism underlying mTORC1 activation and the resultant Treg→Th17 trans-differentiation in SLE patients. Under Aim 3, the role of Rab4A-driven autophagy in lupus will be modeled by the impact of constitutively active Rab4AQ72L on development of autoimmunity and the dependence of pathogenesis on Rab4A, ATG5 and ATG7 and downstream activation of mTORC1 and inhibition of mTORC2. The proposed research is significant because it will advance our basic understanding of autophagosome biogenesis and its impact on T-cell development and plasticity with broad translational relevance for the pathogenesis and treatment of lupus. The approach is innovative as it will employ genetically defined checkpoints of endosomal traffic to influence lupus pathogenesis. The results will bring new perspectives to our understanding of endosome traffic, how it controls autophagosome formation and its role in disease pathogenesis, and will identify new mechanistic targets for treatment of SLE.

 描述（由申请人提供）：系统性红斑狼疮（SLE）是一种病因不明的自身免疫性疾病。发病机制至少部分归因于T细胞功能障碍。因此，拟议的研究将集中在知识的一个关键空白-调节正常T细胞发育的自噬途径如何导致SLE中的促炎性群体偏斜和功能障碍。该项目的中心假设是基于最近的证据，即内体对自噬体形成的贡献以及Rab 4A在狼疮T细胞中增加自噬中的作用。Rab 4A是一种调节内体再循环的小GTdR。它在SLE患者中显著过表达，甚至在疾病发作之前，在狼疮易感小鼠中也是如此。虽然自噬基因，特别是ATG 5，已与SLE遗传相关，但其在发病机制中的作用尚不明确。值得注意的是，ATG 5由CD 71+内体转运，其由Rab 4A再循环。携带组成型活性Rab 4AQ 72 L的新开发小鼠显示出CD 71表达增加和ATG 5消耗。这些小鼠的脾细胞和胸腺细胞显示mTORC 1的活化和FoxP 3的耗竭。虽然mTORC 1通常被认为是自噬的抑制剂，但它在溶酶体表面被激活。因此，基于令人信服的初步数据，特定目的将测试Rab 4A过表达负责加速自噬的工作假设，并通过促进mTORC 1向溶酶体的运输，导致SLE中异常T细胞发育。鉴于GT3抑制剂3-PEHPC在体外使Rab 4A失活并在体内阻断狼疮发病机制，所提出的实验将确定1）Rab 4A是否促进SLE患者中的CD 71/ATG 5依赖性自噬体形成; 2）mTORC 1活化和FoxP 3消耗是否通过内吞运输至溶酶体发生;以及3）Rab 4A的失活是否阻断狼疮易感小鼠中的发病机制。根据目标1，Rab 4A过表达将在SLE患者的纵向研究中作为通过保留CD 71增强自噬体生物合成的原因进行评估。在目标2下，Rab 4A引发的mTOR从抑制性Rab 5+内体到Rheb+溶酶体的运输将被评估为SLE患者中mTORC 1活化和由此产生的Treg→ Th 17转分化的潜在机制。在目标3下，Rab 4A驱动的自噬在狼疮中的作用将通过组成型活性Rab 4AQ 72 L对自身免疫发展的影响以及发病机制对Rab 4A、ATG 5和ATG 7的依赖性以及mTORC 1的下游激活和mTORC 2的抑制来建模。这项研究意义重大，因为它将促进我们对自噬体生物发生及其对T细胞发育和可塑性的影响的基本理解，对狼疮的发病机制和治疗具有广泛的翻译相关性。该方法是创新的，因为它将采用遗传定义的内体运输检查点来影响狼疮发病机制。这些结果将为我们理解内体运输，它如何控制自噬体形成及其在疾病发病机制中的作用带来新的视角，并将确定治疗SLE的新机制靶点。