Mechanisms of Combined Immunodeficiency due to DOCK8 Deficiency

DOCK8 缺陷引起的联合免疫缺陷的机制

• 批准号: 10238058
• 负责人: Talal Amine Chatila
• 金额: $ 35.4万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10238058
• 关键词: Actins; Allergic; Autoantibodies; Autoimmune; Autoimmunity; Bacterial Infections; Binding; Cell Cycle; Cell Differentiation process; Cell Nucleus; Cell physiology; Cells; Cessation of life; Chemosensitization; Cytokinesis; Cytoskeleton; Cytosol; Defect; Deletion Mutation; Dependence; Disease; Exhibits; Failure; Feeds; GTP-Binding Proteins; Gene Expression; Gene Expression Regulation; Gene Targeting; Genes; Genetic Transcription; Grant; Guanine Nucleotide Exchange Factors; Helper-Inducer T-Lymphocyte; IgE; Immune; Immune System Diseases; Immune response; Immune system; Immunity; Immunologic Deficiency Syndromes; Impairment; Importins; Infection; Interruption; Job' s Syndrome; Lymphocyte; Malignant Neoplasms; Mediating; Memory B-Lymphocyte; Missense Mutation; Mitogens; Molecular; Morbidity - disease rate; Mucocutaneous Candidiasis; Mutation; Mycoses; Nuclear; Nuclear Import; Nuclear Translocation; Null Lymphocytes; Phenotype; Phosphorylation; Phosphotransferases; Phosphotyrosine; Play; Point Mutation; Predisposition; Process; Production; Proteins; Recurrence; Regulation; Regulator Genes; Role; STAT3 gene; Signal Transduction; T-Lymphocyte; Tertiary Protein Structure; Testing; Th2 Cells; Tyrosine; Viral; Virus Diseases; atopy; cdc42 GTP-Binding Protein; chemokine; clinical phenotype; congenital immunodeficiency; disease phenotype; early onset; fighting; gain of function; human subject; immune system function; loss of function; loss of function mutation; mutant; novel; preservation; programs; protein expression; response

Dedicator of cytokinesis 8 (DOCK8) is a guanine nucleotide exchange factor (GEF) that coordinates the actin cytoskeleton response to mitogenic and chemokine signals, most notably by regulating the activity of the small GTP binding protein cell division cycle 42 (CDC42) [1]. Its deficiency due to loss-of-function deletions and mutations in DOCK8 underlies the majority of cases of the autosomal recessive form of the hyper IgE syndrome (AR-HIES), a combined primary immunodeficiency disease (PID) characterized by susceptibility to viral bacterial and fungal infections, severe atopy, early onset autoimmunity and malignancy [3-5]. The phenotype of DOCK8 deficiency overlaps with that of the autosomal dominant form of the hyper IgE syndrome (AD-HIES), due to heterozygous loss of function mutations in STAT3. Both diseases exhibit hyper IgE phenotype, and susceptibility to bacterial and candidal infections. AD-HIES is associated with failure of Th17 cell differentiation due to ineffective STAT3 activation. Our preliminary studies revealed a similar defect in Th17 differentiation in DOCK8-deficent subjects. Furthermore, we demonstrate that DOCK8 constitutively binds to STAT3 and promotes its phosphorylation at the regulatory tyrosine (Y)705, as well as phospho-(p)STAT3 nuclear translocation and transcriptional function. DOCK8 deficiency impaired pSTAT3 activation and translocation, indicating a critical role for DOCK8 in STAT3 function. Furthermore, a point mutation that abrogated DOCK8 GEF activity and which recapitulated key attributes of DOCK8 deficiency also impaired STAT3 activation, indicative of the latter's dependence on CDC42 activity. Accordingly we hypothesize that DOCK8 acts as a critical regulator for STAT3 function by controlling its phosphotyrosine phosphorylation and cytoplasmic to nuclear shuttling, a novel and unexpected mechanism by which DOCK8 controls Th17 differentiation and other attributes of STAT3 activities in immune cells. We propose to examine mechanisms of STAT3-DOCK8 interaction and the role of CDC42 in this process. We also propose to examine mechanisms by which DOCK8 shuttles between the cytosol and the nucleus, including its binding to α- and β-importins and to exportin1. We will examine the capacity of DOCK8 to associate with gene targets in STAT3-dependent and independent manner to modulate gene expression. Finally, we will test the hypothesis that DOCK8 deficiency skews the T follicular helper (TFH) cell response towards a Th2 cell-like phenotype and disrupts the differentiation of TFR cells and their regulation of TFH cells by both STAT3-dependent and independent mechanisms, leading to the promotion of IgE and Th2 responses. These studies will elucidate fundamental mechanisms by which DOCK8 may regulate the immune response, the interruption of which precipitates distinct clinical phenotypes associated with DOCK8 deficiency.

胞质分裂贡献因子8（DOCK 8）是一种鸟嘌呤核苷酸交换因子（GEF）， 细胞骨架对促有丝分裂和趋化因子信号的反应，最显著的是通过调节小的 GTP结合蛋白细胞分裂周期42（CDC 42）[1]。其缺陷是由于功能缺失， DOCK 8突变是大多数常染色体隐性形式的高IgE病例的基础 综合征（AR-HIES），一种联合原发性免疫缺陷病（PID），其特征是对 病毒性细菌和真菌感染、严重特应性、早发性自身免疫和恶性肿瘤[3-5]。的 DOCK 8缺乏的表型与高IgE综合征的常染色体显性形式重叠 （AD-HIES），由于STAT 3中的杂合功能缺失突变。这两种疾病都表现出高IgE 表型以及对细菌和念珠菌感染的易感性。AD-HIES与Th 17的失败有关 细胞分化由于无效的STAT 3激活。我们的初步研究揭示了Th 17中的类似缺陷， DOCK 8缺陷受试者的分化。此外，我们证明DOCK 8与 STAT 3并促进其在调节酪氨酸（Y）705处的磷酸化，以及磷酸化-（p）STAT 3 核转位和转录功能。DOCK 8缺陷损害pSTAT 3活化， 这表明DOCK 8在STAT 3功能中的关键作用。此外，一个点突变， 废除DOCK 8 GEF活动并重述DOCK 8缺陷的关键属性也受到损害 STAT 3激活，表明后者依赖于CDC 42活性。因此，我们假设， DOCK 8通过控制其磷酸酪氨酸磷酸化而作为STAT 3功能的关键调节剂， 细胞质到细胞核的穿梭，DOCK 8控制Th 17的一种新的和意想不到的机制 免疫细胞中STAT 3活性的分化和其他属性。我们建议研究 STAT 3-DOCK 8相互作用和CDC 42在此过程中的作用。我们还建议审查机制 DOCK 8通过其在细胞质和细胞核之间穿梭，包括其与α-和β-输入蛋白的结合， 出口1.我们将研究DOCK 8与STAT 3依赖性和非依赖性细胞中基因靶点相关的能力。 以独立的方式调节基因表达。最后，我们将测试DOCK 8缺陷的假设， 使T滤泡辅助（TFH）细胞反应偏向Th 2细胞样表型，并破坏了 TFR细胞的分化及其通过STAT 3依赖性和非依赖性两者对TFH细胞的调节 机制，导致IgE和Th 2反应的促进。这些研究将阐明 DOCK 8可调节免疫应答的机制，免疫应答的中断可促进免疫应答。 与DOCK 8缺陷相关的不同临床表型。