PTPN2 mutations affect islet beta cell susceptibility in T1D

PTPN2 突变影响 T1D 中胰岛β细胞的易感性

• 批准号: 10028702
• 负责人: LORI SUSSEL
• 金额: $ 42.36万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10028702
• 关键词: Affect; Alleles; Autoimmune Process; Autoimmunity; B-Lymphocytes; Beta Cell; Biological Models; CRISPR/Cas technology; Cell Lineage; Cell Survival; Cell model; Cell physiology; Cells; Cellular Metabolic Process; Chronic Disease; Complex; Data; Defect; Development; Disease; Enzymes; Event; Functional disorder; Genes; Genetic Predisposition to Disease; Glucose; HLA Antigens; High Fat Diet; Human; Immune; Immune System Diseases; Immune system; Impairment; Inbred NOD Mice; Individual; Inflammatory; Insulin; Insulin-Dependent Diabetes Mellitus; Knock-out; Knockout Mice; Knowledge; Mediating; Metabolic; Metabolic Pathway; Minor; Mitochondria; Molecular; Mouse Protein; Mus; Mutation; Pancreas; Pathway interactions; Patients; Phenotype; Predisposition; Protein Tyrosine Phosphatase; Pyruvate Kinase; Regulation; Research; Role; Signal Pathway; Signal Transduction; Single Nucleotide Polymorphism; Streptozocin; Stress; Structure of beta Cell of islet; T-Lymphocyte; T-cell protein tyrosine phosphatase; Testing; Tissue Sample; Tissues; Transgenic Mice; Variant; base; cell immortalization; cytokine; diabetes risk; genetic variant; genome wide association study; human pluripotent stem cell; insulin secretion; islet; mutant; novel therapeutics; prevent; protein function; response; risk variant; viral RNA

Type 1 diabetes (T1D) is characterized by the destruction of pancreatic beta cells by an individual’s own immune system. Although T1D is primarily viewed as a disease of the immune system, there is mounting evidence to suggest that insulin-producing β cells may actively contribute to their destruction. Furthermore, recent genome-wide association studies (GWAS) have suggested that although significant genetic predisposition to T1D is conferred by the human leukocyte antigen (HLA) complex, many single nucleotide polymorphisms (SNPs) in non-HLA loci also contribute to the disease {Floyel, 2015 #2}. Importantly, many of these non-HLA variants occur in genes expressed in both immune cell lineages as well as in the targeted β cells. Knowledge of how these minor gene variants affect function of islet b cells will allow us to develop novel therapies that could be effective in preventing progression of T1D. In this proposal, we will use transgenic mice and human b cell models to explore how mutations in the T1D risk allele Protein tyrosine phosphatase N2 (PTPN2), also known as T cell protein tyrosine phosphatase (TC-PTP), affect islet β cell function in the context of T1D and/or T1D mimicking conditions. In mice and humans, PTPN2 is broadly expressed in several tissues, including T cells and islet β cells, however mutations of PTPN2 have predominantly been studied in the T cell context. In mice, PTPN2 has been show to modulate inflammatory signaling in T cells by acting as a negative regulator of JAK/STAT signaling, downstream of a cytokine response. However, there is evidence that PTPN2-mediated autoimmunity cannot be fully explained by T cell dysfunction. T-cell specific inactivation of PTPN2 caused less severe autoimmune phenotypes than observed in global knockout mice. Indeed, in the pancreas, constitutive inactivation of PTPN2 impaired glucose stimulated insulin secretion in mice fed a high fat diet {Xi, 2015 #20}. The function of PTPN2 in β cells has not yet been examined in the context of T1D; however, PTPN2 is upregulated in mouse and human β cells upon treatment with proinflammatory cytokines or double stranded viral RNA, again suggesting an additional role for PTPN2 in islets. To parse out the β cell-specific contribution of PTPN2 mutations to T1D, we have generated a β cell-specific knockout of Ptpn2 (PTPN2-bKO). Our preliminary data indicate that metabolic pathways are altered in PTPN2-bKO islets under T1D mimicking stress conditions. Consistently, we have identified pyruvate kinase M2 (PKM2), an important glycolytic enzyme in the β cell to be a direct target of PTPN2. In addition, we have generated hPSCs deleted for PTPN2 and collected tissue samples from T1D individuals carrying mutations in PTPN2. In this proposal, we will test the hypothesis that disrupted function of PTPN2 in the β cell promotes the development of T1D by compromising β cell metabolic function and survival. In SA1 we will determine the beta cell defects associated with deletion of PTPN2 in basal and autoimmune-mediated conditions. In SA2 we will determine the molecular pathways regulated by PTPN2 in basal and autoimmune-mediated conditions.

1型糖尿病（T1D）的特征是个人的免疫系统破坏了胰腺β细胞。尽管T1D主要被视为免疫系统的疾病，但有越来越多的证据表明，产生胰岛素的β细胞可能会积极促进其破坏。此外，最近全基因组关联研究（GWAS）表明，尽管人类白细胞抗原（HLA）络合物赋予了对T1D的明显遗传易感性，但许多单一核苷酸多态性（SNP）在非HLA基因座中也有助于该疾病{Floyel，2015＃2}。重要的是，这些非HLA变体中的许多都出现在免疫细胞谱系和靶向β细胞中表达的基因中。了解这些次要基因变体如何影响胰岛B细胞的功能将使我们能够开发出可以有效预防T1D进展的新型疗法。该提案，我们将使用转基因小鼠和人类B细胞模型来探索T1D等位基因等位基因酪氨酸磷酸酶N2（PTPN2）（也称为T细胞蛋白酪氨酸磷酸酶（TC-PTPP））如何影响胰岛在T1D和/或T1D MimickImicking的情况下影响胰岛功能。在小鼠和人类中，PTPN2在包括T细胞和胰岛β细胞在内的几个组织中广泛表达，但是PTPN2的突变主要是在T细胞环境中研究的。在小鼠中，PTPN2已被证明是通过充当JAK/Stat信号的负调节剂（细胞因子反应的下游）来调节T细胞中的炎症信号传导。但是，有证据表明PTPN2介导的自身免疫不能通过T细胞功能障碍来完全解释。 PTPN2的T细胞特异性灭活引起的自身免疫表型不如全球敲除小鼠观察到的严重严重。实际上，在胰腺中，PTPN2的构型失活损害了富含高脂饮食的小鼠的胰岛素分泌{XI，2015＃20}。在T1D的背景下，尚未对PTPN2在β细胞中的功能进行检查。但是，在用促炎细胞因子或双链病毒RNA处理后，在小鼠和人β细胞中更新了PTPN2，再次表明PTPN2在胰岛中具有额外的作用。为了解析PTPN2突变对T1D的β细胞特异性贡献，我们产生了PTPN2（PTPN2-BKO）的β细胞特异性敲除。我们的初步数据表明，在T1D模仿应力条件下，PTPN2-BKO胰岛中的代谢途径发生了变化。一致地，我们已经确定丙酮酸激酶M2（PKM2），β细胞中一种重要的糖酵解酶是PTPN2的直接靶标。此外，我们已经生成了针对PTPN2删除的HPSC，并从PTPN2中携带突变的T1D个体收集了组织样品。在此提案中，我们将检验以下假设：β细胞中PTPN2的功能破坏功能会促进受损的β细胞代谢功能和存活的T1D的发展。在SA1中，我们将确定与基本和自身免疫介导的条件下与PTPN2缺失相关的β细胞缺陷。由PTPN2调节的分子途径在基本和自身免疫介导的条件下。