TXNIP Regulation of Endogenous Beta Cell Mass

TXNIP 内源性 β 细胞群的调节

基本信息

批准号：
8870342
负责人：
Anath Shalev
金额：
$ 31.97万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-01-10 至 2016-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8870342
关键词：
3&apos Untranslated Regions Affect Apoptosis Award Beta Cell Binding Cell Line Cell Survival Cell physiology Cells Cellular biology Data Development Diabetes Mellitus Diabetic mouse Diet Dose Down-Regulation Event Gene Expression Gene Targeting Genetic Transcription Glucose Health Human Inbred NOD Mice Injection of therapeutic agent Insulin Insulin Resistance Knockout Mice Leptin Light Measurement Measures MicroRNAs Modeling Molecular Mus Obesity Pancreas Patients Production Protein Deficiency Protein Overexpression Proteins Regulation Role Seeds Serum Serum Markers Signal Pathway Staging Streptozocin Structure of beta Cell of islet System Testing Thioredoxin Transcription Coactivator congenic diabetic follow-up functional decline functional loss in vivo inhibitor/antagonist islet loss of function mouse model mutant novel novel marker overexpression promoter protein expression protein function research study response therapeutic target type I and type II diabetes

项目摘要

DESCRIPTION (provided by applicant): Loss of functional beta cell mass by beta cell apoptosis and inadequate insulin production is a hallmark of type 1 and type 2 diabetes. During the last award period, we have identified thioredoxin-interacting protein (TXNIP) as a critical factor controlling beta cell apoptosis and showed that beta cell TXNIP was upregulated in diabetes, whereas TXNIP deficiency protected against diabetes by promoting beta cell survival. Now we discovered that TXNIP regulates beta cell microRNA expression and particularly induces beta cell expression of a specific microRNA, miR-204. While miR-204 has not been previously implicated in beta cell biology, our preliminary findings suggest that this microRNA is upregulated in diabetes, blocks insulin production and serum levels correlate with the decline of functional beta cell mass associated with diabetes. Our hypothesis is therefore that that TXNIP induces miR-204 resulting in a cascade of events that inhibit insulin production and promote loss of functional beta cell mass. We propose 4 Specific Aims to test this hypothesis. 1. To study the in vivo effects of TXNIP and miR-204 inhibition on functional beta cell mass under normal and diabetic conditions, we will take advantage of our whole body (HcB-19) and beta cell-specific TXNIP-deficient (bTKO) mouse models as well as our double mutant obese and insulin resistant leptin- and TXNIP-deficient mouse (ob/hcb) and will assess the effects of TXNIP deficiency on islet miR-204 expression and beta cell insulin production as compared to control mice. We will also use a novel miR-204 knockout mouse (204KO) to determine the specific role of miR-204 in the control of insulin production and functional beta cell mass under normal conditions and in response to diet- induced obesity and diabetes. 2. To analyze the cellular effects of altered beta cell TXNIP and miR-204 expression, we will overexpress and inhibit TXNIP and miR-204 in INS-1 cells and human islets and use isolated bTKO and 204KO islets and assess changes in insulin expression and secretion. 3. To determine the molecular mechanisms by which miR-204 and TXNIP control beta cell function, we will follow-up on our initial studies suggesting that miR-204 acts via MafA downregulation and will assess how miR-204 and TXNIP affect expression level, insulin promoter occupancy and 3'UTR function of MafA and human MafB. To do so, we will again use our INS-1 cell lines, isolated bTKO and 204KO islets and primary human islets. 4. To evaluate miR- 204 as a potential novel serum marker for functional beta cell mass, we will induce controlled beta cell destruction using multiple low-dose streptozotocin injections as well as analyze spontaneous non-obese diabetic (NOD) mice as a second model of diabetes and will measure serum miR-204 in parallel with whole pancreas insulin content and beta cell mass at different stages of beta cell loss. The results of these studies will provide an in depth understanding of the newly discovered TXNIP/miR- 204/MafA signaling pathway controlling insulin synthesis and may help reveal novel markers for the measurement of functional beta cell mass.

描述（由申请人提供）：通过β细胞细胞凋亡和胰岛素产生不足的功能性β细胞质量损失是1型和2型糖尿病的标志。在最后一个奖项期间，我们已经将硫氧还蛋白相互作用蛋白（TXNIP）确定为控制β细胞凋亡的关键因素，并表明β细胞TXNIP在糖尿病中上调，而TXNIP缺乏症通过促进β细胞存活而受到糖尿病的影响。现在，我们发现TXNIP调节β细胞microRNA表达，特别是诱导特定microRNA miR-204的β细胞表达。尽管miR-204先前尚未与β细胞生物学有关，但我们的初步发现表明该microRNA在糖尿病中被上调，阻断胰岛素的产生和血清水平与与糖尿病相关的功能性β细胞量的下降相关。因此，我们的假设是TXNIP诱导miR-204导致一系列抑制胰岛素产生并促进功能性β细胞量的事件。我们提出了4个特定的目的来检验这一假设。 1。研究在正常和糖尿病条件下TXNIP和miR-204抑制对功能β细胞质量的体内影响，我们将利用我们的整个身体（HCB-19）和β细胞细胞缺乏症（HCB-19）和特异性TXNIP（BTKO）（BTKO）以及我们的双突变肥胖和胰岛素的效果（BTKO）和胰岛素效应（txnip-byb）的效果（与对照小鼠相比，胰岛miR-204表达和β细胞胰岛素产生的TXNIP缺乏。我们还将使用一种新型的miR-204敲除小鼠（204KO）来确定miR-204在正常条件下以及响应饮食诱导的肥胖和糖尿病的响应下，miR-204在控制胰岛素产生和功能β细胞肿块中的特定作用。 2。为了分析改变的β细胞TXNIP和miR-204表达的细胞效应，我们将过表达和抑制INS-1细胞和人类胰岛中的TXNIP和miR-204，并使用分离的BTKO和204KO胰岛，并评估胰岛素表达和分泌的变化。 3。为了确定miR-204和TXNIP控制β细胞功能的分子机制，我们将跟进初步研究，这表明miR-204通过MAFA下调起作用，并将评估miR-204和TxNIP影响表达水平，胰岛素启动子启动子占用者以及MAFA和MAFA和人类MAFB的功能如何影响表达水平。为此，我们将再次使用INS-1细胞系，孤立的BTKO和204KO胰岛和原发性胰岛。 4。要评估miR-204作为功能性β细胞量的潜在新型血清标记物，我们将使用多种低剂量链蛋白酶注射剂诱导受控的β细胞破坏，分析自发性非脂肪糖尿病（NOD）小鼠作为糖尿病的第二个模型，并将与PARCALS的第二个模型与PARCALS的群体相同，将其作为糖尿病的第二个模型，并将其与PARTALEAS相互限制。损失。这些研究的结果将对新发现的TXNIP/MIR-204/MAFA信号传导途径进行深入了解，以控制胰岛素合成，并可能有助于揭示用于测量功能β细胞质量的新标记。