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Mechanisms of AHR Metabolic Toxicity

AHR 代谢毒性机制

基本信息

批准号：
9219030
负责人：
ARLEEN B. RIFKIND
金额：
$ 45.08万
依托单位：
WEILL MEDICAL COLL OF CORNELL UNIV
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-03-01 至 2022-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9219030
关键词：
ADP ribosylation Address Aging Aryl Hydrocarbon Receptor Attention Bioenergetics Biological Biological Assay Biology Chick Embryo Consumption Dioxins Energy Metabolism Environmental Pollution Enzymes Exposure to Failure Fatty Liver Functional disorder Gene Silencing Gene Targeting Genome Stability Genus Hippocampus Gluconeogenesis Glucose Glycolysis Grant Hepatic Hepatocyte Homeostasis Human Impairment Knockout Mice Knowledge Liver Mainstreaming Messenger RNA Metabolic Metabolic Control Metabolic syndrome Mitochondria Modeling Mus Niacinamide Oxidation-Reduction Oxygen Consumption Phosphoenolpyruvate Carboxylase Physiological Preventive Production Proteins Proteomics Publishing Reaction Receptor Activation Research Role SIRT1 gene Scheme Sirtuins Source Technology Testing Tetrachlorodibenzodioxin Toxic Environmental Substances Toxic effect Transcriptional Activation cofactor environmental toxicology glucose production in vivo in vivo Model inhibitor/antagonist novel overexpression prevent response small molecule

项目摘要

ABSTRACT This research will address a major knowledge gap in aryl hydrocarbon receptor (AHR) biology: how transcriptional activation of the AHR by the environmental toxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin, TCDD) causes metabolic toxicities including suppressed glucose production, energy failure and hepatic steatosis. We will investigate the role of NAD+ depletion in AHR metabolic toxicities. NAD+ is a small molecule important in cellular redox reactions and is a required substrate for the catalytic activity of PARPs and sirtuins, enzymes that regulate energy metabolism, genome stability and aging. This research will provide new understanding of the basis of AHR metabolic toxicities by probing our finding that TCDD decreases NAD+ levels through the AHR target gene TiPARP (TCDD-inducible poly ADP-ribosylase, PARP7), one of the PARP enzymes which consume NAD+ while ADP-ribosylating proteins. We will exploit here our discoveries that TiPARP contributes to decreased hepatic glucose production by consuming NAD+ and suppressing induction by sirtuin 1 of PEPCK, a rate limiting enzyme in gluconeogenesis. Longer exposure to TCDD also increases hepatic PARP1 levels suggesting that PARP1 may contribute to lowering NAD+ levels. We propose two connected Specific Aims (SA): SA1 will study the consequences of NAD+ depletion on sirtuin activity and mitochondrial bioenergetics, will establish the role of TiPARP and PARP1 in TCDD toxicities in mammalian model and will seek to identify NAD-repletion as a preventive and corrective strategy against TCDD toxicity. SA2 will examine the role of ADP-ribosylation by TiPARP in AHR action. Specifically, these studies will elucidate the consequences of NAD+ depletion for biological and catalytic activities of Sirts1, 3 and 6, using new sirtuin specific assays (SA1a1). A role of NAD+ depletion by TCDD in mitochondrial bioenergetics will be addressed by studies using Seahorse technology to examine oxygen consumption and glycolysis (SA1a2). Chick embryo hepatocytes will be used throughout the grant, and we will confirm major findings in human primary hepatocytes. Liver-specific TiPARP and PARP1 KO mice will be used to assess their roles in the production of TCDD metabolic toxicities in a mammalian model (SA1b). SA1c will determine whether NAD+ repletion with nicotinamide, and other NAD+ repleting agents, can prevent and possibly correct TCDD toxicities. SA2 will examine the role of ADP-ribosylation by TiPARP in AHR metabolic toxicities as we found that PEPCK is ADP-ribosylated by TiPARP. We will examine (SA2a) the effects of ADP-ribosylation of PEPCK by TiPARP on PEPCK stability and activity and will seek to identify other proteins ADP-ribosylated by TiPARP to reveal new ways by which ADP-ribosylation could participate in AHR action (SA2b). We expect this research to establish a significant mechanism in which NAD+ depletion by PARP activity leads to TCDD hepatic metabolic toxicities and to identify NAD+-repletion as an approach to prevent and/or correct AHR metabolic toxicities in vivo.

抽象的这项研究将解决芳烃受体（AHR）生物学的一个主要知识空白：如何环境毒素 2,3,7,8-四氯二苯并-对二恶英（二恶英， TCDD）会导致代谢毒性，包括抑制葡萄糖产生、能量衰竭和肝损伤脂肪变性。我们将研究 NAD+ 消耗在 AHR 代谢毒性中的作用。 NAD+是一种小分子在细胞氧化还原反应中很重要，并且是 PARP 和 Sirtuins 催化活性所需的底物，调节能量代谢、基因组稳定性和衰老的酶。这项研究将提供新的通过探究 TCDD 降低 NAD+ 的发现来了解 AHR 代谢毒性的基础通过 AHR 靶基因 TiPARP（TCDD 诱导型聚 ADP 核糖基酶，PARP7）（PARP 之一）在 ADP 核糖基化蛋白质的同时消耗 NAD+ 的酶。我们将在这里利用我们的发现 TiPARP 通过消耗 NAD+ 和抑制诱导来减少肝葡萄糖的产生由 PEPCK 的 Sirtuin 1 控制，PEPCK 是糖异生过程中的限速酶。接触 TCDD 的时间越长也会增加肝脏 PARP1 水平表明 PARP1 可能有助于降低 NAD+ 水平。我们建议两个连接的具体目标 (SA)：SA1 将研究 NAD+ 消耗对 Sirtuin 活性的影响，以及线粒体生物能量学，将确定 TiPARP 和 PARP1 在哺乳动物 TCDD 毒性中的作用模型并将寻求将 NAD 补充确定为针对 TCDD 毒性的预防和纠正策略。 SA2 将研究 TiPARP 的 ADP-核糖基化在 AHR 作用中的作用。具体来说，这些研究将使用以下方法阐明 NAD+ 消耗对 Sirts1、3 和 6 的生物和催化活性的影响新的 Sirtuin 特异性检测 (SA1a1)。 TCDD 消耗 NAD+ 在线粒体生物能学中的作用将是使用 Seahorse 技术检查耗氧量和糖酵解 (SA1a2) 的研究解决了这个问题。鸡胚肝细胞将在整个资助过程中使用，我们将确认人类的主要发现原代肝细胞。肝脏特异性 TiPARP 和 PARP1 KO 小鼠将用于评估它们在在哺乳动物模型中产生 TCDD 代谢毒性 (SA1b)。 SA1c将判断是否NAD+ 补充烟酰胺和其他 NAD+ 补充剂可以预防并可能纠正 TCDD 毒性。 SA2 将检查 TiPARP 的 ADP-核糖基化在 AHR 代谢毒性中的作用，正如我们发现的那样 PEPCK 被 TiPARP 进行 ADP 核糖基化。我们将检查（SA2a）PEPCK ADP-核糖基化的影响 TiPARP 对 PEPCK 稳定性和活性进行了评估，并将寻求鉴定 TiPARP 核糖基化的其他蛋白质揭示 ADP-核糖基化参与 AHR 作用的新方法 (SA2b)。我们期待这项研究建立一种重要机制，通过 PARP 活性消耗 NAD+ 导致 TCDD 肝病代谢毒性并确定 NAD+ 补充作为预防和/或纠正 AHR 代谢的方法体内毒性。