Environmental Circadian Disruptors Increase Diabetes and Metabolic Disorders Risk

描述(申请人提供)：暴露在环境化学品中是人类健康的一个主要问题，因为天然和人造物质会对生理过程产生不利影响，从而可能导致肥胖、代谢综合征和2型糖尿病的发生。在成人中，2型糖尿病约占确诊糖尿病病例的90%，是心脏病、中风、肾衰竭、非创伤性下肢截肢和失明的主要风险因素。这项提议的目标是确定影响昼夜节律激素褪黑激素的内分泌干扰物，以及它向目标周围组织发送“时刻”信息的能力。松果体褪黑激素的释放受下丘脑视交叉上核(SCN)生物钟的调节，而SCN又通过激活MT1和MT2褪黑素受体来调节周围靶组织。在胰腺细胞中，褪黑素受体信号的破坏可能改变糖代谢和胰岛素释放的动态平衡节律平衡，从而导致糖尿病和代谢紊乱。我们的主要假设是，某些环境化学物质通过持续和不规律地激活和/或阻断SCN和靶周围组织中的褪黑素受体，作为昼夜节律干扰物(例如。胰岛)。为实现我们的目标而设计的具体目标是：1)使用集成的药物信息学方法从用于计算机2D/3D褪黑激素能药效团指纹识别的环境试剂知识库中鉴定环境昼夜节律干扰物；2a)反复评估环境干扰物的配基亲和力、选择性和有效性，以竞争在哺乳动物CHO细胞中表达的hMT1和hMT2褪黑素受体(在没有和存在GTP的情况下)2[125I]-碘-褪黑素结合hMT1和hMT2褪黑素受体，以及2b)通过在INS1？细胞中表达的大鼠褪黑素受体的功能激活来调节forsklin介导的CRE-荧光素酶报告基因的表达和胰岛素的分泌；3)采用体外生物测定方法，通过改变大鼠INS-1胰腺细胞(MT1)中褪黑素受体的敏感性和信号转导，以及通过减弱褪黑素介导的cAMP形成抑制(MT1、MT2)和蛋白激酶C刺激(MT2)，来确定所选环境化学物质改变糖尿病标志物节律性动态平衡的可能性。此外，还将测量胰腺b细胞的细胞增殖和脂质过氧化，以评估这些干扰物增加糖尿病相关代谢紊乱风险的可能性。我们的综合Chem2Risk战略将为进一步在动物模型中进行测试提供必要的动力，并有助于未来评估与具有类似化学结构特征的环境干扰物相关的风险因素，并建立暴露监管指南。

DESCRIPTION (provided by applicant): Exposure to environmental chemicals is a major concern for human health as natural and man-made substances can adversely affect physiological processes which may contribute to the incidence of obesity, metabolic syndrome, and type 2 diabetes. In adults, type 2 diabetes accounts for about 90% of diagnosed diabetes cases and is a major risk factor for heart disease, stroke, kidney failure, non-traumatic lower-limb amputations and blindness. The goal of this proposal is to identify endocrine disruptors affecting the circadian hormone melatonin and its ability to signal "time-of-day" messages to target peripheral tissues. The release of melatonin from the pineal gland is regulated by biological clocks in the suprachiasmatic nucleus (SCN) of the hypothalamus which in turn regulates peripheral target tissues through activation of MT1 and MT2 melatonin receptors. In pancreatic ß-cells, disruption of melatonin receptor signaling may alter homeostatic rhythmic balance of glucose metabolism and insulin release leading to diabetes and metabolic disorders. Our overarching hypothesis is that, certain classes of environmental chemicals act as circadian disruptors by persistent and irregular activation and/or blockade of melatonin receptors in the SCN and in target peripheral tissues (eg. pancreatic islets). Specific aims designed to accomplish our goals are: 1) to use an integrated pharmacoinformatics approach to identify environmental circadian disruptors from a knowledgebase of environmental agents using in silico 2D/3D melatonergic pharmacophore fingerprinting; 2a) to iteratively assess ligand affinity, selectivity and efficacy of environmental disruptors in competition for 2[125I]- iodomelatonin binding to hMT1 and hMT2 melatonin receptors expressed in mammalian CHO cells both in the absence and presence of GTP, and 2b) to modulate forskolin-mediated CRE-luciferase reporter gene expression and insulin secretion via functional activation of rat melatonin receptors expressed in rat INS1 ß-cells; 3) To determine the potential of selected environmental chemicals to alter the rhythmic homeostatic balance of diabetes markers through changes of melatonin receptor sensitivity and signaling in rat INS-1 pancreatic ß-cells (MT1) altering MT1-mediated sensitization and in SCN 2.2 cells by attenuating melatoin- mediated inhibition of cAMP formation (MT1, MT2) and Protein Kinase C stimulation (MT2) using in vitro bioassays. Furthermore, cell proliferation, and lipid peroxidation in pancreatic b-cells will be measured to assess the potential of these disruptors to increase the risk of diabetes associated metabolic disorders. Our integrated Chem2Risk strategy will provide the essential impetus to pursue further testing in animal models and be useful in future assessment of risk factors associated with environmental disruptors carrying similar chemical-structural features and to establish exposure regulatory guidelines.