Environmental Circadian Disruptors Increase Diabetes and Metabolic Disorders Risk

描述（由申请人提供）：暴露于环境化学品是人类健康的主要问题，因为天然和人造物质会对生理过程产生不利影响，可能导致肥胖症、代谢综合征和2型糖尿病的发生。在成人中，2型糖尿病占诊断糖尿病病例的约90%，是心脏病、中风、肾衰竭、非创伤性下肢截肢和失明的主要危险因素。该提案的目标是确定影响昼夜节律激素褪黑激素及其向目标外周组织发出"一天中的时间"信息的能力的内分泌干扰物。从松果体释放褪黑激素受下丘脑视交叉上核（SCN）中的生物钟调节，下丘脑视交叉上核又通过激活MT 1和MT 2褪黑激素受体调节外周靶组织。在胰腺？-在细胞中，褪黑激素受体信号传导的破坏可能改变葡萄糖代谢和胰岛素释放的稳态节律平衡，导致糖尿病和代谢紊乱。我们的总体假设是，某些类别的环境化学物质通过持续和不规则的激活和/或阻断SCN和靶外周组织中的褪黑激素受体（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，使用计算机2D/3D褪黑激素能药效团指纹图谱从环境因子的知识库中识别环境昼夜节律干扰物; 2a）迭代评估配体亲和力，环境干扰物在竞争2 [125I]-碘褪黑激素与在哺乳动物CHO细胞中表达的hMT 1和hMT 2褪黑激素受体的结合，和2b）调节毛喉素介导的CRE-荧光素酶报告基因表达和胰岛素分泌通过功能激活大鼠INS 1？单元格; 3）通过改变大鼠INS-1胰腺组织中褪黑素受体的敏感性和信号传导，确定选定的环境化学物质改变糖尿病标志物节律性稳态平衡的潜力。细胞（MT1）改变MT1介导的致敏作用，以及SCN 2.2细胞通过减弱褪黑激素介导的cAMP形成抑制（MT1，MT2）和蛋白激酶C刺激（MT2），使用体外生物测定。此外，将测量胰腺b细胞中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潜力。我们的综合Chem2Risk战略将为在动物模型中进行进一步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 ?-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 ?-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 ?-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.