ROLE OF NRF2 IN NITRERGIC MEDIAITED STOMACH MOTILITY

胃轻瘫是糖尿病的常见并发症，可涉及致病性氧化应激。在啮齿类动物模型中，神经元一氧化氮合酶（nNOS）解偶联和活性氧（ROS）增加导致的一氧化氮（NO）生物利用度降低已被证明在胃排空延迟中发挥作用。转录因子核因子（红细胞衍生-2）样2 （NRF2）调控II期抗氧化和解毒基因的表达。在糖尿病啮齿动物模型中的初步研究表明，氧化应激升高时，NRF2及其靶基因Gclc和Gclm的表达受到抑制。我们已经证明，与年龄匹配的野生型小鼠相比，NRF2 （Nfe2/2-/-）的缺失导致四氢生物蝶呤（BH4， nNOS二聚化和酶活性的关键辅助因子）水平下降，这导致氧化应激、nNOS解偶联、NO水平降低、胃氮能神经元功能障碍和胃排空延迟。这些数据支持这样一种观点，即糖尿病患者NRF2表达的缺失会损害抗氧化基因的表达，从而导致NO合成的失调，从而导致胃轻瘫的发生。我们提供的证据表明，性激素，雌二醇-17β (E2)介导的NRF2/nNOS的表达和功能在糖尿病发病过程中受损。此外，我们已经证明糖原合成酶激酶3β (GSK-3β)或E2调节女性胃中NO的合成。这些数据表明，高血糖期间NRF2表达的丧失是GSK-3β/CUL1/SCF/TrCP/RBX1轴激活的结果。我们的中心假设是NRF2调节氮能介导的胃运动。特异性目的1：将验证高血糖期间NRF2表达缺失是GSK-3β/CUL1/SCF/TrCP/RBX1轴激活的结果的假设；专项目的2：验证糖尿病患者NRF2及NRF2调控的抗氧化酶表达恢复后胃运动和胃排空正常的假设；特异性目的3：验证NRF2和nNOS介导的胃运动受女性性激素调节的假说；17-雌二醇（E2）、黄体酮和/或它们在糖尿病动物胃中的受体。特异性目的4：研究牙周病原体是否会抑制肥胖/糖尿病雌性小鼠的胃肠运动。这些研究数据将为nrf2介导的nNOS功能的调控机制提供重要信息，从而增强我们对胃轻瘫病理生理的认识。在这些目标中概述的研究具有翻译相关性，因为它有可能确定糖尿病性胃轻瘫的新治疗方案。

Gastroparesis is a common complication of diabetes and can involve pathogenic oxidative stress. In rodent models, reduced nitric oxide (NO) bioavailability as a result of neuronal nitric oxide synthase (nNOS) uncoupling and increased reactive oxygen species (ROS) has been shown to play a role in delayed gastric emptying. The transcription factor nuclear factor (erythroid-derived-2)-like 2 (NRF2) regulates the expression of Phase II antioxidant and detoxification genes. Preliminary studies in rodent model of diabetes showed that the expression of NRF2 and its target genes, Gclc and Gclm, is suppressed while oxidative stress is elevated. We have demonstrated that loss of NRF2 (Nfe2/2-/-) resulted in decreased levels of tetrahydrobiopterin (BH4, a critical cofactor for nNOS dimerization and enzyme activity) and that this led to oxidative stress, uncoupling of nNOS, reduced NO levels, gastric nitrergic neuron dysfunction, and delayed gastric emptying compared to age-matched wild-type mice. These data support the notion that loss of NRF2 expression in diabetes impairs antioxidant gene expression, which deregulates NO synthesis, thereby contributing to the development of gastroparesis. We provide evidence that sex hormone, estradiol-17β (E2) mediated NRF2/nNOS expression and function is impaired in the onset of diabetes. In addition, we have shown that glycogen synthase kinase 3beta (GSK-3β) or E2 regulate the synthesis of NO in female stomachs. This data suggest that loss of NRF2 expression during hyperglycemia is a consequence of activation of a GSK-3β/CUL1/SCF/TrCP/RBX1 axis. Our central hypothesis is that nitrergic mediated gastric motility is regulated by NRF2. Specific Aim 1: will test the hypothesis that loss of NRF2 expression during hyperglycemia is a consequence of activation of a GSK-3β/CUL1/SCF/TrCP/RBX1 axis; Specific Aim 2: will test the hypothesis that restoration of NRF2 and NRF2-regulated antioxidant enzyme expression in diabetes will result in normal gastric motility and gastric emptying; and Specific Aim 3: will test the hypothesis that NRF2 and nNOS mediated gastric motility are regulated by female sex hormones; 17-estradiol (E2), progesterone and/or their gastric receptors in diabetic animals. Specific Aim 4: Investigate whether periodontal pathogens inhibit gastrointestinal (GI) motility in obese/diabetic female mice. The data from these studies will provide important information as to the mechanisms of regulation of NRF2-mediated nNOS function and thereby enhance our understanding of the pathophysiology of gastroparesis. The research outlined in these aims has translational relevance as it has the potential to identify novel treatment options for diabetes-induced gastroparesis.