Identification and molecular characterization of anti-diabetic flavonoids

描述(由申请人提供)：这项研究的长期目标是识别和表征可以有效预防2型糖尿病(T2D)的天然药物。T2D是慢性胰岛素抵抗和β细胞质量和功能丧失的结果。因此，同时预防胰岛素抵抗和保护功能性细胞团的方法可能是预防T2D的更有效的策略。我们首次发现大豆和一些中草药中存在的异黄酮染料木素可以直接保护糖尿病小鼠的胰腺细胞不受凋亡的影响，改善高血糖，而不影响胰岛素敏感性。而山奈酚是银杏叶中的黄酮醇，可以改善肥胖小鼠的胰岛素敏感性和血糖稳态。值得注意的是，染料木素与山奈酚联合使用对中年肥胖糖尿病小鼠的血糖控制有很强的相加作用。我们在这个年龄段使用小鼠，因为人类的T2D通常发生在中老年。这些令人兴奋的发现表明，使用这些天然化合物有效预防T2D具有巨大的潜力。这项应用的目标是确定染料木素和山奈酚发挥抗糖尿病作用的分子机制。这项资助的中心假设是，膳食中摄入染料木素和山奈酚同时保留了功能性细胞质量，并改善了胰岛素敏感性，从而在预防T2D方面发挥了相加作用。目的1研究金雀异黄素是否通过G蛋白偶联受体GPR30激活G？S，进而刺激cAMP/PKA/CREB和PI3K/Akt通路，从而保护细胞的凋亡。分离的小鼠和人类胰岛将被用来识别金雀异黄素靶向的信号分子。具体地说，将利用GPR30缺陷小鼠以及遗传和药理学探针来探索这些途径是否介导了染料木素在β-细胞中的抗凋亡作用。目的#2将探索染料木素，山奈酚， 或两者的结合对胰岛β细胞功能、能量代谢和胰岛素敏感性的影响，以及体内这些作用的潜在分子机制。我们将首先 使用GPR30显著的糖尿病小鼠来确定金雀异黄素是否通过这种受体改善血糖稳态以及细胞存活和质量。然后，我们将测试山奈酚是否促进能量代谢和胰岛素敏感性，以及这些作用是否通过激活AMPK？？介导，AMPK？？是细胞能量稳态的主要调节因子，也是T2D的潜在治疗靶点。这笔赠款的完成预计将确定染料木素和山奈酚发挥抗糖尿病作用的新机制，这可能会导致开发使用这些低成本天然化合物来预防糖尿病的补充或替代(CAM)策略。糖尿病是美国和世界范围内一个日益严重的公共健康问题。

DESCRIPTION (provided by applicant): The long-range goal of this research is to identify and characterize natural agents that can effectively prevent type 2 diabetes (T2D). T2D is a result of chronic insulin resistance and loss of ?-cell mass and function. Therefore, a method to simultaneously prevent insulin resistance and protect functional ?-cell mass could be a more effective strategy to prevent T2D. We discovered for the first time that genistein, an isoflavone present in soybean and some Chinese herbs, directly protect pancreatic ?-cells from apoptosis and ameliorates hyperglycemia without affecting insulin sensitivity in diabetic mice, while kaempferol, a flavonol present in gingko biloba, improves insulin sensitivity and glucose homeostasis in obese mice. Notably, genistein in combination with kaempferol produces a potent additive effect on blood glycemic control in middle-aged obese diabetic mice. We used mice at this age because T2D usually occurs at middle and older age in humans. These exciting findings demonstrate a great potential for using these natural compounds to effectively prevent T2D. The goal of this application is to determine molecular mechanisms by which genistein and kaempferol exert an anti-diabetic effect. The central hypothesis of this grant is that dietary intae of both genistein and kaempferol simultaneously preserves functional ?-cell mass and improves insulin sensitivity, thereby exerting the additive effect in preventing T2D. Aim #1 will determine whether genistein protects against ?-cell apoptosis through the G-protein coupled receptor GPR30-mediated activation of G?s, and subsequent stimulation of the cAMP/PKA/CREB and PI3K/Akt pathways. Isolated mouse and human islets will be used to identify the signaling molecules targeted by genistein. Specifically, GPR30-deficient mice and genetic and pharmacological probes will be utilized to explore whether these pathways mediate the anti-apoptotic action of genistein in ?-cells. Aim #2 will explore the effects of genistein, kaempferol, or a combination of both on pancreatic beta-cell function, energy metabolism, and insulin sensitivity as well as the underlying molecular mechanisms for these actions in vivo. We will first use GPR30-deificent diabetic mice to determine whether genistein improves glucose homeostasis and ?-cell survival and mass via this receptor. We will then test whether kaempferol promotes energy metabolism and insulin sensitivity and whether these effects are mediated via activation of AMPK??, a master regulator of cellular energy homeostasis and potential therapeutic target for T2D. Completion of this grant is expected to define novel mechanisms by which genistein and kaempferol exert the anti-diabetic effects, which may potentially lead to the development of complementary or alternative (CAM) strategies using these low-cost natural compounds for the prevention of diabetes, a major and growing public health problem in the U.S. and worldwide.