Identification and molecular characterization of anti-diabetic flavonoids

描述（由申请人提供）：本研究的长期目标是鉴定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？-细胞的质量和功能。因此，有一种方法可以同时预防胰岛素抵抗和保护功能？细胞团可能是一种更有效的预防T2D的策略。我们首次发现染料木素，一种存在于大豆和一些中草药中的异黄酮，直接保护胰腺？在糖尿病小鼠中，山奈酚（一种存在于银杏叶中的黄酮醇）可以改善胰岛素敏感性和葡萄糖稳态。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产生了强有力的加性效应。我们使用这个年龄的小鼠，因为T2D通常发生在人类的中老年。这些令人兴奋的发现显示了利用这些天然化合物有效预防T2D的巨大潜力。本应用的目的是确定染料木素和山奈酚发挥抗糖尿病作用的分子机制。这项研究的中心假设是，同时摄入染料木黄酮和山奈酚可以保持功能性？-细胞质量，提高胰岛素敏感性，从而对预防T2D发挥叠加作用。目标1将决定染料木素是否能预防？通过G蛋白偶联受体gpr30介导的G？s，并随后刺激cAMP/PKA/CREB和PI3K/Akt通路。分离的小鼠和人类胰岛将被用来鉴定染料木黄酮靶向的信号分子。具体来说，我们将利用gpr30缺陷小鼠和遗传和药理学探针来探索这些途径是否介导染料木素在细胞中的抗凋亡作用。目标#2将探索染料木素，山奈酚，

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.