Protection against diabetes in db mice by gluthione peroxidase overexpression

描述（由申请人提供）：我的项目是研究增强内在β细胞防御机制是否可以防止氧化应激诱导的细胞损伤。为了达到这一目标，我的研究将解决以下具体目标：在自发性2型糖尿病动物模型db/db小鼠中，确定胰腺细胞特异性过表达抗氧化酶谷胱甘肽过氧化物酶对糖尿病发生和进展的影响。目标2。确定db/db小鼠胰腺β细胞特异性过表达抗氧化酶谷胱甘肽过氧化物酶是否能保护β细胞免受慢性高血糖引起的损伤。目标3。确定胰腺β细胞特异性抗氧化酶谷胱甘肽过氧化物酶的过度表达是否导致β细胞免受因长期暴露于高血糖而导致的β细胞功能下降的特征异常的保护。这包括胰岛素、PDX-1基因和MafA蛋白的表达降低。实验将在2型糖尿病的啮齿动物模型db/db小鼠中进行。我们将比较谷胱甘肽过氧化物酶转基因小鼠和野生型小鼠的发病率、发病时间和疾病严重程度，并将这些参数与β细胞的功能能力（由分泌活性、血浆胰岛素水平、胰腺胰岛素含量和葡萄糖耐量决定）联系起来。我们将通过形态测定法确定胰腺β细胞质量保存的程度和持续时间，并将其与胰岛的结构组织、细胞组成和β细胞凋亡率联系起来。还将分析转基因db/db动物和对照野生型动物的胰腺和离体胰岛中胰岛素、PDX-1和MafA基因和蛋白的表达和亚细胞定位。我们假设，增强内源性胰腺β细胞抗氧化防御将保护β细胞免受长期暴露于高血糖引起的氧化应激损伤，因此，将更好地保护胰腺β细胞的质量和功能，从而延缓或预防2型糖尿病模型中疾病的恶化。相关发现将有助于设计未来的研究，旨在通过在2型糖尿病患者和糖耐量受损的受试者中使用抗氧化药物来保护胰腺β细胞，延缓或预防2型糖尿病。

DESCRIPTION (provided by applicant): My project is to investigate whether the enhancement of intrinsic beta cell defense mechanisms protects against oxidative stress-induced cell damage. To reach this objective my study will address the following specific aims: Aim 1. Determine the effect of pancreatic beta cell-specific overexpression of the antioxidant enzyme glutathione peroxidase on diabetes development and progression in an animal model of spontaneous type 2 diabetes, the diabetic db/db mouse. Aim 2. Determine whether pancreatic beta cellspecific overexpression of the antioxidant enzyme glutathione peroxidase in db/db mice results in the protection of beta cells from damage induced by chronic hyperglycemia. Aim 3. Determine whether pancreatic beta cell-specific overexpression of the antioxidant enzyme glutathione peroxidase results in protection of the beta cells against abnormalities that are characteristically found with declining beta cell function due to chronic exposure to hyperglycemia. These include decreased expression of the insulin and PDX-1 genes and MafA protein. The experiments will be conducted in a rodent model of type 2 diabetes, the db/db mouse. We will compare glutathione peroxidase transgenic and wild type mice for the incidence, time of onset and severity of the disease, and relate these parameters to the functional capacity of the beta cells determined by their secretory activity, plasma insulin levels, pancreatic insulin content, and glucose tolerance. We will determine the extent and duration of preservation of pancreatic beta cell mass by morphometry and relate this to the structural organization of the islets, cellular composition, and beta cell apoptosis rate. Pancreases and isolated islets from transgenic db/db and control wild type animals will also be analyzed for expression and subcellular localization of insulin, PDX-1, and MafA genes and protein. We hypothesize that enhancing endogenous pancreatic beta cell antioxidant defense will protect against beta cell damage due to oxidative stress caused by chronic exposure to hyperglycemia and, hence, will provide a better preservation of the pancreatic beta cell mass and function, resulting in the delay or prevention of the worsening of the disease in this model of type 2 diabetes. Relevant findings will help design future studies aiming to preserve pancreatic beta cells and delay or prevent type 2 diabetes through use of antioxidant drugs in type 2 diabetic patients and subjects with impaired glucose tolerance. PUBLIC HEALTH RELEVANCE: The objective of my study thus relates to the National Institute of Health mission to acquire new knowledge to help prevent, detect, diagnose, and treat disease, and improve human health through biomedical and behavioral research, research training and communications.