Functionally probing hSGLT2 in diabetes treatment and glucose homeostasis

简介（由申请人提供）：糖尿病是21世纪发达国家面临的重大健康挑战之一，对社会和个人都造成了巨大的损失。因此，目前人们对寻找方法来降低由于这组以葡萄糖稳态失调为特征的疾病引起的发病率和死亡率非常感兴趣。其中一个方向是开发药物，通过人钠/葡萄糖共转运蛋白2 （hSGLT2）抑制糖在肾脏中的重吸收；虽然有几十种药物处于研发或早期临床试验阶段，但对hSGLT2知之甚少。它是否类似于它的肠道对应物hSGLTI ？它是如何利用钠梯度来驱动肾脏对糖的再摄取的？哪些分子与hSGLT2结合并被转运，哪些分子在结合和解离之间切换而不被转运？hSGLT2的全局表达（即整个身体）如何在葡萄糖稳态中发挥作用？考虑到这些以及更多相关问题，本研究的目标如下：具体目标1：建立hSGLT2的动力学模型。通过稳态和预稳态分析的新方法（在HEK293细胞中进行膜片钳实验），我们将了解这种低亲和力，高容量转运体的关键步骤和运输特性。特异性目标2：确定hSGLT2的底物、激动剂和拮抗剂。通过一个有效的动力学模型，各种分子的活性将在本研究中得到表征，这些分子的版本是针对hSGLT2的药物治疗的基础。随着hSGLT2底物特异性的进一步完善，我预计这项研究将导致hSGLT2特异性探针的设计和测试，用于正电子发射断层扫描（PET）成像。通过这项研究，我们将了解阻断hSGLT2运输的全球影响，我们将能够对调节和失调的葡萄糖稳态进行功能成像。糖尿病是一种流行病，对研究它的科学家和治疗它的医生都提出了独特的挑战。最近的治疗发展旨在通过人葡萄糖钠共转运蛋白2 （hSGLT2）来靶向肾脏对葡萄糖的重吸收，如果被阻断，则有助于控制血糖水平。本工作的重点是表征这种转运体，以便更好地确定靶向hSGLT2的药物的疗效和副作用，并通过未来的功能成像研究确定hSGLT2对血糖水平的真正影响。

DESCRIPTION (provided by applicant): Diabetes mellitus is one of the great health challenges facing the developed world in the 21st century, with monumental costs levied both to society and the individual. As such, there currently is great interest in finding ways to reduce the morbidity and mortality due to this group of disorders characterized by dysregulated glucose homeostasis. One such direction aims to develop pharmaceutical agents that blunt sugar reabsorption in the kidneys via the human sodium/glucose cotransporter 2 (hSGLT2); and while several dozen drugs are in either research and development or early stage clinical trials, little remains known about hSGLT2. Is it similar to its well-characterized intestinal counterpart hSGLTI ? How does it use a sodium gradient to drive renal reuptake of sugar against a gradient? Which molecules bind to and are transported by hSGLT2 and which toggle between binding and dissociating without being transported? How does global expression (i.e. throughout the entire body) of hSGLT2 play a role in glucose homeostasis? With these, and many more related questions in mind, this study's aims are as follows: Specific Aim 1: Establish a kinetic model for hSGLT2. With novel methods of both steady-state and presteady-state analyses (with patch clamp experiments in HEK293 cells), we will understand key steps and properties of transport by this proposed low-affinity, high-capacity transporter. Specific Aim 2: Identify substrates, agonists, antagonists for hSGLT2. With a working kinetic model, the activity of a variety of molecules - versions of which are the basis of pharmacotherapy aimed at hSGLT2 - will be characterized in this study. As the substrate specificity of hSGLT2 is further refined, I anticipate this research leading to the design and testing of hSGLT2-specific probes for imagining with positron emission tomography (PET). Through this, we will understand the global impact of blocking hSGLT2 transport, and we will be able to functionally image both regulated and dysregulated glucose homeostasis. *A disease of epidemic proportions, diabetes mellitus poses unique challenges to both the scientists who research and physicians who treat it. Recent therapeutic development aims to target the kidneys' reabsorption of glucose through the human sodium glucose cotransporter 2 (hSGLT2) which, if blocked, helps to control blood glucose levels. This work focuses on characterizing this transporter in order to better define efficacy and side effects of drugs targeting hSGLT2, as well as defining hSGLT2's true impact on blood glucose levels through future studies in functional imaging.