Adipose Tissue Angiogenesis and Metabolic Disease

 描述(申请人提供)：代谢性疾病，包括2型糖尿病和非酒精性脂肪性肝病，由能量利用和储存紊乱引起，因此与脂肪组织的生理直接相关。许多成年人拥有代谢活跃的“米色”脂肪组织，其质量与肥胖呈负相关，与代谢健康呈正相关。这种组织是如何产生的，对环境线索的反应，以及它在诊断和治疗方面的潜力是目前正在研究的令人兴奋的问题。然而，缺乏足够的模型来研究人类的这种组织。这一建议是基于我们实验室最近的一项令人兴奋的发现，该发现能够分离和扩增产生白色和米色脂肪细胞的人类原代前脂肪细胞。我们发现，人类“米色”前脂肪细胞定位于脂肪组织血管内，只有在体外促进毛细血管网络扩张的条件下才能增殖。我们现在试图利用这些发现来了解这些细胞形成的细胞和分子基础，以及它们有益的代谢作用的潜在机制。具体目标1：使用新的深度测序和生物信息学方法，使用非常低的RNA输入进行细胞注释，我们将确定白色和“米色”脂肪细胞是否来自相同或不同的脂肪细胞前体细胞。具体目标2：我们的初步研究表明，将人的“米色”脂肪细胞移植到NOD-SCID IL2rγNull(Nsg)小鼠体内可以改善葡萄糖的处理，这表明细胞本身可以提供代谢益处。我们将确定植入的人类“米色”脂肪细胞是通过充当葡萄糖和脂肪利用的能量接收器，还是通过在其他组织中分泌增强葡萄糖耐量和胰岛素敏感性的因子来改善全身葡萄糖代谢。特定的 目的3：我们对人类“米色”脂肪细胞基因表达分析的新发现揭示了强大的神经内分泌因子的mRNAs的诱导，包括在许多人类群体中与肥胖遗传相关的前蛋白转换酶PCSK1。因此，人类“米色”脂肪细胞的有益作用可能是由于神经内分泌功能。质谱学证实了PCSK1片段的分泌，并鉴定了新的分泌肽。这里提出的蛋白质组学分析将进一步确定这些细胞分泌的蛋白质组，并为分析其对全身糖耐量的影响提供必要的信息。这项拟议的工作将回答有关人类“米色”脂肪细胞及其分泌产物的起源、特征和功能特性的关键问题，并为利用这些发现在人类代谢性疾病的诊断和治疗应用方面的临床研究提供基础。

 DESCRIPTION (provided by applicant): Metabolic diseases, including type 2 diabetes and non-alcoholic fatty liver disease, arise from disordered energy utilization and storage, and are therefore directly linked to the physiology of adipose tissue. Many adult humans possess metabolically active "beige" adipose tissue, and its mass shows an inverse correlation with adiposity and a direct correlation with metabolic health. How this tissue arises, responds to environmental cues, and its potential for diagnostic and therapeutic use are exciting questions currently under investigation. However, adequate models to study this tissue from humans are lacking. This proposal is based on an exciting recent finding from our laboratory that enables the isolation and expansion of human primary pre-adipocytes that give rise to white and "beige" adipocytes. We discovered that human "beige" pre-adipocytes are localized within the adipose tissue vasculature, and proliferate only under conditions that promote capillary network expansion in vitro. We now seek to leverage these findings to understand the cell and molecular basis for the formation of these cells, and the mechanisms underlying their beneficial metabolic effects. Specific Aim 1: Using new deep sequencing and bioinformatics approaches that enable cell annotation using very low RNA input we will determine whether white and "beige" adipocytes emerge from the same or distinct pre-adipocyte progenitors. Specific Aim 2: Our preliminary studies indicate that implantation of human "beige" adipocytes into NOD-scid IL2rγnull (NSG) mice improves glucose disposal, suggesting that cells per-se can confer a metabolic benefit. We will determine whether implanted human "beige" adipocytes improve systemic glucose metabolism by acting as an energy sink for glucose and lipid utilization, or by secreting factors that enhance glucose tolerance and insulin sensitivity in other tissues. Specific Aim 3: Our new findings from gene expression analysis of human "beige" adipocytes has revealed induction of mRNAs for potent neuroendocrine factors, including the pro-protein convertase PCSK1 which is genetically associated with obesity in numerous human populations. Thus, the beneficial effect of human "beige" adipocytes may be due to a neuroendocrine function. Mass spectroscopy has confirmed the secretion of fragments of PCSK1, and identified novel secreted peptides. Proteomic analysis proposed here will further define the secreted proteome from these cells, and provide information necessary for analyzing its impact on systemic glucose tolerance. The work proposed will answer pivotal questions regarding the origin, characteristics and functional properties of human "beige" adipocytes and their secreted products, and provide the foundation for clinical studies leveraging these findings for diagnostic and therapeutic applications in human metabolic disease.