Decoding regulation of glucose homeostasis and metabolic responses to mitochondrial stress by AMPK

项目摘要/摘要 高空腹血糖和体重指数分别排在全球死亡风险因素的第3位和第4位 2017年。代谢功能障碍将这些因素与2型糖尿病等现代疾病流行联系在一起 (T2D)。目前的许多疗法和治疗发展计划都侧重于症状，而不是潜在的 代谢障碍在这些疾病中常见的代谢障碍。这项工作的一个主要目标是定义机制 推动适应不良代谢，开发更有效的治疗策略，有可能导致多种疾病 适用性。线粒体损伤(例如氧化代谢效率低下和线粒体不足 质量控制)被认为是这些疾病的主要病理成分。因此，理解 线粒体调节机制结合疾病中的代谢缺陷是一种手段 改进未来的疾病治疗。AMPK是细胞的中枢调节因子 代谢和线粒体生物学的多个方面。有缺陷的AMPK信号通常会与 线粒体损伤在疾病中的病理学特征。然而，了解身体的整体效应 AMPK信号作为代谢功能障碍和疾病的多方面驱动因素受到 缺乏可行的哺乳动物模型。器官特异性AMPK小鼠模型的丢失是解剖的关键 AMPK对体内单个细胞类型的代谢影响，但没有解决体内多器官缺陷 AMPK信号与胰岛素抵抗和T2D相关。此外，发展的整体- AMPKα1和AMPKα2催化亚基(AMPK-DKO)的体内敲除可导致小鼠宫内死亡。至 为了解决这些问题，第一个可诱导的全身AMPK-DKO(iAMPK-DKO)小鼠模型已经被 已生成。这个模型绕过了发育性AMPK-DKO的致命性，并概括了与疾病相关的 AMPK信号通路中的多器官缺陷。该模型的初步数据显示葡萄糖缺乏。 与T2D研究相关的动态平衡，包括吸收后高血糖和糖耐量减低 以及看似自相矛盾的禁食引起的低血糖。此外，将iAMPK-DKO与 基因诱导的小鼠慢性线粒体应激导致独特的代谢谱，这可能是 与血糖控制有关。这个项目的PI在解码体内代谢方面拥有丰富的专业知识 生理学。将这一专业知识与急性分离的器官特异性线粒体功能评估结合起来 原代模型、器官特异性原代细胞的培养、基因表达的分子操作和共聚焦 细胞系统的显微镜将使这一提议的中心假设得到检验：AMPK保存 线粒体代谢维持正常生理性血糖动态平衡，使代谢 在慢性线粒体应激期间保持葡萄糖稳态的灵活性。检验这一假说 提供了对AMPK在糖调节生理学中的作用的洞察，并开始通过 其中AMPK在正常生理和病理性线粒体应激状态下支持血糖稳态。

Project Summary/Abstract High fasting plasma glucose and body mass index ranked 3rd and 4th, respectively, as global mortality risk factors in 2017. Metabolic dysfunction links these factors with modern disease epidemics such as Type 2 diabetes (T2D). Many current therapies and therapeutic development programs focus on symptoms rather than underlying metabolic dysfunction common among these diseases. A primary goal of this work is to define mechanisms driving maladaptive metabolism to develop more effective therapeutic strategies with potential for multi-disease applicability. Mitochondrial impairments (e.g. inefficient oxidative metabolism and insufficient mitochondrial quality control) are hypothesized as major pathologic components in these diseases. Therefore, understanding mechanisms of mitochondrial regulation in conjunction with defective metabolism in diseases is a means towards improving disease treatments going forward. AMP-activated protein kinase (AMPK) is a central regulator of cell metabolism and multiple aspects of mitochondrial biology. Deficient AMPK signaling often overlaps the pathological profile of mitochondrial impairments in disease. However, understanding whole-body effects of deficient AMPK signaling as a multi-faceted driver of metabolic dysfunction and disease has been hampered by lack of viable mammalian models. Organ-specific loss of AMPK mouse models have been critical for dissection of metabolic implications of AMPK for individual cell types in vivo, but do not address multi-organ defects in AMPK signaling that has been associated with insulin resistance and T2D. Additionally, developmental whole- body knockout of AMPKα1 and AMPKα2 catalytic subunits (AMPK-DKO) causes in utero lethality in mice. To address these issues, the first mouse model for inducible, whole-body AMPK-DKO (iAMPK-DKO) has been generated. This model circumvents lethality of developmental AMPK-DKO and recapitulates disease-relevant multi-organ defects in AMPK signaling. Preliminary data from this model demonstrate deficient glucose homeostasis that is relevant to the study of T2D including postabsorptive hyperglycemia and glucose intolerance as well as a seemingly paradoxical fasting induced hypoglycemia. Additionally, combining iAMPK-DKO with genetically induced chronic mitochondrial stress in mice results in unique metabolic profiles, which are likely relevant to glucose control. The PI for this project has extensive expertise with decoding in vivo metabolic physiology. Combining this expertise with assessment of organ-specific mitochondrial function in acutely isolated primary models, culture of organ-specific primary cells, molecular manipulation of gene expression, and confocal microscopy of cellular systems will enable testing of this proposal’s central hypothesis: AMPK preserves mitochondrial metabolism to maintain normal physiologic glucose homeostasis and enables metabolic flexibility to preserve glucose homeostasis during chronic mitochondrial stress. Testing this hypothesis offers insight in to the role of AMPK in glucoregulatory physiology and begins to decode the mechanisms by which AMPK supports glucose homeostasis in normal physiology and pathologic mitochondrial stress.