Autophagy-facilitated secretion in metabolic maintenance

自噬促进代谢维持中的分泌

• 批准号: 10490364
• 负责人: Congcong He
• 金额: $ 40万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-17 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10490364
• 关键词: 5' -AMP-activated protein kinase; Adipocytes; Adipose tissue; Attention; Autophagocytosis; Binding; Biochemical; Biochemistry; Blood Circulation; Cellular biology; Complex; Cyclic AMP-Dependent Protein Kinases; Data; Endocrine Glands; Endoplasmic Reticulum; Genes; Genetic; Goals; High Fat Diet; Homeostasis; Hormonal; Hormones; Human; Hyperactivity; Image; Insulin Resistance; Knock-in Mouse; Knockout Mice; Link; LoxP-flanked allele; Lysosomes; Maintenance; Mediating; Metabolic; Metabolic dysfunction; Metabolic syndrome; Metabolism; Molecular; Mus; Mutant Strains Mice; Mutation; Non-Insulin-Dependent Diabetes Mellitus; Pathway interactions; Pharmacology; Phenocopy; Phenotype; Phosphotransferases; Play; Process; Proteins; Proteomics; Receptor Signaling; Regulation; Research; Role; Serum; Signal Transduction; System; Testing; Tissues; Vesicle; adipokines; adiponectin; feeding; glucose tolerance; improved; insulin sensitivity; insulin sensitizing drugs; mouse model; novel; prevent; response; tool

Project Summary/Abstract The goal of this proposal is to demonstrate a novel non-degradative, non-cell autonomous, mechanism by which the autophagy machinery regulates metabolism. Although emerging evidence suggests that autophagy abnormality is implicated in metabolic dysfunction, the mechanism by which autophagy regulates insulin sensitivity is largely unknown. Autophagy is generally considered as a destruction and degradation process via lysosomes. We recently discovered a new non-degradative function regulated by a ULK1-Vps34-Becn1 autophagy machinery in adipose tissue, which may play a pivotal role in systemic AMPK activation and insulin sensitization. Adiponectin is an adipose-derived hormone (adipokine), whose reduction in circulation is strongly associated with type 2 diabetes (T2D) and metabolic syndrome. Hypoadiponectinemia caused by SNPs or mutations in the Adiponectin gene in humans has been associated with insulin resistance and T2D, and adiponectin knockout mice phenocopy the human phenotypes and develop insulin resistance. However, despite the functional importance of adiponectin, the mechanism that regulates adiponectin secretion has received little research attention and remains obscure. We found that autophagy-hyperactive mutant mice harboring an active mutation in the essential autophagy protein Becn1 (Becn1F121A knock-in mice) have improved insulin sensitivity in response to high-fat diet feeding, which is caused by factors in the circulation. To identify the Becn1-regulated, insulin-sensitizing, circulating factors, we performed a hormonal screen and identified a higher level of adiponectin in the serum of autophagy-hyperactive Becn1F121A mice. We found that on one hand, adipose- specific Becn1F121A expression is sufficient to improve systemic insulin sensitivity and increase circulating adiponectin levels; on the other hand, depleting Becn1, or inhibiting two upstream autophagy kinases, ULK1 and Vps34, reduces circulating adiponectin in mice. Using proteomic and biochemical approaches, we discovered that the exocyst component Sec6/Exoc3 is a binding partner of Becn1, and preferentially binds to the hyperactive form, Becn1F121A. Motivated by the preliminary data, we propose our overall hypothesis that a ULK1-Vps34- Becn1 autophagy axis improves insulin sensitivity by promoting adiponectin secretion via Becn1-exocyst binding in adipocytes. We term this pathway as “autophagy-facilitated secretion”. To test the hypothesis, we propose the following aims, using a combination of genetic, imaging, cell biology, biochemistry, and metabolic approaches: Aim 1 is to determine whether active Becn1 activates AMPK and improves insulin sensitivity via adiponectin signaling; Aim 2 is to determine whether a ULK1-Vps34-Becn1 autophagy axis functions in adipose tissue to non-cell autonomously regulate systemic insulin sensitivity; and Aim 3 is to demonstrate the molecular mechanism by which the Becn1-centered autophagy machinery regulates adiponectin secretion via the crosstalk with the exocyst pathway. Overall, our study will establish a new mechanistic paradigm for the Becn1-centered autophagy pathway in adipose tissue to prevent T2D, beyond its role in self-degradation.

项目摘要/摘要 该提议的目的是展示一种新型的非降解性，非细胞自主机制 自噬机械调节新陈代谢。尽管新兴的证据表明自噬 绝对与代谢功能障碍有关，自噬调节胰岛素的机​​制 灵敏度在很大程度上未知。自噬通常被视为通过 溶酶体。我们最近发现了一个由ULK1-VPS34-BECN1调节的新的非降解功能 脂肪组织中的自噬机械，可能在全身AMPK激活和胰岛素中起关键作用 致敏。脂联素是一种脂肪衍生的马酮（脂蛋白），其循环的减少很大 与2型糖尿病（T2D）和代谢综合征相关。由SNP或 人类脂联素基因中的突变与胰岛素抵抗和T2D有关，并且 脂联素基因敲除小鼠表型人类表型并发展胰岛素抵抗。但是，多皮 脂联素的功能重要性，调节脂联素分泌的机制几乎没有接受 研究注意力并保持晦涩难懂。我们发现具有活性的自噬性突变小鼠 必需自噬蛋白BECN1（BECN1F121A敲入小鼠）中的突变已提高胰岛素敏感性 响应高脂饮食喂养，这是由循环中的因素引起的。确定BECN1受调节的 胰岛素敏感性，循环因素，我们进行了一个马屏幕，并确定了更高水平的 脂联素在自噬型hyperactive becn1f121a小鼠的血清中。我们发现一方面，脂肪 - 特定的BECN1F121A表达足以提高全身性胰岛素灵敏度并增加循环 脂联素水平；另一方面，耗尽BECN1或抑制两个上游自噬激酶，ULK1和 VPS34减少小鼠循环脂联素。使用蛋白质组学和生化方法，我们发现了 外囊肿组件SEC6/EXOC3是BECN1的结合伙伴，优选地与多动态结合 形式，BECN1F121A。在初步数据的激励下，我们提出了我们的总体假设，即ULK1-VPS34- BECN1自噬轴通过通过BECN1-异常结合来促进脂联素分泌来提高胰岛素敏感性 在脂肪细胞中。我们将此途径称为“自噬相关分泌”。为了检验假设，我们提出了 以下目的，结合了遗传，成像，细胞生物学，生物化学和代谢方法： AIM 1是确定主动BECN1是否激活AMPK并通过脂联素提高胰岛素灵敏度 信号传导； AIM 2是确定ULK1-VPS34-BECN1自噬是否在脂肪组织中起作用 非细胞自主调节全身性胰岛素敏感性；目标3是证明分子 以BECN1为中心的自噬机制通过串扰调节脂联素分泌的机制 带有外囊途径。总体而言，我们的研究将建立以BECN1为中心的新机械范式 脂肪组织中的自噬途径可防止T2D，超出其在自我降解中的作用。