Role of endogenous lipids in the regulation of biphasic insulin secretion.

内源性脂质在双相胰岛素分泌调节中的作用。

• 批准号: RGPIN-2016-04145
• 负责人: Joseph, Jamie
• 金额: $ 2.4万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709007
• 关键词: Role; endogenous; lipids; regulation; biphasic

There are three sources of free fatty acids (FFA) 1) exogenously-derived FFAs, 2) endogenously-synthesized FFAs (de novo lipogenesis (DNL)) and 3) release from internal triglyceride stores. DNL occurs primarily in liver cells, however, many tissue types are able to produce limited amounts of lipid. The role of this small amount of DNL in these cell types is not completely understood. For example, insulin secreting cells of the pancreas express enzymes that lead to DNL in proportion to the amount of glucose exposure. This glucose driven DNL has been proposed to be important in generating metabolic signaling molecules important for regulating insulin exocytosis. It has also been suggested that glycerolipid (GL)/ FFA cycling from internal triglyceride stores may also play a role in the regulation of insulin release. Inhibition of this cycling suppresses FFA augmentation of glucose-stimulated insulin release. We have published results showing that the effects of manipulating four key enzymes (PC, CL, ACC and FAS) and three metabolic carriers (pyruvate carrier, citrate carrier and dicarboxylate carrier) that are involved in DNL lead to conflicting results for and against a role of DNL in regulating insulin exocytosis. We will continue to investigate the role of DNL in the regulation of glucose-stimulated insulin release using newly developed tools in the lab. We have also identified several glucose derived endogenous lipid species that may be critical for regulating biphasic insulin secretion using a metabolomics approach. A number of questions arise from these metabolomics studies for example what is the source of these glucose derived endogenous lipids (e.g. release from triglyceride (TG) stores or from DNL) and how might these lipids be involved in regulating biphasic insulin release. We will expand on these studies to further investigate the role of endogenous lipids in the regulation of biphasic insulin release. Hypothesis: Endogenous lipids generate signaling molecules that are critical to the metabolic regulation of biphasic insulin secretion. Experimental approach: We have identified several endogenous lipid species that may be critical for regulating biphasic insulin secretion using a metabolomics approach. We will use molecule cloning techniques, siRNAs and siRNA adenoviruses, metabolic assays, enzymatic assays, secretion assays, fluorescent imaging and metabolomics to measure metabolite profiles and metabolic fluxes in key endocrine models of fuel regulated secretion. The combination of these approaches will allow us to study all aspects of the metabolic regulation of biphasic insulin secretion by DNL. Novelty and significance: It is well known that exogenous lipids regulate insulin secretion but the role of endogenous is less well defined. These studies will provide invaluable insights towards understanding the unique role of lipids play in the regulation of exocytosis.

游离脂肪酸 (FFA) 有三种来源：1) 外源性 FFA，2) 内源合成 FFA（从头脂肪生成 (DNL)），3) 从内部甘油三酯储存中释放。 DNL 主要发生在肝细胞中，然而，许多组织类型能够产生有限量的脂质。这种少量 DNL 在这些细胞类型中的作用尚不完全清楚。例如，胰腺的胰岛素分泌细胞表达与葡萄糖暴露量成比例的导致 DNL 的酶。这种葡萄糖驱动的 DNL 被认为对于产生代谢信号分子非常重要，而代谢信号分子对调节胰岛素胞吐作用很重要。也有人提出，来自内部甘油三酯储存的甘油脂 (GL)/FFA 循环也可能在胰岛素释放的调节中发挥作用。抑制这种循环可以抑制 FFA 对葡萄糖刺激的胰岛素释放的增强。我们发表的结果表明，操纵 DNL 中涉及的四种关键酶（PC、CL、ACC 和 FAS）和三种代谢载体（丙酮酸载体、柠檬酸载体和二羧酸载体）的效果会导致支持和反对某个角色的相互矛盾的结果DNL 在调节胰岛素胞吐作用中的作用我们将继续使用实验室新开发的工具研究 DNL 在调节葡萄糖刺激的胰岛素释放中的作用。我们还鉴定了几种葡萄糖衍生的内源性脂质种类，它们可能对于使用代谢组学方法调节双相胰岛素分泌至关重要。这些代谢组学研究产生了许多问题，例如这些葡萄糖衍生的内源性脂质的来源是什么（例如从甘油三酯（TG）储存或从 DNL 中释放）以及这些脂质如何参与调节双相胰岛素释放。我们将扩展这些研究，以进一步研究内源性脂质在双相胰岛素释放调节中的作用。 假设：内源性脂质产生的信号分子对于双相胰岛素分泌的代谢调节至关重要。 实验方法：我们已经使用代谢组学方法鉴定了几种对于调节双相胰岛素分泌可能至关重要的内源性脂质种类。我们将使用分子克隆技术、siRNA 和 siRNA 腺病毒、代谢测定、酶测定、分泌测定、荧光成像和代谢组学来测量燃料调节分泌的关键内分泌模型中的代谢物谱和代谢通量。这些方法的结合将使我们能够研究 DNL 对双相胰岛素分泌的代谢调节的各个方面。 新颖性和意义：众所周知，外源性脂质调节胰岛素分泌，但内源性脂质的作用尚不清楚。这些研究将为理解脂质在胞吐作用调节中的独特作用提供宝贵的见解。