The role of muscle-derived extracellular vesicles in adipocyte metabolism

细胞外囊泡（EV）是由几乎所有细胞类型释放的膜结合囊泡，其潜在地被称为细胞外囊泡。 介导细胞间通讯，从而在许多生理和病理过程中发挥重要作用。 流程.这种能力依赖于电动汽车作为各种内源性能源的运输工具的能力。 货物分子，如RNA、蛋白质和脂质。还发现EV显示组织特异性 由表面分子（如整合素和聚糖）介导的识别，使其有希望用于药物治疗。 交付应用程序。然而，有必要更好地了解EV组成和货物，以使 使用电动汽车作为运输工具。初步数据表明，在肥大刺激后， EV（mEV）被特异性地递送至脂肪组织。有趣的是，将mEV输送到脂肪组织 在高脂饮食喂养的小鼠中诱导脂肪分解和脂肪减少。这个令人兴奋的初步数据可能代表了第一个 进入了肥胖症治疗的发展阶段。此外，我们的初步数据显示， mEV内的甘油二酯（DAG），其在递送时可介导蛋白激酶C（PKC）活化， 诱导脂肪细胞代谢变化。拟议的项目扩展了我们的初步数据，并基于 关于肥大刺激会改变mEV的脂质组成，导致 脂肪细胞代谢改变。更具体地说，假设肥大刺激将增加 mEV内的DAG浓度，其将通过PKC活化诱导脂肪细胞脂解，导致全身 代谢益处。为了证实我们的初步数据，我们将使用肌肉细胞（C2 C12细胞）， 分离具有或不具有肥大刺激mEV（用胰岛素样生长因子1处理），并进行 这些囊泡的脂质分布。在建立脂质谱后，将mEV转移到脂肪细胞中 （3 T3 L1细胞）或将尾静脉注射到肥胖小鼠中。该项目的目的是测试这种工作 通过追求三个具体目标的假设。具体目的1是确定是否脂质组成的 骨骼肌细胞外囊泡响应于肥大刺激而改变;具体目标2是 确定mEV是否通过PKC激活刺激脂肪细胞脂解;具体目标3是 确定细胞外囊泡是否响应于肥大刺激可以诱导脂肪损失， 增强肥胖小鼠的脂解作用。初步数据表明，mEV对脂肪细胞 代谢和诱导肥胖小鼠的脂肪减少。如果拟议实验的结果提供了证据， 为了支持这一假设，未来的R 01应用程序将寻求严格测试哪一类/哪几类脂质可以 特异性介导脂肪细胞代谢的变化。

Extracellular vesicles (EVs) are membrane-bound vesicles released by virtually all cell types, potentially mediating intercellular communication and thereby play essential roles in many physiological and pathological processes. This capacity relies on EVs’ ability to serve as delivery vehicles for a wide range of endogenous cargo molecules, such as RNAs, proteins, and lipids. EVs have also been found to display tissue-specific recognition mediated by surface molecules (such as integrins and glycans), making them promising for drug delivery applications. However, a better understanding of EV composition and cargo is necessary to enable the use of EVs as delivery vehicles. Preliminary data demonstrate that after a hypertrophic stimulus, muscle-derived EVs (mEVs) are specifically delivered to adipose tissue. Interestingly, the delivery of mEVs to adipose tissue induced lipolysis and fat loss in high-fat-diet-fed mice. This exciting preliminary data could represent the first steps into the development of therapy for obesity. Additionally, our preliminary data indicate high levels of diacylglycerol (DAG) within mEVs, which could, upon delivery, mediate protein kinase C (PKC) activation and induce changes in adipocyte metabolism. The proposed project expands upon our preliminary data and is based on the overarching hypothesis that a hypertrophic stimulus would change the lipid makeup of mEVs, leading to adipocyte metabolism changes. More specifically, it is hypothesized that a hypertrophic stimulus will increase DAG concentration within mEVs that will induce adipocyte lipolysis through PKC activation, resulting in wholebody metabolic benefits. In order to confirm our preliminary data, we will use muscle cells (C2C12 cells) to isolate mEVs with or without a hypertrophic stimulus (treatment with insulin-like growth factor 1) and perform a lipid profile of these vesicles. After establishing the lipid profile, mEVs will be transferred to adipocyte cells (3T3L1 cells) or will be tail vein injected into obese mice. The purpose of this project is to test this working hypothesis by pursuing three specific aims. Specific Aim 1 is to determine whether the lipid composition of skeletal muscle extracellular vesicles is altered in response to a hypertrophic stimulus; Specific Aim 2 is to determine whether mEVs stimulate adipocyte lipolysis through PKC activation; and Specific Aim 3 is to determine whether extracellular vesicles in response to a hypertrophic stimulus can induce fat loss through enhanced lipolysis in obese mice. Preliminary data suggest that mEVs provide beneficial effects on adipocyte metabolism and induce fat loss in obese mice. If the results of the proposed experiments provide evidence to support the hypothesis, a future R01 application will seek to rigorously test which class/classes of lipids can specifically mediate changes in adipocyte metabolism.