Tuning Adipocyte Size and Obesity through SWELL1

项目摘要 健康的脂肪组织扩张对于在营养过剩的情况下维持代谢健康是必要的- 这种情况在美国越来越重要，因为肥胖的发病率估计为美国的33%， 人口因此，阐明调节脂肪细胞的基本营养感受机制， 扩张对于理解和最终治疗肥胖的负面代谢后果至关重要。 我们以前发现了富含亮氨酸重复序列的8A（LRRC8a或SWELL1），这是一种新发现的蛋白质。 体积调节阴离子通道（VRAC）的重要组成部分，作为一种新型的体积感应调节剂， 胰岛素敏感性和胰岛素分泌。我们和其他人发现，SWELL1活性和蛋白质表达是 在代谢不健康的肥胖小鼠和人类中减少-这表明减少的多器官SWELL1 活性/表达有助于肥胖诱导的代谢综合征。我们组有生化的，补丁- 钳和成像证据表明，SWELL1通道复合物也表达和功能， 溶酶体考虑到溶酶体是整合营养感测和AKT-mTOR信号传导的信号中枢， 我们假设溶酶体SWELL1-LRRC8通道通过以下途径参与细胞营养感受： 激活响应于管腔内溶酶体亮氨酸的增加，并且这种信号传导机制 在肥胖引起的糖尿病和胰岛素抵抗的情况下是失调的。为了验证这个假设， 我们结合联合收割机独特的试剂和创新的方法，从Diwan（溶酶体信号），Xu（溶酶体 膜片钳）和Held（质谱）实验室，我们在SWELL1信号传导方面的专业知识， 对来自高度表型化的代谢健康和不健康的人的人脂肪组织样品（Klein 实验室）。我们的目标是了解质膜和溶酶体SWELL1（Lyso-1）的机制。 SWELL1）营养感应及其在疾病状态下如何失调，包括肥胖诱导的葡萄糖 不耐受和胰岛素抵抗。这些研究的基本原理是描述SWELL1的贡献 溶酶体营养传感和mTORC 1激活将促进我们对一个基本的细胞 信号传导机制，并指导糖尿病前期和糖尿病患者的创新治疗方法。 我们提出以下目标： ·AIM#1：描述质膜相对于溶酶体SWELL1信号传导至AKT的机制。 脂肪细胞中的AMPK-mTOR信号传导 ·AIM#2：检查SWELL1信号传导在小鼠肥胖情况下的体内贡献， 人类 从这些研究中获得的知识将描绘一种新的溶酶体离子通道信号通路， 调节肥胖症中的脂肪细胞生长和全身性功能障碍，并为目前的治疗策略提供信息。 正在进行中，以调节SWELL1信号传导，用于治疗肥胖诱导的代谢综合征。

Project Summary Healthy adipose tissue expansion is necessary for maintaining metabolic health in the setting of over-nutrition – a situation that is increasingly relevant in the US, as the incidence of obesity is estimated at 33% of the US population. Therefore, elucidating the fundamental nutrient sensing mechanisms that regulate adipocyte expansion is critical for understanding, and ultimately treating, the negative metabolic consequences of obesity. We previously identified Leucine Rich Repeat Containing 8A (LRRC8a or SWELL1), a newly discovered essential component of the volume-regulated anion channel (VRAC), as a novel volume-sensing regulator of both insulin sensitivity and insulin secretion. We and others find that SWELL1 activity and protein expression is reduced in metabolically unhealthy obese mice and humans – suggesting that reduced multi-organ SWELL1 activity/expression contributes to obesity-induced metabolic syndrome. Our group has biochemical, patch- clamp and imaging evidence that SWELL1 channel complexes are also expressed and functional in lysosomes. Given that lysosomes are signaling hubs that integrate nutrient sensing and AKT-mTOR signaling, we hypothesize that lysosomal SWELL1-LRRC8 channels participate in cellular nutrient sensing by activating in response to increases in intraluminal lysosomal leucine, and that this signaling mechanism is dysregulated in the setting of obesity-induced diabetes and insulin resistance. To test this hypothesis, we combine unique reagents and innovative methods from the Diwan (lysosomal signaling), Xu (lysosomal patch-clamp), and Held (mass spectrometry) laboratories, with our expertise in SWELL1 signaling, and access to human adipose tissue samples from highly phenotyped metabolically healthy and unhealthy humans (Klein laboratory). Our objective is to understand the mechanisms of plasma membrane and lysosomal SWELL1 (Lyso- SWELL1) nutrient sensing and how it is dysregulated in disease states, including obesity-induced glucose intolerance and insulin resistance. The rationale for these studies is that delineating the contribution of SWELL1 to lysosomal nutrient sensing and mTORC1 activation will advance our understanding of a fundamental cellular signaling mechanism and guide innovative therapeutic approaches for patients with prediabetes and diabetes. We propose the following AIMs: · AIM#1: Delineate the mechanisms of plasma membrane versus lysosomal SWELL1 signaling to AKT- AMPK-mTOR signaling in adipocytes · AIM#2: Examine the contribution of SWELL1 signaling in vivo in the setting of obesity in mice and humans The knowledge gained from these studies will delineate a novel lysosomal ion channel signaling pathway that regulates adipocyte growth and systemic dysglycemia in obesity, and inform therapeutic strategies currently underway to modulate SWELL1 signaling for the treatment of obesity-induced metabolic syndrome.