Tuning Adipocyte Size and Obesity through SWELL1

项目摘要 在营养过剩的情况下，健康的脂肪组织扩张对于维持代谢健康是必要的。 这种情况在美国越来越相关，因为肥胖症的发病率估计占美国的33% 人口。因此，阐明调节脂肪细胞的基本营养传感机制 扩张对于理解并最终治疗肥胖的负面新陈代谢后果至关重要。 我们以前发现了一个新发现的富含亮氨酸重复序列8A(LRRC8a或SWELL1) 体积调节阴离子通道(Vrac)的基本成分，作为一种新型的体积敏感调节剂 胰岛素敏感性和胰岛素分泌。我们和其他人发现SWELL1的活性和蛋白表达是 在代谢不健康的肥胖小鼠和人类中减少-表明多器官SWELL1减少 活动/表达有助于肥胖诱导的代谢综合征。我们组有生化，补丁- 钳夹和成像证据表明，SWELL1通道复合体也在 溶酶体。鉴于溶酶体是整合营养感知和AKT-mTOR信号的信号中枢， 我们假设溶酶体SWELL1-LRRC8通道通过以下方式参与细胞营养感知 激活以响应腔内溶酶体亮氨酸的增加，并且这一信号机制 在肥胖引起的糖尿病和胰岛素抵抗的背景下是失调的。为了检验这一假设， 我们结合了Diwan(溶酶体信号转导)、Xu(溶酶体信号转导)的独特试剂和创新方法 膜片钳)，以及拥有我们在SWELL1信号和接入方面的专业知识的(质谱学)实验室 来自高表型代谢健康和不健康人类的脂肪组织样本(Klein 实验室)。我们的目的是了解质膜和溶酶体SWELL1(lyso-SWEL1)的机制。 营养感知及其在疾病状态下如何失调，包括肥胖引起的血糖 不耐受和胰岛素抵抗。这些研究的基本原理是，描绘SWELL1的贡献 溶酶体的营养感知和mTORC1的激活将促进我们对基本细胞 信号机制和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： ·目的1：阐明质膜与溶酶体SWELL1信号转导AKT-1的机制 脂肪细胞中的AMPK-mTOR信号转导 ·目的2：研究体内SWELL1信号在小鼠肥胖和肥胖形成中的作用 人类 从这些研究中获得的知识将描绘出一种新的溶酶体离子通道信号通路 调节肥胖患者的脂肪细胞生长和全身性血糖紊乱，并提供当前的治疗策略 正在调整SWELL1信号以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.