Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea; Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea.
Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea; Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Republic of Korea.
Metabolism. 2020 Aug;109:154280. doi: 10.1016/j.metabol.2020.154280. Epub 2020 May 28.
Obesity is recognized as the cause of multiple metabolic diseases and is rapidly increasing worldwide. As obesity is due to an imbalance in energy homeostasis, the promotion of energy consumption through browning of white adipose tissue (WAT) has emerged as a promising therapeutic strategy to counter the obesity epidemic. However, the molecular mechanisms of the browning process are not well understood. In this study, we investigated the effects of the GATA family of transcription factors on the browning process.
We used qPCR to analyze the expression of GATA family members during WAT browning. In order to investigate the function of GATA3 in the browning process, we used the lentivirus system for the ectopic expression and knockdown of GATA3. Western blot and real-time qPCR analyses revealed the regulation of thermogenic genes upon ectopic expression and knockdown of GATA3. Luciferase reporter assays, co-immunoprecipitation, and chromatin immunoprecipitation were performed to demonstrate that GATA3 interacts with proliferator-activated receptor-γ co-activator-1α (PGC-1α) to regulate the promoter activity of uncoupling protein-1 (UCP-1). Enhanced energy expenditure by GATA3 was confirmed using oxygen consumption assays, and the mitochondrial content was assessed using MitoTracker. Furthermore, we examined the in vivo effects of lentiviral GATA3 overexpression and knockdown in inguinal adipose tissue of mice.
Gata3 expression levels were significantly elevated in the inguinal adipose tissue of mice exposed to cold conditions. Ectopic expression of GATA3 enhanced the expression of UCP-1 and thermogenic genes upon treatment with norepinephrine whereas GATA3 knockdown had the opposite effect. Luciferase reporter assays using the UCP-1 promoter region showed that UCP-1 expression was increased in a dose-dependent manner by GATA3 regardless of norepinephrine treatment. GATA3 was found to directly bind to the promoter region of UCP-1. Furthermore, our results indicated that GATA3 interacts with the transcriptional coactivator PGC-1α to increase the expression of UCP-1. Taken together, we demonstrate that GATA3 has an important role in enhancing energy expenditure by increasing the expression of thermogenic genes both in vitro and in vivo.
GATA3 may represent a promising target for the prevention and treatment of obesity by regulating thermogenic capacity.
肥胖被认为是多种代谢性疾病的病因，且在全球范围内迅速增多。由于肥胖是由于能量平衡失调引起的，因此通过棕色化白色脂肪组织（WAT）促进能量消耗已成为对抗肥胖流行的一种有前途的治疗策略。然而，棕色化过程的分子机制尚不清楚。在这项研究中，我们研究了 GATA 转录因子家族对棕色化过程的影响。
我们使用 qPCR 分析了 WAT 棕色化过程中 GATA 家族成员的表达。为了研究 GATA3 在棕色化过程中的功能，我们使用慢病毒系统进行 GATA3 的异位表达和敲低。Western blot 和实时 qPCR 分析显示，异位表达和敲低 GATA3 可调节产热基因的表达。荧光素酶报告基因分析、共免疫沉淀和染色质免疫沉淀实验表明，GATA3 与过氧化物酶体增殖物激活受体-γ共激活因子 1α（PGC-1α）相互作用，调节解偶联蛋白 1（UCP-1）的启动子活性。通过耗氧量测定证实了 GATA3 通过增强能量消耗，使用 MitoTracker 评估线粒体含量。此外，我们还检查了 GATA3 过表达和敲低慢病毒在小鼠腹股沟脂肪组织中的体内作用。
冷暴露小鼠腹股沟脂肪组织中 Gata3 的表达水平显著升高。GATA3 的异位表达增强了去甲肾上腺素处理后 UCP-1 和产热基因的表达，而 GATA3 的敲低则产生相反的效果。使用 UCP-1 启动子区域的荧光素酶报告基因分析表明，无论是否用去甲肾上腺素处理，GATA3 均可剂量依赖性地增加 UCP-1 的表达。发现 GATA3 直接结合 UCP-1 的启动子区域。此外，我们的结果表明，GATA3 与转录共激活因子 PGC-1α 相互作用，以增加 UCP-1 的表达。总之，我们证明 GATA3 通过增加产热基因的表达在体外和体内均增强能量消耗，从而在增强能量消耗方面发挥重要作用。
GATA3 可能通过调节产热能力成为预防和治疗肥胖的有希望的靶标。
