Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.
Department of Endocrinology and Metabolism, 2nd Xiangya Hospital, Central South University, Changsha, Hunan, China.
Int J Obes (Lond). 2018 Apr;42(4):939-945. doi: 10.1038/ijo.2017.308. Epub 2018 Jan 23.
BACKGROUND/OBJECTIVES: Thermogenic fat is present in humans and emerging evidence indicates that increasing the content and activity of these adipocytes may lead to weight loss and improved metabolic health. Multiple reporter systems have been developed to assay thermogenic fat activity based on the transcriptional and translational activation of Ucp1, the key molecule that mediates nonshivering thermogenesis. Our study aims to develop a much-needed tool to monitor thermogenic fat activity through a mechanism independent of Ucp1 regulation, therefore effectively assaying not only canonical β-adrenergic activation but also various non-UCP1-mediated thermogenic pathways that have been increasingly appreciated.
We detected increased luciferase activity upon thermogenic activation in interscapular brown and inguinal subcutaneous fat in ODD-Luc mice, a hypoxia reporter mouse model. We then developed an OLTAM (ODD-Luc based Thermogenic Activity Measurement) system to assay thermogenic fat cell activity.
In both primary murine and human adipocytes and an immortalized adipose cell line that were transduced with the OLTAM system, luciferase activity can be readily measured and visualized by bioluminescence imaging in response to a variety of stimuli, including UCP1-independent thermogenic signaling. This system can offer a convenient method to assay thermogenic activity for both basic and translational research.
The OLTAM system offers a convenient way to measure the activation of thermogenic fat and presents opportunities to discover novel signaling pathways and unknown compounds targeting metabolically active adipocytes to counteract human obesity.
背景/目的：人类存在生热脂肪，越来越多的证据表明，增加这些脂肪细胞的含量和活性可能导致体重减轻和改善代谢健康。已经开发出多种报告系统来检测生热脂肪活性，这些系统基于 Ucp1 的转录和翻译激活，Ucp1 是介导不颤抖产热的关键分子。我们的研究旨在开发一种急需的工具，通过一种独立于 Ucp1 调节的机制来监测生热脂肪活性，因此不仅可以有效地检测经典的β-肾上腺素能激活，还可以检测各种非 UCP1 介导的生热途径，这些途径越来越受到重视。
我们在 ODD-Luc 小鼠（一种缺氧报告小鼠模型）的肩胛间棕色和腹股沟皮下脂肪中检测到生热激活时的荧光素酶活性增加。然后，我们开发了一种 OLTAM（基于 ODD-Luc 的生热活性测量）系统来检测生热脂肪细胞活性。
在原代鼠和人脂肪细胞以及转染了 OLTAM 系统的永生化脂肪细胞系中，荧光素酶活性可以通过生物发光成像来测量和可视化，以响应各种刺激，包括 UCP1 非依赖性生热信号。该系统为基础研究和转化研究提供了一种方便的方法来检测生热活性。
OLTAM 系统提供了一种测量生热脂肪激活的简便方法，并为发现新的信号通路和针对代谢活跃脂肪细胞的未知化合物提供了机会，以对抗人类肥胖。
