Dataset for: The nuclear Retinoid-related Orphan Receptor RORα controls circadian thermogenic programming in white fat depots

The RORα–deficient staggerer (sg/sg) mouse is lean and resistant to diet-induced obesity. Its thermogenic activity was shown to be increased in brown adipose tissue (BAT), but also in subcutaneous white adipose tissue (WAT) where UCP1 content was enhanced, however without Prdm16 co-expression. Our observation of partial multilocular lipid morphology of WAT in sg/sg mice both in the inguinal and perigonadal sites led us to focus on the phenotype of both fat depots. Because RORα is a nuclear factor acting in the clock machinery, we looked at the circadian expression profile of genes involved in thermogenesis and browning in WAT and BAT depots of sg/sg and WT mice, through Real Time quantitative PCR and Western Blotting. This 24h-period-approach revealed both a rhythmic expression of thermogenic genes in WAT and an increased browning of all the WAT depots tested in sg/sg mice, that indeed involved the canonical browning process (through induction of Pgc-1α and Prdm16). This was associated with an enhanced isoproterenol-induced oxygen consumption rate of WAT explants from sg/sg mice, which was reproducible in WT explants by treatment with a RORα inverse agonist SR 3335, that induced a parallel increase of the UCP1 protein. Inhibitors of browning differentiation such as TLE3 and RIP140 could be new targets of RORα that would be rather implicated in the whitening of adipocytes. Our study showed the pivotal role of RORα as an inhibitor of the thermogenic program in WAT, role that could be counteracted in vivo with the RORα antagonists currently in development.

RORα缺陷型摇摆小鼠（staggerer, sg/sg）体型消瘦，可抵抗饮食诱导的肥胖。已有研究显示，其棕色脂肪组织（brown adipose tissue, BAT）与皮下白色脂肪组织（subcutaneous white adipose tissue, WAT）的产热活性均有所增强，其中皮下WAT内解偶联蛋白1（UCP1）的表达水平升高，但未伴随Prdm16的共表达。我们观察到，sg/sg小鼠腹股沟及附睾周脂肪垫的WAT呈现部分多室脂质形态，由此聚焦于两类脂肪垫的表型特征。鉴于RORα是参与生物钟调控的核因子，我们通过实时定量PCR与蛋白质印迹技术，检测了sg/sg与野生型（wild type, WT）小鼠WAT及BAT中与产热及脂肪组织褐变相关基因的昼夜表达谱。这项为期24小时的研究发现，sg/sg小鼠的WAT中产热基因呈现节律性表达，且所有受试WAT脂肪垫的褐变程度均有所升高，该过程确实通过经典褐变通路（即诱导Pgc-1α与Prdm16的表达）实现。这一现象与sg/sg小鼠WAT外植体的异丙肾上腺素诱导耗氧率升高相关；而采用RORα反向激动剂SR 3335处理野生型外植体，可重现该表型，同时使UCP1蛋白水平同步升高。脂肪细胞褐变分化的抑制剂如TLE3与RIP140，或可成为RORα的新型调控靶点，进而参与脂肪细胞的白色化过程。本研究证实，RORα可作为WAT中产热程序的负调控因子，这一作用可通过当前研发中的RORα拮抗剂在体内进行拮抗。