Thyroid hormones are important modulators of metabolic activity in mammals and alter cholesterol and fatty acid levels through activation of the nuclear thyroid hormone receptor (THR). Currently, there are several THRβ agonists in clinical trials for the treatment of non-alcoholic steatohepatitis (NASH) that have demonstrated the potential to reduce liver fat and restore liver function. In this study, we tested three THRβ-agonism-based NASH treatment candidates, GC-1 (sobetirome), MGL-3196 (resmetirom), and VK2809, and compared their selectivity for THRβ and their ability to modulate the expression of genes specific to cholesterol and fatty acid biosynthesis and metabolism in vitro using human hepatic cells and in vivo using a rat model. Treatment with GC-1 upregulated the transcription of CPT1A in the human hepatocyte-derived Huh-7 cell line with a dose-response comparable to that of the native THR ligand, triiodothyronine (T3). VK2809A (active parent of VK2809), MGL-3196, and VK2809 were approximately 30-fold, 1,000-fold, and 2,000-fold less potent than T3, respectively. Additionally, these relative potencies were confirmed by quantification of other direct gene targets of THR, namely, ANGPTL4 and DIO1 . In primary human hepatocytes, potencies were conserved for every compound except for VK2809, which showed significantly increased potency that was comparable to that of its active counterpart, VK2809A. In high-fat diet fed rats, a single dose of T3 significantly reduced total cholesterol levels and concurrently increased liver Dio1 and Me1 RNA expression. MGL-3196 treatment resulted in concentration-dependent decreases in total and low-density lipoprotein cholesterol with corresponding increases in liver gene expression, but the compound was significantly less potent than T3. In conclusion, we have implemented a strategy to rank the efficacy of THRβ agonists by quantifying changes in the transcription of genes that lead to metabolic alterations, an effect that is directly downstream of THR binding and activation.

中文翻译：

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甲状腺激素受体β激动剂在非酒精性脂肪性肝炎（NASH）的临床开发中对基因转录的调节

甲状腺激素是哺乳动物代谢活动的重要调节剂，并通过激活甲状腺甲状腺激素受体（THR）来改变胆固醇和脂肪酸水平。当前，在用于非酒精性脂肪性肝炎（NASH）的临床试验中，有几种THRβ激动剂已被证明具有减少肝脏脂肪和恢复肝功能的潜力。在这项研究中，我们测试了三种基于THRβ激动剂的NASH治疗候选药物GC-1（Sobetirome），MGL-3196（Resmetirom）和VK2809，并比较了它们对THRβ的选择性以及其调控特定于使用人肝细胞体外和体内使用大鼠模型进行胆固醇和脂肪酸的生物合成和代谢。用GC-1处理可在人肝细胞衍生的Huh-7细胞系中上调CPT1A的转录，其剂量反应可与天然THR配体三碘甲状腺素（T3）媲美。VK2809A（VK2809的活动母体），MGL-3196和VK2809的效价分别比T3低30倍，1,000倍和2,000倍。另外，这些相对效力通过对THR的其他直接基因靶标即ANGPTL4和DIO1的定量证实。在原代人肝细胞中，除VK2809以外，每种化合物的效价均保持不变，VK2809的效价显着提高，可与其活性对应物VK2809A相比。在高脂饮食喂养的大鼠中，单剂量的T3会显着降低总胆固醇水平，并同时增加肝脏Dio1和Me1 RNA的表达。MGL-3196处理导致总浓度和低密度脂蛋白胆固醇的浓度依赖性降低，并相应地增加了肝基因表达，但该化合物的效力明显低于T3。总而言之，我们已经实施了一项策略，通过量化导致代谢改变的基因转录变化来对THRβ激动剂的疗效进行排名，该作用直接在THR结合和激活的下游。