Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana, USA.
Computational Biology and Program in Cardiovascular and Metabolic Disorders, Duke-NUS Graduate Medical School, Singapore, Singapore.
Acta Physiol (Oxf). 2023 May;238(1):e13935. doi: 10.1111/apha.13935. Epub 2023 Feb 7.
Valuable studies have tested the role of UCP1 on body temperature maintenance in mice, and we sought to knockout Ucp1 in rats (Ucp1 ) to provide insight into thermogenic mechanisms in larger mammals.
We used CRISPR/Cas9 technology to create Ucp1 rats. Body weight and adiposity were measured, and rats were subjected to indirect calorimetry. Rats were maintained at room temperature or exposed to 4°C for either 24 h or 14 days. Analyses of brown and white adipose tissue and skeletal muscle were conducted via histology, western blot comparison of oxidative phosphorylation proteins, and qPCR to compare mitochondrial DNA levels and mRNA expression profiles. RNA-seq was performed in skeletal muscle.
Ucp1 rats withstood 4°C for 14 days, but core temperature steadily declined. All rats lost body weight after 14 days at 4°C, but controls increased food intake more robustly than Ucp1 rats. Brown adipose tissue showed signs of decreased activity in Ucp1 rats, while mitochondrial lipid metabolism markers in white adipose tissue and skeletal muscle were increased. Ucp1 rats displayed more visible shivering and energy expenditure than controls at 4°C. Skeletal muscle transcriptomics showed more differences between genotypes at 23°C than at 4°C.
Room temperature presented sufficient cold stress to rats lacking UCP1 to activate compensatory thermogenic mechanisms in skeletal muscle, which were only activated in control rats following exposure to 4°C. These results provide novel insight into thermogenic responses to UCP1 deficiency; and highlight Ucp1 rats as an attractive translational model for the study of thermogenesis.
已有大量研究检测了 UCP1 在维持小鼠体温方面的作用，我们试图敲除大鼠的 UCP1（Ucp1 -/- ），以深入了解大型哺乳动物的产热机制。
我们使用 CRISPR/Cas9 技术构建 Ucp1 -/- 大鼠。测量体重和肥胖程度，并进行间接测热法检测。将大鼠维持在室温或暴露于 4°C 环境 24 小时或 14 天。通过组织学、氧化磷酸化蛋白的 Western blot 比较、线粒体 DNA 水平和 mRNA 表达谱的 qPCR 分析，对棕色和白色脂肪组织以及骨骼肌进行分析。对骨骼肌进行 RNA-seq 分析。
Ucp1 -/- 大鼠能在 4°C 环境中存活 14 天，但核心体温持续下降。所有大鼠在 4°C 环境下 14 天后体重均下降，但对照组的食物摄入量增加幅度大于 Ucp1 -/- 大鼠。Ucp1 -/- 大鼠的棕色脂肪组织活性下降，而白色脂肪组织和骨骼肌的线粒体脂质代谢标志物增加。在 4°C 环境下，Ucp1 -/- 大鼠比对照组更明显地出现颤抖和能量消耗。骨骼肌转录组学显示，在 23°C 下，基因型之间的差异大于在 4°C 下。
室温对缺乏 UCP1 的大鼠造成了足够的冷应激，激活了骨骼肌的代偿性产热机制，而仅在对照组大鼠暴露于 4°C 后才会激活这些机制。这些结果为 UCP1 缺乏引起的产热反应提供了新的见解，并凸显了 Ucp1 -/- 大鼠作为研究产热的有吸引力的转化模型。
