Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal.
Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal.
Int J Mol Sci. 2020 Jan 17;21(2):610. doi: 10.3390/ijms21020610.
Browning of white adipocytes has been proposed as a powerful strategy to overcome metabolic complications, since brown adipocytes are more catabolic, expending energy as a heat form. However, the biological pathways involved in the browning process are still unclear. Aquaglyceroporins are a sub-class of aquaporin water channels that also permeate glycerol and are involved in body energy homeostasis. In the adipose tissue, aquaporin-7 (AQP7) is the most representative isoform, being crucial for white adipocyte fully differentiation and glycerol metabolism. The altered expression of AQP7 is involved in the onset of obesity and metabolic disorders. Herein, we investigated if aquaglyceroporins are implicated in beige adipocyte differentiation, similar to white cells. Thus, we optimized a protocol of murine 3T3-L1 preadipocytes browning that displayed increased beige and decreased white adipose tissue features at both gene and protein levels and evaluated aquaporin expression patterns along the differentiation process together with cellular lipid content. Our results revealed that AQP7 and aquaporin-9 (AQP9) expression was downregulated throughout beige adipocyte differentiation compared to white differentiation, which may be related to the beige physiological role of heat production from oxidative metabolism, contrasting with the anabolic/catabolic lipid metabolism requiring glycerol gateways occurring in white adipose cells.
白色脂肪细胞的褐色化已被提议作为克服代谢并发症的有效策略，因为褐色脂肪细胞更具分解代谢活性，以热能的形式消耗能量。然而，褐色化过程中涉及的生物学途径仍不清楚。水通道蛋白是水通道 aquaporin 的一个亚类，也能渗透甘油，并参与身体能量稳态。在脂肪组织中，水通道蛋白-7（AQP7）是最具代表性的同工型，对于白色脂肪细胞的完全分化和甘油代谢至关重要。AQP7 的表达改变与肥胖和代谢紊乱的发生有关。在此，我们研究了水通道蛋白是否参与褐色脂肪细胞分化，类似于白细胞。因此，我们优化了一种小鼠 3T3-L1 前体脂肪细胞褐色化的方案，该方案在基因和蛋白质水平上均显示出增加的褐色和减少的白色脂肪组织特征，并评估了 aquaporin 在分化过程中的表达模式以及细胞脂质含量。我们的结果表明，与白色分化相比，AQP7 和 aquaporin-9（AQP9）的表达在整个褐色脂肪细胞分化过程中均下调，这可能与褐色脂肪细胞通过氧化代谢产生热量的生理作用有关，与白色脂肪细胞中发生的需要甘油通道的合成代谢/分解代谢脂质代谢形成对比。
