Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan.
Translational Research Center, Research Institute of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan.
Amino Acids. 2018 May;50(5):527-535. doi: 10.1007/s00726-018-2550-6. Epub 2018 Mar 9.
Alterations in adipocyte characteristics are highly implicated in the pathology of obesity. In a recent article, we demonstrated that high-fat diet-induced obesity impairs lysosomal function, thereby suppressing autophagy in mice white adipose tissue. Taurine, an amino acid naturally contained in the normal diet and existing ubiquitously in tissues, has been reported to improve insulin resistance and chronic inflammation in animal models, but underlying mechanisms remain unclear. From these findings, we hypothesized that improvement of obese pathology by taurine may be mediated through recovery of autophagy. In matured 3T3-L1 mouse adipocytes, treatment with taurine-promoted autophagy. Moreover, taurine-induced nuclear translocation of transcription factor EB (TFEB), a master regulator of autophagy- and lysosome-related factors. As this translocation is regulated by several kinase pathways, including extracellular signal-related kinase 1 and 2 (ERK1/2) and mechanistic target of rapamycin protein kinase complex 1 (MTORC1), we examined related signaling elements. Consequently, taurine-reduced phosphorylation levels of ERK1/2 but did not alter the phosphorylation of MTORC1 pathway-associated adenosine monophosphate-activated protein kinase or ribosomal protein S6 kinase. Taken together, these results suggest that taurine may enhance TFEB nuclear translocation through ERK1/2 to accelerate autophagy. The effect discovered in this study may represent a novel mechanism for the improvement of obesity-related pathology by taurine.
脂肪细胞特征的改变与肥胖症的病理高度相关。在最近的一篇文章中,我们证明高脂肪饮食诱导的肥胖会损害溶酶体功能,从而抑制小鼠白色脂肪组织中的自噬。牛磺酸是一种天然存在于正常饮食中的氨基酸,广泛存在于组织中,据报道它可以改善动物模型中的胰岛素抵抗和慢性炎症,但潜在的机制尚不清楚。基于这些发现,我们假设牛磺酸改善肥胖症病理可能是通过恢复自噬来介导的。在成熟的 3T3-L1 小鼠脂肪细胞中,牛磺酸处理促进了自噬。此外,牛磺酸诱导了转录因子 EB(TFEB)的核易位,TFEB 是自噬和溶酶体相关因子的主要调节因子。由于这种易位受多种激酶途径调节,包括细胞外信号相关激酶 1 和 2(ERK1/2)和雷帕霉素靶蛋白激酶复合物 1(MTORC1),我们检查了相关的信号元件。结果表明,牛磺酸降低了 ERK1/2 的磷酸化水平,但不改变 MTORC1 途径相关的腺苷单磷酸激活蛋白激酶或核糖体蛋白 S6 激酶的磷酸化。总之,这些结果表明,牛磺酸可能通过 ERK1/2 增强 TFEB 的核易位,从而加速自噬。本研究发现的效应可能代表了牛磺酸改善肥胖相关病理的一种新机制。