College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China.
College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China.
Cell Signal. 2017 Oct;38:192-200. doi: 10.1016/j.cellsig.2017.07.012. Epub 2017 Jul 19.
Thioredoxin (Txn) system is the most crucial antioxidant defense mechanism in cell consisting of Txn, thioredoxin reductase (TR) and Nicotinamide Adenine Dinucleotide Phosphate (NADPH). Perturbations in Txn system may compromise cell survival through oxidative stress induction. Metabolic activity of insulin plays important roles in fulfilling the stable and persistent demands of heart through glucose metabolism. However, the roles of Txn and Txn system in insulin modulated cardiac energy metabolism have been less reported. Therefore, to investigate the role of Txn in myocardial metabolism, we developed a Se-deficient chicken model (0.033mg/kg) for in-vivo and Txn knock down cardiomyocytes culture model (siRNA) for in-vitro studies. Quantitative real time PCR and western blotting was performed. Se deficiency suppressed Txn and TR in cardiac tissues. Significant increases in ROS (P<0.05) levels signify the onset of oxidative stress and in both models. Se deficiency-induced Txn suppression model and Txn knock down cardiomyocytes models significantly decreased (P<0.05), the mRNA and protein levels of insulin-like growth factors (IGF1, IGF2), IGF-binding proteins (IGFBP2, IGFBP4), insulin receptor (IR), insulin receptor substrates (IRS1, IRS2), and glucose transporters (GLUT1, GLUT3, GLUT8), however, IGFBP3 expression increased in Txn knock down cardiomyocytes. In addition, in contrast to their respective controls, Se deficiency-induced Txn depleted tissues and Txn deleted cardiomyocytes showed suppression in mRNA and protein levels of PI3K, AKT, P-PI3K, and repression in FOX, P-FOX JNK genes. Combing the in vitro and in vivo experiments, we demonstrate that Txn gene suppression can cause dysfunction of insulin-modulated cardiac energy metabolism and increase insulin resistance through PI3K-Akt pathway inhibition. Herein, we conclude that inactivation of Txn system can alter cellular insulin response through IRS/PI3K/Akt pathway repression and JNK and FOX expression. These findings point out that Txn system can redox regulate the insulin dependent glucose metabolism in heart and is essential for cell vitality. Moreover, the increased expression of IGFBP3 indicates that it can be a potential negative modulator of metabolic activity of insulin in Txn deficient cells.
硫氧还蛋白（Txn）系统是细胞中最重要的抗氧化防御机制，由 Txn、硫氧还蛋白还原酶（TR）和烟酰胺腺嘌呤二核苷酸磷酸（NADPH）组成。Txn 系统的紊乱可能通过诱导氧化应激而危及细胞存活。胰岛素的代谢活性在通过葡萄糖代谢满足心脏的稳定和持续需求方面发挥着重要作用。然而，Txn 和 Txn 系统在胰岛素调节心脏能量代谢中的作用报道较少。因此，为了研究 Txn 在心肌代谢中的作用，我们建立了体内缺乏硒的鸡模型（0.033mg/kg）和体外 Txn 敲低心肌细胞培养模型（siRNA）进行研究。进行了定量实时 PCR 和 Western 印迹分析。硒缺乏抑制了心脏组织中的 Txn 和 TR。ROS（P<0.05）水平的显著增加表明氧化应激的发生，两种模型均如此。硒缺乏诱导的 Txn 抑制模型和 Txn 敲低心肌细胞模型显著降低（P<0.05），胰岛素样生长因子（IGF1、IGF2）、胰岛素结合蛋白（IGFBP2、IGFBP4）、胰岛素受体（IR）、胰岛素受体底物（IRS1、IRS2）和葡萄糖转运体（GLUT1、GLUT3、GLUT8）的 mRNA 和蛋白水平，然而，在 Txn 敲低心肌细胞中 IGFBP3 的表达增加。此外，与各自的对照相比，硒缺乏诱导的 Txn 耗尽组织和 Txn 缺失心肌细胞表现出 PI3K、AKT、P-PI3K 的 mRNA 和蛋白水平抑制以及 FOX、P-FOX JNK 基因的抑制。综合体内外实验，我们证明 Txn 基因抑制可通过抑制 PI3K-Akt 通路导致胰岛素调节的心脏能量代谢功能障碍和胰岛素抵抗。因此，我们得出结论，Txn 系统的失活可以通过 IRS/PI3K/Akt 通路的抑制和 JNK 和 FOX 表达改变细胞对胰岛素的反应。这些发现表明，Txn 系统可以通过氧化还原调节心脏中胰岛素依赖的葡萄糖代谢，并且对于细胞活力至关重要。此外，IGFBP3 的表达增加表明它可能是 Txn 缺陷细胞中胰岛素代谢活性的潜在负调节剂。
