Department of Cardiology and Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
Center for Cardiovascular Research and Integrative Medicine, School of Pharmacy, University of Wyoming, Laramie, WY, 82071, USA.
Aging Cell. 2017 Oct;16(5):976-987. doi: 10.1111/acel.12616. Epub 2017 Jul 5.
Aging is accompanied with unfavorable geometric and functional changes in the heart involving dysregulation of Akt and autophagy. This study examined the impact of Akt2 ablation on life span and cardiac aging as well as the mechanisms involved with a focus on autophagy and mitochondrial integrity. Cardiac geometry, contractile, and intracellular Ca properties were evaluated using echocardiography, IonOptix edge-detection and fura-2 techniques. Levels of Sirt1, mitochondrial integrity, autophagy, and mitophagy markers were evaluated using Western blot. Our results revealed that Akt2 ablation prolonged life span (by 9.1%) and alleviated aging (24 months)-induced unfavorable changes in myocardial function and intracellular Ca handling (SERCA2a oxidation) albeit with more pronounced cardiac hypertrophy (58.1%, 47.8%, and 14.5% rises in heart weight, wall thickness, and cardiomyocyte cross-sectional area). Aging downregulated levels of Sirt1, increased phosphorylation of Akt, and the nuclear transcriptional factor Foxo1, as well as facilitated acetylation of Foxo1, the effects of which (except Sirt1 and Foxo1 acetylation) were significantly attenuated or negated by Akt2 ablation. Advanced aging disturbed autophagy, mitophagy, and mitochondrial integrity as evidenced by increased p62, decreased levels of beclin-1, Atg7, LC3B, BNIP3, PTEN-induced putative kinase 1 (PINK1), Parkin, UCP-2, PGC-1α, and aconitase activity, the effects of which were reversed by Akt2 ablation. Aging-induced cardiomyocyte contractile dysfunction and loss of mitophagy were improved by rapamycin and the Sirt1 activator SRT1720. Activation of Akt using insulin or Parkin deficiency prevented SRT1720-induced beneficial effects against aging. In conclusion, our data indicate that Akt2 ablation protects against cardiac aging through restored Foxo1-related autophagy and mitochondrial integrity.
衰老是伴随着心脏的不利几何和功能变化的,涉及 Akt 和自噬的失调。本研究探讨了 Akt2 缺失对寿命和心脏衰老的影响以及涉及自噬和线粒体完整性的机制。使用超声心动图、IonOptix 边缘检测和 fura-2 技术评估心脏几何形状、收缩和细胞内 Ca 特性。使用 Western blot 评估 Sirt1、线粒体完整性、自噬和噬线粒体标志物的水平。我们的结果表明,Akt2 缺失延长了寿命(延长了 9.1%),并缓解了衰老(24 个月)引起的心肌功能和细胞内 Ca 处理(SERCA2a 氧化)的不利变化,尽管心脏肥大更为明显(心脏重量、壁厚度和心肌细胞横截面积分别增加 58.1%、47.8%和 14.5%)。衰老下调了 Sirt1 水平,增加了 Akt 的磷酸化和核转录因子 Foxo1,以及促进了 Foxo1 的乙酰化,这些效应(除了 Sirt1 和 Foxo1 乙酰化)被 Akt2 缺失显著减弱或消除。晚期衰老扰乱了自噬、噬线粒体和线粒体完整性,表现为 p62 增加,beclin-1、Atg7、LC3B、BNIP3、PTEN 诱导的假定激酶 1(PINK1)、Parkin、UCP-2、PGC-1α 和 aconitase 活性降低,这些效应被 Akt2 缺失逆转。雷帕霉素和 Sirt1 激活剂 SRT1720 改善了衰老引起的心肌收缩功能障碍和噬线粒体丧失。使用胰岛素或 Parkin 缺乏激活 Akt 可防止 SRT1720 诱导的对衰老的有益作用。总之,我们的数据表明,Akt2 缺失通过恢复 Foxo1 相关的自噬和线粒体完整性来保护心脏免受衰老的影响。
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