Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA; Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA; Department of Geriatrics, Xijing Hospital Air Force University, Xi'an 710032, China.
J Mol Cell Cardiol. 2018 Jun;119:40-50. doi: 10.1016/j.yjmcc.2018.04.009. Epub 2018 Apr 13.
Aging is usually accompanied with overt structural and functional changes as well as suppressed autophagy in the heart although the precise regulatory mechanisms are somewhat unknown. Here we evaluated the role of the innate proinflammatory mediator toll-like receptor 4 (TLR4) in cardiac aging and the underlying mechanism with a focus on autophagy. Cardiac geometry and function were monitored in young or old wild-type (WT) and TLR4 knockout (TLR4) mice using echocardiography, IonOptix® edge-detection and fura-2 techniques. Levels of autophagy and mitophagy, nuclear receptor corepressor 1 (NCoR1) and histone deacetylase I (HDAC1) were examined using western blot. Transmission electronic microscopy (TEM) was employed to monitor myocardial ultrastructure. Our results revealed that TLR4 ablation alleviated advanced aging (24 months)-induced changes in myocardial remodeling (increased heart weight, chamber size, cardiomyocyte cross-sectional area), contractile function and intracellular Ca handling as well as autophagy and mitophagy [Beclin-1, Atg5, LC3B, PTEN-induced putative kinase 1 (PINK1), Parkin and p62]. Aging downregulated levels of NCoR1 and HDAC1 as well as their interaction, the effects were significantly attenuated or negated by TLR4 ablation. Advanced aging disturbed myocardial ultrastructure as evidenced by loss of myofilament alignment and swollen mitochondria, which was obliterated by TLR4 ablation. Moreover, aging suppressed autophagy (GFP-LC3B puncta) in neonatal mouse cardiomyocytes, the effect of which was negated by the TLR4 inhibitor CLI-095. Inhibition of HDCA1 using apicidin cancelled off CLI095-induced beneficial response of GFP-LC3B puncta against aging. Our data collectively indicate a role for TLR4-mediated autophagy in cardiac remodeling and contractile dysfunction in aging through a HDAC1-NCoR1-dependent mechanism.
衰老是一个普遍的现象，通常伴随着明显的结构和功能改变，以及心肌自噬的抑制，尽管确切的调节机制尚不清楚。在这里，我们评估了固有促炎介质 Toll 样受体 4 (TLR4) 在心脏衰老中的作用及其潜在机制，重点是自噬。我们使用超声心动图、IonOptix®边缘检测和 fura-2 技术监测年轻或年老的野生型 (WT) 和 TLR4 敲除 (TLR4) 小鼠的心脏几何形状和功能。使用 Western blot 检测自噬和线粒体自噬、核受体共抑制因子 1 (NCoR1) 和组蛋白去乙酰化酶 I (HDAC1) 的水平。透射电子显微镜 (TEM) 用于监测心肌超微结构。我们的结果表明，TLR4 缺失减轻了高级衰老 (24 个月)引起的心肌重构 (心重、心室大小、心肌细胞横截面积增加)、收缩功能和细胞内 Ca 处理以及自噬和线粒体自噬的变化[Beclin-1、Atg5、LC3B、PTEN 诱导的假定激酶 1 (PINK1)、Parkin 和 p62]。衰老降低了 NCoR1 和 HDAC1 的水平及其相互作用，TLR4 缺失显著减弱或消除了这些作用。高级衰老破坏了心肌超微结构，表现为肌原纤维排列紊乱和线粒体肿胀，TLR4 缺失则消除了这些变化。此外，衰老抑制了新生鼠心肌细胞的自噬 (GFP-LC3B 斑点)，TLR4 抑制剂 CLI-095 消除了衰老的这种作用。使用 apicidin 抑制 HDCA1 消除了 CLI095 诱导的 GFP-LC3B 斑点对衰老的有益反应。我们的数据共同表明，TLR4 介导的自噬通过 HDAC1-NCoR1 依赖性机制在心脏重构和衰老引起的收缩功能障碍中发挥作用。
