Reynolds Matthew R, Singh Itender, Azad Tej D, Holmes Brandon B, Verghese Phillip B, Dietrich Hans H, Diamond Marc, Bu Guojun, Han Byung Hee, Zipfel Gregory J
Department of Neurological Surgery, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, Campus Box 8057, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA.
Department of Neurology, Washington University School of Medicine, Hope Center Program on Protein Aggregation and Neurodegeneration, Charles F. and Joanne Knight Alzheimer's Disease Research Center, St. Louis, Missouri, USA.
Mol Neurodegener. 2016 Jan 22;11:9. doi: 10.1186/s13024-016-0073-8.
Substantial evidence suggests that amyloid-β (Aβ) species induce oxidative stress and cerebrovascular (CV) dysfunction in Alzheimer's disease (AD), potentially contributing to the progressive dementia of this disease. The upstream molecular pathways governing this process, however, are poorly understood. In this report, we examine the role of heparan sulfate proteoglycans (HSPG) in Aβ-induced vascular smooth muscle cell (VSMC) dysfunction in vitro.
Our results demonstrate that pharmacological depletion of HSPG (by enzymatic degradation with active, but not heat-inactivated, heparinase) in primary human cerebral and transformed rat VSMC mitigates Aβ(1-40⁻) and Aβ(1-42⁻)induced oxidative stress. This inhibitory effect is specific for HSPG depletion and does not occur with pharmacological depletion of other glycosaminoglycan (GAG) family members. We also found that Aβ(1-40) (but not Aβ(1-42)) causes a hypercontractile phenotype in transformed rat cerebral VSMC that likely results from a HSPG-mediated augmentation in intracellular Ca(2+) activity, as both Aβ(1-40⁻)induced VSMC hypercontractility and increased Ca(2+) influx are inhibited by pharmacological HSPG depletion. Moreover, chelation of extracellular Ca(2+) with ethylene glycol tetraacetic acid (EGTA) does not prevent the production of Aβ(1-40⁻) or Aβ(1-42⁻)mediated reactive oxygen species (ROS), suggesting that Aβ-induced ROS and VSMC hypercontractility occur through different molecular pathways.
Taken together, our data indicate that HSPG are critical mediators of Aβ-induced oxidative stress and Aβ(1-40⁻)induced VSMC dysfunction.
大量证据表明，淀粉样β蛋白（Aβ）可诱导阿尔茨海默病（AD）中的氧化应激和脑血管（CV）功能障碍，这可能是导致该疾病进行性痴呆的原因。然而，目前对这一过程的上游分子途径了解甚少。在本报告中，我们研究了硫酸乙酰肝素蛋白聚糖（HSPG）在体外Aβ诱导的血管平滑肌细胞（VSMC）功能障碍中的作用。
我们的结果表明，在原代人脑血管平滑肌细胞和转化的大鼠VSMC中，通过用活性（而非热灭活）肝素酶进行酶促降解来药理学性去除HSPG，可减轻Aβ（1-40⁻）和Aβ（1-42⁻）诱导的氧化应激。这种抑制作用对HSPG的去除具有特异性，在药理学性去除其他糖胺聚糖（GAG）家族成员时不会发生。我们还发现，Aβ（1-40）（而非Aβ（1-42））会在转化的大鼠脑血管平滑肌细胞中引起超收缩表型，这可能是由HSPG介导的细胞内Ca（2+）活性增强所致，因为药理学性去除HSPG可抑制Aβ（1-40⁻）诱导的VSMC超收缩和Ca（2+）内流增加。此外，用乙二醇四乙酸（EGTA）螯合细胞外Ca（2+）并不能阻止Aβ（1-40⁻）或Aβ（1-42⁻）介导的活性氧（ROS）的产生，这表明Aβ诱导的ROS和VSMC超收缩是通过不同的分子途径发生的。
综上所述，我们的数据表明，HSPG是Aβ诱导的氧化应激和Aβ（1-40⁻）诱导的VSMC功能障碍的关键介质。
