Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
Neurochem Int. 2011 Oct;59(5):600-9. doi: 10.1016/j.neuint.2011.04.009. Epub 2011 Jun 15.
Huntington's disease (HD) is a genetic neurodegenerative disorder characterized by striatal neurodegeneration, involving apoptosis. FK506, an inhibitor of calcineurin (or protein phosphatase 3, formerly known as protein phosphatase 2B), has shown neuroprotective effects in several cellular and animal models of HD. In the present study, we show the protective effects of FK506 in two striatal HD models, primary rat striatal neurons treated with 3-nitropropionic acid (3-NP) and immortalized striatal STHdh cells derived from HD knock-in mice expressing normal (STHdh(7/7)) or full-length mutant huntingtin (FL-mHtt) with 111 glutamines (STHdh(111/111)), under basal conditions and after exposure to 3-NP or staurosporine (STS). In rat striatal neurons, FK506 abolished 3-NP-induced increase in caspase-3 activation, DNA fragmentation/condensation and necrosis. Nevertheless, in STHdh(111/111) cells under basal conditions, FK506 did not prevent, in a significant manner, the release of cytochrome c and apoptosis inducing factor (AIF) from mitochondria, or alter Bax/Bcl-2 ratio, but significantly reverted caspase-3 activation. In STHdh(111/111) cells treated with 0.3mM 3-NP or 25 nM STS, linked to high necrosis, exposure to FK506 exerted no significant effects on caspase-3 activation. However, treatment of STHdh(111/111) cells exposed to 10nM STS with FK506 effectively prevented cell death by apoptosis and moderate necrosis. The results suggest that FK506 may be neuroprotective against apoptosis and necrosis under mild cell death stimulus in the presence of FLmHtt.
亨廷顿病（HD）是一种遗传性神经退行性疾病，其特征是纹状体神经退行性变，涉及细胞凋亡。FK506 是钙调神经磷酸酶（或蛋白磷酸酶 3，以前称为蛋白磷酸酶 2B）的抑制剂，在几种 HD 的细胞和动物模型中显示出神经保护作用。在本研究中，我们在两种纹状体 HD 模型中显示了 FK506 的保护作用，即用 3-硝基丙酸（3-NP）处理的原代大鼠纹状体神经元和源自携带正常（STHdh(7/7)）或全长突变亨廷顿蛋白（FL-mHtt）的 HD 基因敲入小鼠的永生化纹状体 STHdh 细胞，FL-mHtt 携带 111 个谷氨酰胺（STHdh(111/111)），在基础条件下以及暴露于 3-NP 或 staurosporine（STS）后。在大鼠纹状体神经元中，FK506 消除了 3-NP 诱导的 caspase-3 活化、DNA 片段化/浓缩和坏死的增加。然而，在基础条件下的 STHdh(111/111)细胞中，FK506 并没有显著阻止细胞色素 c 和凋亡诱导因子（AIF）从线粒体释放，也没有改变 Bax/Bcl-2 比值，但显著逆转了 caspase-3 的活化。在 STHdh(111/111)细胞中用 0.3mM 3-NP 或 25 nM STS 处理，与高坏死相关，暴露于 FK506 对 caspase-3 活化没有显著影响。然而，FK506 处理暴露于 10nM STS 的 STHdh(111/111)细胞可有效防止凋亡和中等坏死导致的细胞死亡。结果表明，在存在 FLmHtt 的情况下，FK506 可能对轻度细胞死亡刺激下的凋亡和坏死具有神经保护作用。
