Human immunodeficiency virus-1 Tat activates calpain proteases via the ryanodine receptor to enhance surface dopamine transporter levels and increase transporter-specific uptake and Vmax.
Human immunodeficiency virus-1 Tat activates calpain proteases via the ryanodine receptor to enhance surface dopamine transporter levels and increase transporter-specific uptake and Vmax.
复制标题
DOI：
10.1523/jneurosci.1042-10.2010
复制
发表时间：
2010-10-20
期刊：
影响因子：
--
通讯作者：
Gelbard HA
中科院分区：
文献类型：
--
作者：
Perry SW;Barbieri J;Tong N;Polesskaya O;Pudasaini S;Stout A;Lu R;Kiebala M;Maggirwar SB;Gelbard HA
尽管联合抗逆转录病毒治疗（cART）成功降低了病毒载量，但HIV相关神经系统疾病（HAND）仍会导致显著的发病率。多巴胺（DA）系统在HAND中特别脆弱。我们推测，早期的，“可逆的”DA能突触功能障碍发生DA能神经元损失之前很久。因此，老龄化的HIV感染者可能容易患上其他与年龄相关的神经退行性疾病，如帕金森病（PD），这强调了了解HAND和PD中共有分子靶点的必要性。以前我们报道过神经毒性的HIV-1反式激活因子（达特）通过ryanodine受体（RyR）的激活，严重破坏线粒体和内质网的钙稳态。在这里，我们进一步报告，达特破坏DA转运蛋白（DAT）的活性和功能，导致质膜（PM）DAT增加和DAT Vmax增加，而Km或总DAT蛋白没有变化。达特也增加钙蛋白酶蛋白酶活性在PM，证明了由TIRF显微镜下的可切割的荧光钙蛋白酶底物。Tat增加的PM DAT和钙蛋白酶活性被RyR拮抗剂ryanodine和dantrolene、钙蛋白酶抑制剂calpastatin和GSK-3β的特异性抑制剂阻断。我们得出结论，达特通过钙和钙蛋白酶介导的机制激活RyR，该机制上调DAT向PM的运输，并且不依赖于DAT蛋白合成，从而加强了RyR和GSK-3β抑制作为HAND临床治疗方法的可行性。最后，我们通过强调已发表的HAND患者纹状体中DAT水平增加的人类数据，并在Tat表达转基因小鼠中证明类似的发现，为这些发现提供了关键的翻译相关性。
HIV-associated neurologic disease (HAND) still causes significant morbidity, despite success reducing viral loads with combination antiretroviral therapy (cART). The dopamine (DA) system is particularly vulnerable in HAND. We hypothesize that early, “reversible” DAergic synaptic dysfunction occurs long before DAergic neuron loss. As such, aging HIV-infected individuals may be vulnerable to other age-related neurodegenerative diseases like Parkinson’s Disease (PD), underscoring the need to understand shared molecular targets in HAND and PD. Previously we reported that the neurotoxic HIV-1 transactivating factor (Tat) acutely disrupts mitochondrial and endoplasmic reticulum calcium homeostasis via ryanodine receptor (RyR) activation. Here we further report that Tat disrupts DA transporter (DAT) activity and function, resulting in increased plasma membrane (PM) DAT and increased DAT Vmax, without changes in Km or total DAT protein. Tat also increases calpain protease activity at the PM, demonstrated by TIRF microscopy of a cleavable fluorescent calpain substrate. Tat-increased PM DAT and calpain activity are blocked by the RyR antagonists ryanodine and dantrolene, the calpain inhibitor calpastatin, and by a specific inhibitor of GSK-3β. We conclude that Tat activates RyRs via a calcium and calpain mediated mechanism that upregulates DAT trafficking to the PM, and is independent of DAT protein synthesis, reinforcing the feasibility of RyR and GSK-3β inhibition as clinical therapeutic approaches for HAND. Finally we provide key translational relevance for these findings by highlighting published human data of increased DAT levels in striata of HAND patients, and demonstrating similar findings in Tat-expressing transgenic mice.