The anhydrobiotic tardigrade, Hypsibius exemplaris, was previously considered to require de novo gene expression and protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) activity for successful anhydrobiosis. These indicate that H. exemplaris has signal transduction systems responding to desiccation stress, with the involvement of phosphorylation events. To this end, we carried out time-series phosphoproteomics of H. exemplaris exposed to mild desiccation stress and detected 48 phosphoproteins with significant differential regulations. Among them, immediate and successive reduction of phosphorylation levels of AMP-activated protein kinase (AMPK) was observed. The subsequent chemical genetic approach showed that AMPK was activated during the preconditioning stage for anhydrobiosis, and inhibition of its activity impaired successful anhydrobiosis. As PP2A is known to dephosphorylate AMPK in other organisms, we suggested that decreased phosphorylation levels of AMPK upon mild desiccation stress were caused by dephosphorylation by PP2A. Accordingly, phosphoproteomics of animals pre-treated with the PP1/PP2A inhibitor cantharidic acid (CA) lacked the decrease in phosphorylation levels of AMPK. These observations suggest that AMPK activity is required for successful anhydrobiosis in H. exemplaris, and its phosphorylation state is possibly regulated by PP2A.

中文翻译：

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AMPK活性是在缓坡蛇蝎示例中诱导脱水生物所必需的，其潜在的上调因子是PP2A。

以前认为无水生的节肢动物Hypsibius examplemplaris需要从头表达基因并需要蛋白磷酸酶1（PP1）和蛋白磷酸酶2A（PP2A）活性才能成功进行脱水。这些表明，示例性链球菌具有信号转导系统，其响应于脱水应激，并涉及磷酸化事件。为此，我们对暴露于轻度干燥压力下的示例链球菌进行了时间序列磷酸化蛋白质组学分析，并检测到48种具有明显差异调控的磷酸化蛋白。其中，观察到AMP激活蛋白激酶（AMPK）的磷酸化水平立即和连续降低。随后的化学遗传方法表明AMPK在脱水生物的预处理阶段被激活，抑制其活性会破坏脱水生物的成功。由于已知PP2A在其他生物中会使AMPK脱磷酸，因此我们认为，轻度的脱水胁迫下AMPK的磷酸化水平降低是由PP2A的脱磷酸作用引起的。因此，用PP1 / PP2A抑制剂邻苯二甲酸（CA）预处理的动物的磷酸化蛋白质组学缺乏AMPK磷酸化水平的降低。这些观察结果表明，AMPK活性是示例性嗜血杆菌中成功的脱水生物所必需的，并且其磷酸化状态可能由PP2A调节。用PP1 / PP2A抑制剂Cantharidic Acid（CA）预处理的动物的磷酸化蛋白质组学缺乏AMPK磷酸化水平的降低。这些观察结果提示，AMPK活性是在示例性嗜血杆菌中成功进行脱水生物活性所必需的，并且其磷酸化状态可能由PP2A调节。用PP1 / PP2A抑制剂Cantharidic Acid（CA）预处理的动物的磷酸化蛋白质组学缺乏AMPK磷酸化水平的降低。这些观察结果表明，AMPK活性是示例性嗜血杆菌中成功的脱水生物所必需的，并且其磷酸化状态可能由PP2A调节。