Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, USA.
Department of Neurology, University of Pittsburgh, Pittsburgh, USA.
Neurobiol Dis. 2023 Oct 15;187:106305. doi: 10.1016/j.nbd.2023.106305. Epub 2023 Sep 18.
Ischemic stroke, constituting 80-90% of all strokes, is a leading cause of death and long-term disability in adults. There is an urgent need to discover new targets and therapies for this devastating condition. Protein kinase D (PKD), as a key target of diacylglycerol involved in ischemic responses, has not been well studied in ischemic stroke, particularly PKD2. In this study, we found that PKD2 expression and activity were significantly upregulated in the ipsilateral side of the brain after transient focal cerebral ischemia, which coincides with the upregulation of PKD2 in primary neurons in response to in vitro ischemia, implying a potential role of PKD2 in neuronal survival in ischemic stroke. Using kinase-dead PKD2 knock-in (PKD2-KI) mice, we examined whether loss of PKD2 activity affected stroke outcomes in mice subjected to 1 h of transient middle cerebral artery occlusion (tMCAO) and 24 h of reperfusion. Our data demonstrated that PKD2-KI mice exhibited larger infarction volumes and worsened neurological scores, indicative of increased brain injury, as compared to the wild-type (WT) mice, confirming a neuroprotective role of PKD2 in ischemia/reperfusion (I/R) injury. Mouse primary neurons obtained from PKD2-KI mice also exhibited increased cell death as compared to the WT neurons when subjected to in vitro ischemia. We have further identified AKT and CREB as two main signaling nodes through which PKD2 regulates neuronal survival during I/R injury. In summary, PKD2 confers neuroprotection in ischemic stroke by promoting AKT and CREB activation and targeted activation of PKD2 may benefit neuronal survival in ischemic stroke.
缺血性脑卒中占所有脑卒中的 80-90%，是成年人死亡和长期残疾的主要原因。因此，迫切需要为这种破坏性疾病寻找新的靶点和治疗方法。蛋白激酶 D (PKD) 作为二酰基甘油参与缺血反应的关键靶点，在缺血性脑卒中，尤其是 PKD2 中尚未得到充分研究。在这项研究中，我们发现短暂性局灶性脑缺血后大脑对侧 PKD2 表达和活性显著上调，这与体外缺血时原代神经元中 PKD2 的上调相吻合，提示 PKD2 在缺血性脑卒中神经元存活中可能发挥作用。我们使用激酶失活 PKD2 敲入（PKD2-KI）小鼠，研究了 PKD2 活性丧失是否会影响 1 小时短暂性大脑中动脉闭塞（tMCAO）和 24 小时再灌注后小鼠的卒中结局。我们的数据表明，与野生型（WT）小鼠相比，PKD2-KI 小鼠表现出更大的梗死体积和更严重的神经评分，表明脑损伤增加，证实了 PKD2 在缺血/再灌注（I/R）损伤中的神经保护作用。与 WT 神经元相比，来自 PKD2-KI 小鼠的原代神经元在体外缺血时也表现出更高的细胞死亡。我们进一步确定 AKT 和 CREB 是 PKD2 在 I/R 损伤中调节神经元存活的两个主要信号节点。综上所述，PKD2 通过促进 AKT 和 CREB 激活来发挥神经保护作用，靶向激活 PKD2 可能有益于缺血性脑卒中的神经元存活。
