Deficiency in Protein Kinase D Activity exacerbates post‐stroke injuries and impairs functional recovery after ischemic stroke in Mice

Abstract

Diacylglycerol signaling network is a key mediator of neurovascular injuries after ischemic stroke. As a primary target of diacylglycerol, the family of protein kinase D (PKD) has been implicated in pathological processes involved in ischemia-reperfusion injuries after stroke, however, its in vivo function in the disease has not been thoroughly evaluated. This study aims to investigate whether loss of PKD activity affects ischemic stroke outcomes in mice. Homozygous kinase-dead PKD2 knock-in mice (KI) were obtained by intercrossing mice heterozygous for an inactivating mutation of PKD2S707A/S711A. PKD2 KI and wild type (WT) mice were subjected to 1 h of middle cerebral artery occlusion (MCAO) and 24 h of reperfusion. Infarct volumes and neurological scores were measured and compared between KI and WT mice after reperfusion. To gain insights into the mechanisms of PKD signaling, expression and activity of PKD isoforms and their downstream targets were evaluated by quantitative real-time PCR (qRT-PCR) and Western blot. Our data showed that catalytic deficiency of PKD aggravated post-stroke brain infarction and edema, correlating to worsened neurological scores in mice. Cellular analysis showed that all three PKD isoforms were expressed in mouse neuronal cells and activated in response to in vitro ischemia, correlating to changes of several downstream signaling events, supporting their involvement in pathological processes of neuronal injury. Our findings support a neuroprotective role of PKD in ischemic stroke and suggest potential therapeutic targets for neuroprotection.