Rab27a‐dependent exosomes protect against cerebral ischemic injury by reducing endothelial oxidative stress and apoptosis

Abstract

Introduction: Multicellular crosstalk within the brain tissue has been suggested to play a critical role in maintaining cerebral vascular homeostasis. Exosomes (EXs) mediated cell-cell communication, but its role in cerebral ischemic injury is largely unknown.Rab27a is one of the major genes controlling EX release. Here, we explored the role of Rab27a in regulating brain EXs secretion, and the effects of Rab27a-mediated EXs on ischemia evoked cerebral vascular disruption and brain injury.Methods: Cerebral ischemia was induced in Rab27a knockout (Rab27a −/− ) and wide type (WT) mice by transient middle cerebral artery occlusion (tMCAO). Differential gene expression analysis was performed in ischemic brain tissue by using mRNA sequencing. EXs isolated from brain tissue of Rab27a −/− and WT mice (EX WT or EX Rab27a−/− ) were pre-administrated into tMCAO operated Rab27a −/− mice or oxygen and glucose deprivation (OGD) treated primary brain vascular endothelial cells (ECs). Results:We demonstrated that Rab27a expression in the peri-infarct area of brain was significantly elevated, which was associated with local elevation in EXs secretion.Rab27a deficiency dramatically decreased the level of EXs in brain tissue of normal and tMCAO-treated mice, and Rab27a −/− mice displayed an increase in infarct volume and NDS, and a decrease in cMVD and CBF following tMCAO. Pre-infusion of EX WT increased the brain EXs levels in the tMCAO operated Rab27a −/− mice, accompanied with an increase in cMVD and CBF, and a decrease in infarct volume, NDS, ROS production, and apoptosis. The effects of EX Rab27a−/− infusion were much diminished although in a dose-dependent manner. In OGD-treated ECs, EX Rab27a−/− showed less effectivity than EX WT in decreasing ROS overproduction and apoptosis, paralleling with down-regulated expression of NOX2 and cleaved caspase-3.

Effects of a Global Rab27a Null Mutation on Murine PVAT and Cardiovascular Function

“…35,37 While other strains exist, we present a novel strain on a C57BL/6J background. 38,39 Utilizing the CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat–associated 9) technology, we created novel Rab27a global and conditional null strains by targeting exon 4, which is the first conserved exon among known Rab27a transcripts (Figure S1A). In vitro validation of the designed single guide RNA was performed to identify selectivity in genomic targeting of these regions within the Rab27a sequence before microinjection (Figure S1B).…”

Advancing stroke therapy: A deep dive into early phase of ischemic stroke and recanalization

“…This cellular process can be initiated either by the extrinsic death receptor pathway or the intrinsic mitochondrial pathway, both ultimately leading to the activation of executioner caspases. Dysregulation of apoptotic signaling and oxidative stress‐induced vascular injury and integrity disruption play a pivotal role in the initiation and development of IS and contribute to neuronal cell death and BBB disruption after ischemic stroke and recanalization therapy 113 . Excessive endothelial apoptosis is implicated in worse outcomes and hemorrhagic transformation following thrombolysis In MCAO mice, miR‐503 level was significantly increased in brain and contributed to endothelial cell (EC) dysfunction by promoting apoptosis.…”

“…Dysregulation of apoptotic signaling and oxidative stress‐induced vascular injury and integrity disruption play a pivotal role in the initiation and development of IS and contribute to neuronal cell death and BBB disruption after ischemic stroke and recanalization therapy. 113 Excessive endothelial apoptosis is implicated in worse outcomes and hemorrhagic transformation following thrombolysis In MCAO mice, miR‐503 level was significantly increased in brain and contributed to endothelial cell (EC) dysfunction by promoting apoptosis. While inhibition of miR‐503 ameliorated apoptosis of ECs, oxidative stress, BBB permeability, and neurological damage after stroke.…”

Extracellular Vesicles in Pathophysiology: A Prudent Target That Requires Careful Consideration

“…In a study by Ma et al, RAB27A was found to be an important regulator of EV secretion in the brain, which further provides protection against cerebral ischemia in an ischemic stroke mouse model. Brain-derived EVs obtained from RAB27A knockout mice also fail to attenuate ischemic injury in vivo, which implies that the RAB27A-dependent secretion of EVs may be critical to brain functioning [269]. Another study revealed that the siRNA-mediated knockdown of RAB27A attenuates hair growth in vitro [270].…”