Rab7a is required to degrade select blood-brain barrier junctional proteins after ischemic stroke

Adherens (AJ) and tight junction (TJ) integrity is critical for blood-brain barrier (BBB) function in the healthy brain. Junction disassembly due to degradation of AJ and TJ proteins leads to acute BBB dysfunction after ischemic stroke, but the mechanisms are not fully understood. Here, we show that endothelial cell deletion of Rab7a, a small GTPase crucial for protein degradation through the endolysosomal system, reduces acute BBB dysfunction and improves neuronal health in mice after ischemic stroke by preventing degradation of select junctional proteins and preserving TJ structural morphology. Two pro-inflammatory cytokines, TNF and IL1{beta}, that trigger barrier disruption in brain endothelial cells (BECs) in vitro and are upregulated in stroke, contribute to Rab7a activation. Silencing Rab7a in vitro partially rescues cytokine-driven barrier disruption in BECs by reducing internalization of some junctional proteins and the formation of F-actin bundles at cell junctions. Rab7a is, therefore, critical for degradation of select junctional proteins during the acute BBB damage after ischemic stroke.