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

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• The blood-brain barrier (BBB) maintains brain homeostasis through intact adherens and tight junctions.
• Ischemic stroke causes BBB dysfunction due to the degradation of junctional proteins, but the underlying mechanisms remain unclear.

Purpose of the Study:

• To investigate the role of Rab7a, a key regulator of endolysosomal degradation, in BBB integrity following ischemic stroke.
• To determine if targeting Rab7a can mitigate BBB dysfunction and improve neuronal outcomes after stroke.

Main Methods:

• Genetic deletion of Rab7a in mouse endothelial cells.
• Histopathological analysis of mouse brains post-ischemic stroke.
• Confocal and electron microscopy to assess tight junction morphology.
• In vitro studies using primary mouse brain endothelial cells (BECs) stimulated with TNFα and IL1β, or subjected to oxygen-glucose deprivation.

Main Results:

• Endothelial cell-specific deletion of Rab7a significantly reduced acute BBB leakage and improved neuronal health after ischemic stroke in mice.
• Rab7a deletion preserved the structural integrity of tight junctions.
• Pro-inflammatory cytokines TNFα and IL1β, upregulated post-stroke, activated Rab7a in BECs, while oxygen-glucose deprivation did not.
• Rab7a is essential for the degradation of specific BEC junctional proteins contributing to BBB permeability.

Conclusions:

• Rab7a plays a critical role in the degradation of endothelial cell junctional proteins, leading to BBB dysfunction after ischemic stroke.
• Targeting Rab7a presents a potential therapeutic strategy to protect the BBB and improve outcomes in ischemic stroke patients.