Neuronal Zinc Transporter ZnT3 Modulates Cerebral Ischemia-Induced Blood-Brain Barrier Disruption

Area of Science:

• Neuroscience
• Biochemistry
• Pathology

Background:

• Zinc is crucial in brain function, but its accumulation post-stroke contributes to blood-brain barrier (BBB) damage.
• The source and mechanism of free zinc-induced BBB disruption following cerebral ischemia remain unclear.

Purpose of the Study:

• To identify the source of elevated free zinc in brain microvessels after ischemia.
• To elucidate the mechanism by which free zinc mediates ischemia-induced BBB damage.

Main Methods:

• Utilized cellular and animal models of ischemic stroke, including neuronal-specific zinc transporter 3 (ZnT3) knockout mice.
• Measured extracellular fluid zinc (ECF-Zn) levels and BBB permeability in a rat stroke model.
• Investigated the interaction between ECF-Zn and metalloproteinase-2 (MMP-2) activity.

Main Results:

• Cerebral ischemia increased ECF-Zn, exacerbating BBB damage.
• Suppression of ZnT3 significantly reduced ECF-Zn and BBB permeability.
• Elevated ECF-Zn directly activated MMP-2 by increasing its zinc content, leading to tight junction protein degradation and BBB disruption.

Conclusions:

• Neuronal ZnT3 plays a key role in modulating ischemia-induced BBB disruption.
• A novel mechanism of MMP-2 activation via ECF-Zn contributes to BBB damage after stroke.
• ZnT3 represents a potential therapeutic target for stroke treatment.