PARP1 modulates BBB function via regulating NLRC5 in cerebral endothelial cells during ischemic stroke

Area of Science:

• Neuroscience
• Molecular Biology
• Pathophysiology

Background:

• Ischemic stroke (IS) is a leading cause of death and disability globally.
• Blood-brain barrier (BBB) dysfunction is a key feature of IS, but its mechanisms are not fully understood.
• Endothelial cells form the BBB, and their dysfunction contributes to IS pathology.

Purpose of the Study:

• To investigate the role of NOD-like receptor family CARD domain containing 5 (NLRC5) in IS-induced BBB dysfunction.
• To elucidate the molecular mechanisms by which NLRC5 affects BBB integrity and neurological outcomes after IS.
• To explore the therapeutic potential of targeting Poly (ADP-ribose) polymerase 1 (PARP1) in IS.

Main Methods:

• Quantitative analysis of NLRC5 expression in brain endothelial cells following IS.
• Endothelial cell-specific knockdown of NLRC5 using Adeno-Associated Virus Serotype 9 (AAV9).
• Immunoprecipitation-mass spectrometry and co-immunoprecipitation to identify protein interactions.
• Assessment of BBB permeability, neurological deficits, cerebral blood flow, and neuroinflammation.
• Pharmacological inhibition of PARP1 using PJ34.

Main Results:

• NLRC5 expression was significantly decreased in brain endothelial cells after IS.
• NLRC5 knockdown exacerbated BBB dysfunction, neurological deficits, and neuroinflammation while delaying cerebral blood flow recovery.
• NLRC5 was found to interact with PARP1, leading to NLRC5 downregulation via PARP1-mediated PARylation, ubiquitination, and proteasomal degradation.
• Inhibition of PARP1 with PJ34 attenuated IS-induced BBB dysfunction.

Conclusions:

• PARP1-mediated degradation of NLRC5 is a novel mechanism contributing to BBB dysfunction in IS.
• Targeting PARP1 represents a promising therapeutic strategy for mitigating IS-related brain injury and improving recovery.