The mechanism of NEDD4 attenuating intracerebral hemorrhage injury through restoring glymphatic function by ubiquitin-mediated degradation of LPAR1.

BACKGROUND: Intracerebral hemorrhage (ICH) induces severe neurological injury, and the glymphatic system plays a critical role in post-ICH brain recovery. This study investigated the role of neural precursor cell expressed developmentally down-regulated protein 4 (NEDD4), an E3 ubiquitin ligase, in modulating glymphatic function and neuroprotection after ICH. METHODS: An ICH model was established in mice via intrastriatal collagenase injection. Neurological function was assessed using modified Neurological Severity Score (mNSS). Histopathological damage was evaluated by hematoxylin and eosin (H＆E) staining and Nissl staining. Evaluate Aquaporin-4 (AQP4) polarization and glymphatic system function through the co-localization of AQP4 and CD31, as well as cerebrospinal fluid (CSF) tracing with RITC-Dextran. Molecular mechanisms were explored in vitro using hemin-treated astrocytes. The physical interaction between NEDD4 and lysophosphatidic acid receptor 1 (LPAR1) was validated via co-immunoprecipitation. Ubiquitination assays and pathway analysis verified the ubiquitination of LPAR1 by NEDD4 and the subsequent suppression of the LPAR1/RhoA/MMP9 axis. RESULTS: NEDD4 was significantly downregulated in peri-lesional astrocytes after ICH. NEDD4 overexpression improved neurological function, reduced hematoma volume and cerebral edema. Meanwhile, NEDD4 overexpression alleviated ICH-induced glymphatic dysfunction by promoting AQP4 polarization. Mechanistically, NEDD4 bound to LPAR1 and promoted its ubiquitin-mediated degradation, suppressing the RhoA/matrix MMP9 axis. Co-overexpression of LPAR1 abolished NEDD4-induced AQP4 polarization and glymphatic protection. CONCLUSION: NEDD4 attenuates ICH injury by ubiquitinating LPAR1 and inhibiting RhoA/MMP9 signaling, thereby restoring AQP4 polarization and glymphatic function. Targeting the NEDD4/LPAR1 axis may offer a novel therapeutic strategy for ICH.