Impaired autophagy from TRPV4 activation drives α-synuclein pathology in a Parkinson's disease model: A toxicological insight.

Abstract

The environmental toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a prototypical agent for modeling Parkinson's disease (PD). Our previous study demonstrated that calcium channel transient receptor potential vanilloid 4 (TRPV4) mediates MPTP-induced endoplasmic reticulum (ER) stress and inflammation, leading to loss of dopamine neurons and movement disorder. Here, we investigated whether TRPV4 activation impairs clearance of pathological α-Synuclein (α-Syn) via the autophagy-lysosomal pathway (ALP), contributing to cognitive deficits in PD. We used C57BL/6J mice subjected to intracerebral injection of adeno-associated virus in substantia nigra to knockdown or overexpress TRPV4, followed by MPTP treatment. Novel object recognition and Morris water maze tests, immunohistochemistry, electron microscopy, and western blot were employed to assess the role of TRPV4 in modulating α-Syn via ALP. We found that targeting TRPV4 to counteract neurotoxicity improved cognitive dysfunction in PD mice. Mechanistically, MPTP-triggered toxic stress and TRPV4 overexpression induced accumulation of α-Syn and autophagosomes in hippocampus. Critically, TRPV4 knockdown significantly alleviated MPTP-induced α-Syn accumulation. Western blot analysis revealed that TRPV4 impaired α-Syn clearance via the ALP, as evidenced by dysregulation of key ALP components: LC3B, p62, lysosome-associated membrane protein 1, and transcription factor EB. In conclusion, our data are consistent with a model in which TRPV4 contributes to α-Syn accumulation through impairment of the ALP. This work establishes a direct link between TRPV4 and impaired α-Syn clearance, identifying TRPV4 not only as a mediator of ER stress and inflammation but as a critical molecular sensor that disrupts proteostasis. This positions TRPV4 as a promising therapeutic target for counteracting MPTP-induced neurodegeneration.