The emerging role and therapeutic targeting of autophagy-lysosome pathway in the pathogenesis of Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopaminergic neuron loss and the accumulation of misfolded α-synuclein, yet the underlying mechanisms remain incompletely understood. Over the past two decades, genetic discoveries have highlighted the convergence of multiple familial PD genes on the autophagy-lysosome pathway (ALP), a key cellular system responsible for the degradation and recycling of intracellular components. Recent studies have further revealed that components of the ALP not only mediate the clearance of α-synuclein aggregates but also, under certain pathological conditions, contribute to their propagation via lysosomal exocytosis or secretory autophagy. The precise functions of autophagy are highly context-dependent, with neuronal and glial cells exhibiting distinct ALP dynamics that shift with development, stress, and aging. In this review, we summarize current knowledge on the physiological regulation of autophagy in the brain and critically examine its involvement in PD pathogenesis, incorporating mechanistic insights from familial models and emerging evidence from sporadic PD. We also explore translational implications, focusing on efforts to identify ALP-related biomarkers in cerebrospinal fluid and urine, and on the therapeutic potential of modulating ALP activity. Although the causality between ALP dysfunction and PD remains elusive, mounting evidence supports its contribution to disease progression, particularly through impaired lysosomal homeostasis and disrupted intracellular trafficking. Future research should aim to define cell type-specific ALP alterations, clarify the bidirectional interactions between α-synuclein and autophagic machinery, and develop in vivo tools to monitor autophagy activity and secretory signatures. A deeper understanding of these processes will be crucial for refining PD models, discovering robust fluid biomarkers, and designing targeted therapies capable of modifying disease trajectory.