Therapeutic potential of cAMP-mediated lysosomal pH modulation in ATP6V1B2-related neuropathology.

Pathogenic variants in ATP6V1B2, which encodes a critical subunit of vacuolar-type H+-ATPases (V-ATPases), disrupt lysosomal acidification via haploinsufficiency and clinically manifest as intellectual disability and seizure disorders. Despite significant morbidity, mechanism-based therapies remain an unmet need. Through integrated clinical analysis of a Chinese cohort and systematic literature review, we delineated genotype-phenotype correlations in ATP6V1B2-related syndromes. Isogenic HEK293T models (ATP6V1B2R506X/+ and ATP6V1B2R506X/R506X) were generated using CRISPR/Cas9 for dynamic lysosomal pH monitoring via ratiometric RpH-LAMP1-3×flag imaging to evaluate pathophysiological mechanisms. Parallel investigations in Atp6v1b2R506X/R506X mice incorporated continuous video-EEG monitoring, behavioral assessments, western blot analyses, and transmission electron microscopy to evaluate therapeutic responses. Drug concentrations in plasma and brain homogenates were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Clinical analysis revealed central nervous system manifestations (epilepsy, intellectual disability, developmental delay) as primary morbidity determinants. Cellular studies demonstrated significant increase of lysosomal pH in mutant cells compared to wild-type control. Remarkably, treatment with the cAMP analog CPT-cAMP restored lysosomal acidification in a concentration-dependent manner. In vivo studies confirmed spontaneous seizure activity in mutant mice and CPT-cAMP's penetration of the BBB was confirmed by LC-MS/MS. Intraperitoneal CPT-cAMP administration (20 mg/kg) exerted triple therapeutic effects: (1) significant reduction in seizure frequency, (2) improved cognitive performance in behavioral paradigms, and (3) restoration of autophagic flux through resolution of autophagosome accumulation. These findings establish proof-of-concept for cAMP-mediated lysosomal pH modulation as a viable therapeutic strategy. Our results position CPT-cAMP as a promising candidate for addressing both neurological and cognitive manifestations in ATP6V1B2-related disorders.