Loss of the batten disease protein CLN3 leads to mis-trafficking of M6PR and defective autophagic-lysosomal reformation
Alessia Calcagnì, Leopoldo Staiano, Nicolina Zampelli, Nadia Minopoli, Niculin J. Herz, Giuseppe Di Tullio, Tuong Huynh, Jlenia Monfregola, Alessandra Esposito, Carmine Cirillo, Aleksandar Bajić, Mahla Zahabiyon, Rachel Curnock, Elena Polishchuk, Luke Parkitny, Diego L. Medina, Nunzia Pastore, Peter J. Cullen, Giancarlo Parenti, Maria Antonietta De Matteis, Paolo Grumati, Andrea Ballabio
Abstract
Batten disease, one of the most devastating types of neurodegenerative lysosomal storage disorders, is caused by mutations in CLN3. Here, we show that CLN3 is a vesicular trafficking hub connecting the Golgi and lysosome compartments. Proteomic analysis reveals that CLN3 interacts with several endo-lysosomal trafficking proteins, including the cation-independent mannose 6 phosphate receptor (CI-M6PR), which coordinates the targeting of lysosomal enzymes to lysosomes. CLN3 depletion results in mis-trafficking of CI-M6PR, mis-sorting of lysosomal enzymes, and defective autophagic lysosomal reformation. Conversely, CLN3 overexpression promotes the formation of multiple lysosomal tubules, which are autophagy and CI-M6PR-dependent, generating newly formed proto-lysosomes. Together, our findings reveal that CLN3 functions as a link between the M6P-dependent trafficking of lysosomal enzymes and lysosomal reformation pathway, explaining the global impairment of lysosomal function in Batten disease.