Dissecting lysosomal signals to fight Pompe disease


Pre-Clinical Research

Poster Number: M247


Andrea Armani, PhD, University of Zurich, Tenzin Kunchok, Whitehead Institute for Biomedical Research, Paolo Grumati, PhD, Telethon Institute for Genetic and Medicine, Harvey F. Lodish, PhD, Whitehead Institute for Biomedical Research, David M. Sabatini, MD, PhD, Institute of Organic Chemistry and Biochemistry of the CAS, Adriano Aguzzi, MD, University of Zurich

Pompe disease (PD) is a rare genetic disorder stemming from mutations inactivating the gene coding for acid maltase (GAA), the enzyme that breaks down glycogen inside lysosomes. Due to the impairment in the function of these organelles, PD has been the first described lysosomal storage disease, affecting 1 in 40,000 live births. GAA deficiency leads to pathological glycogen accumulation in several tissues; in the infantile form, glycogen accumulation is causing a severe cardiomyopathy that can be successfully reverted by enzyme replacing therapy (ERT). Moreover, both infantile forms and late onset ones (LPOD) presents a severe, ERT resistant and progressive skeletal muscle wasting and weakness that force patients to wheelchairs and mechanical ventilation. Unfortunately, to date, respiratory failure is still the main cause of death in LOPD patients, even if in treatment.
Studies clarifying the pathogenic cascade guided the optimization of available therapies, paving the basis for the development of next-generation ERT; however, no systematic assessment of lysosomal signaling abnormalities during PD progression has been made due to major technical challenges in the isolation of functional organelles. For this reason, we first developed an innovative in vivo system where the GAA KO model was crossed to the LysoTag mouse line; we then exploited the Pompe LysoTag model to optimize a robust protocol for rapid lysosomes immunopurification starting from skeletal muscles, diaphragm and heart. This system allows a reliable enrichment of organelles pure from other cellular components while preserving their structural and functional integrity, thus favouring the identification of new signals that are lost in total cell lysates. Via unbiased approaches, we next applied this method to investigate lysosomes content, interactome and function in healthy and pathological tissues at different time points of the disease progression. Surprisingly, our preliminary data found a precocious alteration in some lysosomal enzymes import/processing in a tissue dependent manner; however, further investigations are needed to better clarify this finding and establish its involvement in disease pathogenesis.
So far, our approach identified a novel precocious lysosomal signaling alteration, highlighting the potential of this project in filling fundamental gaps in the comprehension of GAA deficiency pathogenesis, with the final goal to serve as a platform for new therapies development.