Muscle Proteomic Profile before and after Enzyme Replacement Therapy in Late-Onset Pompe Disease

Manuela Moriggi,Pietro Barbacini,Cinzia Bragato,Daniele Capitanio,Lorenzo Maggi,Cecilia Gelfi,Marina Mora,Maurizio Moggio,Enrica Torretta,Patrizia Sartori

doi:10.3390/ijms22062850

Abstract

Mutations in the acidic alpha-glucosidase (GAA) coding gene cause Pompe disease. Late-onset Pompe disease (LOPD) is characterized by progressive proximal and axial muscle weakness and atrophy, causing respiratory failure. Enzyme replacement therapy (ERT), based on recombinant human GAA infusions, is the only available treatment; however, the efficacy of ERT is variable. Here we address the question whether proteins at variance in LOPD muscle of patients before and after 1 year of ERT, compared withhealthy age-matched subjects (CTR), reveal a specific signature. Proteins extracted from skeletal muscle of LOPD patients and CTR were analyzed by combining gel based (two-dimensional difference gel electrophoresis) and label-free (liquid chromatography-mass spectrometry) proteomic approaches, and ingenuity pathway analysis. Upstream regulators targeting autophagy and lysosomal tethering were assessed by immunoblotting. 178 proteins were changed in abundance in LOPD patients, 47 of them recovered normal level after ERT. Defects in oxidative metabolism, muscle contractile protein regulation, cytoskeletal rearrangement, and membrane reorganization persisted. Metabolic changes, ER stress and UPR (unfolded protein response) contribute to muscle proteostasis dysregulation with active membrane remodeling (high levels of LC3BII/LC3BI) and accumulation of p62, suggesting imbalance in the autophagic process. Active lysosome biogenesis characterizes both LOPD PRE and POST, unparalleled by molecules involved in lysosome tethering (VAMP8, SNAP29, STX17, and GORASP2) and BNIP3. In conclusion this study reveals a specific signature that suggests ERT prolongation and molecular targets to ameliorate patient’s outcome.

Highlights

Pompe disease is a lysosomal storage disorder caused by mutations in the gene coding for acid alpha-glucosidase (GAA)
Lateonset Pompe disease (LOPD) PRE muscle is characterized by glycogen overload in lysosomes, disorganization of the mitochondrial structure, derangement of myofibrils with disrupted sarcomeres, and disorganization of triad junction
LOPD POST muscle is characterized by recovery of lysosomal glycogen accumulation, indicating the positive effect of Enzyme replacement therapy (ERT) on lysosome dysfunction

Summary

Introduction

Pompe disease is a lysosomal storage disorder caused by mutations in the gene coding for acid alpha-glucosidase (GAA). This enzyme is responsible for glycogen breakdown in lysosomes. Late-onset Pompe disease (LOPD) is characterized by up to ∼20% normal residual GAA activity, and by progressive general proximal and axial muscle weakness and atrophy, leading to respiratory failure, ambulation deficiency, and/or hyperCKemia without cardiac involvement in the majority of patients [2,3]. The degree of deficiencies correlates with disease duration, increasing with time the need for ventilation support and wheelchair dependency [4]. ERT efficacy in improving muscle symptoms is variable and independent of disease duration and extent of enzyme deficiency [8,9]

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