Protein aggregation in inclusion body and myofibrillar myopathies

The overarching goal of this R01 is to explore the hypothesis that a prion-like mechanism of proteopathic spread occurs in inclusion body myopathy (IBM). IBM patient muscle has two distinct pathologies, 1) protein inclusions containing aggregated proteins such as TDP-43 and desmin and 2) rimmed vacuoles consisting of autophagosomes, lysosomes and endosomes. How these two pathologies are pathomechanistically connected is unclear. We suggest that aggregated proteins such as TDP-43 and desmin enter the endolysosomal system damaging the membrane leading to a failure in lysosomal degradation and signaling pathways resulting in muscle degeneration. Our aims will test 1) confirm that muscle derived TDP-43 proteopathic seeds can induce TDP-43 aggregation in recipient myofibers. 2) Demonstrate that proteopathic seeds can induce lysosomal membrane permeabilization resulting in autophagic and lysosomal dysfunction 3) Evaluate myofiber to myofiber propagation of proteopathic aggregates. Upon completion of these aims, we will have defined a unique mechanism of IBM pathogenesis and identified a novel point of therapeutic intervention by blocking the spread of protein aggregates.