Role of annexin A2 in muscle repair. Mus musculus

Repair of injured muscle involves repair of injured myofibers through the involvement of dysferlin and its interacting partners, including annexin. Studies with mice and patients have established that dysferlin deficit leads to chronic inflammation and adipogenic replacement of the diseased muscle. However, longitudinal analysis of annexin deficit on muscle pathology and function is lacking. Here we show that unlike annexin A1, but similar to dysferlin, lack of annexin A2 (AnxA2) causes poor myofiber repair and progressive weakening with age. However, unlike dysferlin-deficient muscle, AnxA2-deficient muscles do not exhibit chronic inflammation or adipogenic replacement. Deletion of AnxA2 in dysferlin deficient mice reduces inflammation, adipogenic replacement, and loss in muscle function caused by dysferlin deficit. These results show that: a) AnxA2 facilitates myofiber repair, b) chronic inflammation and adipogenic replacement of dysferlinopathic muscle requires AnxA2, and c) inhibiting AnxA2-mediated inflammation is a novel therapeutic avenue for dysferlinopathy. Overall design: For this study total RNA was extracted from the gastrocnemius muscle of 24 weeks old mouse samples (Wild type n=4 and Anxa2 knockout n=4).