Muscle fiber types switched during the development of experimental autoimmune myasthenia gravis via the PI3K/Akt signaling pathway.

Abstract

As one of the largest organs of our human body, skeletal muscle has good research prospects in myasthenia gravis (MG), the symptoms of which include systemic skeletal muscle weakness. Skeletal muscle is composed of two types of muscle fibers. Different fiber subtypes can be converted into each other; however, the underlying mechanism is not yet clear. In this paper, we firstly established an experimental autoimmune myasthenia gravis (EAMG) rat model and found that the skeletal muscle fibers of the EAMG group were atrophied, with a change in the proportion of fiber subtypes, which switched from type IIa to type I in the EAMG group at the peak stage, as verified by histological and molecular analyses. Second-generation sequencing results predicted that the PI3K-Akt signaling pathway might be involved in the switch, and the mRNA expression levels of the PI3K-Akt pathway-related genesNr4a1, IL2rb, Col1A1 and Ddit4 were significantly different. In conclusion, this study indicates that the switch of muscle fiber subtypes in MG via the PI3K-Akt signaling pathway may be a potential target for the treatment of MG-related skeletal muscle atrophy in the future.