Loss of Dystrobrevin Causes Muscle Degeneration and a Short Lifespan in Caenorhabditis elegans

Duchene’s muscular dystrophy (DMD) is an inherited disorder in an X-linked recessive manner. Lack of dystrophin causes progressive muscle degeneration. Dystrophin structurally connects to actin filaments at the N-terminus while the C-terminus interacts with an integral domain of the dystroglycan complex. Among the associated molecules, dystrobrevin acts as a modulator protein exerting dystrophin's function for strengthening the cell stability. Previous data has reported the delayed muscle degeneration following an overexpression of the dystrobrevin (dyb) gene in the DMD-phenotype C. elegans, whose dystrophin (dys) gene was missing. This finding indicates the role of a modulator protein, rather than dystrophin, to maintain the cell integrity. The present study aims to investigate the phenotypes of C. elegans, due to dyb- or dys-deficiency. When compared with the wild-type, the dyb-deficient worms exhibited uncoordinated locomotion and lysis of the muscular layer in the body wall and internal organs as well as those observed in the dys-deficient worms. The ultrastructure of both mutant worms appeared severe muscle degeneration, decrease of the mitochondria, and replacement of fibrotic tissue, particularly the dys-mutant which was even more severe. Additionally, a shorter lifespan was observed with a 17 % reduction (p < 0.05) in dyb-deficient worms and 27 % reduction (p < 0.05) in dys-deficient worms when compared to wild-type. It is speculated that dystrobrevin may stabilize the cell through interaction with other protein complexes at the plasma membrane while it also binds to dystrophin. Therefore, the loss of dystrobrevin is also sufficient to disrupt the signaling pathway and causes muscle degeneration.