Overexpression of the dystrophins Dp40 and Dp40(L170P) modifies neurite outgrowth and the protein expression profile of PC12 cells

Dp40 is ubiquitously expressed including the central nervous system. In addition to being present in the nucleus, membrane, and cytoplasm, Dp40 is detected in neurites and postsynaptic spines in hippocampal neurons. Although Dp40 is expressed from the same promoter as Dp71, its role in the cognitive impairment present in Duchenne muscular dystrophy patients is still unknown. Here, we studied the effects of overexpression of Dp40 and Dp40(L170P) during the neuronal differentiation of PC12 Tet-On cells. We found that Dp40 overexpression increased the percentage of PC12 cells with neurites and neurite length, while Dp40(L170P) overexpression decreased them compared to Dp40 overexpression. Two-dimensional gel electrophoresis analysis showed that the protein expression profile was modified in nerve growth factor-differentiated PC12-Dp40(L170P) cells compared to that of the control cells (PC12 Tet-On). The proteins α-internexin and S100a6, involved in cytoskeletal structure, were upregulated. The expression of vesicle-associated membrane proteins increased in differentiated PC12-Dp40 cells, in contrast to PC12-Dp40(L170P) cells, while neurofilament light-chain was decreased in both differentiated cells. These results suggest that Dp40 has an important role in the neuronal differentiation of PC12 cells through the regulation of proteins involved in neurofilaments and exocytosis of synaptic vesicles, functions that might be affected in PC12-Dp40(L170P).