Overexpression of mutant dystrophin Dp71[INCREMENT]₇₈-₇₉ stimulates cell proliferation

Abstract

Dp71 dystrophin is the main DMD gene product expressed in the central nervous system. Experiments using PC12 cells as a neuronal model have shown that Dp71 isoforms are involved in differentiation, adhesion, cell division, and nuclear architecture. To contribute to the knowledge of Dp71 domains function, we previously reported the isolation and partial characterization of the dystrophin Dp71[INCREMENT]78-79 (a mutant that lacks exons 71, 78, and 79), which stimulates the neuronal differentiation of PC12-C11 clone. In this article, we generated a doxycycline (Dox)-inducible expression system in PC12 Tet-On cells (B10 cells) to overexpress and control the transcription of Dp71[INCREMENT]78-79. Western blotting and confocal microscopy showed an increase in the amount of Dp71[INCREMENT]78-79 (217±75-fold) with the addition of Dox to growth medium. Cell proliferation assays and morphometric analyses demonstrated that Dp71[INCREMENT]78-79 increases the growth rate of B10 cells and reduces the nerve growth factor-neuronal differentiation. Western blotting analysis revealed an upregulation in the expression of proliferating cell nuclear antigen, focal adhesion kinase, and β-dystroglycan in B10 cells compared with control cells. Our results show that the inducible expression of Dp71[INCREMENT]78-79 increases the growth rate of PC12 Tet-On cells, suggesting a role of this protein in cell proliferation.