Differential expression of Dp71 and Dp40 isoforms in proliferating and differentiated neural stem cells: Identification of Dp40 splicing variants.

Dp71 and Dp40 are the main products of the DMD gene in the central nervous system, and they are developmentally regulated from the early stages of embryonic development to adulthood. To further study the roles of Dp71 and Dp40 during cell proliferation and neural differentiation, we analyzed Dp71/Dp40 isoform expression at the mRNA level by RT-PCR assays to identify alternative splicing (AS) in the isoforms expressed in rat neural stem/progenitor cells (NSPCs) and in differentiated cells (neurons and glia). We found that proliferating NSPCs expressed Dp71d, Dp71d, Dp71f, Dp71f, Dp71d and Dp40, as well as two Dp40 isoforms: Dp40 and Dp40. In differentiated cells we also found the expression of Dp71d, Dp71d, Dp71f, Dp71f and Dp40. However, the expression frequencies were different in both stages. In addition, in differentiated cells, we found Dp71f, and interestingly, we did not find the expression of Dp71d or the newly identified Dp40 isoforms. In this work we show that NSPC differentiation is accompanied by changes in Dp71/Dp40 isoform expression, suggesting different roles for these isoforms in NSPCs proliferation and neuronal differentiation, and we describe, for the first time, alternative splicing of Dp40.