Dp71ab/DAPs complex composition changes during the differentiation process in PC12 cells

PC12 cells express different Dp71 isoforms originated from alternative splicing; one of them, Dp71ab lacks exons 71 and 78. To gain insight into the function of Dp71 isoforms we identified dystrophin associated proteins (DAPs) that associate in vivo with Dp71 ab during nerve growth factor (NGF) induced differentiation of PC12 cells. DAPs expression was analyzed by RT-PCR, Western blot and indirect immunofluorescence, showing the presence of each mRNA and protein corresponding to α-, β-, γ-, δ-, and ε-sarcoglycans as well as ζ-sarcoglycan mRNA. Western blot analysis also revealed the expression of β-dystroglycan, α1-syntrophin, α1-, and β-dystrobrevins. We have established that Dp71ab forms a complex with β-dystroglycan, α1-syntrophin, β-dystrobrevin, and α-, β- and γ-sarcoglycans in undifferentiated PC12 cells. In differentiated PC12 cells, the complex composition changes since Dp71ab associates only with β-dystroglycan, α1 -syntrophin, β-dystrobrevin, and δ-sarcoglycan. Interestingly, neuronal nitric oxide synthase associates with the Dp71ab/DAPs complex during NGF treatment, raising the possibility that Dp71 ab may be involved in signal transduction events during neuronal differentiation.