Alternative processing of the gene transcripts encoding a plasma-membrane and a sarco/endoplasmic reticulum Ca2+ pump during differentiation of BC3H1 muscle cells.

The effect of differentiation on the RNA processing of the PMCA1 gene encoding a plasma-membrane Ca2+ pump and of the SERCA2 gene encoding a sarco(endo)plasmic reticulum Ca2+ pump was studied in the myogenic BC3H1 cell line. A differentiation stage-dependent change in the RNA processing was observed for both genes. Proliferating myoblasts only expressed the non-muscle mRNA isoform whereas in differentiated cells muscle-specific processing became activated. The switch to muscle-specific RNA processing for both the PMCA1 and SERCA2 genes was found to be linked to the myogenic conversion of the BC3H1 cells. Our results furthermore indicated that the myogenic RNA processing could be reversed for both types of Ca2+ pumps since the expression of the PMCA1 and SERCA2 muscle-specific messengers was rapidly down-regulated by cycloheximide treatment.