Brain- and muscle-type promoters of the dystrophin gene are selected in peripheral lymphocytes and Epstein Barr virus-transformed lymphoblastoid [correction of lymphoplastoid] cells

Abstract

Promoter-specific transcripts of the dystrophin gene in peripheral lymphocytes and Epstein Barr virus-transformed lymphoblastoid cells were analysed using reverse transcription-nested polymerase chain reaction. Two DNA fragments, corresponding to the alternative first exons transcribed from either brain- or muscle-type promoters, were both amplified from cDNA prepared from normal lymphocytes and lymphoblastoid cells. The nucleotide sequences of the amplified products were 100% homologous to the 5' termini of the cDNA of brain- and muscle-type dystrophins, respectively. Neither fragment was amplified from the lymphoblastoid cells of a patient with Duchenne muscular dystrophy, who has a partial deletion involving the brain- and muscle-type promoters in the dystrophin gene. These findings showed that the brain-type as well as the muscle-type promoter of the dystrophin gene was active in lymphocytes and lymphoblastoid cells.