Transcriptional control of c-myc gene expression during stimulation of murine B lymphocytes

The binding of ligand to surface IgR results in the initial activation of B cells. As shown by experiments in which B cells are polyclonally stimulated with anti-Ig antibody, this includes an early increase in c-myc gene expression. In our study a correlation between increases in the rate of gene transcription and the level of c-myc mRNA was observed both with the brief increase in c-myc expression that is induced by anti-Ig, as well as with the more intense and prolonged expression of c-myc that follows treatment with anti-Ig plus the cytoskeleton perturbing agent, cytochalasin. Elevation of the rate of initiation was detected with both stimulatory regimens although the combination of anti-Ig plus cytochalasin increased the rate of elongation in addition to the rate of initiation. These results suggest that stimulation of B lymphocytes alters expression of trans-acting factors that regulate transcription of the c-myc gene.