Repression of c- myc Transcription by Blimp-1, an Inducer of Terminal B Cell Differentiation

Transcription of c- myc in plasma cells, which are terminally differentiated B cells, is repressed by plasmacytoma repressor factor. This factor was identified as Blimp-1, known for its ability to induce B cell differentiation. Blimp-1 repressed c- myc promoter activity in a binding site–dependent manner. Treatment of BCL 1 lymphoma cells with interleukin-2 (IL-2) plus IL-5 induced Blimp-1 and caused a subsequent decline in c-Myc protein. Ectopic expression of Blimp-1 in Abelson-transformed precursor B cells repressed endogenous c-Myc and caused apoptosis; Blimp-1–induced death was partially overcome by ectopic expression of c-Myc. Thus, repression of c- myc is a component of the Blimp-1 program of terminal B cell differentiation.