BLIMP-1, A NOVEL ZINC FINGER-CONTAINING PROTEIN THAT CAN DRIVE THE MATURATION OF B-LYMPHOCYTES INTO IMMUNOGLOBULIN-SECRETING CELLS

We describe a novel gene, Blimp-1 (for B lymphocyte-induced maturation protein), transcripts of which are rapidly induced during the differentiation of B lymphocytes into immunoglobulin secretory cells and whose expression is characteristic of late B and plasma cell lines. The 856 amino acid open reading frame contains five Kruppel-type zinc finger motifs and proline-rich and acidic regions similar to those of known transcription factors. Serological studies show an similar to 100 kd protein that localizes to the nucleus. Stable or transient transfection of Blimp-1 into B cell lymphoma lines leads to the expression of many of the phenotypic changes associated with B cell differentiation into an early plasma cell stage, including induction of J chain message and immunoglobulin secretion, up-regulation of Syndecan-1, and increased cell size and granularity. Thus, Blimp-1 appears to be a pleiotropic regulatory factor capable of at least partially driving the terminal differentiation of B cells.