BCL-6 gene product, a 92- to 98-kD nuclear phosphoprotein, is highly expressed in germinal center B cells and their neoplastic counterparts

Abstract

The BCL-6 gene is known to be located on chromosome 3q27, at the breakpoint of the 3q27-associated translocations that occur frequently in human non-Hodgkin's lymphomas (NHLs). To identify the BCL-6 protein, two antibodies that recognized distinct domains of this protein were raised in rabbits. Immunoprecipitation and immunoblotting of lysates of BCL-6-expressing cells using both antibodies showed a broad 92- to 98- kD band. Dephosphorylation of BCL-6 protein reduced the size of this band to 87 kD, suggesting that BCL-6 may be expressed in a phosphorylated form. Immunostaining with both antibodies showed that BCL-6 protein was localized in the nuclei of most of the germinal center B cells and a small number of marginal zone B cells. Furthermore, BCL-6 protein was expressed in follicular, Burkitt's, and diffuse large B-cell lymphomas. These results suggest that the BCL-6 protein, expressed in B cells of the germinal centers which are important in the maturation of immune responses, may play some physiological role(s) in the germinal center B cells.

Immunohistochemical diagnosis of the cagA‐gene genotype of Helicobacter pylori with anti‐East Asian CagA‐specific antibody

“…SDS-PAGE and Western blot analysis with α-EAS Ab was performed on lysates extracted from E. coli in which GST-Western CagA fusion protein (lanes1,5,9,13) or GST-East Asian CagA fusion protein (lanes 2, 6, 10, 14) had been induced, and lysates extracted from the Western cagA-positive H. pylori (lanes3,7,11,15) or East Asian cagA-positive H. pylori(lanes 4, 8, 12, 16). The presence of CagA protein in both types of H. pylori was confirmed by Western blot analysis with α-CagA Ab, which is immunoreactive with both East Asian and Western CagA (lanes[13][14][15][16].…”

“…GST fusion proteins were induced and affinity-purified according to the method described previously. (14) Western blot analysis. Western blot analysis was performed as described.…”

“…Detection of East Asian cytotoxinassociated antigen A by Western blot analysis with anti-East Asian CagA-specific antibody. Coomassiestained SDS-PAGE gel (lanes 1-4) and Western blot analysis with α-EAS Ab (lanes 5-8), antigenpreabsorbed α-EAS Ab (lanes 9-12), and α-CagA Ab (lanes[13][14][15][16]. SDS-PAGE and Western blot analysis with α-EAS Ab was performed on lysates extracted from E. coli in which GST-Western CagA fusion protein (lanes1,5,9,13) or GST-East Asian CagA fusion protein (lanes 2, 6, 10, 14) had been induced, and lysates extracted from the Western cagA-positive H. pylori (lanes3,7,11,15) or East Asian cagA-positive H. pylori(lanes 4, 8, 12, 16).…”

Genetic and epigenetic factors involved in B‐cell lymphomagenesis

“…Although this is true for translocation of BCL1/cyclin D1, it is not for that of BCL2 or BCL6. The mRNA levels and expression levels of gene products of BCL2 and BCL6 in cell line or lymphoma samples without translocation can be as much as those in samples with translocation, [3][4][5][6][7] which indicates that overexpression of the TJR gene is not essential. In order to gain a full understanding of the effect of transcriptional deregulation by chromosome translocation, it is important first to understand the normal transcriptional regulations of these TJR genes (Fig.…”

“…Several lines of evidence suggest that BCL1, BCL2 and BCL6 genes are regulated differently during the course of B-cell development. [3][4][5][6][7] In the normal developmental stages, the TJR genes are down-regulated at the stage where the related lymphomas arise (Fig. 2).…”