BCL6

BCL6 Full Name

B-cell CLL/lymphoma 6

BCL6 Introduction

B-cell CLL/lymphoma 6 (BCL6) is a sequence-specific transcriptional repressor that serves as the master regulator of the germinal center (GC) reaction, a critical process in the adaptive immune system. Structurally, BCL6 belongs to the BTB/POZ-zinc finger family of transcription factors. It utilizes its C-terminal zinc finger domain to bind specific DNA motifs and its N-terminal BTB domain to recruit chromatin-modifying co-repressor complexes, such as SMRT, NCOR, and BCOR, which silence target genes. Physiologically, BCL6 is essential for the development of high-affinity antibodies. It temporarily suppresses genes involved in DNA damage sensing (e.g., TP53), apoptosis, and cell cycle arrest, allowing B cells to undergo rapid proliferation and somatic hypermutation without triggering cell death. Crucially, BCL6 also represses PRDM1 (encoding BLIMP1), thereby blocking premature differentiation into plasma cells until the affinity maturation process is complete.

Figure 1. Structure and function of the BCL6 protein. (Source: Liongue C, et al. 2024)

The pathogenic deregulation of BCL6 is a hallmark of several lymphoid malignancies. Because BCL6 permits cells to tolerate genetic damage and block differentiation, its constitutive expression acts as a potent oncogenic driver. This is most prominently observed in Diffuse Large B-Cell Lymphoma (DLBCL), the most common type of non-Hodgkin lymphoma, and Follicular Lymphoma (FL). In these diseases, chromosomal translocations affecting the 3q27 locus (where the BCL6 gene resides) or somatic mutations in the BCL6 promoter region prevent the normal downregulation of the protein. This "locks" the malignant B cells in a proliferative, undifferentiated germinal center state, fueling tumor growth and contributing to chemotherapy resistance.

Alternate Names for BCL6

BCL6; B-cell CLL/lymphoma 6; BCL5; LAZ3; BCL6A; ZNF51; ZBTB27; B-cell lymphoma 6 protein; BCL-5; BCL-6

• Immunohistochemistry Antibodies for Pathology

• 1. Liongue C, et al. B Cell Lymphoma 6 (BCL6): A Conserved Regulator of Immunity and Beyond. Int J Mol Sci. 2024 Oct 11;25(20):10968.
  2. Basso K, et al. BCL6: master regulator of the germinal center reaction and key oncogene in B cell lymphomagenesis. Adv Immunol. 2010;105:193-210.