BCL6

B-cell lymphoma 6 protein is a is_associated_with::protein that in humans is encoded by the BCL6 is_associated_with::gene. Like is_associated_with::BCL2, is_associated_with::BCL3, BCL5, BCL7A, is_associated_with::BCL9, and is_associated_with::BCL10, it has clinical significance in is_associated_with::lymphoma.

Function
The protein encoded by this gene is an evolutionarily conserved is_associated_with::zinc finger transcription factor and contains an N-terminal POZ/BTB domain. This protein acts as a sequence-specific repressor of transcription, and has been shown to modulate the STAT-dependent is_associated_with::Interleukin 4 (IL-4) responses of is_associated_with::B cells. This protein can interact with several corepressor complexes to inhibit transcription. This gene is found to be frequently translocated and hypermutated in is_associated_with::diffuse large B cell lymphoma (DLBCL),  and contributes to the pathogenesis of DLBCL. An exon 7 skipping splice variant encodes a shorter form of the protein which lacks the first two zinc fingers of the is_associated_with::DNA binding domain.

Physiologically, BCL6 is a master transcription factor which leads the differentiation of naive helper T cells in Follicular Helper T cells (TFH cells). Its action is negatively regulated by the gene is_associated_with::PRDM1 encoding the transcription factor Blimp-1.

Diagnostic utility
The presence of BCL6 can be demonstrated in tissue sections using is_associated_with::immunohistochemistry. It is exclusively present in the B-cells of both healthy and neoplastic is_associated_with::germinal centres. It therefore demonstrates both reactive hyperplasia in lymph nodes and a range of is_associated_with::lymphomas derived from follicular B-cells, such as is_associated_with::Burkitt's lymphoma, is_associated_with::follicular lymphoma, and the nodular lymphocyte predominant subtype of is_associated_with::Hodgkin's disease. It is often used together with antibodies to is_associated_with::Bcl-2 antigen to distinguish neoplastic follicles from those found in benign hyperplasia, for which Bcl-2 is negative.

Interactions
BCL6 has been shown to interact with

HSP90
 * is_associated_with::BCOR,
 * is_associated_with::C-jun,
 * is_associated_with::HDAC1,
 * is_associated_with::HDAC4,
 * is_associated_with::HDAC7A,
 * HDAC5,
 * is_associated_with::IRF4,
 * NCOR2,
 * is_associated_with::ZBTB7A
 * T-bet,
 * ZBTB16