title: Bcl6 controls granzyme B expression in effector CD8+ T cells.
abstract: Bcl6, a sequence-specific transcriptional repressor, is important for generation and maintenance of memory CD8(+) T cells. Although memory CD8(+) T cells are generated from effector CD8(+) T cells, a role for Bcl6 in effector CD8(+) T cells is largely unknown. We show here that Bcl6 expression was transiently induced in activated CD8(+) T cells and continuously up-regulated in effector CD8(+) T cells. The amount of granzyme B mRNA among effector molecules produced by effector CD8(+) T cells inversely correlated with the amount of Bcl6 mRNA in CD8(+) T cells. Overexpression of Bcl6 in CD8(+) T cells resulted in lower killing activity at their effector phase, supporting the reduction of granzyme B expression in effector CD8(+) T cells by Bcl6. We identified a putative Bcl6-binding DNA sequence in the promoter region of the granzyme B gene. Binding of Bcl6 to the Bcl6-binding sequence was detected in naive CD8(+) T cells but not in activated CD8(+) T cells by chromatin immunoprecipitation assay. Furthermore, the Bcl6-binding sequence was required for Bcl6 to repress the luciferase reporter gene expression controlled by the granzyme B promoter. Thus, the granzyme B gene is a molecular target of Bcl6 in effector CD8(+) T cells.
authors.affiliation: Department of Developmental Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yoshida
authors.forename: Akemi
authors.initials: A
authors.lastname: Sakamoto
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Yamashita
authors.forename: Eggi
authors.initials: E
authors.lastname: Arguni
authors.forename: Satoshi
authors.initials: S
authors.lastname: Horigome
authors.forename: Masafumi
authors.initials: M
authors.lastname: Arima
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hatano
authors.forename: Naohiko
authors.initials: N
authors.lastname: Seki
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Ichikawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tokuhisa
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D053804:Granzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D051560:Proto-Oncogene Proteins c-bcl-6
chemical_list: C490010:Bcl6 protein, mouse; D004268:DNA-Binding Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D053804:Granzymes; C509214:Gzmb protein, mouse