Cyclic AMP response element-binding protein positively regulates production of IFN-gamma by T cells in response to a microbial pathogen.
IFN-gamma is essential for resistance to many intracellular pathogens, including Mycobacterium tuberculosis. Transcription of the IFN-gamma gene in activated T cells is controlled by the proximal promoter element (-73 to -48 bp). CREB binds to the IFN-gamma proximal promoter, and binding is enhanced by phosphorylation of CREB. Studies in human T cell lines and in transgenic mice have yielded conflicting results about whether CREB is a positive or a negative regulator of IFN-gamma transcription. To determine the role of CREB in mediating IFN-gamma production in response to a microbial pathogen, we evaluated the peripheral blood T cell response to M. tuberculosis in healthy tuberculin reactors. EMSAs, chromatin immunoprecipitation, and Western blotting demonstrated that stimulation of PBMC with M. tuberculosis induced phosphorylation and enhanced binding of CREB to the IFN-gamma proximal promoter. Neutralization of CREB with intracellular Abs or down-regulation of CREB levels with small interfering RNA decreased M. tuberculosis-induced production of IFN-gamma and IFN-gamma mRNA expression. In addition, M. tuberculosis-stimulated T cells from tuberculosis patients, who have ineffective immunity, showed diminished IFN-gamma production, reduced amounts of CREB binding to the IFN-gamma proximal promoter, and absence of phosphorylated CREB. These findings demonstrate that CREB positively regulates IFN-gamma production by human T cells that respond to M. tuberculosis.
Samten
Buka
B
Center for Pulmonary and Infectious Disease Control, Department of Microbiology and Immunology, University of Texas Health Center, Tyler, TX 75708, USA.
Howard
Susan T
ST
Weis
Steven E
SE
Wu
Shiping
S
Shams
Homayoun
H
Townsend
James C
JC
Safi
Hassan
H
Barnes
Peter F
PF
D050882:CREB-Binding Protein; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007424:Intracellular Fluid / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D007963:Leukocytes, Mononuclear / Q000378:metabolism / Q000382:microbiology; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000472:pathogenicity; D009687:Nuclear Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000276:immunology; D011485:Protein Binding / Q000276:immunology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000494:pharmacology; D012694:Serine / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D015534:Trans-Activators; D015854:Up-Regulation / Q000276:immunology*
D017362:Cyclic AMP Response Element-Binding Protein; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D015534:Trans-Activators; D012694:Serine; D007371:Interferon-gamma; D050882:CREB-Binding Protein; C494363:CREBBP protein, human