title: Critical role for transcription factor C/EBP-beta in regulating the expression of death-associated protein kinase 1.
abstract: Transcription factor C/EBP-beta regulates a number of physiological responses. During an investigation of the growth-suppressive effects of interferons (IFNs), we noticed that cebpb(-/-) cells fail to undergo apoptosis upon gamma IFN (IFN-gamma) treatment, compared to wild-type controls. To examine the basis for this response, we have performed gene expression profiling of isogenic wild-type and cebpb(-/-) bone marrow macrophages and identified a number of IFN-gamma-regulated genes that are dependent on C/EBP-beta for their expression. These genes are distinct from those regulated by the JAK-STAT pathways. Genes identified in this screen appear to participate in various cellular pathways. Thus, we identify a new pathway through which the IFNs exert their effects on cellular genes through C/EBP-beta. One of these genes is death-associated protein kinase 1 (dapk1). DAPK1 is critical for regulating the cell cycle, apoptosis, and metastasis. Using site-directed mutagenesis, RNA interference, and chromatin immunoprecipitation assays, we show that C/EBP-beta binds to the promoter of dapk1 and is required for the regulation of dapk1. Both mouse dapk1 and human dapk1 exhibited similar dependences on C/EBP-beta for their expression. The expression of the other members of the DAPK family occurred independently of C/EBP-beta. Members of the C/EBP family of transcription factors other than C/EBP-beta did not significantly affect dapk1 expression. We identified two elements in this promoter that respond to C/EBP-beta. One of these is a consensus C/EBP-beta-binding site that constitutively binds to C/EBP-beta. The other element exhibits homology to the cyclic AMP response element/activating transcription factor binding sites. C/EBP-beta binds to this site in an IFN-gamma-dependent manner. Inhibition of ERK1/2 or mutation of an ERK1/2 site in the C/EBP-beta protein suppressed the IFN-gamma-induced response of this promoter. Together, our data show a critical role for C/EBP-beta in a novel IFN-induced cell growth-suppressive pathway via DAPK1.
authors.affiliation: Department of Microbiology and Immunology, University of Maryland School of Medicine, 660 West Redwood St., Howard Hall 350, Baltimore, MD 21201, USA. dkalvako@umaryland.edu
authors.forename: Padmaja
authors.initials: P
authors.lastname: Gade
authors.forename: Sanjit K
authors.initials: SK
authors.lastname: Roy
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Shreeram C
authors.initials: SC
authors.lastname: Nallar
authors.forename: Dhananjaya V
authors.initials: DV
authors.lastname: Kalvakolanu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D064550:Death-Associated Protein Kinases; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic
chemical_list: D051017:Apoptosis Regulatory Proteins; D022782:CCAAT-Enhancer-Binding Protein-beta; D007371:Interferon-gamma; C579096:DAPK1 protein, human; C579106:Dapk1 protein, mouse; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases