Differential roles of C/EBP beta regulatory domains in specifying MCP-1 and IL-6 transcription.
ABSTRACT C/EBPbeta is a member of the CCAAT/enhancer binding protein family of transcription factors and has been shown to be a critical transcriptional regulator of various proinflammatory genes, including IL-6 and MCP-1. To examine the roles of the C/EBPbeta transactivation and regulatory domains in LPS-induced MCP-1 and IL-6 expression, we expressed various N-terminal truncations and deletions of C/EBPbeta in P388 murine B lymphoblasts, which lack endogenous C/EBPbeta expression and are normally unresponsive to LPS for expression of IL-6 and MCP-1. Unexpectedly, a region between amino acids 105 and 212 of C/EBPbeta that includes regulatory domains 1 and 2 facilitates C/EBPbeta activation of IL-6 expression, while having an inhibitory effect on MCP-1 expression. Thus, this region can mediate promoter-specific effects on cytokine and chemokine gene transcription. LIP, the naturally occurring truncated form of C/EBPbeta, largely retains these regulatory domains and stimulates IL-6 but not MCP-1 transcription.
- SourceAvailable from: Marleen Gloger[Show abstract] [Hide abstract]
ABSTRACT: The capacity of dendritic cells (DCs) to regulate tumour-specific adaptive immune responses depends on their proper differentiation and homing status. Whereas DC-associated tumour-promoting functions are linked to T-cell tolerance and formation of an inflammatory milieu, DC-mediated direct effects on tumour growth have remained unexplored. Here we show that deletion of DCs substantially delays progression of Myc-driven lymphomas. Lymphoma-exposed DCs upregulate immunomodulatory cytokines, growth factors and the CCAAT/enhancer-binding protein β (C/EBPβ). Moreover, Eμ-Myc lymphomas induce the preferential translation of the LAP/LAP* isoforms of C/EBPβ. C/EBPβ(-/-) DCs are unresponsive to lymphoma-associated cytokine changes and in contrast to wild-type DCs, they are unable to mediate enhanced Eμ-Myc lymphoma cell survival. Antigen-specific T-cell proliferation in lymphoma-bearing mice is impaired; however, this immune suppression is reverted by the DC-restricted deletion of C/EBPβ. Thus, we show that C/EBPβ-controlled DC functions are critical steps for the creation of a lymphoma growth-promoting and -immunosuppressive niche.Nature Communications 09/2014; · 10.74 Impact Factor
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ABSTRACT: OBJECTIVE: Persistent inflammation and impaired adipogenesis are frequent features of obesity and underlie the development of its complications. However, the factors behind adipose tissue dysfunction are not completely understood. We have previously shown that histone demethylase KDM1A is required for adipogenesis. DESIGN AND METHODS: Kdm1a expression was knocked down in 3T3-L1 preadipocytes by siRNA transfection and whole-genome expression profiling was performed by microarray hybridization. The role of NF-κβ and C/EBPβ was analyzed by incubation with the inhibitor parthenolide and by cebpb knockdown, respectively. RESULTS: Knockdown of kdm1a or rcor2 in 3T3-L1 preadipocytes results in impaired differentiation and induction of inflammatory gene expression. Enhanced expression of il6 in kdm1a knocked down preadipocytes is associated with increased recruitment of C/EBPβ and the NF-β subunit RelA to the il6 promoter. Cebpb knockdown attenuates the induction of il6 expression in kdm1a knocked down cells, whereas simultaneous cebpb knockdown and NF-β inhibition abrogates it. Dietary-induced and genetic mouse models of obesity display decreased KDM1A in adipose tissue, and this correlates with increased expression of proinflammatory genes and C/EBPβ. CONCLUSION: KDM1A represses the expression of inflammatory genes in preadipocytes. Dysregulated kdm1a expression in preadipocytes may thus participate in the development of obesity-associated inflammation.Obesity 04/2013; · 3.92 Impact Factor
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ABSTRACT: Environmental pollutants, such as bisphenol A (BPA), have the potential to affect the differentiation processes and the biology of the adipose tissue. The 3T3-L1 model is one of the murine cell models used extensively for the investigation of the molecular events that govern the differentiation of adipocytes from a committed preadipocyte to a mature, lipid laden adipocyte. Most of the studies investigating the effects of BPA on preadipocyte differentiation have investigated the effects of this chemical in the presence of an optimal differentiation cocktail containing high concentrations of the synthetic glucocorticoid dexamethasone, conditions that result in 90% to 100% of differentiated adipocytes. Our studies employed the 3T3-L1 cell model in the absence of exogenous glucocorticoids. We show that BPA is able to increase the differentiation of the 3T3-L1 cells under these conditions. Furthermore, the effect of BPA was observed in the absence of the synthetic glucocorticoid (dexamethasone), a hormone known to be required for the differentiation of the 3T3-L1 cells. In addition, BPA upregulated the mRNA expression and protein levels of the terminal marker of adipogenesis the fatty acid binding protein (aP2) in these cells. Interestingly, the known modulators of adipogenesis such as the peroxisome proliferator-activated receptor (PPAR) γ or CCAAT enhancer binding protein (C/EBP) α were not elevated at the mRNA or protein level in response to BPA. Furthermore, BPA upregulated the expression levels of the marker of adipogenesis aP2, through an effect on the transcriptional activity of C/EBPδ and the glucocorticoid receptor (GR) at its promoter.Adipocyte. 07/2014; 3(3):170-9.