title: p100 Deficiency is insufficient for full activation of the alternative NF-κB pathway: TNF cooperates with p52-RelB in target gene transcription.
abstract: BACKGROUND
  Constitutive activation of the alternative NF-κB pathway leads to marginal zone B cell expansion and disorganized spleen microarchitecture. Furthermore, uncontrolled alternative NF-κB signaling may result in the development and progression of cancer. Here, we focused on the question how does the constitutive alternative NF-κB signaling exert its effects in these malignant processes.
  
  
  RESULTS
  To explore the consequences of unrestricted alternative NF-κB activation on genome-wide transcription, we compared gene expression profiles of wild-type and NF-κB2/p100-deficient (p100(-/-)) primary mouse embryonic fibroblasts (MEFs) and spleens. Microarray experiments revealed only 73 differentially regulated genes in p100(-/-) vs. wild-type MEFs. Chromatin immunoprecipitation (ChIP) assays showed in p100(-/-) MEFs direct binding of p52 and RelB to the promoter of the Enpp2 gene encoding ENPP2/Autotaxin, a protein with an important role in lymphocyte homing and cell migration. Gene ontology analysis revealed upregulation of genes with anti-apoptotic/proliferative activity (Enpp2/Atx, Serpina3g, Traf1, Rrad), chemotactic/locomotory activity (Enpp2/Atx, Ccl8), and lymphocyte homing activity (Enpp2/Atx, Cd34). Most importantly, biochemical and gene expression analyses of MEFs and spleen, respectively, indicated a marked crosstalk between classical and alternative NF-κB pathways.
  
  
  CONCLUSIONS
  Our results show that p100 deficiency alone was insufficient for full induction of genes regulated by the alternative NF-κB pathway. Moreover, alternative NF-κB signaling strongly synergized both in vitro and in vivo with classical NF-κB activation, thereby extending the number of genes under the control of the p100 inhibitor of the alternative NF-κB signaling pathway.
authors.affiliation: Research Group Immunology, Leibniz-Institute for Age Research - Fritz-Lipmann-Institute, Jena, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Lovas
authors.forename: Anja
authors.initials: A
authors.lastname: Weidemann
authors.forename: Daniela
authors.initials: D
authors.lastname: Albrecht
authors.forename: Lars
authors.initials: L
authors.lastname: Wiechert
authors.forename: Debra
authors.initials: D
authors.lastname: Weih
authors.forename: Falk
authors.initials: F
authors.lastname: Weih
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D051379:Mice; D052003:NF-kappa B p52 Subunit / Q000172:deficiency* / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D015398:Signal Transduction; D013154:Spleen / Q000378:metabolism; D051841:Transcription Factor RelB / Q000378:metabolism*; D014158:Transcription, Genetic; D048069:Tumor Necrosis Factors / Q000378:metabolism*; D000099189:Lysophospholipase D
chemical_list: D052003:NF-kappa B p52 Subunit; D010727:Phosphoric Diester Hydrolases; D051841:Transcription Factor RelB; D048069:Tumor Necrosis Factors; D000099189:Lysophospholipase D; C498207:Nfkb2 protein, mouse