title: Transgenic overexpression of Tcfap2c/AP-2gamma results in liver failure and intestinal dysplasia.
abstract: BACKGROUND
  The transcription factor Tcfap2c has been demonstrated to be essential for various processes during mammalian development. It has been found to be upregulated in various undifferentiated tumors and is implicated with poor prognosis. Tcfap2c is reported to impinge on cellular proliferation, differentiation and apoptosis. However, the physiological consequences of Tcfap2c-expression remain largely unknown.
  
  
  RESULTS
  Therefore we established a gain of function model to analyze the role of Tcfap2c in development and disease. Induction of the transgene led to robust expression in all tissues (except brain and testis) and lead to rapid mortality within 3-7 days. In the liver cellular proliferation and apoptosis was detected. Accumulation of microvesicular lipid droplets and breakdown of major hepatic metabolism pathways resulted in steatosis. Serum analysis showed a dramatic increase of enzymes indicative for hepatic failure. After induction of Tcfap2c we identified a set of 447 common genes, which are deregulated in both liver and primary hepatocyte culture. Further analysis showed a prominent repression of the cytochrome p450 system, PPARA, Lipin1 and Lipin2. These data indicate that in the liver Tcfap2c represses pathways, which are responsible for fatty acid metabolism. In the intestine, Tcfap2c expression resulted in expansion of Sox9 positive and proliferative active epithelial progenitor cells resulting in dysplastic growth of mucosal crypt cells and loss of differentiated mucosa.
  
  
  CONCLUSIONS
  The transgenic mice show that ectopic expression of Tcfap2c is not tolerated. Due to the phenotype observed, iTcfap2c-mice represent a model system to study liver failure. In intestine, Tcfap2c induced cellular hyperplasia and suppressed terminal differentiation indicating that Tcfap2c serves as a repressor of differentiation and inducer of proliferation. This might be achieved by the Tcfap2c mediated activation of Sox9 known to be expressed in intestinal and hepatic stem/progenitor cell populations.
authors.affiliation: Department of Developmental Pathology, Institute of Pathology, University of Bonn Medical School, Bonn, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Holl
authors.forename: Peter
authors.initials: P
authors.lastname: Kuckenberg
authors.forename: Tatiana
authors.initials: T
authors.lastname: Woynecki
authors.forename: Angela
authors.initials: A
authors.lastname: Egert
authors.forename: Astrid
authors.initials: A
authors.lastname: Becker
authors.forename: Sebastian
authors.initials: S
authors.lastname: Huss
authors.forename: Dirk
authors.initials: D
authors.lastname: Stabenow
authors.forename: Andreas
authors.initials: A
authors.lastname: Zimmer
authors.forename: Percy
authors.initials: P
authors.lastname: Knolle
authors.forename: René
authors.initials: R
authors.lastname: Tolba
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Fischer
authors.forename: Hubert
authors.initials: H
authors.lastname: Schorle
mesh_terms: D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation; D002478:Cells, Cultured; D007410:Intestinal Diseases / Q000209:etiology / Q000378:metabolism*; D050356:Lipid Metabolism / Q000235:genetics / Q000502:physiology; D017093:Liver Failure / Q000209:etiology / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission; D009687:Nuclear Proteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D047493:PPAR alpha / Q000378:metabolism; D010711:Phosphatidate Phosphatase / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050656:Transcription Factor AP-2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D009687:Nuclear Proteins; D047493:PPAR alpha; C583890:Tfap2c protein, mouse; D050656:Transcription Factor AP-2; C418978:Lpin1 protein, mouse; D010711:Phosphatidate Phosphatase; C540254:Lipin 2 protein, mouse