Abstract
BackgroundThe 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.Methodology/Principal FindingsTherefore 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.ConclusionsThe 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.
Highlights
The family of Activator Protein-2 (AP-2) transcription factors is highly conserved in mice (Tcfap2a–e) and humans (TFAP2A–E)
The transgenic mice show that ectopic expression of Tcfap2c is not tolerated
This might be achieved by the Tcfap2c mediated activation of Sox9 known to be expressed in intestinal and hepatic stem/progenitor cell populations
Summary
The family of Activator Protein-2 (AP-2) transcription factors is highly conserved in mice (Tcfap2a–e) and humans (TFAP2A–E). Tcfap2a, as first protein of the transcription factor family was isolated from HeLa cells in 1988 [1], followed by the isoforms Tcfap2b [2], Tcfap2c [3], Tcfap2d [4] and Tcfap2e [5]. AP-2 proteins have been demonstrated to modulate various signaling pathways during development, cell growth, differentiation and apoptosis [6,7,8,9,10]. AP-2 proteins are known to orchestrate the balance between cellular growth and differentiation and are essential for maintaining cellular homeostasis [11]. The transcription factor Tcfap2c has been demonstrated to be essential for various processes during mammalian development. The physiological consequences of Tcfap2c-expression remain largely unknown
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