Characterization of the transcriptional signature of C/EBPbeta isoforms (LAP/LIP) in Hep3B cells: Implication of LIP in pro-survival functions

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• 作者：Gaë ; lle Saint-Auret¹ ; ⁵ ; ^{gaelle.saint-auret@cea.fr"" rel=""nofollow} ; Jean-Louis Danan² ; ³ ; Martine Hiron¹ ; Cé ; line Blache¹ ; Eric Sulpice⁵ ; Simon Tendil⁴ ; Maryvonne Daveau¹ ; Xavier Gidrol⁴ ; ⁵ ; ^† ; ; Jean-Philippe Salier¹ ; ^† ;
• 关键词：C/EBPbeta isoforms ; Transcriptome ; ChIP-on-chip ; Hepatoma cell death ; Target genes
• 刊名：Journal of Hepatology
• 出版年：2011
• 出版时间：June 2011
• 年：2011
• 卷：54
• 期：6
• 页码：1185-1194
• 全文大小：1613 K

文摘

Background & Aims

C/EBPbeta is an important mediator of several cellular processes, such as differentiation, proliferation, and survival of hepatic cells. However, a complete catalog of the targets of C/EBPbeta or the mechanism by which this transcription factor regulates certain liver-dependent pathways has not been clearly determined. Two major natural isoforms of this transcription factor exist: the liver-enriched activating protein (LAP) and the liver-enriched inhibitory protein (LIP), a functional LAP antagonist. In this study, we used the opposing transcriptional effects driven by LAP and LIP to determine the genuine C/EBPbeta molecular signature in the Hep3B human hepatoma cell line. We subsequently investigated the role of each of the LAP and LIP isoforms in drug-induced Hep3B cell death.

Methods

We engineered Hep3B cells with regulated LAP or LIP expression using the Tet-off expression system. The genes that showed inverse regulation by LAP and LIP were identified by cDNA array analysis. The cohort of direct-C/EBPbeta-targets was distinguished from indirect-targets by ChIP-on-chip analysis.

Results

We characterized 676 genes by this approach. Among these genes, 39 are novel direct targets of C/EBPbeta. Eleven of these new direct targets are involved in cell survival, suggesting critical roles for LAP/LIP isoforms in this cellular process. Therefore, we examined the effects of LAP and LIP over-expression on cell survival. We show that LIP promotes survival in staurosporine- or taxol-induced Hep3B cell death.

Conclusions

Our study provides new molecular and cellular insights into the role of C/EBPbeta in cells of hepatic origin.