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Updated: Apr 13, 2026
Hepatocyte-specific Ablation in Zebrafish to Study Biliary-driven Liver Regeneration
Published on: May 20, 2015
Gadd45beta promotes hepatocyte survival during liver regeneration in mice by modulating JNK signaling
Salvatore Papa1, Francesca Zazzeroni, Yang-Xin Fu
1Ben May Department for Cancer Research and Department of Pathology, University of Chicago, Chicago, Illinois 60637, USA.
Abstract:
In the liver, the JNK cascade is induced downstream of TNF receptors (TNFRs) in response to inflammatory, microbial, and toxic challenges. Sustained activation of JNK triggers programmed cell death (PCD), and hepatocyte survival during these challenges requires induction of the NF-kappaB pathway, which antagonizes this activation by upregulating target genes. Thus, modulation of JNK activity is crucial to the liver response to TNFR-mediated challenge. The basis for this modulation, however, is unknown. Here, we investigated the role of the NF-kappaB target Gadd45b in the regulation of hepatocyte fate during liver regeneration after partial hepatectomy. We generated Gadd45b(-/-) mice and found that they exhibited decreased hepatocyte proliferation and increased PCD during liver regeneration. Notably, JNK activity was markedly increased and sustained in livers of Gadd45b(-/-) mice compared with control animals after partial hepatectomy. Furthermore, imposition of a Jnk2-null mutation, attenuating JNK activity, completely rescued the regenerative response in Gadd45b(-/-) mice. Interestingly, Gadd45beta ablation did not affect hepatotoxic JNK signaling after a TNFR-mediated immune challenge, suggesting specificity in the inducible hepatic program for JNK restraint activated during distinct TNFR-mediated challenges. These data provide a basis for JNK suppression during liver regeneration and identify Gadd45beta as a potential therapeutic target in liver diseases.
Insights
Gadd45b deficiency impairs liver regeneration by increasing JNK activity, leading to reduced hepatocyte proliferation and increased cell death. Restoring JNK regulation rescues this defect, highlighting Gadd45b
Area of Science:
- Hepatology
- Molecular Biology
- Immunology
Background:
- Liver injury involves Tumor Necrosis Factor Receptor (TNFR) signaling, activating the JNK cascade.
- Sustained JNK activation promotes programmed cell death (PCD), while NF-kappaB signaling promotes hepatocyte survival.
- Mechanisms regulating JNK activity in the liver remain unclear.
Purpose of the Study:
- To investigate the role of NF-kappaB target Gadd45b in regulating hepatocyte fate during liver regeneration.
- To determine Gadd45b's involvement in modulating JNK activity post-partial hepatectomy.
Main Methods:
- Generation and analysis of Gadd45b knockout (Gadd45b(-/-)) mice.
- Assessment of hepatocyte proliferation and PCD during liver regeneration.
- Measurement of JNK activity in liver tissues.
- Analysis of Jnk2-null mutation effects in Gadd45b(-/-) mice.
- Evaluation of Gadd45beta's role in TNFR-mediated hepatotoxic signaling.
Main Results:
- Gadd45b(-/-) mice showed reduced hepatocyte proliferation and increased PCD during liver regeneration.
- JNK activity was significantly elevated and sustained in Gadd45b(-/-) livers post-partial hepatectomy.
- A Jnk2-null mutation rescued the regenerative defect in Gadd45b(-/-) mice.
- Gadd45beta ablation did not impact JNK signaling during TNFR-mediated immune challenges.
Conclusions:
- Gadd45b is essential for suppressing JNK activity during liver regeneration.
- Gadd45b deficiency impairs liver regeneration by promoting JNK-mediated hepatocyte death.
- Gadd45beta represents a specific therapeutic target for liver diseases involving impaired regeneration.
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