Tmub1 negatively regulates liver regeneration via inhibiting STAT3 phosphorylation

Area of Science:

• Hepatology
• Molecular Biology
• Regenerative Medicine

Background:

• Transmembrane and ubiquitin-like domain-containing 1 (Tmub1) is known to negatively regulate hepatocyte proliferation.
• The precise molecular mechanisms by which Tmub1 influences liver regeneration remain largely unelucidated.

Purpose of the Study:

• To investigate the role and molecular mechanisms of Tmub1 in regulating liver regeneration.
• To explore the interaction between Tmub1 and STAT3 signaling pathways in hepatocytes.

Main Methods:

• In vivo studies using mouse models with partial hepatectomy (PHx) and Tmub1 overexpression vectors.
• In vitro loss- and gain-of-function studies in human hepatocyte Lo2 cells.
• Coimmunoprecipitation, chromatin immunoprecipitation, and luciferase reporter gene assays to analyze protein interactions and gene regulation.

Main Results:

• Overexpression of Tmub1 impaired liver regeneration in mice after PHx.
• Tmub1 was found to inhibit STAT3 phosphorylation and STAT3 signaling activation in hepatocytes.
• STAT3 activation reversed Tmub1's inhibitory effects, while STAT3 inhibition abolished Tmub1 knockdown's promoting effects, indicating a functional link.
• Tmub1 interacts with STAT3, and STAT3 directly binds to and activates the Tmub1 promoter, suggesting a negative feedback loop.

Conclusions:

• Tmub1 acts as a significant negative regulator of hepatocyte proliferation during liver regeneration.
• The mechanism involves the inhibition of STAT3 signaling, establishing a novel Tmub1-STAT3 regulatory axis.
• These findings provide insights into potential therapeutic strategies for enhancing liver regeneration.