JUNB/AP-1 controls IFN-γ during inflammatory liver disease

Area of Science:

• Immunology
• Hepatology
• Molecular Biology

Background:

• The transcription factor c-JUN/AP-1 in hepatocytes mediates cell survival during hepatitis.
• The specific roles of other JUN proteins, like JUNB, in liver disease are less understood.

Purpose of the Study:

• To investigate the molecular function of JUNB in immune cells and hepatocytes during acute liver injury.
• To elucidate the role of JUNB in the pathogenesis of experimental hepatitis.

Main Methods:

• Utilized experimental models of hepatitis (ConA and α-galactosyl-ceramide).
• Generated mice with targeted deletion of Junb in immune cells and hepatocytes.
• Analyzed IFN-γ expression, NK/NKT cell activity, and STAT1 pathway activation.

Main Results:

• JUNB deletion in immune cells and hepatocytes protected against hepatitis, particularly in NK/NKT cell-mediated models.
• Absence of JUNB in immune cells reduced IFN-γ secretion from NK/NKT cells, decreasing STAT1 activation.
• Ifng was identified as a direct transcriptional target of JUNB.

Conclusions:

• JUNB promotes hepatocyte death in acute hepatitis by regulating IFN-γ production in immune cells.
• JUNB acts antagonistically to the hepatoprotective function of c-JUN/AP-1 in hepatocytes.