Apoptosis induced by Fas signaling does not alter hepatic hepcidin expression

Area of Science:

• Molecular Biology
• Immunology
• Hepatology

Background:

• Hepcidin is a key regulator of iron metabolism.
• Apoptosis, or programmed cell death, plays a role in various physiological and pathological processes.
• The relationship between apoptosis and hepcidin gene expression in the liver requires further elucidation.

Purpose of the Study:

• To investigate the regulation of human hepcidin (HAMP) and mouse hepcidin (hepcidin-1 and hepcidin-2) gene expression in the liver.
• To determine if apoptosis, induced via Fas receptor activation, influences hepcidin expression in vivo and in vitro.

Main Methods:

• In vitro: HepG2 cells treated with CH11 (anti-Fas antibody) to induce apoptosis.
• In vivo: C57BL/6NCR and C57BL/6J mice injected with Jo2 (anti-mouse Fas antibody).
• Assessed apoptosis (caspase-3 activity), liver injury (ALT/AST), acute phase reaction (IL-6, SAA3), and hepcidin gene expression (qPCR). Analyzed transcription factor activity (Stat3, Smad4, NF-κB) via Western blotting and promoter binding via ChIP assays.

Main Results:

• In vitro, CH11 induced apoptosis in HepG2 cells but did not alter HAMP expression.
• In vivo, Jo2 induced apoptosis, liver injury, and acute phase response in mice, but hepcidin-1 mRNA levels remained unchanged.
• Fas receptor activation and subsequent apoptosis did not lead to changes in hepatic hepcidin gene expression, even with altered transcription factor activity.

Conclusions:

• Apoptosis induced through Fas receptor activation does not regulate human or mouse hepcidin gene expression in the liver.
• Hepcidin regulation is independent of Fas-mediated apoptotic pathways in hepatic cells.