Dual function of angiogenin-4 inducing intestinal stem cells and apoptosis

Area of Science:

• Gastroenterology and Hepatology
• Cell Biology
• Microbiology

Background:

• The intestinal epithelium relies on soluble crypt niche factors for homeostasis.
• Antimicrobial proteins, like Angiogenin-4 (Ang4), are crucial for maintaining gut health.
• The specific role of Ang4 in intestinal epithelial cell (IEC) development and the crypt niche was previously unknown.

Purpose of the Study:

• To investigate the function of Angiogenin-4 (Ang4) within the intestinal crypt niche.
• To determine Ang4's role in the development and maintenance of intestinal epithelial cells (IECs) and intestinal stem cells (ISCs).
• To elucidate the signaling pathways influenced by Ang4 in the gut.

Main Methods:

• Analysis of Ang4 expression in Paneth cells and goblet cells.
• Functional studies using intestinal organoids and IEC cell lines.
• Assessment of Wnt and Notch signaling pathways.
• Evaluation of Lgr5+ stem cell expansion and IEC apoptosis.

Main Results:

• Ang4 is highly expressed by Paneth cells (small intestine) and Reg4-expressing goblet cells (colon), both contributing to ISC maintenance.
• Ang4 promotes Lgr5+ ISC expansion and organoid growth by inducing Wnt and Notch signaling.
• Ang4 induces IEC apoptosis in a concentration-dependent manner.

Conclusions:

• Angiogenin-4 (Ang4) is a dual-function protein crucial for intestinal homeostasis.
• Ang4 acts as a novel crypt niche factor, promoting ISC expansion and inducing IEC apoptosis.
• Understanding Ang4's functions provides insights into gut development and disease.