Mesenchymal GDNF promotes intestinal enterochromaffin cell differentiation

Area of Science:

• Gastroenterology
• Cell Biology
• Developmental Biology

Background:

• Enteroendocrine cells (EECs) mature along the intestinal crypt-villus axis, but niche signals governing this process are unclear.
• Subepithelial myofibroblasts (SEMFs) and their secreted factors are potential regulators of intestinal epithelial cell differentiation.

Purpose of the Study:

• To investigate the role of Glial cell line-derived neurotrophic factor (GDNF) in EEC differentiation.
• To explore the reciprocal interactions between EECs and intestinal stem cells (ISCs).

Main Methods:

• Analysis of GDNF and RET expression in intestinal tissues.
• Mouse organoid culture to assess GDNF-RET signaling effects on EEC gene expression.
• In vivo studies to confirm findings in a physiological context.
• Investigation of serotonin (5-HT) receptor expression in Lgr5+ ISCs and assessment of 5-HT's effect on ISC clonogenicity.

Main Results:

• GDNF is expressed by SEMFs, and its receptor RET is found on EECs.
• GDNF-RET signaling upregulates EEC differentiation genes, including Tph1, and increases enterochromaffin cell (EC) numbers.
• 5-HT receptor Htr4 is enriched in Lgr5+ ISCs, and 5-HT reduces ISC clonogenicity.

Conclusions:

• GDNF-RET signaling is a key regulator of EEC differentiation and serotonin production.
• Serotonin emerges as a potential niche factor influencing Lgr5+ ISC activity.
• These findings have implications for understanding intestinal regeneration mechanisms.