Erk and MAPK signaling is essential for intestinal development through Wnt pathway modulation

Area of Science:

• Developmental Biology
• Cell Signaling
• Gastroenterology

Background:

• Intestinal stem cell (ISC) homeostasis relies on niche factors and signaling pathways.
• The Erk/Mapk pathway's role in ISC regulation and intestinal development is not fully understood.

Purpose of the Study:

• To investigate the function of Erk1 and Erk2 (Erk1/2) in intestinal epithelial cells during embryonic development.
• To elucidate the mechanisms by which Erk1/2 signaling influences ISC maintenance, proliferation, and differentiation.

Main Methods:

• Conditional deletion of Erk1/2 in intestinal epithelial cells using genetic models.
• Analysis of ISC proliferation, migration, and differentiation markers.
• Assessment of Wnt, Indian hedgehog, and Bmp4 signaling pathways.
• Pharmacological inhibition of mTor signaling with rapamycin.

Main Results:

• Erk1/2 deletion in embryonic intestinal epithelial cells led to increased proliferation, ISC expansion, and polyp formation, resulting in postnatal lethality.
• Deficiency in Erk1/2 impaired secretory cell differentiation and mesenchymal cell proliferation/maturation.
• Erk1/2 depletion activated Wnt signaling via cell-autonomous and non-autonomous mechanisms, involving Ras/Raf-Akt-mTor cascades.
• Erk1/2 deficiency reduced Indian hedgehog and mesenchymal Bmp4 expression.

Conclusions:

• Erk/Mapk signaling is a critical regulator of Wnt signaling during intestinal development.
• Erk1/2 coordinates epithelial-mesenchymal interactions essential for intestinal homeostasis.
• Targeting mTor signaling offers a potential therapeutic strategy for Erk1/2-related intestinal disorders.