COX-1/PGE₂/EP4 alleviates mucosal injury by upregulating β-arr1-mediated Akt signaling in colitis

Area of Science:

• Gastroenterology and Immunology
• Molecular and Cellular Biology

Background:

• Ulcerative colitis (UC) involves impaired mucosal barrier function.
• Cyclooxygenase-1 (COX-1) and prostaglandin E2 (PGE2) are recognized protective mediators in UC.
• The role of β-arrestin1 (β-arr1) in PGE2-mediated signaling and mucosal integrity is not fully understood.

Purpose of the Study:

• To investigate the interaction between PGE2 and β-arr1 in maintaining mucosal barrier integrity during colitis.
• To elucidate the signaling pathway involved in PGE2-mediated mucosal protection.

Main Methods:

• Analysis of COX-1, PGE2, and EP4 expression in UC patients and dextran sulfate sodium (DSS)-induced colitis mouse models.
• Assessment of colitis severity and signaling pathway activation (PI3K/Akt) in wild-type (WT) and β-arr1 deficient mice.
• In vitro studies using HCT116 cells with β-arr1 siRNA to evaluate the effect of PGE2 on β-arr1 expression and signaling.

Main Results:

• COX-1, PGE2, and EP4 were downregulated in UC patients and DSS-induced colitis mice.
• PGE2 treatment alleviated mucosal injury and upregulated EP4 in WT mice.
• β-arr1 deficiency exacerbated colitis and downregulated PI3K/Akt signaling.
• PGE2 treatment upregulated β-arr1 expression in vivo and in vitro.

Conclusions:

• The COX-1/PGE2/EP4 pathway upregulates β-arr1, which mediates Akt signaling to protect the colonic mucosa.
• This pathway is crucial for maintaining mucosal barrier integrity during colitis.
• Targeting the COX-1/PGE2 pathway holds potential for UC treatment.