Neurotensin stimulates IL-8 expression in human colonic epithelial cells through Rho GTPase-mediated NF-kappa B...

Area of Science:

• Gastroenterology
• Molecular Biology
• Cell Signaling

Background:

• Neurotensin (NT) is a neuropeptide involved in intestinal inflammation.
• NT stimulates interleukin-8 (IL-8) expression through MAPK and NF-kappaB pathways in colonic cells.
• The precise molecular mechanism of NT-induced cytokine expression remained unclear.

Purpose of the Study:

• To investigate the role of Rho family proteins in NT-induced IL-8 expression.
• To elucidate the molecular pathway linking NT to IL-8 production in human colonic epithelial cells.

Main Methods:

• Utilized dominant-negative mutants of RhoA, Rac1, and Cdc42 to inhibit endogenous Rho proteins.
• Assessed IL-8 protein production and promoter activity.
• Performed Western blot analysis to detect protein activation and phosphorylation.
• Measured NF-kappaB-dependent reporter gene expression and DNA binding activity.

Main Results:

• Inhibition of RhoA, Rac1, and Cdc42 blocked NT-induced IL-8 production and promoter activity.
• NT significantly activated RhoA, Rac1, and Cdc42.
• Rho protein inhibition suppressed NT-induced NF-kappaB reporter gene expression and DNA binding.
• NT-induced p38 MAPK phosphorylation was not affected by Rho protein inhibition.

Conclusions:

• NT-stimulated IL-8 expression is mediated by a Rho-dependent pathway involving NF-kappaB activation.
• Rho family proteins are key regulators in the NT signaling cascade leading to IL-8 production.
• This study clarifies a critical molecular mechanism in NT-driven intestinal inflammation.