Expression of PPARγ is reduced by medium supplementation with L-glutamine in human colorectal Caco-2 cells

• Published in: International journal of molecular medicine Vol. 22; no. 6; pp. 825 - 832
• Main Authors: Fiatte, Cathy, Huin, Cécile, Collet, Philippe, Plénat, François, Dauça, Michel, Schohn, Hervé
• Format: Journal Article
• Language: English
• Published: D.A. Spandidos 01-12-2008
• ISSN: 1107-3756
• DOI: 10.3892/ijmm_00000091

Peroxisome proliferator-activated receptor-γ (PPARγ) belongs to the nuclear
hormone receptor family. This receptor is implicated in colon cell differentiation
and in colon cancer. Receptor activation by specific agonists has been shown to
protect against colon cancer progression. PPARγ protein content within cells is
modulated by several mechanisms, including proteasome degradation, activation
of Wnt signalling pathways and presence of fermentation products such as butyrate.
Herein, we investigated the impact of L-glutamine on PPARγ expression during the
differentiation of Caco-2 cells grown in medium containing dialyzed fetal calf
serum supplemented or not with L-glutamine. Using RT-PCR and Western blotting,
we demonstrated that PPARγ expression was decreased when L-glutamine was added
to the medium. Using immunohistochemistry, we demonstrated that PPARγ immunostaining
was mainly found in cytoplasm when cells were cultured with L-glutamine while
it was found in nuclei and cytoplasm when cells were grown without the addition
of L-glutamine. Supershift retardation assays demonstrated a decrease of PPARγ
binding onto consensus peroxisome proliferator response element. We concluded
that L-glutamine modulated PPARγ expression in Caco-2 cells.