CFTR Depletion Results in Changes in Fatty Acid Composition and Promotes Lipogenesis in Intestinal Caco 2/15 Cells

PLoS One

Rémi Rabasa-Lhoret¹  Alain Moreau¹  Yves Berthiaume²  Geneviève Mailhot³  Emile Levy³ 

[1] Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada;Diabetes and Metabolic Diseases Research Group, Institut de Recherches Cliniques and Centre Hospitalier de l'Université de Montréal (CHUM)-Hôtel-Dieu, Université de Montréal, Montreal, Quebec, Canada;Research Centre, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada

关键词: Lipids;    Gastrointestinal tract;    Fatty acids;    Cell differentiation;    Lipoproteins;    Lipogenesis;    Gene expression;    Protein expression;   

DOI  :  10.1371/journal.pone.0010446

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

Background Abnormal fatty acid composition (FA) in plasma and tissue lipids frequently occurs in homozygous and even in heterozygous carriers of cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The mechanism(s) underlying these abnormalities remained, however, poorly understood despite the potentially CFTR contributing role.Methodology/Principal Findings The aim of the present study was to investigate the impact of CFTR depletion on FA uptake, composition and metabolism using the intestinal Caco-2/15 cell line. shRNA-mediated cftr gene silencing induced qualitative and quantitative modifications in FA composition in differentiated enterocytes as determined by gas-liquid chromatography. With the cftr gene disruption, there was a 1,5 fold increase in the total FA amount, largely attributable to monounsaturated and saturated FA compared to controls. The activity of delta-7 desaturase, estimated by the 16:1(n-7)/16:0, was significantly higher in knockdown cells and consistent with the striking elevation of the n-7 FA family. When incubated with [14C]-oleic acid, CFTR-depleted cells were capable of quick incorporation and export to the medium concomitantly with the high protein expression of L-FABP known to promote intracellular FA trafficking. Accordingly, lipoprotein vehicles (CM, VLDL, LDL and HDL), isolated from CFTR knockdown cells, exhibited higher levels of radiolabeled FA. Moreover, in the presence of [14C]-acetate, knockdown cells exhibited enhanced secretion of newly synthesized phospholipids, triglycerides, cholesteryl esters and free FA, thereby suggesting a stimulation of the lipogenic pathway. Conformably, gene expression of SREBP-1c, a key lipogenic transcription factor, was increased while protein expression of the phosphorylated and inactive form of acetylCoA carboxylase was reduced, confirming lipogenesis induction. Finally, CFTR-depleted cells exhibited lower gene expression of transcription factors (PPARα, LXRα, LXRβ and RXRα).Conclusions/Significance Collectively, our results indicate that CFTR depletion may disrupt FA homeostasis in intestinal cells through alterations in FA uptake and transport combined with stimulation of lipogenesis that occurs by an LXR/RXR-independent mechanism. These findings exclude a contributing role of CFTR in CF-associated fat malabsorption.

【 授权许可】

CC BY