title: CFTR depletion results in changes in fatty acid composition and promotes lipogenesis in intestinal Caco 2/15 cells.
abstract: 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.
  
  
  RESULTS
  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 (PPARalpha, LXRalpha, LXRbeta and RXRalpha).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Research Centre, CHU Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Mailhot
authors.forename: Rémi
authors.initials: R
authors.lastname: Rabasa-Lhoret
authors.forename: Alain
authors.initials: A
authors.lastname: Moreau
authors.forename: Yves
authors.initials: Y
authors.lastname: Berthiaume
authors.forename: Emile
authors.initials: E
authors.lastname: Levy
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics / Q000378:metabolism; D018938:Caco-2 Cells; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000172:deficiency* / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D016086:Lentivirus / Q000378:metabolism; D050155:Lipogenesis; D026901:Membrane Transport Proteins / Q000378:metabolism; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D026901:Membrane Transport Proteins; D047492:Peroxisome Proliferator-Activated Receptors; D011956:Receptors, Cell Surface; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000103:Acetyl-CoA Carboxylase
references.citation: Arch Dis Child. 2000 May;82(5):394-9
references.pmid: 10799435
references.citation: J Lipid Res. 1986 Jan;27(1):114-20
references.pmid: 3958609
references.citation: Biochim Biophys Acta. 1985 Jan 25;812(2):460-72
references.pmid: 3967022
references.citation: Eur J Pediatr. 1997 Dec;156(12):952-6
references.pmid: 9453380
references.citation: Gut. 1985 Sep;26(9):892-901
references.pmid: 3849459
references.citation: Am J Physiol Gastrointest Liver Physiol. 2006 Apr;290(4):G609-15
references.pmid: 16223944
references.citation: J Biol Chem. 2002 Aug 30;277(35):31646-55
references.pmid: 12070142
references.citation: Diabetes. 2003 Oct;52(10):2539-45
references.pmid: 14514638
references.citation: Am J Physiol Renal Physiol. 2005 Nov;289(5):F1103-15
references.pmid: 15914772
references.citation: J Nutr. 2002 Jan;132(1):11-9
references.pmid: 11773501
references.citation: Respir Res. 2009 Apr 03;10:26
references.pmid: 19344509
references.citation: Lipids Health Dis. 2009 Aug 27;8:37
references.pmid: 19712485
references.citation: Biochem J. 1992 Aug 1;285 ( Pt 3):725-9
references.pmid: 1323271
references.citation: J Lipid Res. 1989 Oct;30(10):1483-90
references.pmid: 2614252
references.citation: Diabetes. 2006 May;55(5):1316-26
references.pmid: 16644688
references.citation: J Cyst Fibros. 2007 Sep;6(5):320-6
references.pmid: 17257908
references.citation: Mol Cell Biochem. 2009 Jun;326(1-2):79-86
references.pmid: 19116776
references.citation: Biochim Biophys Acta. 2000 Sep 27;1487(2-3):309-18
references.pmid: 11018482
references.citation: J Pediatr Gastroenterol Nutr. 2002 Sep;35(3):246-59
references.pmid: 12352509
references.citation: FASEB J. 1991 Oct;5(13):2761-9
references.pmid: 1916101
references.citation: Am J Physiol Gastrointest Liver Physiol. 2005 Apr;288(4):G646-53
references.pmid: 15528257
references.citation: Proc Natl Acad Sci U S A. 2003 Mar 18;100(6):3077-82
references.pmid: 12629214
references.citation: Am J Clin Nutr. 2009 Sep;90(3):477-84
references.pmid: 19587087
references.citation: Am J Clin Nutr. 2002 Jun;75(6):1005-11
references.pmid: 12036806
references.citation: Am J Clin Nutr. 1999 Jan;69(1):127-34
references.pmid: 9925134
references.citation: Am J Physiol Gastrointest Liver Physiol. 2009 Dec;297(6):G1239-49
references.pmid: 19808659
references.citation: N Engl J Med. 2004 Feb 5;350(6):560-9
references.pmid: 14762183
references.citation: J Nutr. 2009 Dec;139(12):2358-64
references.pmid: 19828687
references.citation: J Biol Chem. 2006 Feb 17;281(7):4231-41
references.pmid: 16361706
references.citation: Am J Physiol. 1992 Feb;262(2 Pt 1):G319-26
references.pmid: 1539663
references.citation: Pediatr Res. 1985 Jan;19(1):104-9
references.pmid: 3918287
references.citation: Am J Physiol Gastrointest Liver Physiol. 2000 Jul;279(1):G12-9
references.pmid: 10898742
references.citation: J Nutr. 2003 Jul;133(7):2180-3
references.pmid: 12840175
references.citation: Am J Physiol. 1998 Aug;275(2):G244-9
references.pmid: 9688651
references.citation: J Lipid Res. 2006 Oct;47(10):2112-20
references.pmid: 16829661
references.citation: Am J Physiol Gastrointest Liver Physiol. 2004 Sep;287(3):G726-33
references.pmid: 15130874
references.citation: Prostaglandins Leukot Essent Fatty Acids. 2008 Jul-Aug;79(1-2):47-53
references.pmid: 18757191
references.citation: Pediatr Res. 2000 Mar;47(3):344-50
references.pmid: 10709733
references.citation: Biochem Biophys Res Commun. 2006 Jan 6;339(1):248-54
references.pmid: 16297872
references.citation: Am J Physiol. 1993 Nov;265(5 Pt 1):G955-62
references.pmid: 8238525
references.citation: J Lipid Res. 2008 Aug;49(8):1692-700
references.pmid: 18441018
references.citation: Lancet. 2009 May 30;373(9678):1891-904
references.pmid: 19403164
references.citation: J Lipid Res. 2008 Sep;49(9):1946-54
references.pmid: 18480495
references.citation: Proc Natl Acad Sci U S A. 1999 Nov 23;96(24):13995-4000
references.pmid: 10570187
references.citation: J Pediatr. 2001 Nov;139(5):650-5
references.pmid: 11713441
references.citation: Clin Nutr. 2000 Dec;19(6):387-94
references.pmid: 11104588
references.citation: Am J Physiol Gastrointest Liver Physiol. 2004 Jun;286(6):G1032-41
references.pmid: 14739145
references.citation: Annu Rev Nutr. 2004;24:345-76
references.pmid: 15189125
references.citation: Cell Signal. 2006 Oct;18(10):1595-603
references.pmid: 16466905
references.citation: FASEB J. 1995 May;9(8):626-35
references.pmid: 7768354
references.citation: Metabolism. 2006 Sep;55(9):1192-200
references.pmid: 16919538
references.citation: Am J Physiol Gastrointest Liver Physiol. 2008 Nov;295(5):G873-85
references.pmid: 18772361
references.citation: J Nutr. 2000 Dec;130(12):2870-5
references.pmid: 11110839
references.citation: J Lipid Res. 2004 Dec;45(12):2277-86
references.pmid: 15466369
references.citation: Am J Physiol Gastrointest Liver Physiol. 2002 Aug;283(2):G340-6
references.pmid: 12121881
references.citation: Nutr Metab (Lond). 2005 May 03;2(1):11
references.pmid: 15869703
references.citation: Am J Physiol Gastrointest Liver Physiol. 2007 Dec;293(6):G1178-89
references.pmid: 17916647
references.citation: J Clin Invest. 2008 Mar;118(3):956-64
references.pmid: 18292813
references.citation: Biochem Biophys Res Commun. 2002 Nov 1;298(3):309-16
references.pmid: 12413941