title: Iron-ascorbate alters the efficiency of Caco-2 cells to assemble and secrete lipoproteins.
abstract: Although oxidative stress has been implicated in development of gut pathologies, its role in intestinal fat transport has not been investigated. We assessed the effect of Fe(2+)-ascorbate-mediated lipid peroxidation on lipid synthesis, apolipoprotein biogenesis, and lipoprotein assembly and secretion. Incubation of postconfluent Caco-2 cells with iron(II)-ascorbate (0.2 mM/2 mM) in the apical compartment significantly promoted malondialdehyde formation without affecting sucrase activity, transepithelial resistance, DNA and protein content, and cell viability. However, addition of the oxygen radical-generating system reduced 1) [(14)C]oleic acid incorporation into cellular triglycerides (15%, P < 0.0002) and phospholipids (16%, P < 0.0005); 2) de novo synthesis of cellular apolipoprotein A-I (apo A-I) (18%, P < 0.05), apo A-IV (38%, P < 0.05), and apo B-48 (45%, P < 0.003) after [(35)S]methionine addition; and 3) production of chylomicrons (50%), VLDL (40%), LDL (37%), and HDL (30%) (all P < 0.0001). In contrast, increased total cellular cholesterol formation (96%, P < 0.0001), assayed by [(14)C]acetate incorporation, was noted, attributable to marked elevation (70%, P < 0.04) in activity of DL-3-hydroxy-3-methyl-glutaryl-CoA reductase, the rate-limiting enzyme in cholesterol synthesis. The ratio of Acyl-CoA to cholesterol acyltransferase, the esterifying cholesterol enzyme, remained unchanged. Fe(2+)-ascorbate-mediated lipid peroxidation modifies intracellular fat absorption and may decrease enterocyte efficiency in assembling and transporting lipids during gut inflammation.
authors.affiliation: Centre de Recherche, Hôpital Sainte-Justine, University of Montreal, Quebec, Canada H3T 1C5.
authors.forename: F
authors.initials: F
authors.lastname: Courtois
authors.forename: I
authors.initials: I
authors.lastname: Suc
authors.forename: C
authors.initials: C
authors.lastname: Garofalo
authors.forename: M
authors.initials: M
authors.lastname: Ledoux
authors.forename: E
authors.initials: E
authors.lastname: Seidman
authors.forename: E
authors.initials: E
authors.lastname: Levy
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology; D001054:Apolipoproteins A / Q000096:biosynthesis / Q000378:metabolism*; D001055:Apolipoproteins B / Q000096:biosynthesis / Q000378:metabolism*; D001205:Ascorbic Acid / Q000494:pharmacology*; D002084:Butylated Hydroxytoluene / Q000494:pharmacology; D018938:Caco-2 Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D002250:Carbon Radioisotopes; D020895:Enterocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004951:Esterification; D005296:Ferrous Compounds / Q000494:pharmacology*; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D007408:Intestinal Absorption / Q000187:drug effects; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D019301:Oleic Acid / Q000378:metabolism / Q000493:pharmacokinetics; D018384:Oxidative Stress / Q000187:drug effects*; D002785:Sterol O-Acyltransferase / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D002250:Carbon Radioisotopes; D005296:Ferrous Compounds; C051140:iron(II)-ascorbic acid complex; D002084:Butylated Hydroxytoluene; D019301:Oleic Acid; D008315:Malondialdehyde; D006903:Hydroxymethylglutaryl CoA Reductases; D002785:Sterol O-Acyltransferase; D001205:Ascorbic Acid