Iron-ascorbate alters the efficiency of Caco-2 cells to assemble and secrete lipoproteins.
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.
Courtois
F
F
Centre de Recherche, Hôpital Sainte-Justine, University of Montreal, Quebec, Canada H3T 1C5.
Suc
I
I
Garofalo
C
C
Ledoux
M
M
Seidman
E
E
Levy
E
E
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
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