Polarized secretion of newly synthesized lipoproteins by the Caco-2 human intestinal cell line
Lipoprotein secretion by Caco-2 cells, a human intestinal cell line, was studied in cells grown on inserts containing a Millipore filter (0.45 micron), separating secretory products from the apical and basolateral membranes into separate chambers. Under these conditions, as observed by electron microscopy, the cells formed a monolayer of columnar epithelial cells with microvilli on the apical surface and tight junctions between cells. The electrical resistances of the cell monolayers were 250-500 ohms/cm2. Both /sup 14/C-labeled lipids and /sup 35/S-labeled proteins were used to assess lipoprotein secretion. After a 24-hr incubation with (/sup 14/C)oleic acid, 60-80% of the secreted triglyceride (TG) was in the basolateral chamber; 40% of the TG was present in the d less than 1.006 g/ml (chylomicron + VLDL) fraction and 50% in the 1.006 less than d less than 1.063 g/ml (LDL) fraction. After a 4-hr incubation with (/sup 35/S)methionine, apolipoproteins were found to be major secretory products with 75-100% secreted to the basolateral chamber. Apolipoproteins B-100, B-48, E, A-I, A-IV, and C-III were identified by immunoprecipitation. The d less than 1.006 g/ml fraction was found to contain all of the major apolipoproteins, while the LDL fraction contained primarily apoB-100 and apoE; the HDL (1.063 less than d less than 1.21 g/ml) fraction principally contained apoA-I and apoA-IV. Mn-heparin precipitated all of the (/sup 35/S)methionine-labeled apoB-100 and B-48 and a majority of the other apolipoproteins, and 80% of the (/sup 14/C)oleic acid-labeled triglyceride, but only 15% of the phospholipid, demonstrating that Caco-2 cells secrete triglyceride-rich lipoproteins containing apoB.
- Research Organization:
- New York Univ. School of Medicine, NY (USA)
- OSTI ID:
- 5356941
- Journal Information:
- J. Lipid Res.; (United States), Journal Name: J. Lipid Res.; (United States) Vol. 28:11; ISSN JLPRA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
AMINES
AMINO ACIDS
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
ANTICOAGULANTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOHYDRATES
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CENTRIFUGATION
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DRUGS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
EPITHELIUM
ESTERS
EVEN-ODD NUCLEI
GASTROINTESTINAL TRACT
HEMATOLOGIC AGENTS
HEPARIN
INTESTINES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPIDS
LIPOPROTEINS
LIPOTROPIC FACTORS
MAMMALS
MAN
METHIONINE
MICROSCOPY
MONOCARBOXYLIC ACIDS
MUCOPOLYSACCHARIDES
NUCLEI
OLEIC ACID
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PHYSICAL PROPERTIES
POLYSACCHARIDES
PRIMATES
PROTEINS
RADIOISOTOPES
SACCHARIDES
SECRETION
SEPARATION PROCESSES
SULFUR 35
SULFUR ISOTOPES
TISSUES
TRACER TECHNIQUES
TRIGLYCERIDES
ULTRACENTRIFUGATION
VERTEBRATES