Effect of apolipoproteins E and C-III on the interaction of chylomicrons with parenchymal and non-parenchymal cells from rat liver
| Autor: | L M Scheek, P.H.E. Groot, T. J. C. Van Berkel, Johan K. Kruijt |
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| Rok vydání: | 1983 |
| Předmět: |
Male
Apolipoprotein E medicine.medical_specialty Time Factors In Vitro Techniques Biochemistry Apolipoproteins E Internal medicine Chylomicrons Parenchyma medicine Animals Apolipoproteins C Molecular Biology Triglycerides Apolipoprotein C-III Chemistry digestive oral and skin physiology Temperature food and beverages Rats Inbred Strains Cell Biology In vitro Rats Apolipoproteins Endocrinology Liver lipids (amino acids peptides and proteins) Lymph Chylomicron binding Research Article Chylomicron |
| Zdroj: | Biochemical Journal. 216:71-80 |
| ISSN: | 0264-6021 |
| DOI: | 10.1042/bj2160071 |
| Popis: | [3H]Triacylglycerol-labelled chylomicrons were isolated from intestinal lymph, obtained from rats made hypolipidaemic by treatment with pharmacological amounts of 17 alpha-ethynyloestradiol. Oestrogen treatment results in a large reduction in the content of apolipoproteins (apo) E and C of lymph chylomicrons. Upon incubation in vitro with freshly isolated parenchymal and non-parenchymal cells the apo E-, apo C-poor chylomicrons became readily cell-associated. With increasing chylomicron concentrations this cell-association was saturable and half-maximal cell-association was achieved at about 0.55 mg of triacylglycerol/ml. The cell-association was time- and temperature-dependent. A more than 90% inhibition of the cell-association of the [3H]triacylglycerol moiety was observed with both parenchymal and non-parenchymal cells when pure apo C-III (12.6 micrograms/mg of triacylglycerol) was incorporated into the chylomicrons. These data indicate that apo E-, apo C-poor chylomicrons are bound to both parenchymal and non-parenchymal liver cells at a high-affinity site of limited capacity and that binding to this site is strongly inhibited by apo C-III. With apo C-III-enriched chylomicrons simultaneous determination of the cell-association of the 125I-apo C-III and the [3H]triacylglycerol moiety indicated that more 125I-apo C-III becomes associated to the cells than expected on the basis of [3H]triacylglycerol radioactivity measurements. It is suggested that upon cell-association of apo C-III its binding to the chylomicron particles is lost. Consequently the occupation of the cellular recognition site by apo C-III prevents further chylomicron binding and thus leads to a decrease of the cell-association level of the [3H]triacylglycerol moiety. Apo E enrichment of the chylomicrons led to an increased cell-association rate with parenchymal cells and to a marked increase of the cell-association level with non-parenchymal cells. The cell-association of the apo E radioactivity followed closely the [3H]triacylglycerol radioactivity, indicating that the particle-apo E complex is bound as a unity. The apo E effects were opposed by apo C-III. With apo E-, apo C-III-enriched chylomicrons more 125I-apo E became associated with the cells than could be expected on the basis of the [3H]triacylglycerol measurements. It is concluded that apo C-III can weaken the interaction of apo E with the chylomicrons leading to the cell-association of free apo E. It appears that subtle changes in the apo E and/or apo C-III content of chylomicrons can influence the interaction with both parenchymal and non-parenchymal liver cells.(ABSTRACT TRUNCATED AT 400 WORDS) |
| Databáze: | OpenAIRE |
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