Effects of individual fatty acids on cellular lipid synthesis, lipoprotein secretion, and receptor-mediated lipoprotein uptake in Hep-G2 cells
Dokko, Ryowon Choue
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https://hdl.handle.net/2142/19391
Description
Title
Effects of individual fatty acids on cellular lipid synthesis, lipoprotein secretion, and receptor-mediated lipoprotein uptake in Hep-G2 cells
Author(s)
Dokko, Ryowon Choue
Issue Date
1993
Doctoral Committee Chair(s)
Cho, B.H.
Department of Study
Nutritional Sciences
Discipline
Nutritional Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Health Sciences, Nutrition
Language
eng
Abstract
Effects of individual fatty acids on lipoprotein synthesis and secretion were studied in Hep-G2 cells. The cellular uptake rate of 18:0, 18:1, 18:2 and 18:3 was very similar. The synthesis of triglyceride was significantly increased by fatty acids inclusion; triglyceride synthesis was highest with 18:0 followed by 18:1, 18:2 and 18:3 and secretion was highest with 18:1 followed by 18:2, 18:3 and 18:0.
The synthesis and secretion of phospholipid was significantly increased by fatty acid inclusion. No comparative effect was found among fatty acids tested with an exception of 18:3 which has the lowest effect on phospholipid secretion. $\sp{14}$C-acetate incorporation into cellular and medium cholesterol was significantly higher in all fatty acid groups compared to that of the control. For cholesterol secretion no significant difference among fatty acids tested was noted. However, 18:3 caused least cholesterol synthesis when it was compared with 18:1.
The inclusion of fatty acids showed notable changes in the fatty acid compositions of the cellular and medium lipids, mainly reflective the specific fatty acid added.
Although the incorporation of $\sp3$H-leucine into cellular or medium protein (d $>$ 1.21 g/ml) was not affected by addition of fatty acids the incorporation of radioactivity into apolipoprotein was significantly increased (d $<$ 1.21 g/ml).
All fatty acids stimulated the incorporation of $\sp3$H-leucine into apolipoprotein B. However, there was no significant change in the incorporation of $\sp3$H-leucine into Apo E, Apo A-I and Apo C.
The exposure of Hep-G2 cells to $\sp{125}$I-LDL in the medium resulted in a rapid internalization of LDL into the cell. Hep-G2 cells internalized $\sp{125}$I-LDL via two pathways, a saturable, high affinity pathway and an unsaturable, low-affinity pathway.
All fatty acids significantly increased LDL binding and internalization of $\sp{125}$I-LDL. Among different fatty acids, stearic acid caused least uptake of LDL. The addition of fatty acids caused significantly increased degradation of $\sp{125}$I-labeled LDL. The amount of accumulated acid-soluble materials in the medium was least in stearic acid group.
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