The regulation of lipid synthesis and secretion by phosphatidylcholine was investigated in CaCo-2 cells grown on semipermeable filters. In cells incubated with 1 mM taurocholate and 100–500 μM phosphatidylcholine, cholesteryl ester synthesis was decreased, triacylglycerol synthesis was increased modestly, whereas phospholipid synthesis was unaffected. Acyl-CoA–cholesterol acyltransferase activity was decreased secondary to a decrease in the substrate (cholesterol) supply. The basolateral secretion of newly synthesized triacylglycerol and triacylglycerol mass was significantly increased by phosphatidylcholine, whereas cellular triacylglycerol mass decreased. This effect was not specific for phosphatidylcholine as phosphatidylethanolamine and phosphatidylserine also increased the secretion of newly synthesized triacylglycerols. Dioleoylphosphatidylcholine was as effective as egg phosphatidylcholine in increasing triacylglycerol transport. Dipalmitoylphosphatidylcholine, in contrast, was without effect. Phosphatidylcholine also increased the basolateral secretion of apolipoprotein B (apoB) mass without altering apoB mRNA levels. Disruption of the Golgi apparatus by monensin or brefeldin A prevented the increase in apoB secretion by phosphatidylcholine. Compared with microsomes prepared from control cells, those from cells incubated with phosphatidylcholine contained more newly synthesized apoB. The percentage of new synthesized apoB isolated from the lumen of microsomes (as an estimate of apoB destined for secretion), however, was similar in the two preparations. Thus in CaCo-2 cells incubated with phosphatidylcholine, the transport of apoB and triacylglycerols is increased whereas cholesteryl ester synthesis and secretion are decreased. A normally functioning secretory pathway is required for phosphatidylcholine to increase triacylglycerol-rich lipoprotein secretion.
Skip Nav Destination
Article navigation
Research Article|
March 01 1996
Phosphatidylcholine increases the secretion of triacylglycerol-rich lipoproteins by CaCo-2 cells
F. Jeffrey FIELD
F. Jeffrey FIELD
*
* University of Iowa, Department of Internal medicine and the Veterans Administration, Iowa City, IA 52242, U.S.A.
*To whom correspondence should be addressed.
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
August 30 1995
Revision Received:
October 23 1995
Accepted:
November 02 1995
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 314 (2): 569–575.
Article history
Received:
August 30 1995
Revision Received:
October 23 1995
Accepted:
November 02 1995
Citation
Satya N. MATHUR, Ella BORN, Shubha MURTHY, F. Jeffrey FIELD; Phosphatidylcholine increases the secretion of triacylglycerol-rich lipoproteins by CaCo-2 cells. Biochem J 1 March 1996; 314 (2): 569–575. doi: https://doi.org/10.1042/bj3140569
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.