Document Detail

Phosphatidylcholine deficiency upregulates enzymes of triacylglycerol metabolism in CHO cells.
MedLine Citation:
PMID:  15175356     Owner:  NLM     Status:  MEDLINE    
We studied the regulation of triacylglycerol (TAG) metabolism by phosphatidylcholine (PC) in CHO MT58 cells, which are deficient in PC synthesis because of a temperature-sensitive CTP:phosphocholine cytidylyltransferase. At the permissive growth temperature (34 degrees C), these cells contained 49% less TAG and 30% less PC than wild-type CHO K1 cells. Treatment with dipalmitoylphosphatidylcholine normalized both the PC and TAG levels. Despite low TAG levels, the incorporation of [14C]oleate into TAG was increased in CHO MT58 cells. The in vitro de novo synthesis of TAG and the activity of diacylglycerol acyltransferase were 90% and 34% higher, respectively. Two other key enzyme activities in TAG synthesis, acyl-CoA synthetase and mitochondrial glycerol-3-phosphate acyltransferase (GPAT), increased by 48% and 2-fold, respectively, and mitochondrial GPAT mRNA increased by approximately 4-fold. Additionally, TAG hydrolysis was accelerated in CHO MT58 cells, and in vitro lipolytic activity increased by 68%. These studies suggest that a homeostatic mechanism increases TAG synthesis and recycling in response to PC deficiency. TAG recycling produces diacylglycerol and fatty acids that can be substrates for de novo PC synthesis and for lysophosphatidylcholine (lysoPC) acylation. In CHO MT58 cells, in which de novo PC synthesis is blocked, lysoPC acylation with fatty acid originating from TAG may represent the main pathway for generating PC.
J Matías Caviglia; I Nelva T De Gómez Dumm; Rosalind A Coleman; R Ariel Igal
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-06-01
Journal Detail:
Title:  Journal of lipid research     Volume:  45     ISSN:  0022-2275     ISO Abbreviation:  J. Lipid Res.     Publication Date:  2004 Aug 
Date Detail:
Created Date:  2004-07-15     Completed Date:  2005-02-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376606     Medline TA:  J Lipid Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1500-9     Citation Subset:  IM    
Copyright Information:
Copyright 2004 American Society for Biochemistry and Molecular Biology, Inc.
Instituto de Investigaciones Bioquímicas de La Plata, Universidad Nacional de La Plata, 1900-La Plata, Argentina.
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MeSH Terms
CHO Cells
Carbon Radioisotopes
Choline-Phosphate Cytidylyltransferase / deficiency,  metabolism*
Glycerol-3-Phosphate O-Acyltransferase / metabolism
Oleic Acid / metabolism
Phosphatidylcholines / deficiency*,  metabolism
Triglycerides / metabolism*
Reg. No./Substance:
0/Carbon Radioisotopes; 0/Phosphatidylcholines; 0/Triglycerides; 112-80-1/Oleic Acid; EC O-Acyltransferase; EC Cytidylyltransferase

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