Document Detail

Phorbol esters modulate phospholipid metabolism in a human cholinergic cell line, LA-N-2: a possible role for the base exchange enzymes.
MedLine Citation:
PMID:  1527804     Owner:  NLM     Status:  MEDLINE    
It was shown that in LA-N-2 cells prelabeled with [3H-methyl]choline for 24 hr (Singh et al.: Mol Chem Neuropathol 14:53-66, 1991) the major intracellular and extracellular hydrophilic compound was phosphorylcholine. LA-N-2 cells were labeled with [14C-methyl]choline for 24 hr, harvested, and incubated in Hepes/BSA/saline buffer for varying periods of time. The radioactive compound present in the cytosol and released into Hepes/BSA/saline buffer medium in the presence or absence of TPA was phosphorylcholine. There was a gradual increase in the appearance of radioactivity in the medium and this corresponded to a gradual decline in the radioactivity present in the cytosolic compartment with a statistically significant P value of less than .005. Identical results were obtained with prelabeled cells subsequently incubated with TPA. There was no significant change in the amount of radioactivity associated with lipid suggesting that the phosphorylcholine may be released directly from the cytosolic compartment into the medium rather than originating through a phospholipase-C catalyzed hydrolysis of phosphatidylcholine. This possibility received support from experiments in which cells were electropermeabilized in the presence of radioactive phosphorylcholine. It was found that the introduced [14C]phosphorylcholine was released intact into the incubation medium from the cytosolic compartment. The incorporation of [14C]choline, [14C]ethanolamine, and [14C]serine by LA-N-2 cells into their corresponding phospholipids was investigated in the presence or absence of TPA. The presence of TPA increased the amount of radioactivity incorporated into the phospholipids with a corresponding decrease in the amount of radioactivity in the cytosolic compartment compared to control cultures. There were no detectable differences between TPA exposed and control cells in the distribution of radioactivity in free choline, phosphorylcholine, or CDP-choline of [14C] choline labeled cells. This indicates that the increased lipid labeling was not accompanied by enhanced labeling of the intermediates of the de novo pathway. This effect of TPA in altering the distribution of labeling of the cytosolic and lipid components was not demonstrable with cells grown in the presence of 10(-5) M retinoic acid.
I N Singh; D G McCartney; G Sorrentino; R Massarelli; J N Kanfer
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of neuroscience research     Volume:  32     ISSN:  0360-4012     ISO Abbreviation:  J. Neurosci. Res.     Publication Date:  1992 Aug 
Date Detail:
Created Date:  1992-10-19     Completed Date:  1992-10-19     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  7600111     Medline TA:  J Neurosci Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  583-92     Citation Subset:  IM    
Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
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MeSH Terms
Cells, Cultured
Choline / metabolism
Ethanolamines / metabolism
Lipid Metabolism
Nerve Tissue Proteins / metabolism
Parasympathetic Nervous System / drug effects,  enzymology,  metabolism*
Phorbol Esters / pharmacology*
Phosphatidylserines / metabolism
Phospholipids / metabolism*
Protein Kinase C / metabolism
Serine / metabolism
Tetradecanoylphorbol Acetate / pharmacology
Tretinoin / pharmacology
Reg. No./Substance:
0/Ethanolamines; 0/Nerve Tissue Proteins; 0/Phorbol Esters; 0/Phosphatidylserines; 0/Phospholipids; 16561-29-8/Tetradecanoylphorbol Acetate; 302-79-4/Tretinoin; 56-45-1/Serine; 62-49-7/Choline; EC Kinase C

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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