The metabolic fate of [3H-methyl]choline in cultured human neuroblastoma cell lines, LA-N-1 and LA-N-2.
The conversion of choline in cultures of the human neuroblastoma cell lines, LA-N-1 and LA-N-2 cells, was investigated in order to identify potential precursors in acetylcholine (AcCho) synthesis. LA-N-1, a catecholaminergic and LA-N-2, a cholinergic, cell line were incubated with [3H-methyl]choline (Cho) for varying periods of time up to 72 h. The radioactivity present in lipids and water-soluble metabolites increased linearly up to 24 h in both cell lines. Approximately 20% of the radioactivity associated with the water-soluble metabolites in both control (untreated) and retinoic acid-induced differentiated (RA-treated cells) LA-N-2 cells was present as Cho and AcCho. There was no detectable AcCho in the catecholaminergic cell line, LA-N-1. The untreated and RA-treated LA-N-1 and LA-N-2 cells were labeled for 24 h with [3H-methyl]Cho, followed by a chase in growth medium containing 100 microM unlabeled choline. The distribution of radioactivity in the LA-N-2 cells was 6-10% of AcCho, 84-89% as phosphocholine (PCho), 1-3% as glycerophosphocholine (GroPCho), and 2-4% as Cho. The distribution of radioactivity in the LA-N-1 cells was similar except for the absence of AcCho. The distribution of radioactivity in the culture medium of LA-N-1 cells was 70-80% as Cho, 20-30% as PCho, and 1-3% as GroPCho. In contrast, the radioactivity was equally distributed between Cho (50%) and PCho (50%), with only 1-3% as GroPCho in the medium of LA-N-2 cells.
Singh
I N
IN
Department of Biochemistry and Molecular Biology, University of Manitoba, Faculty of Medicine, Winnipeg.
Sorrentino
G
G
Massarelli
R
R
Kanfer
J N
JN
D000109:Acetylcholine / Q000378:metabolism; D002454:Cell Differentiation; D002794:Choline / Q000031:analogs & derivatives* / Q000378:metabolism; D002855:Chromatography, Thin Layer; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D014212:Tretinoin / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology
D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; C017506:methylcholine; D014212:Tretinoin; D002794:Choline; D000109:Acetylcholine