title: PC12 variants deficient in catecholamine transport.
abstract: We have isolated PC12 cell variants deficient in transporter-mediated uptake of 3,4-dihydroxyphenylethylamine (dopamine). The variants either were obtained nonselectively, or they were selected by resistance to guanethidine or N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Dopamine uptake into guanethidine-resistant cells occurred with a decreased Vmax; the Km for dopamine and inhibition by guanethidine were normal. MPTP-resistant cells lacked the capacity to take up dopamine. Most of the variants resembled wild-type PC12 in their response to nerve growth factor and the storage and secretion of dopamine. MPTP-resistant cells exhibited several deficiencies in addition to dopamine transport, i.e., no measurable storage of dopamine or acetylcholine and no observable response to nerve growth factor. Wild-type and variant cells were compared with respect to the labeling of cell proteins with [3H]xylamine, which binds covalently to certain proteins apparently only after entering PC12 via the catecholamine transporter. When intact variant cells were used, there was markedly reduced labeling of the proteins by [3H]xylamine. Almost all of these proteins were readily labeled when cell homogenates were exposed to [3H]xylamine. However, MPTP-resistant cells were missing three of these proteins. Northern blot analysis with cDNA clones revealed that the MPTP-resistant cells had markedly reduced levels of several specific mRNA species.
mesh_terms: D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D000310:Adrenal Gland Neoplasms / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D050482:Catecholamine Plasma Membrane Transport Proteins; D002460:Cell Line; D004298:Dopamine / Q000378:metabolism; D004351:Drug Resistance; D014644:Genetic Variation; D006145:Guanethidine / Q000494:pharmacology; D026901:Membrane Transport Proteins; D051379:Mice; D008970:Molecular Weight; D009588:Nitrogen Mustard Compounds / Q000378:metabolism; D010673:Pheochromocytoma / Q000235:genetics / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
chemical_list: D002352:Carrier Proteins; D050482:Catecholamine Plasma Membrane Transport Proteins; D026901:Membrane Transport Proteins; D009588:Nitrogen Mustard Compounds; D011506:Proteins; D011725:Pyridines; D012333:RNA, Messenger; C493212:Slc22a1 protein, rat; C026131:xylamine; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D011188:Potassium; D004298:Dopamine; D006145:Guanethidine