Effect of nerve growth factor on the synthesis of amino acids in PC12 cells

✍ Scribed by H. R. Zielke; J. T. Tildon; F. C. Kauffman; P. J. Baab

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 670 KB
• Volume: 22
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490220407

✦ Synopsis

Radioactive short-chain fatty acids preferentially label glutamine relative to glutamate in brain due to compartmentation of glutamine and glutamate. To determine whether this phenomenon occurs in a single cell culture model, we examined the effect of fatty acid chain length on the synthesis as well as pool size of selected amino acids in rat pheochromocytoma PC12 cells, a cell culture model of the large glutamate compartment in neurons. IntracelIuIar 14C-amino acids were quantitated by HPLC, and the incorporation of [U-'4C]-glucose, [l-14C]-butyrate, [l-14C]-octanoate, and [l-'4C]-palmitate into five amino acids was measured in native and NGF-treated PC12 cells. NGF pretreatment decreased the intracellular concentration of amino acids as did addition of fatty acids but these effects were not additive. Specific activities of amino acids in native cells labelled by 14Coctanoate were 1,300 DPMhmol, 490 DPMhmol, 200 DPMhmol, and 110 DPM/nmol for glutamate, aspartate, glutamine, and serine, respectively. No radioactivity was detected in alanine. Similar specific activities were noted when 14C-butyrate was the precursor; however, there was at least 5-fold less if 14C-palmitate was the precursor. Pretreatment of cells with NGF decreased the specific activity of amino acids by 2545%. Specific activities of amino acids synthesized from 14C-glucose decreased in the following order: glutamate, 1,640 DPMhmol; aspartate, 1,210 DPMhmol; alanine, 580 DPMhmol; glutamine, 275 DPMhmol; and serine, 80 DPMhmol for native cells. NGF pretreatment decreased the specific activities of glutamate and glutamine, but not of the other 3 amino acids. The preferred precursor for glutamate synthesis in native PC12 cells was glucose followed by octanoate, butyrate and palmitate (16:6:3:1).