Glutamine uptake and metabolism to N-acetylaspartylglutamate (NAAG) by crayfish axons and glia

Buttram, J.G; Engler, Jeffrey A.; Grossfeld, Robert M.; Urazaev, A. Kh.; Lieberman, Edward M.

doi:10.1016/s1096-4959(02)00124-0

Cited by 8 publications

(7 citation statements)

References 40 publications

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“…Although early reports described the synthesis of Nacetyl-peptides, including NAAG, in brain homogenates (Reichelt et al 1971;Reichelt and Kvamme 1973;Reichelt et al 1976;Lahdesmaki and Timonen 1982), these results have not been reproducible in other laboratories. In contrast to those unconfirmed reports of NAAG biosynthesis in homogenates, NAAG synthesis from radiolabeled precursors has been reliably demonstrated predominantly in explanted neuronal tissues such as rat dorsal root ganglia , frog retina (Williamson and Neale 1988), crayfish nerve cord (Buttram et al 2002) and hemisected rat spinal cord (Gehl et al 2004). The capacity to synthesize NAAG is lost upon neural tissue homogenization, but the reason remains unknown.…”

Section: Discussionmentioning

confidence: 79%

“…In contrast to those unconfirmed reports of NAAG biosynthesis in homogenates, NAAG synthesis from radiolabeled precursors has been reliably demonstrated predominantly in explanted neuronal tissues such as rat dorsal root ganglia (Cangro et al . 1987), frog retina (Williamson and Neale 1988), crayfish nerve cord (Buttram et al . 2002) and hemisected rat spinal cord (Gehl et al .…”

Section: Discussionmentioning

confidence: 99%

“…NAAG biosynthesis has also been reported to occur in two types of glial cell; primary cultures of rat cortical astrocytes (Gehl et al . 2004) and crayfish nerve‐cord glial cells (Buttram et al . 2002).…”

Section: Discussionmentioning

confidence: 99%

“…The current investigations were greatly facilitated by the use of this model system. NAAG biosynthesis has also been reported to occur in two types of glial cell; primary cultures of rat cortical astrocytes (Gehl et al 2004) and crayfish nerve-cord glial cells (Buttram et al 2002). These systems were reported to display robust synthesis of a radiolabeled compound that comigrated with NAAG chromatographically.…”

Section: Discussionmentioning

confidence: 99%

“…NAAG biosynthesis has also been demonstrated in explanted frog retinas (Williamson and Neale 1988), crayfish nerve-cord preparations (Urazaev et al 2001;Buttram et al 2002) and, more recently, in acutely isolated and hemisected rat spinal cord (Gehl et al 2004). The incorporation of radiolabeled precursors into NAAG in these model systems was low, and the studies were hampered by the difficulty in obtaining viable neural tissues.…”

mentioning

confidence: 99%

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Regulation of N‐acetylaspartate and N‐acetylaspartylglutamate biosynthesis by protein kinase activators

Arun¹,

Madhavarao²,

Moffett³

et al. 2006

Journal of Neurochemistry

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The neuronal dipeptide N-acetylaspartylglutamate (NAAG) is thought to be synthesized enzymatically from N-acetylaspartate (NAA) and glutamate. We used radiolabeled precursors to examine NAA and NAAG biosynthesis in SH-SY5Y human neuroblastoma cells stimulated with activators of protein kinase A (dbcAMP; N6,2¢-O-dibutyryl cAMP) and protein kinase C (PMA; phorbol-12-myristate-13-acetate). Differentiation over the course of several days with dbcAMP resulted in increased endogenous NAA levels and NAAG synthesis from L-[ 3 H]glutamine, whereas PMA-induced differentiation reduced both. Exogenously applied NAA caused dose dependent increases in intracellular NAA levels, and NAAG biosynthesis from L-[ 3 H]glutamine, suggesting precursorproduct and mass-action relationships between NAA and NAAG. Incorporation of L-[ 3 H]aspartate into NAA and NAAG occurred sequentially, appearing in NAA by 1 h, but not in NAAG until between 6 and 24 h. Synthesis of NAAG from L-[ 3 H]aspartate was increased by dbcAMP and decreased by PMA at 24 h. The effects of PMA on L-[ 3 H]aspartate incorporation into NAA were temporally biphasic. Using short incubation times (1 and 6 h), PMA increased L-[ 3 H]aspartate incorporation into NAA, but with longer incubation (24 h), incorporation was significantly reduced. These results suggest that, while the neuronal production of NAA and NAAG are biochemically related, significant differences exist in the regulatory mechanisms controlling their biosynthesis.

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