Limits...
Requirement for cGMP in nerve cell death caused by glutathione depletion.

Li Y, Maher P, Schubert D - J. Cell Biol. (1997)

Bottom Line: The neurotransmitter glutamate kills immature cortical neurons and a hippocampal nerve cell line via an oxidative pathway associated with glutathione depletion.The resultant cGMP modulates the increase in intracellular calcium that precedes cell death because sGC inhibitors prevent calcium elevation and the cGMP analogue potentiates the increase in intracellular calcium.These results suggest that the final pathway of glutamate induced nerve cell death is through a cGMP-modulated calcium channel.

View Article: PubMed Central - PubMed

Affiliation: Cellular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.

ABSTRACT
Glutathione depletion occurs in several forms of apoptosis and is associated with Parkinson's disease and HIV toxicity. The neurotransmitter glutamate kills immature cortical neurons and a hippocampal nerve cell line via an oxidative pathway associated with glutathione depletion. It is shown here that soluble guanylyl cyclase (sGC) activity is required for nerve cell death caused by glutathione depletion. Inhibitors of sGC block glutamate toxicity and a cGMP analogue potentiates cell death. Glutamate also induces an elevation of cGMP that occurs late in the cell death pathway. The resultant cGMP modulates the increase in intracellular calcium that precedes cell death because sGC inhibitors prevent calcium elevation and the cGMP analogue potentiates the increase in intracellular calcium. These results suggest that the final pathway of glutamate induced nerve cell death is through a cGMP-modulated calcium channel.

Show MeSH

Related in: MedlinePlus

sGC inhibitor  LY83583 does not prevent  the depletion of glutathione  by glutamate or BSO. HT22  cells were treated with either  5 mM glutamate or 50 μM  BSO in the presence or absence of 2 μM LY83583 for  various times. The cells were  collected and assayed for glutathione levels and protein  content. The data are presented relative to controls (0  h, no treatment). The level of glutathione was 12.4 ± 0.62 nmol/mg  protein and 8.08 ± 0.08 nmol/mg protein for cells grown in FCS-containing medium and horse serum–containing medium, respectively. Horse serum was used when BSO toxicity was studied  because it gave more sensitive and consistent results (Li et al., 1997).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2140210&req=5

Figure 2: sGC inhibitor LY83583 does not prevent the depletion of glutathione by glutamate or BSO. HT22 cells were treated with either 5 mM glutamate or 50 μM BSO in the presence or absence of 2 μM LY83583 for various times. The cells were collected and assayed for glutathione levels and protein content. The data are presented relative to controls (0 h, no treatment). The level of glutathione was 12.4 ± 0.62 nmol/mg protein and 8.08 ± 0.08 nmol/mg protein for cells grown in FCS-containing medium and horse serum–containing medium, respectively. Horse serum was used when BSO toxicity was studied because it gave more sensitive and consistent results (Li et al., 1997).

Mentions: Since the activation of 12-LOX has been experimentally linked to the reduced level of intracellular GSH (Li et al., 1997), it was asked if GSH depletion is also sufficient to activate sGC-mediated cell death. To determine if sGC is also involved in neuronal cell death associated with GSH depletion, the effect of sGC inhibitors on BSO toxicity was examined. BSO, a specific inhibitor of γ-glutamylcysteine synthetase, the rate-limiting enzyme in GSH synthesis, depletes intracellular GSH and causes cell death in a time- and dose-dependent manner in both HT22 cells and primary cortical neurons (Li et al., 1997). An overnight exposure of HT22 cells or primary cortical neurons to 50 μM BSO causes glutathione depletion (Fig. 2) and a dramatic loss of cell viability (Fig. 1, C and D). sGC inhibitors LY83583, methylene blue, and N-methyl-hydroxylamine all block BSO toxicity in a manner similar to that of glutamate, suggesting that sGC is directly linked to neuronal cell death caused by GSH depletion. There are, however, differences in the pharmacology of sGC inhibitors that prevent glutamate- and BSO-induced cell death. These differences may be due to the fact that at least the early events are different for these two models of cell death, because glutamate interferes with the cystine uptake while BSO directly inhibits GSH synthesis.


Requirement for cGMP in nerve cell death caused by glutathione depletion.

Li Y, Maher P, Schubert D - J. Cell Biol. (1997)

sGC inhibitor  LY83583 does not prevent  the depletion of glutathione  by glutamate or BSO. HT22  cells were treated with either  5 mM glutamate or 50 μM  BSO in the presence or absence of 2 μM LY83583 for  various times. The cells were  collected and assayed for glutathione levels and protein  content. The data are presented relative to controls (0  h, no treatment). The level of glutathione was 12.4 ± 0.62 nmol/mg  protein and 8.08 ± 0.08 nmol/mg protein for cells grown in FCS-containing medium and horse serum–containing medium, respectively. Horse serum was used when BSO toxicity was studied  because it gave more sensitive and consistent results (Li et al., 1997).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2140210&req=5

Figure 2: sGC inhibitor LY83583 does not prevent the depletion of glutathione by glutamate or BSO. HT22 cells were treated with either 5 mM glutamate or 50 μM BSO in the presence or absence of 2 μM LY83583 for various times. The cells were collected and assayed for glutathione levels and protein content. The data are presented relative to controls (0 h, no treatment). The level of glutathione was 12.4 ± 0.62 nmol/mg protein and 8.08 ± 0.08 nmol/mg protein for cells grown in FCS-containing medium and horse serum–containing medium, respectively. Horse serum was used when BSO toxicity was studied because it gave more sensitive and consistent results (Li et al., 1997).
Mentions: Since the activation of 12-LOX has been experimentally linked to the reduced level of intracellular GSH (Li et al., 1997), it was asked if GSH depletion is also sufficient to activate sGC-mediated cell death. To determine if sGC is also involved in neuronal cell death associated with GSH depletion, the effect of sGC inhibitors on BSO toxicity was examined. BSO, a specific inhibitor of γ-glutamylcysteine synthetase, the rate-limiting enzyme in GSH synthesis, depletes intracellular GSH and causes cell death in a time- and dose-dependent manner in both HT22 cells and primary cortical neurons (Li et al., 1997). An overnight exposure of HT22 cells or primary cortical neurons to 50 μM BSO causes glutathione depletion (Fig. 2) and a dramatic loss of cell viability (Fig. 1, C and D). sGC inhibitors LY83583, methylene blue, and N-methyl-hydroxylamine all block BSO toxicity in a manner similar to that of glutamate, suggesting that sGC is directly linked to neuronal cell death caused by GSH depletion. There are, however, differences in the pharmacology of sGC inhibitors that prevent glutamate- and BSO-induced cell death. These differences may be due to the fact that at least the early events are different for these two models of cell death, because glutamate interferes with the cystine uptake while BSO directly inhibits GSH synthesis.

Bottom Line: The neurotransmitter glutamate kills immature cortical neurons and a hippocampal nerve cell line via an oxidative pathway associated with glutathione depletion.The resultant cGMP modulates the increase in intracellular calcium that precedes cell death because sGC inhibitors prevent calcium elevation and the cGMP analogue potentiates the increase in intracellular calcium.These results suggest that the final pathway of glutamate induced nerve cell death is through a cGMP-modulated calcium channel.

View Article: PubMed Central - PubMed

Affiliation: Cellular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.

ABSTRACT
Glutathione depletion occurs in several forms of apoptosis and is associated with Parkinson's disease and HIV toxicity. The neurotransmitter glutamate kills immature cortical neurons and a hippocampal nerve cell line via an oxidative pathway associated with glutathione depletion. It is shown here that soluble guanylyl cyclase (sGC) activity is required for nerve cell death caused by glutathione depletion. Inhibitors of sGC block glutamate toxicity and a cGMP analogue potentiates cell death. Glutamate also induces an elevation of cGMP that occurs late in the cell death pathway. The resultant cGMP modulates the increase in intracellular calcium that precedes cell death because sGC inhibitors prevent calcium elevation and the cGMP analogue potentiates the increase in intracellular calcium. These results suggest that the final pathway of glutamate induced nerve cell death is through a cGMP-modulated calcium channel.

Show MeSH
Related in: MedlinePlus