Toxicity of beta-amyloid in HEK293 cells expressing NR1/NR2A or NR1/NR2B N-methyl-D-aspartate receptor subunits.
Neurotoxicity induced by beta-amyloid peptide (Abeta) involves glutamate toxicity, resulting from overactivation of N-methyl-D-aspartate (NMDA) receptors and elevation of intracellular calcium. However, the heterogeneity of the NMDA receptors, frequently composed of NR1 and NR2A-D subunits, has been less studied. Thus, we determined the contribution of NMDA receptor subtypes on Abeta(1-40) toxicity in HEK293 cells transiently expressing NR1/NR2A or NR1/NR2B subunits. Analysis of lactate dehydrogenase (LDH) release and trypan blue exclusion revealed an increase in Abeta(1-40) toxicity upon NR1/NR2A expression, compared to NR1/NR2B, indicating loss of plasma membrane integrity. Furthermore, Abeta(1-40) decreased intracellular ATP in cells expressing NR1/NR2A. MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate), a noncompetitive NMDA receptor antagonist, partially prevented the decrease in cell viability and the energy impairment. These differences were not accounted for by the activation of caspases 2, 3, 8 and 9 or calpains or by DNA fragmentation, excluding the hypothesis of apoptosis. Functional NR1/NR2A and NR1/NR2B receptor subtypes were further evidenced by single-cell calcium imaging. Stimulation of NR1/NR2A receptors with NMDA/glycine revealed an increase in intracellular calcium in cells pre-exposed to Abeta(1-40). Opposite effects were observed upon activation of NR1/NR2B receptors. These results suggest that NR1/NR2A-composed NMDA receptors mediate necrotic cell death in HEK293 cells exposed to Abeta(1-40) through changes in calcium homeostasis.
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CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-N GENE-Y GENE-Y GENE-N GENE-N CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-N GENE-Y GENE-Y CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-Y GENE-Y CHEMICAL GENE-Y GENE-Y GENE-N CHEMICAL CHEMICAL CHEMICAL CHEMICAL
NMDA NMDA lactate trypan blue glutamate ATP MK-801 (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate NMDA N-methyl-D-aspartate N-methyl-D-aspartate caspases 2, 3, 8 and 9 NR1 NR2A NR1 NR2B N-methyl-D-aspartate (NMDA) receptors NR1 NR2A Abeta(1-40) NR1 calcium NR2B NR1 NR2A NMDA receptors Abeta(1-40) NMDA receptors beta-amyloid peptide NR1 NR2A-D NMDA receptor NMDA Abeta(1-40) NR1 NR2A NR1 NR2B Abeta lactate dehydrogenase LDH Abeta(1-40) NR1 glycine NR2A NR1 NR2B Abeta(1-40) NR1 NR2A NMDA receptor beta-amyloid NR1 NR2A calcium NR1 NR2B N-methyl-D-aspartate receptor NMDA NMDA calcium calcium