of work: Glutamate receptors play a pivotal role in several brain functions including fast excitatory neurotransmission, induction and maintenance of long term potentiation, and synaptic plasticity. However, over-activation of these receptors is thought to initiate a common final pathway of neuronal cell death in both acute and chronic brain insults. A major focus of this project is to discover the pathological roles that excitatory amino acid (glutamate) receptors play in neuronal cell loss in aging and Alzheimer's Disease, and the mechanisms by which this cell loss occurs. One of our objectives is to determine how the N-methyl-D-Aspartate 1 receptor gene (NMDAR1) and other family member genes are regulated at the transcriptional level. Another objective of this project is to determine the mechanism by which glutamate causes cell death and the role activation of glutamate receptors plays in initiating a genetic cascade of programmed cell death. The promoter region of the NMDAR1 contains several transcriptional elements in the proximal region responsible for both basal, inducible, and neuronal specific expression. In recent work, we showed that nerve growth factor and other neurotrophins were able to stimulate expression of NMDAR1 promoter-Luciferase reporter constructs in PC12 cells. This stimulation was induced through activation of high affinity TrkA receptors and subsequent activation of a Ras/Raf MAP kinase pathway. We showed by electro-mobility shift assays that this activation may be mediated through both GSG and Sp1 transcription factor activation. Other elements in the NMDAR1 promoter are being studied including two Cyclic AMP responsive consensus sites in the proximal region. Also, we showed that glutamate treatment of a hippocampal cell line caused cell death which could be prevented by the over-expression of Bcl-2 protein. Since Bcl-2 can protect and we see increased amounts of DNA laddering in glutamate treated cells, the results suggest that this line may be a good model to study neuronal apoptosis. These cells express AMPA and kainate subtype glutamate receptors. NT2-N cells, on the other hand express the NMDA subtype of receptor and may be a good model of glutamate-induced necrotic cell death.
