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 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 gene contains several transcriptional elements in the proximal region responsible for basal, NGF-inducible, and neuronal specific expression. These include GSG and overlapping Sp1 elements and a Neuron Restrictive Silencer Element (NRSE). It also contains retinoic acid (RA) responsive elements. We recently showed that RA treatment of human NT2 teratocarcinoma cells will cause them to differentiate into a neuronal phenotype and express glutamate responsive calcium channels. Undifferentiated NT2 cells do not express NMDAR1 subunits. We showed that RA treatment induces about a 10 fold increase in NMDAR1 mRNA as measured by real-time RT/PCR. Two other NMDA receptor subunits were expressed in both undifferentiated and differentiated NT2 cells and their message levels varied less than 2 fold during RA treatment. Interestingly, an inhibitory NMDA subunit, NR3, may be present in differentiated neurons. These results emphasize the importance of the NMDAR1 subunit in forming functional NMDA receptors and but also suggest important subunit interactions and post-translational events in the regulation of NMDA receptor activity. - glutamate, NT2N neurons, excitotoxicity, transcription factors, Sp1, MEF2C, apoptosis
