Infusion of the biological sciences with genetic sequencing of entire genomes has sped discovery, but complete utilization of this information awaits detailed information about gene regulation. Nowhere is this more apparent than in the nervous system, where environmental interactions with genetic information take the form of learning and memory. Glutamate is a paramount neurotransmitter in these processes, but also becomes a neurotoxin in several neurodegenerative conditions. Published literature suggests that activation of glutamate receptors can induce the transcription factor NF-kappa-B in CNS neurons; glutamatergic input has also been implicated in an apparent constitutive basal activity of NF-kappa-B in these cells. However, more stringent tests performed in support of this proposal indicate that glutamate does not activate NF-kappa-B DNA-binding in neurons cultured from the cerebral cortex. Furthermore, the only factors constitutively binding NF-kappa-B target sites are Sp1 and related proteins, and glutamate decreases this activity. Together, these results indicate that NF-kappa-B is not a glutamate-responsive transcription factor as previously thought. But considerable evidence still suggests that kappa-B elements control genes important for neuronal viability. The following hypothesis will be tested: Sp1-related proteins influence survival-promoting genes through binding to kappa-B elements, and glutamate toxicity involves a reduced binding of kappa-B elements by both Sp1 and NF-kappa-B. First, glutamate-evoked events that squelch NF-kappa-B activity in cortical neurons will be elucidated through tests of post-translational modifications and interactions with other proteins. Second, the role of NF-kappa-B in protection of neurons against glutamate toxicity will be examined. Third, mechanisms by which glutamate suppresses the activity of Sp1-related factors will be explored. Finally, the ability of Sp1-related proteins to control neuronal transcription through kappa-B cis elements, with particular regard to survival-promoting genes, will be explored. These studies should shed light on a contentious issue, namely, the role of NF-kappa-B and its DNA target sites in cerebral neurons. As such, this body of work could have direct impact on the mechanisms by which a major neurotransmitter impacts on the genetic correlates of memory, learning, and excitotoxic cell death, paradigms of considerable significance to human mental health.

R01NS046439

2004-01-20

2009-12-31