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Gas1 is induced during and participates in excitotoxic neuronal death
Britt Mellström1, Valentin Ceña, Monica Lamas
1Departamento de Biologia Molecular y Celular, Centro Nacional de Biotecnologia, 28049 Madrid, Spain. bmellstr@cnb.uam.es
Abstract:
We have performed differential screening to identify genes participating in NMDA-induced neuronal death. The gas1 (growth arrest-specific gene 1) gene, whose product is known to inhibit cell cycle progression, was induced in cultured corticohippocampal neurons committed to die after a brief exposure to NMDA. Overexpression of Gas1 in cultured hippocampal neurons and in human neuroblastoma NB69 cells produced a marked reduction in the number of viable cells. Furthermore, gas1 antisense oligodeoxynucleotide or antisense mRNA protected hippocampal neurons or NB69 cells from neuronal death. Importantly, Gas1-induced neuronal death was attenuated by coexpression of the human Bcl-2 protein or the baculoviral caspase inhibitor OpIAP2. While Gas1 does not directly interact with Bcl-2, OpIAP2 coimmunoprecipitates with Gas1. In addition, induction of gas1 also occurred in rat brain in two models of excitotoxicity: delayed neuronal death after intraperitoneal kainate injection and neuronal death in hippocampal slices after ischemia. These results indicate that Gas1 is induced by activation of glutamate receptors and is part of the gene expression program directing neuronal death after mild excitotoxic insults.
Insights
Growth arrest-specific gene 1 (Gas1) promotes NMDA-induced neuronal death by inhibiting cell cycle progression. Inhibiting Gas1 protects neurons, indicating its role in excitotoxicity.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- NMDA receptor activation can lead to neuronal death, a process implicated in various neurological disorders.
- The specific genes and molecular mechanisms underlying NMDA-induced neuronal death are not fully understood.
Purpose of the Study:
- To identify genes involved in NMDA-induced neuronal death using differential screening.
- To elucidate the role of the growth arrest-specific gene 1 (Gas1) in this process.
Main Methods:
- Differential screening of genes induced by NMDA exposure in cultured neurons.
- Overexpression and antisense inhibition of Gas1 in neuronal and neuroblastoma cell lines.
- Assessment of cell viability and neuronal death.
- Co-immunoprecipitation assays to study protein interactions.
- Analysis of Gas1 induction in animal models of excitotoxicity (kainate injection, ischemia).
Main Results:
- Gas1 was significantly induced in neurons undergoing NMDA-induced death.
- Overexpression of Gas1 exacerbated cell death, while antisense inhibition protected cells.
- Gas1-induced death was partially rescued by Bcl-2 and OpIAP2, with OpIAP2 co-immunoprecipitating with Gas1.
- Gas1 was also induced in rat models of kainate-induced excitotoxicity and ischemia-induced neuronal death.
Conclusions:
- Gas1 is a key mediator of NMDA-induced neuronal death, acting downstream of glutamate receptor activation.
- Gas1 is part of the gene expression program that directs neuronal death following excitotoxic insults.
- Gas1's pro-death role may involve interactions with caspase pathways, as suggested by OpIAP2 interaction.