In trisomy 16 mouse, increased gene dosage of SOD-1, APP, glutamate R5 receptor,etc. activates prooxidant processes. If the antioxidant defense is insufficient reactive oxygen species (ROS) overproduction could potentially be harmful and evoke age-related pathologies including cancer, cardiovascular and neurodegenerative diseases. The objectives of this project are:1. to study in neuronal and glial primary cultures of trisomy 16 mouse embryos various stress response genes that are regulated by ROS. The effect of ROS on metallothionein (MT-I/II isoforms), heat shock protein (HSP-70), thioredoxin peroxidases, and transcription factor AP-1 was compared in diploid and trisomy 16 primary cultures.2. to study in neuronal and glial primary cultures of trisomy 16 mouse embryos the effect of ROS and heavy metals on the transcriptional regulation of MT-I/II and on the antioxidant- and metal-response element-binding factors. In control conditions, protein oxidation was 50 % higher in trisomy 16 primary cultures than in those of diploid littermates. After exposure to 0.01 mM hydrogen peroxide or 0.05 mM kainic acid a 2.5- to 3-fold increase of protein carbonyl groups was found was found in trisomy 16 but not in diploid cells. This finding suggests that the metabolism of endogenously formed ROS may be impaired in trisomy 16 cells. Western blotting revealed a 2 fold increase of MT-I/II 1 h after exposure to 0.01 mM hydrogen peroxide in trisomy 16 but not control cells. The increase of basal MT- I/II level was due to an upregulation of MT-I/II RNA expression. A 15 min exposure to 0.01 mM hydrogen peroxide of neuronal primary cultures elicited after 30 min a 6-fold higher increase of AP-1 DNA-binding activity in trisomy 16 than in diploid cultures. Whereas, exposure of glial primary cultures to 0.01 mM hydrogen peroxide elicited a 2-fold increase of AP-1 DNA-binding activity in both trisomy 16 and diploid cells. Exposure of trisomy 16 neuronal primary cultures to 0.01 mM hydrogen peroxide increased the number of apoptotic nuclei. Since AP-1 can up- or down-regulate apoptosis depending on the microenvironment, cell type, and stress indicia the present results suggest that the increased ROS level in trisomy 16 cells elicits apoptosis. This inference is supported by reports in the literature showing a reduction in number of neurons and neuronal differentiation in trisomy 16 primary cultures and in human trisomy 21 brains. - trisomy 16 mouse, primary cultures, astrocytes, neurons, metallothionein, protein oxidation, reactive oxygen species
