Scientific Journal Info
The exact target of Valproic Acid, or VPA, is unknown, and scientists have been trying to find out what it is. They know that VPA and Lithium are two very similar treatments, and they know the direct targets of Lithium. One of these targets is glycogen synthase kinase-3β. GSK-β is a negative regulator of the Wnt signaling pathway, which regulates processes such as axonal remodeling, cellular proliferation, embryonic patterning, and organogenesis. GSK-β phosphorylates β-catenin, which leads to its degradation. Thus, the inhibition of GSK-β leads to the accumulation of β-catenin, which then leads to the transcription of Wnt genes. The connection between this and Bipolar Disorder has not been determined, but it has been proposed that VPA is an inhibitor of GSK-β. It has also been proposed that VPA inhibits histone deacetylase (HDAC), which is a negative regulator of gene expression.
To test this proposition, the scientists put VPA and Lithium to a test. They acquired plasmids (3 wild type Lef-OT and 3 mutated Lef-OF), which they transfected with pcDNA3.1. After 24 hours of transfection, they added LiCl (Lithium) and VPA to the cells. This prepared them for immunoblotting. The results of this experiment led to the conclusion that VPA activates Tcf/Lef-dependent transcription and synergizes with Lithium, activates transcription factors, increases β-catenin levels, and inhibits HDAC. These findings allow the scientists to come to a more solid conclusion that VPA and Lithium operate independently in their treatment of Bipolar Disorder.
The experiment allowed the scientists to see that VPA activates transcription through diverse promoters. They came to this conclusion by transfecting Neuro2A cells with Lef-OT or Lef-OF, together with a control reporter (pRL-SV40) encoding Renilla luciferase driven by the SV-40 promotor. VPA was found to activate OT-Lef up to 6-fold in Neuro2A cells. Lithium didn’t stimulate this. This suggests that VPA acts in a different way than Lithium and thus could involve a more direct activation of transcription.
The scientists also found that VPA increases β-catenin levels through a novel mechanism. While Lithium also increases β-catenin levels, the two drugs differed in the rate of accumulation. It is possible that VPA has a longer delay in the accumulation of β-catenin because it acts by increasing the expression of β-catenin. This would separate the drug from Lithium, which stabilizes the protein.
They were able to determine that VPA inhibits histone deacetylase by preparing nuclear extracts from HeLa cells, which express multiple HDACs, and examined their activity in the presence of VPA. HDACs are important negative regulators of transcription, which allows the scientists to come to the consensus that the inhibition of HDAC describes the increased levels of reporter activity.
While it is possible to compare VPA to Lithium, the exact mechanisms of action for which VPA acts as an anticonvulsant, mood stabilizer, and teratogen are still to be defined. The research conducted by these scientists helps to create a clearer picture about what is going on when VPA is in the body.
To test this proposition, the scientists put VPA and Lithium to a test. They acquired plasmids (3 wild type Lef-OT and 3 mutated Lef-OF), which they transfected with pcDNA3.1. After 24 hours of transfection, they added LiCl (Lithium) and VPA to the cells. This prepared them for immunoblotting. The results of this experiment led to the conclusion that VPA activates Tcf/Lef-dependent transcription and synergizes with Lithium, activates transcription factors, increases β-catenin levels, and inhibits HDAC. These findings allow the scientists to come to a more solid conclusion that VPA and Lithium operate independently in their treatment of Bipolar Disorder.
The experiment allowed the scientists to see that VPA activates transcription through diverse promoters. They came to this conclusion by transfecting Neuro2A cells with Lef-OT or Lef-OF, together with a control reporter (pRL-SV40) encoding Renilla luciferase driven by the SV-40 promotor. VPA was found to activate OT-Lef up to 6-fold in Neuro2A cells. Lithium didn’t stimulate this. This suggests that VPA acts in a different way than Lithium and thus could involve a more direct activation of transcription.
The scientists also found that VPA increases β-catenin levels through a novel mechanism. While Lithium also increases β-catenin levels, the two drugs differed in the rate of accumulation. It is possible that VPA has a longer delay in the accumulation of β-catenin because it acts by increasing the expression of β-catenin. This would separate the drug from Lithium, which stabilizes the protein.
They were able to determine that VPA inhibits histone deacetylase by preparing nuclear extracts from HeLa cells, which express multiple HDACs, and examined their activity in the presence of VPA. HDACs are important negative regulators of transcription, which allows the scientists to come to the consensus that the inhibition of HDAC describes the increased levels of reporter activity.
While it is possible to compare VPA to Lithium, the exact mechanisms of action for which VPA acts as an anticonvulsant, mood stabilizer, and teratogen are still to be defined. The research conducted by these scientists helps to create a clearer picture about what is going on when VPA is in the body.
This figure compares the rate of β-catenin and β-tubulin accumulation between VPA and Lithium. We can observe that VPA operates much slower than Lithium, with accumulation of β-catenin occurring after 10 hours, which with Lithium we can see accumulation after just 30 minutes. Both treatments are affective at rapidly increasing the rate of β-tubulin. This figure helps to support the notion that VPA and Lithium operate different in their mechanisms.
Link to article:
http://www.jbc.org/content/276/39/36734.long
Link to article:
http://www.jbc.org/content/276/39/36734.long