Altered Wnt signalling in the teenage suicide brain: focus on glycogen synthase kinase-3β and β-catenin

Glycogen synthase kinase (GSK)-3 beta and beta-catenin are important components of the Wnt signalling pathway, which is involved in numerous physiological functions such as cognition, brain development and cell survival. Their abnormalities have been implicated in mood disorders and schizophrenia. Teenage suicide is a major public health concern; however, very little is known about its neurobiology. In order to examine if abnormalities of GSK-3 beta and beta-catenin are associated with teenage suicide, we determined the gene and protein expression of GSK-3 beta and beta-catenin in the prefrontal cortex (PFC) and hippocampus obtained from 24 teenage suicide victims and 24 normal control subjects. Protein expression was determined using Western blot with specific antibodies and gene expression (mRNA levels) was determined using the real-time polymerase chain reaction method. No significant change was observed in the GSK-3 beta protein levels either in the PFC or hippocampus of suicide victims compared to controls. However, protein levels of pGSK-3 beta-ser(9) were significantly decreased in the PFC and hippocampus of suicide victims compared to normal controls. We also found that GSK-3 beta mRNA levels were significantly decreased in the PFC but not in the hippocampus of teenage suicide victims compared to controls. Mean protein and mRNA levels of beta-catenin were significantly decreased in both the PFC and hippocampus of teenage suicide group compared to controls. The observation that there is a decrease in beta-catenin and pGSK-3 beta-ser(9) in the PFC and hippocampus of teenage suicide victims does indicate a disturbance in the Wnt signalling pathway in teenage suicide.