Verification of putative novel Wnt/ β-catenin pathway targets using alternative effectors

Abstract

The Wnt/β-catenin pathway plays important roles in embryogenesis, development and tissue homeostasis in adult organisms. Mutations in almost any member of this pathway have been associated with a disease including Alzheimer’s disease, schizophrenia and cancer. Therefore understanding the mechanisms through which Wnt/β-catenin pathway acts and identification of new downstream elements carry a major importance in genetic and cancer research, and also diagnosis and treatment of many diseases. We have previously conducted SAGE (Serial Analysis of Gene Expression) and genome-wide microarray screens and using the results of these experiments as a starting point we have previously identified BRI3 (Brain Protein I3) and HSF2 (Heat Shock Factor 2) as novel Wnt/β-catenin pathway targets and verified our findings using various methods such as inhibition of GSK3 activity by lithium treatment, chromatin immunoprecipitatiton and luciferase activity assays. To strengthen our hypothesis the effect of hyperctive Wnt/β-catenin pathway in Snu449 cells on these genes was examined and also several methods that stimulate the pathway were compared. We have observed increased BRI3 and HSF2 mRNA levels in response to lithium treatment in Snu449 cells, and in response to Wnt agonist treatment in both Snu449 cells and Huh7 cells. These findings have supported out hypothesis that BRI3 and HSF2 transcriptions are regulated by the Wnt/β-catenin pathway.