Characterization of putative Wnt3a-Inducible Enhancers

The Wnt signaling pathway has been previously shown to play a major role in regulating bone metabolism and it is emerging as a target for the therapeutic intervention of bone thinning disorders such as osteoporosis. Several Wnt proteins have been shown to be expressed in bone and mutations in Wnt pathway members such as Wnt co-receptor Lrp5 and Wnt inhibitor Sost have been shown to be associated with low or high bone mass disorders, however, very little is known about specific roles played by different Wnt ligands in bone development, repair and remodeling. To identify downstream targets of Wnt signaling we sequence RNA synthesized by Wnt3a treated osteoblasts and found 214 genes to be significantly up-regulated by >2-fold in the presence of Wnt3a ligand. Computational analysis of ChipSeq data in the loci of these 214 genes predicted 163 putative Wnt-inducible enhancers. In this project, we sought to functionally validate these putative enhancer elements that may account for the Wnt3a-dependent activation of these 214 transcripts. Candidate enhancers were cloned, transfected into osteoblast-like cell lines, and examined for transgene expression in the presence and absence of recombinant Wnt3a protein. Preliminary data suggests that several noncoding elements may have enhancer properties both in the absence or presence of Wnt3a, in vitro.