Mapping of the Wnt/β-Catenin/TCF Response Elements in the Human Versican Promoter
Versican, a chondroitin sulfate proteoglycan, is one of the main components of the extracellular matrix and is considered to be crucial to several key cellular processes involved in development and disease. There is differential temporal and spatial expression of versican by multiple cell types and in different developmental and pathological timeframes. In order to fully appreciate the functional roles of versican as it relates to changing patterns of expression in development and disease, an in-depth knowledge of versican’s biosynthetic processing is necessary. We have recently shown that β-catenin/T-cell factor (TCF) complex formation at the versican promoter site is essential for activation of versican transcription. The transcriptional activator β-catenin is the key mediator of the canonical Wnt signaling pathway. However, β-catenin does not itself bind DNA and thus functions via interaction with TCF/Lymphoid-enhancing factor (LEF) transcription factors. These proteins contain a high-mobility group (HMG) box that binds DNA in a sequence-specific manner. Thus, in the case of active Wnt signaling, β-catenin activates, in cooperation with proteins of the TCF/LEF family, the expression of a wide variety of target genes. The goal of this chapter is to describe the techniques used to elucidate the transcriptional control of versican by the β-catenin/TCF response elements in its promoter site and to demonstrate how this signaling may be assayed experimentally. These approaches provide insight into the transcriptional regulation of the versican gene and provide the basis for the identification of novel Wnt/β-catenin/TCF-regulated genes that are part of the signaling machinery regulating early embryogenesis, neoplasia, and cardiovascular remodeling.
Key wordsVersican Wnt pathway β-catenin TCF/LEF recognition site Luciferase Promoter activity EMSA
This work was supported in part by a Grant-in-Aid from the Heart and Stroke Foundation of British Columbia and Yukon.
- 15.Lin, H., Ignatescu, M., Wilson, J.E., Roberts, C.R., Horley, K.J., Winters, G.L., et al. (1996) Prominence of apolipoproteins B, (a), and E in the intimae of coronary arteries in transplanted human hearts: geographic relationship to vessel wall proteoglycans. J Heart Lung Transplant. 15, 1223–1232.PubMedGoogle Scholar
- 16.Lin, H., Wilson, J.E., Roberts, C.R., Horley, K.J., Winters, G.L., Costanzo, M.R., and McManus, B.M. (1996) Biglycan, decorin, and versican protein expression patterns in coronary arteriopathy of human cardiac allograft: distinctness as compared to native atherosclerosis. J Heart Lung Transplant. 15, 1233–1247.PubMedGoogle Scholar
- 23.Campbell, J.H. and Campbell, G.R. (1993) Culture techniques and their applications to studies of vascular smooth muscle. Clin Sci (Lond) 85, 501–513.Google Scholar