In vitro selection and characterization of TCF-1 binding RNA aptamers.

TCF proteins are architectural transcription factors that bind to beta-catenin when the Wnt signaling pathway is activated. TCF-1 is specifically expressed in T-cell lineages and its interaction with beta-catenin is thought to be critical for early T-cell development. However, the mechanisms underlying activation of TCF-1 during T-cell development are not completely understood. With the aim of developing RNA aptamers that bind to TCF-1 and regulate its activity, we screened an RNA library consisting of random sequences of 70 nucleotides and were able to isolate aptamers that bind to TCF-1 with high affinity and specificity. We employed RNase footprinting to characterize the RNA structures and map their binding sites for TCF-1. It is hoped that the selected aptamers will regulate TCF-1 activity in vivo, thereby providing a unique tool for modulating TCF-1 function in early T-cell development.