Screening of nucleic acids affinity to recombinant human TGF-? RⅡ / 第三军医大学学报

ABSTRACT

Objective To select the aptamer to an extracellular soluble fragment of recombinant human TGF-? receptor Ⅱ (TGF-? RⅡ) in order to antagonize TGF-? effectively by using systematic evolution of ligants by exponential enrichment (SELEX). Methods Initial random RNA library was transcripted in vitro from ssDNA 5′-TAATACGACTCACTATAGGGAGGACGATGCGG-N60-CAGACGACTCCCCGA-3′; rhTGF-? RⅡ was used as target protein. Totally,selection of 8 times was carried out in SELEX experiment. Membrane binding assay was performed to detect the evolution of enriched RNA library; Electrophoretic mobility shift assay (EMSA) was done to determine the affinity between the selected nucleic acid sequence and TGF-? RⅡ. Results Evolution of the enriched RNA library along the increased affinity to TGF-? RⅡ was observed with the development of selection. Two types of dominant sequences were isolated and named as sequence A and sequence B. In membrane binding assay,both sequences A and B showed obvious affinity to TGF-? RⅡ. However,no retarded bands were seen in EMSA. Conclusion The affinity of sequences A and B to TGF-? RⅡ is beyond satisfaction. However,possible sequences with improved affinity to TGF-? RⅡ can be selected by post-SELEX on the basis of candidate sequences A and B.