Construction and function of a fusion protein consisting of a single‑chain variable fragment and RBP4

Preeclampsia is one of the complications of pregnancy. Often presenting as new‑onset hypertension and proteinuria after 20 weeks of gestation in a previously normotensive patient, it can progress rapidly to serious complications, and is a leading cause of maternal and perinatal mortality. The present study involved the construction of a fusion protein consisting of a single‑chain antibody variable fragment (scFv) and the retinol‑binding protein 4 (RBP4). and investigated the function of this protein. The MaxCodon™ Optimization Program (v13) was used to optimize the amino acid sequence of the scFv‑RBP4 fusion protein and full‑length splice primers were designed by Detai Bio Tech. The scFv‑RBP4 gene was inserted into a proEM expression vector using double digestion, and the accuracy of the final expression vector was confirmed by restriction enzyme digestion and sequencing. The plasmid was transfected into DH5α competent cells and the plasmid was extracted from cells using a transfection reagent. The plasmid and scFv‑RBP4 fusion protein were purified by nickel‑iminodiacetic acid affinity chromatography. Cell proliferation was determined using the Cell Counting Kit‑8 assay and cell invasion was measured using a Transwell invasion assay. The results from the digestion and sequencing showed that the scFv‑RBP4 fusion protein was constructed correctly and that the purity of the target protein was >90%. The scFv‑RBP4 fusion protein was stably expressed in 293T cells. The scFv‑RBP4 fusion protein was extracted from the 293T cells and functional studies were carried out. The scFv‑RBP4 fusion protein significantly increased the invasion, but not the proliferation, of HTR8/SVneo cells.