DECIDUAL PROLACTIN-RELATED PROTEIN - HETEROLOGOUS EXPRESSION AND CHARACTERIZATION

As a first step in understanding the role of decidual PRL-related prot ein (dPRP) during pregnancy, we have generated recombinant dPRP protei n. In this report, we present data on the generation, purification, an d characterization of recombinant dPRP protein. The dPRP complementary DNA was subcloned into the pMSXND vector, and the vector was transfec ted into Chinese hamster ovary (CHO) cells by electroporation. After a ppropriate selection, amplification, and induction procedures, recombi nant dPRP was purified from conditioned medium of the CHO-dPRP cells u sing ultrafiltration, size-exclusion chromatography, and reverse phase HPLC. Recombinant dPRP was found to possess electrophoretic mobility, immunoreactivity, and N-terminal amino acid sequence identical to tho se of dPRP isolated from decidual tissue. Polyclonal antibodies were g enerated to the recombinant dPRP and used for Western blot analysis. d PRP is capable of binding heparin, and a significant fraction of synth esized dPRP resides within the decidual extracellular matrix. Recombin ant dPRP failed to bind to PRL receptors and showed no stimulatory act ivity in the PRL-dependent rat Nb-2 lymphoma cell proliferation assay. Additional studies have shown that heterologous expression of dPRP in CHO cells significantly increased the ability of CHO cells to form tu mors in athymic mice. In conclusion, recombinant dPRP possesses charac teristics similar to those of dPRP of decidual origin and is a heparin -binding protein that may facilitate the establishment of pregnancy.