EXPRESSION AND PURIFICATION OF BIOLOGICALLY-ACTIVE PORCINE FOLLICLE-STIMULATING-HORMONE IN INSECT CELLS BEARING A BACULOVIRUS VECTOR

Biologically active recombinant porcine FSH (rec-pFSH) free from the c ognate pituitary glycoprotein hormone LH was produced. It was synthesi zed by a baculovirus vector-insect cell system using two cDNAs encodin g the glycoprotein alpha and FSH beta subunits. Its antigenicity was t he same as that of pFSH prepared from the pituitary. Glycosylation of rec-pFSH was shown by tunicamycin treatment but the molecular mass of each subunit was lower than that of pituitary-derived FSH, because of the absence of trimming of terminal sugars in insect cells. Rec-pFSH w as secreted into the culture medium at about 1 mg/l and purified in si x fractions, because of the heterogeneity of the sugar group, by S-Sep harose and concanavalin A-Sepharose column chromatography. The biologi cal activity of rec-pFSH was examined by measuring its effect on proge sterone secretion from porcine granulosa cells and germinal vesicle br eakdown (GVBD) of porcine oocytes. It showed adequate activity with re spect to progesterone secretion, although some fractions rich in the s ugar group showed lower activity than that of pituitary-derived FSH. I t exhibited higher GVBD activity than that of pituitary-derived FSH at concentrations as low as 1 ng/ml. These results demonstrate that the baculovirus vector-insect cell system can provide biologically active rec-pFSH.