Recombinant coagulation factor VIIa--from molecular to clinical aspects of a versatile haemostatic agent.

Recombinant factor VIIa (rFVIIa, NovoSeven) is currently the only bypassing agent produced by recombinant technology for the treatment of haemophiliacs whose disease is complicated by inhibitory antibodies. In addition, recombinant production of FVIIa has made it widely available for a variety of purposes and accelerated the growth of our knowledge about FVIIa by generating an abundance of clinical and biochemical data. This fascinating molecule has turned out to be a safe haemostatic agent with great potential in the clinic and has inspired the generation of improved variants currently in (pre-)clinical testing.

More than one intracellular processing bottleneck delays the secretion of coagulation factor VII.

Coagulation factor VII (FVII) is a vitamin K-dependent glycoprotein that undergoes extensive post-translational modification prior to secretion. Secretion of FVII proteins from producer cells is a slow process. To identify bottlenecks for the transport of FVII through the secretory pathway of FVII-producing cells, we analysed the processing of intracellular FVII by pulse-chase of FVII producing CHO cells followed by radioimmuno precipitation, SDS-PAGE, and autoradiography.

All post-translational modifications except propeptide cleavage are required for optimal secretion of coagulation factor VII.

Human coagulation factor VII (FVII) has two N-glycosylation sites (N145 and N322) and two O-glycosylation sites (S52 and S60). In transiently transfected COS-7 cells, all combinations of N- and O-glycosylation knock-out mutations reduced the release of FVII to the medium. Pulse-chase analysis of CHO-K1 cell lines expressing recombinant FVII demonstrated that virtually all wild-type FVII synthesized was secreted from the cells, whereas both N- and O-glycosylation knock-out mutations induced partial intracellular degradation of the synthesized FVII.

Posttranslational N-glycosylation takes place during the normal processing of human coagulation factor VII.

N-glycosylation is normally a cotranslational process that occurs during translocation of the nascent protein to the endoplasmic reticulum. In the present study, however, we demonstrate posttranslational N-glycosylation of recombinant human coagulation factor VII (FVII) in CHO-K1 and 293A cells. Human FVII has two N-glycosylation sites (N145 and N322).