Von Willebrand factor targets IL-8 to Weibel-Palade bodies in an endothelial cell line.

Vascular endothelial cells are able to store the chemotactic cytokine interleukin-8 (IL-8) in specialized storage vesicles, Weibel-Palade bodies, together with von Willebrand factor (VWF) and P-selectin. We investigated whether VWF plays a role in the sorting of IL-8 into these organelles. We examined the effect of VWF expression on IL-8 targeting in an endothelial cell line (EC-RF24).

Intracellular accumulation of factor VIII induced by missense mutations Arg593-->Cys and Asn618-->Ser explains cross-reacting material-reduced haemophilia A.

Patients with cross-reacting material (CRM)-reduced haemophilia A exhibit reduced levels of factor VIII antigen. In this study, we determined the molecular basis of the genetic defect in the factor VIII gene induced by either the Arg593-->Cys or the Asn618-->Ser missense mutation, identified in two CRM-reduced haemophilia A patients. We introduced either the Arg593-->Cys or the Asn618-->Ser mutation into a B-domain-deleted factor VIII cDNA and expressed the modified cDNAs in C127 cells.

Intracellular retention of a factor VIII protein with an Arg2307-->Gln mutation as a cause of haemophilia A.

Substitution of Arg2307 by Gln in factor VIII has been found to be associated with mild to moderate haemophilia A [Gitschier, Wood, Shuman and Lawn (1986) Science 232, 1415-1416]. We have introduced this particular point mutation into a B-domain-deleted factor VIII cDNA and expressed the modified cDNA in C127 cells. Cells expressing the resulting protein, termed des-(868-1562)-factor VIII-R2307Q, were compared with those expressing the previously characterized des-(868-1562)-factor VIII.

Characterization of des-(741-1668)-factor VIII, a single-chain factor VIII variant with a fusion site susceptible to proteolysis by thrombin and factor Xa.

A factor VIII variant has been characterized in which the heavy chain is directly fused to the light chain. Des-(741-1668)-factor VIII lacks the processing site at Arg1648, as Arg740 of the heavy chain is fused to Ser1669 of the light chain. The sequence of the fusion site is similar to that of other cleavage sites in factor VIII.