Expression and Functional Characterization of Recombinant Human Vascular Cell Adhesion Molecule-1 (VCAM1) Synthesized by Baculovirus-Infected Insect Cells

Abstract

Vascular cell adhesion molecule-i (VCAM1) is a cell surface glycoprotein produced by the vascular endothelium, as well as on macrophage-like and dendritic cell types, in response to certain inflammatory stimuli. VCAM1 interacts with the integrin VLA4 present on mononuclear leukocytes. We have isolated the cDNA for VCAM1 using RT-PCR by screening a cDNA library from IL-1β-activated human endothelial cells. To obtain large quantities of VCAM1 for structural and functional studies, we have produced this protein in insect cells using a baculovirus expression system. Insect cells infected with recombinant virus synthesized human VCAM1 at levels exceeding 3% of total cellular protein following 72 h postinfection. VCAM1-expressing insect cells were shown to bind specifically to a variety of VLA4 expressing cell lines (Jurkat, THP-1, U937). Thus, recombinant VCAM1 protein produced in the baculovirus expression system was localized to the cell surface and was biologically active. Large-scale availability of this adhesion protein should enhance efforts toward the discovery of new antiadhesive (anti-inflammatory and antiatherogenic) therapeutics.