Recombinant expression in human cells of active integrin alpha 1 beta 1-blocking RTS-disintegrin jerdostatin

Jerdostatin, an RTS short disintegrin cloned from Protobothrops jerdonii and recombinantly produced in Escherichia coli, is a potent and specific antagonist of the alpha(1)beta(1) integrin. Jerdostatin selectively blocked the adhesion of alpha(1)beta(1)-K562 cell to collagens I and IV in vitro and angiogenesis in vivo. Here we report the recombinant production of jerdostatin in a mammalian cell system, a prerequisite for developing a conditional transgenic mouse to investigate the effect of systemic expression of jerdostatin on tumor development. For proper export of jerdostatin, a secretion leader sequence was engineered at the protein's N-terminus. A FLAG epitope was also included at the N-terminus of the mature disintegrin to facilitate its isolation and characterization of recombinant jerdostatin (rJerd). This pRc-CMV/FLAG-rJerd construct was transiently expressed in HEK-293 cells and was efficiently secreted into the culture medium. rJerd bound to recombinant soluble alpha(1)beta(1) integrin in a saturable and cation-independent manner. Soluble rJerd also inhibited the binding of alpha(1)beta(1) integrin to the CB3 fragment of collagen IV in a dose-dependent manner (IC(50) 570 nM). Mammalian cell-expressed jerdostatin disrupted the adhesion of RuGli cells to collagen IV. Our results highlight pRc-CMV/FLAG-rJerd as a suitable construct for expressing soluble active alpha(1)beta(1)-blocking jerdostatin in a mammalian cell system.