The integrin PSI domain has an endogenous thiol isomerase function and is a novel target for antiplatelet therapy

作者：Guangheng Zhu, Qing Zhang, Emily C. Reddy, Naadiya Carrim, Yunfeng Chen, Xiaohong Xu, Miao Xu, Yiming Wang, Yan Hou, Li Ma, Yan Li, Rui Min, Tania N. Petruzziello-Pellegrini, Christopher Lavalle, Tyler W. Stratton, Xi Lei, Reheman Adili, Pingguo Chen, Cheng Zhu, John A. Wilkins, Richard O. Hynes, John Freedman, Heyu Ni · 发表于：Blood · 年份：2017 · DOI：10.1182/blood-2016-07-729400 · 被引用次数：77 · 研究领域：Platelet Disorders and Treatments、Cell Adhesion Molecules Research、Blood properties and coagulation

Integrins are a large family of heterodimeric transmembrane receptors differentially expressed on almost all metazoan cells. Integrin β subunits contain a highly conserved plexin-semaphorin-integrin (PSI) domain. The CXXC motif, the active site of the protein-disulfide-isomerase (PDI) family, is expressed twice in this domain of all integrins across species. However, the role of the PSI domain in integrins and whether it contains thiol-isomerase activity have not been explored. Here, recombinant PSI domains of murine β3, and human β1 and β2 integrins were generated and their PDI-like activity was demonstrated by refolding of reduced/denatured RNase. We identified that both CXXC motifs of β3 integrin PSI domain are required to maintain its optimal PDI-like activity. Cysteine substitutions (C13A and C26A) of the CXXC motifs also significantly decreased the PDI-like activity of full-length human recombinant β3 subunit. We further developed mouse anti-mouse β3 PSI domain monoclonal antibodies (mAbs) that cross-react with human and other species. These mAbs inhibited αIIbβ3 PDI-like activity and its fibrinogen binding. Using single-molecular Biomembrane-Force-Probe assays, we demonstrated that inhibition of αIIbβ3 endogenous PDI-like activity reduced αIIbβ3-fibrinogen interaction, and these anti-PSI mAbs inhibited fibrinogen binding via different levels of both PDI-like activity-dependent and -independent mechanisms. Importantly, these mAbs inhibited murine/human platelet aggregat...