Implantation serine proteinase 2 is a monomeric enzyme with mixed serine proteolytic activity and can silence signalling via proteinase activated receptors
Implantation serine proteinase 2 (ISP2), a S1 family serine proteinase, is known for its role in the critical processes of embryo hatching and implantation in the mouse uterus. Native implantation serine proteinases (ISPs) are co-expressed and co-exist as heterodimers in uterine and
blastocyst tissues. The ISP1–ISP2 enzyme complex shows trypsin-like substrate specificity. In contrast, we found that ISP2, isolated as a 34 kDa monomer from a Pichia pastoris expression system, exhibited a mixed serine proteolytic substrate specificity, as determined by a phage
display peptide cleavage approach and verified by the in vitro cleavage of synthetic peptides. Based upon the peptide sequence substrate selectivity, a database search identified many potential ISP2 targets of physiological relevance, including the proteinase activated receptor 2 (PAR2). The
in vitro cleavage studies with PAR2-derived peptides confirmed the mixed substrate specificity of ISP2. Treatment of cell lines expressing proteinase-activated receptors (PARs) 1, 2, and 4 with ISP2 prevented receptor activation by either thrombin (PARs 1 and 4) or trypsin (PAR2). The disarming
and silencing of PARs by ISP2 may play a role in successful embryo implantation.
Keywords: exposition sur phage; implantation; phage display; proteinase activated receptors; protéases à sérine; récepteurs activés par les protéases; serine proteinases; spécificité de substrat; substrate specificity
Document Type: Research Article
Affiliations: 1: Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada. 2: Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
Publication date: 01 January 2013
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