title: Genome-wide protein QTL mapping identifies human plasma kallikrein as a post-translational regulator of serum uPAR levels.
abstract: The soluble cleaved urokinase plasminogen activator receptor (scuPAR) is a circulating protein detected in multiple diseases, including various cancers, cardiovascular disease, and kidney disease, where elevated levels of scuPAR have been associated with worsening prognosis and increased disease aggressiveness. We aimed to identify novel genetic and biomolecular mechanisms regulating scuPAR levels. Elevated serum scuPAR levels were identified in asthma (n=514) and chronic obstructive pulmonary disease (COPD; n=219) cohorts when compared to controls (n=96). In these cohorts, a genome-wide association study of serum scuPAR levels identified a human plasma kallikrein gene (KLKB1) promoter polymorphism (rs4253238) associated with serum scuPAR levels in a control/asthma population (P=1.17 × 10(-7)), which was also observed in a COPD population (combined P=5.04 × 10(-12)). Using a fluorescent assay, we demonstrated that serum KLKB1 enzymatic activity was driven by rs4253238 and is inverse to scuPAR levels. Biochemical analysis identified that KLKB1 cleaves scuPAR and negates scuPAR's effects on primary human bronchial epithelial cells (HBECs) in vitro. Chymotrypsin was used as a proproteolytic control, while basal HBECs were used as a control to define scuPAR-driven effects. In summary, we reveal a novel post-translational regulatory mechanism for scuPAR using a hypothesis-free approach with implications for multiple human diseases.
authors.affiliation: 2Division of Respiratory Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK. michael.portelli@nottingham.ac.uk.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Portelli
authors.forename: Mateusz
authors.initials: M
authors.lastname: Siedlinski
authors.forename: Ceri E
authors.initials: CE
authors.lastname: Stewart
authors.forename: Dirkje S
authors.initials: DS
authors.lastname: Postma
authors.forename: Maartje A
authors.initials: MA
authors.lastname: Nieuwenhuis
authors.forename: Judith M
authors.initials: JM
authors.lastname: Vonk
authors.forename: Peter
authors.initials: P
authors.lastname: Nurnberg
authors.forename: Janine
authors.initials: J
authors.lastname: Altmuller
authors.forename: Miriam F
authors.initials: MF
authors.lastname: Moffatt
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wardlaw
authors.forename: Stuart G
authors.initials: SG
authors.lastname: Parker
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Connolly
authors.forename: Gerard H
authors.initials: GH
authors.lastname: Koppelman
authors.forename: Ian
authors.initials: I
authors.lastname: Sayers
mesh_terms: D001249:Asthma / Q000097:blood; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002478:Cells, Cultured; D055106:Genome-Wide Association Study / Q000379:methods*; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics; D020842:Plasma Kallikrein / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood; D012333:RNA, Messenger / Q000235:genetics; D055293:Receptors, Urokinase Plasminogen Activator / Q000097:blood* / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D055293:Receptors, Urokinase Plasminogen Activator; D020842:Plasma Kallikrein
keywords: GWAS; HBECs; cellular proliferation and wound repair; proteolysis; respiratory disease