title: Prostate-specific membrane antigen (PSMA)-mediated laminin proteolysis generates a pro-angiogenic peptide.
abstract: Prostate-specific membrane antigen (PSMA) is a membrane-bound glutamate carboxypeptidase expressed in a number of tissues. PSMA participates in various biological functions depending on the substrate available in the particular tissue; in the brain, PSMA cleaves the abundant neuropeptide N-acetyl-aspartyl-glutamate to regulate release of key neurotransmitters, while intestinal PSMA cleaves polyglutamated peptides to supply dietary folate. PSMA expression is also progressively upregulated in prostate cancer where it correlates with tumor progression as well as in tumor vasculature, where it regulates angiogenesis. The previous research determined that PSMA cleavage of small peptides generated via matrix metalloprotease-mediated proteolysis of the extracellular matrix protein laminin potently activated endothelial cells, integrin signaling and angiogenesis, although the specific peptide substrates were not identified. Herein, using enzymatic analyses and LC/MS, we unequivocally demonstrate that several laminin-derived peptides containing carboxy-terminal glutamate moieties (LQE, IEE, LNE) are bona fide substrates for PSMA. Subsequently, the peptide products were tested for their effects on angiogenesis in various models. We report that LQ, the dipeptide product of PSMA cleavage of LQE, efficiently activates endothelial cells in vitro and enhances angiogenesis in vivo. Importantly, LQE is not cleaved by an inactive PSMA enzyme containing an active site mutation (E424S). Endothelial cell activation by LQ was dependent on integrin beta-1-induced activation of focal adhesion kinase. These results characterize a novel PSMA substrate, provide a functional rationale for the upregulation of PSMA in cancer cells and tumor vasculature and suggest that inhibition of PSMA could lead to the development of new angiogenic therapies.
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Conway
authors.affiliation: Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, 21205, USA.|Department of Molecular and Comparative Pathobiology, Johns Hopkins University, Baltimore, MD, 21205, USA.
authors.forename: Camilo
authors.initials: C
authors.lastname: Rojas
authors.affiliation: Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, 21205, USA.
authors.forename: Jesse
authors.initials: J
authors.lastname: Alt
authors.affiliation: Laboratory of Structural Biology, Institute of Biotechnology, Czech Academy of Sciences, 25250, Vestec, Czech Republic.
authors.forename: Zora
authors.initials: Z
authors.lastname: Nováková
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Spencer M
authors.initials: SM
authors.lastname: Richardson
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Tori C
authors.initials: TC
authors.lastname: Rodrick
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Julio L
authors.initials: JL
authors.lastname: Fuentes
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Noah H
authors.initials: NH
authors.lastname: Richardson
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Attalla
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Samantha
authors.initials: S
authors.lastname: Stewart
authors.affiliation: Department of Biology, College of Liberal Arts and Science, Lipscomb University, Nashville, TN, 37204, USA.
authors.forename: Beshoy
authors.initials: B
authors.lastname: Fahmy
authors.affiliation: Laboratory of Structural Biology, Institute of Biotechnology, Czech Academy of Sciences, 25250, Vestec, Czech Republic.
authors.forename: Cyril
authors.initials: C
authors.lastname: Barinka
authors.affiliation: Center for Vascular Biology, The University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT, 06030, USA.
authors.forename: Mallika
authors.initials: M
authors.lastname: Ghosh
authors.affiliation: Center for Vascular Biology, The University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT, 06030, USA. lshapiro@uchc.edu.
authors.forename: Linda H
authors.initials: LH
authors.lastname: Shapiro
authors.affiliation: Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD, 21205, USA. bslusher@jhmi.edu.|Department of Neurology, Johns Hopkins University, Baltimore, MD, 21205, USA. bslusher@jhmi.edu.
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Slusher
mesh_terms: D042501:Angiogenic Proteins / Q000378:metabolism*; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion; D004151:Dipeptides / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D043425:Glutamate Carboxypeptidase II / Q000235:genetics / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D006868:Hydrolysis; D019012:Integrin beta1 / Q000378:metabolism; D007797:Laminin / Q000378:metabolism*; D008297:Male; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D018919:Neovascularization, Physiologic; D010446:Peptide Fragments / Q000378:metabolism; D059748:Proteolysis; D013379:Substrate Specificity
chemical_list: D042501:Angiogenic Proteins; D000954:Antigens, Surface; D004151:Dipeptides; D019012:Integrin beta1; D007797:Laminin; D050505:Mutant Proteins; D010446:Peptide Fragments; C027172:isospaglumic acid; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II
keywords: Angiogenesis; Extracellular matrix; GCPII; Laminin; PSMA; Peptides