Stimulation of plasminogen activation by recombinant cellular prion protein is conserved in the NH2-terminal fragment PrP23-110.
The cellular prion protein (PrP(c)), tissue-type plasminogen activator (t-PA) and plasminogen are expressed in synaptic membranes in vivo. In the central nervous system the fibrinolytic system is associated with excitotoxin-mediated neurotoxicity and Alzheimer's disease. Recently binding of the disease associated isoform of the prion protein (PrP(Sc)) to plasminogen and stimulation of t-PA activity have been reported. In this study the interaction of PrP(c) and plasminogen was investigated using chromogenic assays in vitro. We found that plasmin is able to cleave recombinant PrP(c) at lysine residue 110 generating an NH(2)-terminal truncated molecule that has previously been described as a major product of PrP(c) metabolism. We further characterized the proteolytic fragments with respect to their ability to stimulate plasminogen activation in vitro. Our results show that the NH(2)-terminal part of PrP(c) spanning amino acids 23-110 (PrP23-110) together with low molecular weight heparin stimulates t-PA mediated plasminogen activation in vitro. The apparent rate constant was increased 57 fold in the presence of 800 nM PrP23-110. Furthermore, we compared the stimulation of t-PA activity by PrP(c) and beta-amyloid peptide (1-42). While the activity of the beta-amyloid was independent of low molecular weight heparin, PrP23-110 was approximately 4- and 37 fold more active than beta-amyloid in the absence or presence of low molecular weight heparin. In summary, plasmin cleaves PrP(c) in vitro and the liberated NH(2)-terminal fragment accelerates plasminogen activation. Cleavage of PrP c has previously been reported. Thus cleavage of PrP(c) enhancing plasminogen activation at the cell surface could constitute a regulatory mechanism of pericellular proteolysis.
Praus
Michael
M
Institut für Laboratoriumsmedizin und Pathobiochemie, Charité Berlin, Medizinische Fakultät der Humboldt Universität zu Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany. michael.praus@charite.de
Kettelgerdes
Gerhard
G
Baier
Michael
M
Holzhütter
Hermann-Georg
HG
Jungblut
Peter R
PR
Maissen
Manuela
M
Epple
Guido
G
Schleuning
Wolf-Dieter
WD
Köttgen
Eckart
E
Aguzzi
Adriano
A
Gessner
Reinhard
R
D000595:Amino Acid Sequence / Q000502:physiology; D016229:Amyloid beta-Peptides / Q000494:pharmacology; D005341:Fibrinolysin / Q000378:metabolism; D005342:Fibrinolysis / Q000502:physiology; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D010446:Peptide Fragments / Q000494:pharmacology; D010958:Plasminogen / Q000187:drug effects / Q000378:metabolism*; D018621:PrPC Proteins / Q000378:metabolism / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000378:metabolism
D016229:Amyloid beta-Peptides; D006495:Heparin, Low-Molecular-Weight; D010446:Peptide Fragments; D018621:PrPC Proteins; D011994:Recombinant Proteins; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin