Competition between plasminogen and procathepsin B as a probe to demonstrate the in vitro activation of procathepsin B by the tissue plasminogen activator.
The tissue plasminogen activator (tPA) was found to activate in vitro the procathepsin B purified from malignant ascitic fluids. This activation was time and dose dependent, and was associated with the processing of procathepsin B. The present study shows that tPA is a fast activator of procathepsin B in a neutral pH range, such that generation of cathepsin B activity and processing of procathepsin B are achieved after a 5-min incubation time at 37 degrees C, pH 7.4. In contrast, competition between plasminogen and procathepsin B was observed for the activation and processing by tPA. From these findings, a plasminogen activator pathway for procathepsin B activation related to the plasminogen concentration may exist. In vivo this pathway may be involved in a proteolytic cascade linked to invasion and metastasis.
Biochimie des Protéases, Faculté de Médecine Broussais Hôtel-Dieu, Université Pierre et Marie Curie, Paris, France.
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V
Dalet-Fumeron
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Boudjennah
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Pagano
D001667:Binding, Competitive; D002401:Cathepsin B / Q000378:metabolism*; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D010958:Plasminogen / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
D004792:Enzyme Precursors; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; C057832:procathepsin B; D002401:Cathepsin B