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Human plasma fibronectin as a substrate for human urokinase
L I Gold1, R Schwimmer, J P Quigley
1NYU Medical Center, Department of Pathology, New York 10016.
The Biochemical Journal
|September 1, 1989
Summary
Urokinase (UK) directly degrades plasma fibronectin (Fn), an extracellular matrix component. This breakdown may facilitate tumor cell invasion and metastasis by releasing Fn.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Malignant transformation involves increased protease expression, aiding tumor cell invasion.
- Proteases degrade extracellular matrices, facilitating tumor cell movement.
- Plasma fibronectin (Fn) is a key extracellular matrix component.
Purpose of the Study:
- To investigate if plasma fibronectin (Fn) is a direct substrate for urokinase (UK).
- To elucidate the mechanism and products of UK-mediated Fn degradation.
Main Methods:
- Incubation of human plasma Fn with human UK under plasminogen-free conditions.
- Time- and dose-dependent analysis of Fn cleavage.
- Analysis of proteolytic digestion products using SDS-PAGE (implied).
Main Results:
- UK directly cleaved human plasma Fn in a time- and dose-dependent manner.
- Cleavage resulted in the formation of three fragments (210, 200, and 25 kDa) from the dimeric Fn.
- UK likely cleaves Fn at two sites, N-terminal to interchain disulfide bonds.
Conclusions:
- Plasma fibronectin is a direct substrate for urokinase (UK).
- UK-mediated degradation of Fn may contribute to tumor cell invasion and metastasis.
- Tumor cells with high UK levels may degrade extracellular Fn.