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Heparanase activity in cultured endothelial cells
K Godder1, I Vlodavsky, A Eldor
1Department of Radiation Oncology, Memorial-Sloan Kettering Cancer Center, New York, New York 10021.
Journal of Cellular Physiology
|August 1, 1991
Summary
Endothelial cells (EC) possess heparanase, an enzyme that degrades heparan sulfate (HS) in the extracellular matrix (ECM). Unlike other cells, EC do not readily release this enzyme, impacting HS-regulated processes.
Area of Science:
- Cell Biology
- Biochemistry
- Extracellular Matrix Biology
Background:
- Heparan sulfate (HS) is a crucial component of the extracellular matrix (ECM) involved in cell signaling and tissue regulation.
- Heparanase is an endoglycosidase responsible for HS degradation, but its presence and regulation in endothelial cells (EC) are not fully understood.
Purpose of the Study:
- To identify and characterize heparanase activity in cultured endothelial cells (EC).
- To investigate the requirements for heparanase release from EC and its role in HS degradation within the subendothelial ECM.
Main Methods:
- Incubation of metabolically labeled ECM with intact EC, EC lysates, or conditioned media.
- Analysis of released sulfated products using gel filtration (Sepharose 6B).
- Assessment of heparanase activity in various EC types and under different stimulation conditions.
Main Results:
- Human umbilical vein endothelial cells (HUVEC) and human saphenous vein endothelial cells (HSVEC) lysates exhibited significant heparanase activity, degrading HS into smaller fragments.
- Other EC types showed varying levels of activity, with some exhibiting none.
- Intact HUVEC displayed low intrinsic activity, and enzyme release was not induced by various agents as long as cells remained viable.
Conclusions:
- Endothelial cells possess intracellular heparanase but differ from other cell types in their limited ability to release the enzyme.
- The inability of EC to readily release heparanase suggests a unique regulatory mechanism for HS degradation in these cells.
- Heparanase release during vessel wall injury could play a role in regulating EC and smooth muscle growth in processes like wound healing and atherosclerosis.