Glucose-induced endothelial heparanase secretion requires cortical and stress actin reorganization.
OBJECTIVE
Heparanase, which specifically cleaves carbohydrate chains of heparan sulfate, has been implicated in the pathology of diabetes-associated complications. Using high glucose (HG) to replicate hyperglycaemia observed following diabetes, the present study was designed to determine the mechanism by which HG initiates endothelial heparanase secretion.


RESULTS
To examine the effect of HG on endothelial heparanase, bovine coronary artery endothelial cells were incubated with 25 mM glucose. Strategies using different agonists and antagonists were used to determine the mechanism behind HG-induced heparanase secretion. In endothelial cells, heparanase colocalized with lysosomes predominately around the nucleus, and HG caused its dispersion towards the plasma membrane for subsequent secretion. ATP release, purinergic receptor activation, cortical actin disassembly, and stress actin formation were essential for this HG-induced heparanase secretion. With HG, phosphorylation of filamin likely contributed to the cortical actin disassembly, whereas Ca(2+)/calmodulin-dependent protein kinase II and p38 mitogen-activated protein kinase /heat shock protein 25 phosphorylation mediated stress actin formation. The endothelial secreted heparanase in response to HG demonstrated endoglucuronidase activity, cleaved heparan sulfate, and released attached proteins like lipoprotein lipase and basic fibroblast growth factor.


CONCLUSIONS
Our results suggest that HG is a potent stimulator of endothelial heparanase secretion. These data may assist in devising new therapeutic strategies to prevent or delay the cardiovascular complications associated with diabetes.
Wang
Fang
F
Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146, East Mall, Vancouver, BC, Canada V6T 1Z3.
Wang
Ying
Y
Kim
Min Suk
MS
Puthanveetil
Prasanth
P
Ghosh
Sanjoy
S
Luciani
Dan S
DS
Johnson
James D
JD
Abrahani
Ashraf
A
Rodrigues
Brian
B
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D018920:Coculture Techniques; D003285:Contractile Proteins / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D064448:Filamins; D005947:Glucose / Q000378:metabolism*; D005966:Glucuronidase / Q000378:metabolism*; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006497:Heparan Sulfate / Q000378:metabolism; D006943:Hyperglycemia / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000201:enzymology; D010766:Phosphorylation; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058473:Receptors, Purinergic P2Y2; D022502:Stress Fibers / Q000378:metabolism*; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000099175:Heparanase
D000255:Adenosine Triphosphate; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D003285:Contractile Proteins; D064448:Filamins; D005947:Glucose; D005966:Glucuronidase; D055551:HSP27 Heat-Shock Proteins; D006497:Heparan Sulfate; D008840:Microfilament Proteins; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; D048051:p38 Mitogen-Activated Protein Kinases; D000099175:Heparanase