Laminar shear stress inhibits cathepsin L activity in endothelial cells.
OBJECTIVE
The cysteine proteases, cathepsins, have been implicated in vascular remodeling and atherosclerosis, processes known to be regulated by shear stress. It is not known, however, whether shear regulates cathepsins. We examined the hypothesis that shear stress regulates cathepsin activity in endothelial cells.


RESULTS
Mouse aortic endothelial cells (MAECs) exposed to atheroprotective, unidirectional laminar shear (LS) degraded significantly less BODIPY-labeled elastin and gelatin in comparison to static and proatherogenic oscillatory shear (OS). The cathepsin inhibitor E64 also reduced this activity. Gelatin zymography showed that cathepsin activity of MAECs was blunted by LS exposure and by a cathepsin L inhibitor but not by cathepsin B and S inhibitors, whereas a cathepsin K inhibitor had a minor effect. Cathepsin L siRNA knocked down cathepsin L expression, gelatinase, and elastase activity in OS and static MAECs. A partial reduction of cathepsin B protein raised the possibility that the siRNA effect on the matrix protease activity could have been attributable to cathepsin L or B. Cathepsin B activity study using the synthetic peptide showed it was not regulated by shear.


CONCLUSIONS
These results suggest that cathepsin L is a shear-sensitive matrix protease and that it may play an important role in flow-mediated vascular remodeling and atherogenic responses.
Platt
Manu O
MO
Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, 308D WMB, Atlanta, GA 30322, USA.
Ankeny
Randall F
RF
Jo
Hanjoong
H
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000201:enzymology*; D002401:Cathepsin B / Q000378:metabolism; D056668:Cathepsin L; D002403:Cathepsins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000201:enzymology*; D005109:Extracellular Matrix / Q000201:enzymology; D018093:Gelatinases / Q000378:metabolism; D051379:Mice; D010196:Pancreatic Elastase / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D013314:Stress, Mechanical
D034741:RNA, Small Interfering; D002403:Cathepsins; D010447:Peptide Hydrolases; D010196:Pancreatic Elastase; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L; C534278:Ctsl protein, mouse; D018093:Gelatinases