Legumain and cathepsin-L expression in human unstable carotid plaque.
OBJECTIVE
The cysteine protease, legumain, is thought to have a role in the processing and activation of proteases such as cathepsin-L, which have been implicated in plaque rupture. This study aimed to determine: if legumain activity is up-regulated in unstable areas of plaque; the effect of legumain over-expression on the activity of cathepsin-L and the effect of mutation of the legumain RGD sequence on its cellular location.


RESULTS
Legumain was measured in human carotid plaque extracts (n=17) using a novel ELISA and modified activity assay. Unstable regions of plaque contained more than twice the amount of legumain protein (P<0.001) and activity (P<0.03) compared with stable regions of the same plaque. Over-expression of legumain in THP-1 macrophages using an adenoviral construct resulted in the processing of cathepsin-L from its 30kDa to its 25kDa form compared with controls.


CONCLUSIONS
Unstable regions of plaque contain increased levels of active legumain. Over-expression of legumain in macrophages alters intracellular processing of cathepsin-L to its mature 25kDa form. This may be a means by which legumain could contribute to plaque instability.
Mattock
K L
KL
King's College London BHF Centre, Cardiovascular Division, NIHR Biomedical Research Centre at Guy's & St Thomas' NHS Foundation Trust, UK.
Gough
P J
PJ
Humphries
J
J
Burnand
K
K
Patel
L
L
Suckling
K E
KE
Cuello
F
F
Watts
C
C
Gautel
M
M
Avkiran
M
M
Smith
A
A
D002340:Carotid Artery Diseases / Q000378:metabolism*; D056668:Cathepsin L / Q000096:biosynthesis*; D003546:Cysteine Endopeptidases / Q000096:biosynthesis*; D006801:Humans; D066298:In Vitro Techniques; D000099240:Asparaginyl Endopeptidase
D056668:Cathepsin L; D003546:Cysteine Endopeptidases; D000099240:Asparaginyl Endopeptidase