Cathepsin V, but not cathepsins L, B and K, may release angiostatin-like fragments from plasminogen.
Abstract Cathepsin V is a lysosomal cysteine peptidase highly expressed in corneal epithelium; however, its function in the eye is still unknown. Here, we describe the capability of cathepsin V to hydrolyze plasminogen, which is also expressed in human cornea at levels high enough to produce physiologically relevant amounts of angiostatin-related molecules. The co-localization of these two proteins suggests an important role for the enzyme in the maintenance of corneal avascularity, essential for optimal visual performance. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of plasminogen digestion by cathepsin V revealed the generation of three major products of 60, 50 and 40 kDa, which were electrotransferred to polyvinylidene difluoride membranes and excised for characterization. NH(2)-terminal amino acid sequencing of these fragments revealed the sequences EKKVYL, TEQLAP and LLPNVE, respectively. These data are compatible with cleavage sites at plasminogen F94-E95, S358-T359 and V468-L469 peptide bonds generating fragments of the five-kringle domains. In contrast, we did not detect any plasminogen degradation by cathepsins B, K and L. Using a Matrigel assay, we confirmed the angiogenesis inhibition activity on endothelial cells caused by plasminogen processing by cathepsin V. Our results suggest a novel physiological role for cathepsin V related to the control of neovascularization in cornea.
Puzer
Luciano
L
Faculty of Dentistry and UBC Centre for Blood Research, 2350 Health Sciences Mall, Vancouver V6T1Z3, BC, Canada. lpuzer@yahoo.com.br
Barros
Nilana M T
NM
Paschoalin
Thaysa
T
Hirata
Izaura Y
IY
Tanaka
Aparecida S
AS
Oliveira
Marcelo C
MC
Brömme
Dieter
D
Carmona
Adriana K
AK
D020533:Angiogenesis Inhibitors; D043168:Angiostatins; D002401:Cathepsin B / Q000378:metabolism; D056657:Cathepsin K; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism*; D003315:Cornea / Q000098:blood supply; D003546:Cysteine Endopeptidases / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects; D019573:Epithelium, Corneal / Q000187:drug effects; D006801:Humans; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D010446:Peptide Fragments / Q000032:analysis*; D010958:Plasminogen / Q000378:metabolism
D020533:Angiogenesis Inhibitors; D010446:Peptide Fragments; D043168:Angiostatins; D010958:Plasminogen; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L; C534130:CTSK protein, human; D056657:Cathepsin K; C117627:CTSV protein, human