Active matrix metalloproteinase-2 promotes apoptosis of hepatic stellate cells via the cleavage of cellular N-cadherin.
OBJECTIVE
Hepatic stellate cells (HSC) are known to synthesise excess matrix that characterises liver fibrosis and cirrhosis. Activated HSC express the matrix-degrading matrix metalloproteinase enzymes (MMPs) and their tissue inhibitors (TIMPs). During spontaneous recovery from experimental liver fibrosis, the expression of TIMP-1 declines and hepatic collagenolytic activity increases. This is accompanied by HSC apoptosis. In this study, we examine a potential mechanism whereby MMP activity might induce HSC apoptosis by cleaving N-cadherin at the cell surface.


RESULTS
N-cadherin expression was upregulated in human HSC during activation in culture. Addition of function-blocking antibodies or a peptide targeting the extracellular domain of N-cadherin, to cultured HSC, promoted apoptosis. During apoptosis, there was cleavage of N-cadherin into 20-100 kDa fragments. MMP-2 became activated early during HSC apoptosis and directly cleaved N-cadherin in vitro. Addition of activated MMP-2 to HSCs in culture resulted in enhanced apoptosis and loss of N-cadherin.


CONCLUSIONS
Together, these studies identify a role for both N-cadherin and MMP-2 in mediating HSC apoptosis, where N-cadherin works to provide a cell survival stimulus and MMP-2 promotes HSC apoptosis concomitant with N-cadherin degradation.
Hartland
Stephen N
SN
MRC/University of Edinburgh Centre for Inflammation Research, Edinburgh, UK.
Murphy
Frank
F
Aucott
Rebecca L
RL
Abergel
Armand
A
Zhou
Xiaoying
X
Waung
Julian
J
Patel
Nishit
N
Bradshaw
Catherine
C
Collins
Jane
J
Mann
Derek
D
Benyon
R Christopher
RC
Iredale
John P
JP
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects; D015820:Cadherins / Q000378:metabolism*; D002251:Carbon Tetrachloride; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004789:Enzyme Activation; D005912:Gliotoxin / Q000494:pharmacology; D055166:Hepatic Stellate Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000139:chemically induced / Q000201:enzymology* / Q000473:pathology; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors
D015703:Antigens, CD; C050361:CDH2 protein, human; D015820:Cadherins; C489083:Cdh2 protein, mouse; D011994:Recombinant Proteins; D005912:Gliotoxin; D003513:Cycloheximide; D002251:Carbon Tetrachloride; D053148:Caspase 3; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse