Granzyme B induces smooth muscle cell apoptosis in the absence of perforin: involvement of extracellular matrix degradation.

TitleGranzyme B induces smooth muscle cell apoptosis in the absence of perforin: involvement of extracellular matrix degradation.
Publication TypeJournal Article
Year of Publication2004
AuthorsChoy, JC, H Y Hung, V, Hunter, AL, Cheung, PK, Motyka, B, Goping, ISwie, Sawchuk, T, R Bleackley, C, Podor, TJ, McManus, BM, Granville, DJ
JournalArterioscler Thromb Vasc Biol
Volume24
Issue12
Pagination2245-50
Date Published2004 Dec
ISSN1524-4636
KeywordsAnimals, Apoptosis, Caspase 3, Caspases, Cell Line, Tumor, Cell Survival, Coronary Vessels, Extracellular Matrix, Extracellular Matrix Proteins, Granzymes, HeLa Cells, Humans, Membrane Glycoproteins, Mice, Mice, Inbred C57BL, Muscle, Smooth, Vascular, Myocytes, Smooth Muscle, Perforin, Pore Forming Cytotoxic Proteins, Rats, Serine Endopeptidases, Spleen
Abstract

OBJECTIVE: T cell-induced cytotoxicity, of which granzyme B is a key mediator, is believed to contribute to the pathogenesis of inflammatory vascular diseases. In this report, we investigate the mechanism of granzyme B-induced smooth muscle cell (SMC) death.METHODS AND RESULTS: The addition of purified granzyme B alone to cultured SMCs caused a significant reduction in cell viability. Chromatin condensation, phosphatidylserine externalization, and membrane blebbing were observed, indicating that the mechanism of granzyme B-induced SMC death was through apoptosis. Activated splenocytes from perforin-knockout mice induced SMC death through a granzyme B-mediated pathway. Inhibition of the proteolytic activities of caspases and granzyme B prevented granzyme B-induced SMC death, whereas attenuation of granzyme B internalization with mannose-6-phosphate (M6P) did not. Further, granzyme B induced the cleavage of several SMC extracellular proteins, including fibronectin, and reduced focal adhesion kinase phosphorylation.CONCLUSIONS: These results indicate that granzyme B can induce apoptosis of SMCs in the absence of perforin by cleaving extracellular proteins, such as fibronectin.

DOI10.1161/01.ATV.0000147162.51930.b7
Alternate JournalArterioscler. Thromb. Vasc. Biol.
PubMed ID15472125