Extracellular Matrix Remodeling by Human Granzyme B via Cleavage of Vitronectin, Fibronectin, and Laminin

Abstract

Human granzyme B (GrB) released from cytotoxic lymphocytes plays a key role in the induction of target cell apoptosis when internalized in the presence of perforin. Here we demonstrate that GrB also possesses a potent extracellular matrix remodeling activity. Both native and recombinant GrB caused detachment of immortalized and transformed cell lines, primary endothelial cells, and chondrocytes. Cell detachment by GrB induced endothelial cell death (anoikis). GrB also inhibited tumor cell spreading, migration, and invasion in vitro. Investigation into the underlying mechanism revealed that GrB efficiently cleaves three proteins involved in extracellular matrix structure and function: vitronectin, fibronectin, and laminin. In vitronectin, GrB cleaves after an Arg-Lys-Asp (RGD) motif, which is part of the integrin-binding site found in matrix proteins. We propose that targeting of the integrin-extracellular matrix interface by GrB may allow perforin-independent killing of target cells via anoikis, restrict motility of tumor cells, facilitate lymphocyte migration, or directly reduce virus infectivity. It may also contribute to tissue destruction in diseases in which extracellular GrB is evident, such as rheumatoid arthritis and atherosclerosis.

Emerging roles of serine proteinases in tissue turnover in arthritis

“…Granzyme B-positive cells are detectable at the cartilage-pannus junction (65,66), and granzyme B is expressed by chondrocytes (67). Thus, granzyme B may contribute directly to ECM degradation, because it can degrade aggrecan, vitronectin, fibronectin, and laminin (66,68,69) (Figure 1). …”

Granzyme B is expressed in mouse mast cells in vivo and in vitro and causes delayed cell death independent of perforin

“…These extracellular activities of gzms are implicated in inflammation and processes of leukocyte extravasation. 10,12,13 Both, gzmA and/or gzmB cleave extracellular proteins such as fibronectin, collagen IV, vitronectin and/or laminin. 8,10,11 GzmB also degrades the cartilage proteoglycan aggrecan, 14 induces perf-independent cell detachment and delayed cell death (anoikis) in adherent smooth muscle cells (SMCs) 11 and in EC.…”

“…8,10,11 GzmB also degrades the cartilage proteoglycan aggrecan, 14 induces perf-independent cell detachment and delayed cell death (anoikis) in adherent smooth muscle cells (SMCs) 11 and in EC. 10 This occurs by remodeling of the extracellular matrix. 10 Here, we report on the expression of gzmB in skinassociated and in in vitro-differentiated mouse mast cells and provide evidence that mast cell-derived gzmB induces cell detachment and cell death of adherent target cells.…”

“…10 This occurs by remodeling of the extracellular matrix. 10 Here, we report on the expression of gzmB in skinassociated and in in vitro-differentiated mouse mast cells and provide evidence that mast cell-derived gzmB induces cell detachment and cell death of adherent target cells.…”

A ‘polarized’ look at α-tubulin cleavage by granzyme B

“…Indeed granzyme B has recently been shown to cleave extra cellular proteins such as vitronectin, fibronectin and laminin to induce tissue rearrangement without killing the target. 16 In contrast, Adrain et al 13 showed that when cells were treated with lethal concentrations of granzyme B, inhibition of caspases prevented cellular rearrangements in short-term (47 h) assays. It is of note that the cytoskeletal rearrangements reported by Buzza et al, 16 …”