The granzyme B inhibitor proteinase inhibitor 9 (PI9) is expressed by human mast cells

Bladergroen, Bellinda A.; Strik, Merel C.M.; Wolbink, Angela M.; Wouters, Dorine; Broekhuizen, Roel; Kummer, J. Alain; Hack, C. E.

doi:10.1002/eji.200425949

Cited by 35 publications

(26 citation statements)

References 30 publications

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“…PI-9 is expressed by lymphocytes (87,91), dendritic cells (DCs) (92), cells at immune privileged sites (testis and placenta) (14,93,94), endothelial and mesothelial cells (95), and finally mast cells (96). This in vivo distribution pattern supports the idea that PI-9 protects effector, accessory, and bystander cells from ectopic GzmB during an immune response.…”

Section: Gzmb Endogenous Inhibitorsmentioning

confidence: 56%

Death by a Thousand Cuts: Granzyme Pathways of Programmed Cell Death

Chowdhury

Lieberman

2008

Annu. Rev. Immunol.

545

580

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The granzymes are cell death-inducing enzymes, stored in the cytotoxic granules of cytotoxic T lymphocytes and natural killer cells, that are released during granule exocytosis when a specific virus-infected or transformed target cell is marked for elimination. Recent work suggests that this homologous family of serine esterases can activate at least three distinct pathways of cell death. This redundancy likely evolved to provide protection against pathogens and tumors with diverse strategies for evading cell death. This review discusses what is known about granzyme-mediated pathways of cell death as well as recent studies that implicate granzymes in immune regulation and extracellular proteolytic functions in inflammation.

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Section: Gzmb Endogenous Inhibitorsmentioning

confidence: 56%

Death by a Thousand Cuts: Granzyme Pathways of Programmed Cell Death

Chowdhury

Lieberman

2008

Annu. Rev. Immunol.

545

580

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“…20 Mouse mAb PI9-101 (IgG1) directed against human PI9 is a novel antibody raised against soluble recombinant human PI9 produced in yeast (a kind gift from Dr. W Kisiel, Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA) and cross-reaction for other homologous serpins (PI6, PI8 and PAI-2) was excluded in a similar way as described previously for other intracellular serpins. 19 Protein A-purified PI9-101 was coupled to CNBr-Sepharose-4B. The following mouse mAbs were used: anti-caspase-4 (Tx, IgG1), anti-caspase-8 (5F7, IgG2b) and anti-caspase-10 (4C1, IgG1) were obtained from MBL (Nagoya, Japan); anti-caspase-3 (clone 19, IgG2a), anti-FADD (IgG1) and anti-RIP1 (clone 38, IgG2a) were from Transduction laboratories (Lexington, KY, USA); anticaspase-6 (clone B93-4, IgG1) was from Pharmingen (San Diego, CA, USA); and anti-FLAG (M2) antibody was purchased from Sigma.…”

Section: Methodsmentioning

confidence: 99%

“…The PI9 ELISA was performed essentially as described previously. 19 A rabbit polyclonal anti-PI9 antibody (1 mg/ml) was used for coating microtiter plates, and biotinylated mAb PI9-101 (about 5 mg/ml) for detection. Recombinant human PI9 produced in yeast served as a standard.…”

Section: Methodsmentioning

confidence: 99%

Ectopic expression of the serine protease inhibitor PI9 modulates death receptor-mediated apoptosis

et al. 2007

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Apoptosis is a highly controlled process, whose triggering is associated with the activation of caspases. Apoptosis can be induced via a subgroup of the tumor necrosis factor (TNF) receptor superfamily, which recruit and activate pro-caspase-8 and -10. Regulation of apoptosis is achieved by several inhibitors, including c-FLICE-inhibitory protein, which prevents apoptosis by inhibiting the pro-apoptotic activation of upstream caspases. Here we show that the human intracellular serine protease inhibitor (serpin), protease inhibitor 9 (PI9), inhibits TNF-, TNF-related apoptosis-inducing ligand-and Fas ligand-mediated apoptosis in certain TNF-sensitive cell lines. The reactive center P1 residue of PI9 was required for this inhibition since PI9 harboring a GluAla mutation in its reactive center failed to impair death receptor-induced cell death. This suggests a classical serpin-protease interaction. Indeed, PI9 inhibited apoptotic death by directly interacting with the intermediate active forms of caspase-8 and -10. This indicates that PI9 can regulate pro-apoptotic apical caspases. Apoptosis is a highly controlled process, whose triggering is mainly associated with the activation of proteolytic enzymes.1,2 In the immune system, apoptotic death in target cells is mediated by cytotoxic lymphocytes (CL) including natural killer cells and cytotoxic T lymphocytes. These cells induce apoptosis via two different pathways: (a) the degranulation pathway and (b) a membrane receptor-ligand interaction involving members of the tumor necrosis family (TNF).2,3 In both pathways, activation of protease cascades plays an essential role in apoptotic death.Granules of CL contain several serine proteases called granzymes, of which granzyme B is the most important. Granzyme B possesses a unique Asp-ase activity and, upon entering the target cell, cleaves and activates pro-caspase-3 and other substrates to initiate apoptotic death. Target cell death can also be induced by members of the TNF family, such as membrane-bound Fas ligand (FasL) on the CL that interacts with its receptor Fas. Soluble-and membrane-bound TNF and TNF-related apoptosis-inducing ligand (TRAIL) also mediate death via their respective receptors, TNF receptor (TNF-R1) and TRAIL receptors (TRAIL-R1 and -R2). 4 Activation of these receptors lead to recruitment of the adaptor molecule, Fas-associated death domain (FADD). 5,6The death effector domain (DED) of FADD then recruits procaspase-8 and procaspase-10 via homotypic interaction with the DEDs in these caspases. Ligand, receptor, adaptor proteins and caspases form the death-inducing signaling complex (DISC). The high local concentration of procaspases promotes auto-activation and release into the cytosol triggering subsequent cleavage of downstream effector caspases (caspase-3, -6 and -7) leading to apoptotic death. Altogether, the induction and execution of apoptosis by CLs is mediated both by cysteine proteases, such as caspases, and by serine proteases, such as granzymes.Activation of apoptotic proteases within the...

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“…29,53 Although the function of gzmB produced by these cells is unknown, it seems to be granule associated. 28 Not surprisingly, SERPINB9 is also present in most if not all of these cells, 24,54 suggesting that it provides protection against gzmB in these settings as well.…”

Section: Serpinb9 and Granzyme Bmentioning

confidence: 99%

Control of granzymes by serpins

2009

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Although proteolysis mediated by granzymes has an important role in the immune response to infection or tumours, unrestrained granzyme activity may damage normal cells. In this review, we discuss the role of serpins within the immune system, as specific regulators of granzymes. The well-characterised human granzyme B-SERPINB9 interaction highlights the cytoprotective function that serpins have in safeguarding lymphocytes from granzymes that may leak from granules. We also discuss some of the pitfalls inherent in using rodent models of granzyme-serpin interactions and the ways in which our understanding of serpins can help resolve some of the current, contentious issues in granzyme biology. Cell Death and Differentiation (2010) 17, 586-595; doi:10.1038/cdd.2009; published online 6 November 2009As described elsewhere in this series, granzymes are key mediators of cytotoxic lymphocyte (CL) function, exhibiting both intracellular and extracellular functions. Thus, it is imperative that their activities be tightly controlled. Too little activity reduces the effectiveness of the immune system, resulting in infection and cancer. Conversely, overactivity can lead to disease caused by tissue destruction and cellular apoptosis. This review focusses on the manner in which granzyme activity is controlled at the posttranslational level by members of the serpin superfamily.The serpin superfamily is an ever-expanding group of structurally related proteins, currently comprising approximately 1000 members across all kingdoms of life. 1,2 Serpins function as intracellular or extracellular regulators of a wide range of physiological processes such as complement activation, blood coagulation and apoptosis. Within the vertebrate immune system, they control proteases of the classical and innate complement systems, and are also potent inhibitors of many leukocyte granule proteases. Serpin StructureStructures of almost 100 serpins from viruses to humans have been determined and all conform to the same basic architecture first described in 1984. The fold comprises nine a-helices, three b-sheets and a variable reactive centre loop (RCL), which is the primary site of interaction with target proteases (Figure 1a). The first structure determined was human SERPINA1 cleaved within the RCL. 3 Surprisingly, it was found that the residues around the cleavage point were separated by almost 70 Å , with the N-terminal portion of the RCL inserted into b-sheet A to form a fully antiparallel sixstranded sheet. It has subsequently been shown that, in the native state, the RCL is solvent exposed, and that its insertion into b-sheet A is a consequence of the inhibitory mechanism. The RCL is flanked by two highly conserved motifs (the proximal and distal hinges) that permit its insertion into b-sheet A. Insertion is also facilitated by the breach and shutter regions that assist the opening of b-sheet A and by the movement of helix F. 4 The RCL is a critical determinant of serpin inhibitory specificity, acting as a pseudosubstrate and cleavage site for the...

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The granzyme B inhibitor proteinase inhibitor 9 (PI9) is expressed by human mast cells

Cited by 35 publications

References 30 publications

Death by a Thousand Cuts: Granzyme Pathways of Programmed Cell Death

Death by a Thousand Cuts: Granzyme Pathways of Programmed Cell Death

Ectopic expression of the serine protease inhibitor PI9 modulates death receptor-mediated apoptosis

Control of granzymes by serpins

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