Extracellular Transglutaminase 2 Is Catalytically Inactive, but Is Transiently Activated upon Tissue Injury

Siegel, Matthew; Strnad, Pavel; Watts, Richard E.; Choi, Kihang; Jabrì, Bana; Omary, M. Bishr; Khosla, Chaitan

doi:10.1371/journal.pone.0001861

Cited by 184 publications

(218 citation statements)

References 48 publications

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“…TG2 was shown to bind to extracellular matrix components and also to β1-and β3-integrins or other cell surface receptors or co-receptors such as platelet-derived growth factor receptor (PDGFR) or syndecan-4 on the cell surface, enhancing cell adhesion [27,[38][39][40]. Interestingly, some of the ECM-related TG2 functions are independent of enzyme activity [5,41]. Here we demonstrate that S100A4 have a role in TG2-mediated cell adhesion as measured by a real-time impedance-based assay: immobilizing TG2 and S100A4 on fibronectin-coated plates (in the presence of Ca 2+ ) significantly increased cell adhesion.…”

Section: Discussionmentioning

confidence: 99%

“…In the extracellular matrix, where the concentration of Ca 2+ is generally high and the level of GTP is relatively low, one would expect that TG2 has a high cross-linking activity. However, several evidences demonstrate that ECM-or plasma membrane-bound TG2 is mainly inactive due to disulfide bond formation and protein-protein interactions and only becomes activated by the induction of certain stressors [4][5][6]. In the extracellular milieu, the effect of TG2 on cell-ECM adhesion and cell migration depends on its interaction with ECM-related proteins.…”

Section: Introductionmentioning

confidence: 99%

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Metastasis-associated S100A4 is a specific amine donor and an activity-independent binding partner of transglutaminase-2

Biri

Kiss

Király

et al. 2015

Biochemical Journal

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Transglutaminase-2 (TG2) is best known as a Ca 2+ -dependent cross-linking enzyme; however, some of its extracellular matrix-related functions are independent from its catalytic activity and include matrix remodeling, adhesion and migration. S100A4 belongs to the Ca 2+ -binding EF-hand S100 protein family and acts both intra-and extracellularly through binding to various partners. It regulates cell migration and its overexpression is strongly associated with metastasis and poor survival in various cancers. TG2 has recently been suggested to mediate S100A4-dependent tumor cell migration. Here we provide evidence that S100A4 is an interacting partner and also specific amine donor of TG2. TG2 incorporates a glutamine donor peptide to Lys100 in the C-terminal random coil region of S100A4. Importantly, the enzyme activity is not necessary for the interaction: S100A4 also binds to TG2 in the presence of a specific inhibitor that keeps the enzyme in an open conformation, or to an enzymatically inactive mutant. We also found that S100A4 considerably enhances TG2-mediated adhesion of A431 epithelial carcinoma cells to the extracellular matrix. This role is independent of enzyme activity and requires the open conformation of TG2. We propose that S100A4 stabilizes the open conformation of TG2, which binds to its cell surface receptor in this state and increases cell adhesion.Summary: S100A4 and transglutaminase-2 have a role in metastasis. S100A4 is an interaction partner and specific amine substrate of transglutaminase-2, promoting its open conformation and leading to enhanced cell adhesion. Studying their interaction could contribute to the better understanding of metastasis.Running title: S100A4: substrate and binding partner of transglutaminase-2

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Metastasis-associated S100A4 is a specific amine donor and an activity-independent binding partner of transglutaminase-2

Biri

Kiss

Király

et al. 2015

Biochemical Journal

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“…Studies performed in mice have shown that extracellular TG2 exists predominantly in a catalytically inactive form under normal conditions but can become activated through inflammation or in the presence of a reducing agent (18,29). The latter observation suggests that the enzyme is inactivated by oxidation in the extracellular environment.…”

Section: Discussionmentioning

confidence: 99%

“…Cysteine oxidation inactivates TG2 (17,27,28), and intramolecular disulfide bond formation presumably leads to TG2 inactivation in the extracellular environment (18,29). To study the structural properties of oxidized TG2, we also performed local-exchange analysis on iTG2, which had been incubated with oxidized glutathione before the addition of Ca 2+ .…”

Section: Disulfide Bond Formation In Itg2 Prevents the Stabilizing Efmentioning

confidence: 99%

Activity-regulating structural changes and autoantibody epitopes in transglutaminase 2 assessed by hydrogen/deuterium exchange

Iversen

Mysling

Hnida

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The multifunctional enzyme transglutaminase 2 (TG2) is the target of autoantibodies in the gluten-sensitive enteropathy celiac disease. In addition, the enzyme is responsible for deamidation of gluten peptides, which are subsequently targeted by T cells. To understand the regulation of TG2 activity and the enzyme's role as an autoantigen in celiac disease, we have addressed structural properties of TG2 in solution by using hydrogen/deuterium exchange monitored by mass spectrometry. We demonstrate that Ca 2+ binding, which is necessary for TG2 activity, induces structural changes in the catalytic core domain of the enzyme. Cysteine oxidation was found to abolish these changes, suggesting a mechanism whereby disulfide bond formation inactivates the enzyme. Further, by using TG2-specific human monoclonal antibodies generated from intestinal plasma cells of celiac disease patients, we observed that binding of TG2 by autoantibodies can induce structural changes that could be relevant for the pathogenesis. Detailed mapping of two of the main epitopes targeted by celiac disease autoantibodies revealed that they are located adjacent to each other in the N-terminal part of the TG2 molecule.

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“…Low Ca 2ϩ concentration and high GTP/GDP concentration in the cytosol typically prevent TG2 activation within cells. Despite conditions in the extracellular milieu that favor activation, extracellular TG2 also appears to be predominantly inactive under normal conditions but can be activated by certain types of inflammation and cell injury (9).…”

Section: Human Transglutaminase 2 (Tg2)mentioning

confidence: 99%

Redox Regulation of Transglutaminase 2 Activity

Stamnæs

Pinkas

Fleckenstein

et al. 2010

Journal of Biological Chemistry

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166

186

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Transglutaminase 2 (TG2) in the extracellular matrix is largely inactive but is transiently activated upon certain types of inflammation and cell injury. The enzymatic activity of extracellular TG2 thus appears to be tightly regulated. As TG2 is known to be sensitive to changes in the redox environment, inactivation through oxidation presents a plausible mechanism. Using mass spectrometry, we have identified a redox-sensitive cysteine triad consisting of Cys 230 Human transglutaminase 2 (TG2) 2 modifies protein-or peptide-bound glutamine residues by either cross-linking their reactive carboxamide side chains to primary amines or by deamidation, converting glutamine residues to glutamate (1, 2). Ca 2ϩ is required for this catalytic activity and induces conformational changes in the enzyme, which arrange the active-site residues for catalysis, including Cys 277 (3-6). As TG2 is abundantly expressed in both the intracellular and extracellular environments of many tissues, its catalytic activity must be tightly regulated to avoid excess modification of cellular and tissue components. GTP and GDP act as allosteric inhibitors by inducing a closed conformation in which the active site is buried (6 -8). Low Ca 2ϩ concentration and high GTP/GDP concentration in the cytosol typically prevent TG2 activation within cells. Despite conditions in the extracellular milieu that favor activation, extracellular TG2 also appears to be predominantly inactive under normal conditions but can be activated by certain types of inflammation and cell injury (9).The catalytic activity of TG2 is implicated in the pathogenesis of several human diseases, including celiac disease (10). Celiac disease is caused by an aberrant immune response to proline-and glutamine-rich peptides from dietary gluten in the small intestine of genetically predisposed individuals (11). In the celiac immune response, the enzymatic activity of TG2 is crucial, as TG2-mediated deamidation of gluten peptides increases their T-cell antigenicity (12, 13).In contrast to our knowledge of the mechanistic basis for TG2 inactivity in the intracellular environment, the mechanisms underlying regulation of TG2 activity in the extracellular compartment remain unclear. TG2 harbors no disulfide bonds in its native state, which is unusual for enzymes in the extracellular environment (14). Previous studies have shown that TG2 is susceptible to oxidation, resulting in inactivation (19 -22). Thus, modulation of enzymatic activity through oxidation presents a plausible mechanism for regulation of extracellular TG2 activity. We have investigated the events underlying oxidative inactivation of TG2 and report the identification of a redox-sensitive cysteine triad consisting of Cys 230 , Cys 370 , and Cys 371 . Within this triad, Cys 230 appears to set the threshold for intramolecular disulfide bond formation and thereby inactivation. Oxidation was influenced by the presence of Ca 2ϩ and substrate, suggesting that the local environment can modulate and fine-tune oxidative inactivation of T...

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Extracellular Transglutaminase 2 Is Catalytically Inactive, but Is Transiently Activated upon Tissue Injury

Cited by 184 publications

References 48 publications

Metastasis-associated S100A4 is a specific amine donor and an activity-independent binding partner of transglutaminase-2

Metastasis-associated S100A4 is a specific amine donor and an activity-independent binding partner of transglutaminase-2

Activity-regulating structural changes and autoantibody epitopes in transglutaminase 2 assessed by hydrogen/deuterium exchange

Redox Regulation of Transglutaminase 2 Activity

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