Specificity of Tissue Transglutaminase Explains Cereal Toxicity in Celiac Disease

Vader, L. Willemijn; Ru, Arnoud de; Wal, Yvonne van der; Kooy, Yvonne; Benckhuijsen, Willemien E.; Mearin, M. Luisa; Drijfhout, Jan W.; Veelen, Peter A. van; Koning, Frits

doi:10.1084/jem.20012028

Cited by 331 publications

(279 citation statements)

References 18 publications

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“…Our data (i.e. TG2 preferred mostly QxP but not QP or QxxP) are in accordance with a previous report on specificity of guinea pig TG2 where deamidation within synthetic substitution analogs of gliadin peptides was analyzed by tandem mass spectrometry (24). Unlike the previous report, we also found an influence of residues in position Ϫ1.…”

Section: Sequence Specificity Of Tg2 Explains the Competition Data Ofcontrasting

confidence: 46%

Gliadin T Cell Epitope Selection by Tissue Transglutaminase in Celiac Disease

Fleckenstein

Molberg

Qiao

et al. 2002

Journal of Biological Chemistry

206

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Tissue transglutaminase (TG2) can modify proteins by transamidation or deamidation of specific glutamine residues. TG2 has a major role in the pathogenesis of celiac disease as it is both the target of disease-specific autoantibodies and generates deamidated gliadin peptides that are recognized by CD4؉ , DQ2-restricted T cells from the celiac lesions. Capillary electrophoresis with fluorescence-labeled gliadin peptides was used to separate and quantify deamidated and transamidated products. In a competition assay, the affinity of TG2 to a set of overlapping ␥-gliadin peptides was measured and compared with their recognition by celiac lesion T cells. Peptides differed considerably in their competition efficiency. Those peptides recognized by intestinal T cell lines showed marked competition indicating them as excellent substrates for TG2. The enzyme fine specificity of TG2 was characterized by synthetic peptide libraries and mass spectrometry. Residues in positions ؊1, ؉1, ؉2, and ؉3 relative to the targeted glutamine residue influenced the enzyme activity, and proline in position ؉2 had a particularly positive effect. The characterized sequence specificity of TG2 explained the variation between peptides as TG2 substrates indicating that the enzyme is involved in the selection of gluten T cell epitopes. The enzyme is mainly localized extracellularly in the small intestine where primary amines as substrates for the competing transamidation reaction are present. The deamidation could possibly take place in this compartment as an excess of primary amines did not completely inhibit deamidation of gluten peptides at pH 7.3. However, lowering of the pH decreased the reaction rate of the TG2-catalyzed transamidation, whereas the rate of the deamidation reaction was considerably increased. This suggests that the deamidation of gluten peptides by TG2 more likely takes place in slightly acidic environments.The food-sensitive enteropathy celiac disease (CD) 1 is a chronic inflammatory disorder with a multifactorial etiology (1, 2). The disease is precipitated by dietary wheat gluten and related proteins in barley and rye. The ingestion of such proteins induces mucosal lymphocyte infiltration and villus atrophy. Subjects with active disease have autoantibodies specific for the enzyme tissue transglutaminase (3). CD shows a strong genetic association with the genes encoding for HLA-DQ2 and -DQ8 (1). Gluten-reactive CD4 ϩ T cells isolated from the small intestine of CD patients are almost exclusively restricted by either of these HLA molecules (4, 5), and activation of such T cells is probably a critical event in the disease development (1). Interestingly, the gluten-reactive T cells of the celiac lesion predominantly recognize gluten peptides in which certain glutamines are converted to glutamic acid by deamidation (6). Evidence indicates that tissue transglutaminase (TG2) can mediate this deamidation in vivo (7-9). TG2 is best known for its ability to catalyze an acyl transfer reaction in which the carboxamide group of a p...

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Section: Sequence Specificity Of Tg2 Explains the Competition Data Ofcontrasting

confidence: 46%

Gliadin T Cell Epitope Selection by Tissue Transglutaminase in Celiac Disease

Fleckenstein

Molberg

Qiao

et al. 2002

Journal of Biological Chemistry

206

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“…tTG is released from fibroblasts in the setting of inflammation; this also occurs with infection or other perturbations of the mucosal integrity that might serve as triggering or enabling events for the development of enteropathy from gliadin sensitivity (31)(32)(33)(34)(35)(36). Deamidation of the specific peptides is believed to result in improved binding to specific pockets in the DQ molecule.…”

Section: Discussionmentioning

confidence: 99%

HLA-DQ Determines the Response to Exogenous Wheat Proteins: A Model of Gluten Sensitivity in Transgenic Knockout Mice

Black¹,

Murray

David³

2002

The Journal of Immunology

137

107

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We have investigated the genetic basis of the immune response to dietary gluten in HCD4/DQ8 and HCD4/DQ6 double transgenic mice. Mice were immunized with gluten i.p. or individual peptides s.c. and spleen or draining lymph node T cells were challenged in vitro. Strong proliferative responses to gluten were seen in the HCD4/DQ8 mice, whereas the HCD4/DQ6 mice responded to gluten poorly. A series of overlapping peptides spanning gliadin were synthesized. The HCD4/DQ8 mice reacted to many of the individual peptides of gliadin, while the HCD4/DQ6 mice were relatively unresponsive. T cells isolated from HCD4/DQ8 mice also responded well to modified (deamidated) versions of the gliadin peptides, whereas HCD4DQ6 mice did not. The T cell response to gluten was CD4 dependent and DQ restricted and led to the production of cytokines IL-6, TGF-β, and IL-10. Finally, intestinal lymphocytes isolated from gluten-fed HCD4/DQ8 mice displayed an activated phenotype. These data suggest that this HLA class II transgenic murine model of gluten sensitivity may provide insight into the initiation of the MHC class II-restricted gluten sensitivity in celiac disease.

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“…The consensus QXXP (whereas X stands for any amino acid) is a poor TG target, at least in gluten peptides in vitro (30). Thus, we first added rTG2 to Sf9-expressed, mutated ShhN lacking all three glutamine residues (Gln-47, -101, and -117, ShhN 3xQ ) (Supplement 2) after heparin-Sepharose pulldown from crude cell lysates.…”

Section: Ud Oligomerization Depends On a Highly Conserved N-terminal mentioning

confidence: 99%

Heparan Sulfate and Transglutaminase Activity Are Required for the Formation of Covalently Cross-linked Hedgehog Oligomers

Dierker

Dreier

Migone

et al. 2009

Journal of Biological Chemistry

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Sonic hedgehog (Shh) signaling plays major roles in embryonic development and has also been associated with the progression of certain cancers. Here, Shh family members act directly as long range morphogens, and their ability to do so has been linked to the formation of freely diffusible multimers from the lipidated, cell-tethered monomer (ShhNp). In this work we demonstrate that the multimeric morphogen secreted from endogenous sources, such as mouse embryos and primary chick chondrocytes, consists of oligomeric substructures that are "undisruptable" by boiling, denaturants, and reducing agents. Undisruptable (UD) morphogen oligomers vary in molecular weight and possess elevated biological activity if compared with recombinant Sonic hedgehog (ShhN). However, ShhN can also undergo UD oligomerization via a heparan sulfate (HS)-dependent mechanism in vitro, and HS isolated from different sources differs in its ability to mediate UD oligomer formation. Moreover, site-directed mutagenesis of conserved ShhN glutamine residues abolishes UD oligomerization, and inhibitors directed against transglutaminase (TG) activity strongly decrease the amount of chondrocyte-secreted UD oligomers. These findings reveal an unsuspected ability of the N-terminal hedgehog (Hh) signaling domain to form biologically active, covalently crosslinked oligomers and a novel HS function in this TG-catalyzed process. We suggest that in hypertrophic chondrocytes, HS-assisted, TG-mediated Hh oligomerization modulates signaling via enhanced protein signaling activity. Hedgehog (Hh)4 family members are involved in tissue patterning and progenitor cell proliferation by activation of distinct target genes in a concentration-dependent manner. In vertebrates, three closely related Hh morphogens (Sonic hedgehog (Shh), Indian hedgehog (Ihh), and Desert hedgehog) have been described, and a single ortholog is expressed in Drosophila melanogaster. Production of active morphogen begins with the cleavage of the signal sequence followed by autocatalytic cleavage of the 45-kDa precursor molecule to yield a 19-kDa N-terminal signaling domain. This domain becomes C-terminal-cholesterol-modified during processing and N-terminal-palmitoylated, resulting in a dual-lipidated molecule tightly bound to the surface of producing cells that constitutes the active morphogen (called ShhNp, if derived from the Shh precursor, or IhhNp, if derived from the Ihh precursor) (1). On the (Drosophila) cell surface, lipidated morphogen monomers are organized into suboptical oligomers that are further recruited to preexisting heparan sulfate proteoglycan (HSPG)-rich membrane subdomains to form large, visible multimeric clusters (2). Morphogen release from the cell surface then depends on the expression of Dispatched (3) and ADAM (a disintegrin and metalloprotease) family members. The latter mediate morphogen shedding in an HSregulated way, as has recently been shown for ShhNp in transfected Bosc23 cells, a HEK 293T-derived cell line (4).In addition to HS-regulated ShhNp shedding, HS is...

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Specificity of Tissue Transglutaminase Explains Cereal Toxicity in Celiac Disease

Cited by 331 publications

References 18 publications

Gliadin T Cell Epitope Selection by Tissue Transglutaminase in Celiac Disease

Gliadin T Cell Epitope Selection by Tissue Transglutaminase in Celiac Disease

HLA-DQ Determines the Response to Exogenous Wheat Proteins: A Model of Gluten Sensitivity in Transgenic Knockout Mice

Heparan Sulfate and Transglutaminase Activity Are Required for the Formation of Covalently Cross-linked Hedgehog Oligomers

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