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Przyklenk M, Karmacharya S, Bonasera D, Pasanen-Zentz AL, Kmoch S, Paulsson M, Wagener R, Liccardi G, Schiavinato A. ANTXR1 deficiency promotes fibroblast senescence: implications for GAPO syndrome as a progeroid disorder. Sci Rep 2024; 14:9321. [PMID: 38653789 PMCID: PMC11039612 DOI: 10.1038/s41598-024-59901-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 04/16/2024] [Indexed: 04/25/2024] Open
Abstract
ANTXR1 is one of two cell surface receptors mediating the uptake of the anthrax toxin into cells. Despite substantial research on its role in anthrax poisoning and a proposed function as a collagen receptor, ANTXR1's physiological functions remain largely undefined. Pathogenic variants in ANTXR1 lead to the rare GAPO syndrome, named for its four primary features: Growth retardation, Alopecia, Pseudoanodontia, and Optic atrophy. The disease is also associated with a complex range of other phenotypes impacting the cardiovascular, skeletal, pulmonary and nervous systems. Aberrant accumulation of extracellular matrix components and fibrosis are considered to be crucial components in the pathogenesis of GAPO syndrome, contributing to the shortened life expectancy of affected individuals. Nonetheless, the specific mechanisms connecting ANTXR1 deficiency to the clinical manifestations of GAPO syndrome are largely unexplored. In this study, we present evidence that ANTXR1 deficiency initiates a senescent phenotype in human fibroblasts, correlating with defects in nuclear architecture and actin dynamics. We provide novel insights into ANTXR1's physiological functions and propose GAPO syndrome to be reconsidered as a progeroid disorder highlighting an unexpected role for an integrin-like extracellular matrix receptor in human aging.
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Affiliation(s)
- Matthias Przyklenk
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany
| | - Shreya Karmacharya
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany
| | - Debora Bonasera
- Genetic Instability, Cell Death and Inflammation Laboratory, Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany
| | - Arthur-Lauri Pasanen-Zentz
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany
| | - Stanislav Kmoch
- Research Unit of Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Mats Paulsson
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Raimund Wagener
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany
| | - Gianmaria Liccardi
- Genetic Instability, Cell Death and Inflammation Laboratory, Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany
| | - Alvise Schiavinato
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
- Department of Pediatrics and Adolescent Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
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ANTXR1 as a potential sensor of extracellular mechanical cues. Acta Biomater 2023; 158:80-86. [PMID: 36638946 DOI: 10.1016/j.actbio.2023.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 12/18/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
Cell adhesion molecules mediate cell-cell or cell-matrix interactions, some of which are mechanical sensors, such as integrins. Emerging evidence indicates that anthrax toxin receptor 1 (ANTXR1), a newly identified cell adhesion molecule, can also sense extracellular mechanical signals such as hydrostatic pressure and extracellular matrix (ECM) rigidity. ANTXR1 can interact with ECM through connecting intracellular cytoskeleton and ECM molecules (just like integrins) to regulate numerous biological processes, such as cell adhesion, cell migration or ECM homeostasis. Although with high structural similarity to integrins, its functions and downstream signal transduction are independent from those of integrins. In this perspective, based on existing evidence in literature, we analyzed the structural and functional evidence that ANTXR1 can act as a potential sensor for extracellular mechanical cues. To our knowledge, this is the first in-depth overview of ANTXR1 from the perspective of mechanobiology. STATEMENT OF SIGNIFICANCE: An overview of ANTXR1 from the perspective of mechanobiology; An analysis of mechanical sensitivity of ANTXR1 in structure and function; A summary of existing evidence of ANTXR1 as a potential mechanosensor.
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Al Kaissi A, Hilmi M, Betadolova Z, Bouchoucha S, Trofimova S, Shboul M, Rustamov G, Dwera W, Sigl K, Kenis V, Kircher SG. Infantile systemic hyalinosis: Variable grades of severity. Afr J Paediatr Surg 2021; 18:224-230. [PMID: 34341308 PMCID: PMC8423165 DOI: 10.4103/ajps.ajps_162_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/18/2020] [Accepted: 01/15/2021] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Infantile systemic hyalinosis (ISH) is an autosomal recessively inherited disorder. The classical natural history of the disease is characterised by hypotonia, multiple contractures, skin lesions, osteopenia, joint pain, bone fractures, persistent diarrhoea and growth deficiency. MATERIALS AND METHODS Two children manifested the severe type of ISH underwent genotypic confirmation. In order to identify which other family members have inherited the disease. We included siblings and cousins in this study. The baseline tool to study other family subjects was based on the phenotypic characterisations of each child. RESULTS . Two children with the severe type of ISH showed craniosynostosis (brachycephaly and scaphocephaly) associated with multiple contractures, progressive joint osteolysis ending up with multiple joint dislocations. The full exome sequencing was carried out, revealing a previously reported heterozygous nonsense mutation с.1294С>Т and a novel heterozygous non-synonymous substitution c. 58T>A in ANTRX2 gene. Three children (sibling and cousins) manifested variable clinical manifestations relevant to ISH. Specifically, asymptoamtic skin and skeletal abnormalities of hypoplastic clavicles and 'shepherd's crook' deformity and coxa vara. CONCLUSION It is mandatory to perform extensive family pedigree search to detect asymptomatic clinical features in siblings and cousins in families with first degree related marriages. Interestingly, in the mild and the moderate types of ISH, we observed undescribed combination of asymptomatic skin and skeletal abnormalities. This is a comparative study between the severe and the mild/moderate types in a group of children from consanguineous families. Our current study extends the phenotypic characterisations of ISH.
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Affiliation(s)
- Ali Al Kaissi
- Orthopedic Hospital of Spesing, Pediatric Department, Vienna, Austria
| | - Marwa Hilmi
- Family Medicine Operations, Omar Bin Al Khatab Hospital, Doha, Qatar
| | - Zulfiya Betadolova
- Pediatric clinic «Kidney», Makhachkala, Republic of Dagestan, Russian Federation, Russia
| | - Sami Bouchoucha
- Pediatric Orthopedic Surgery, The Béchir-Hamza Children's Hospital or Bab Saadoun, Tunis, Tunisia
| | - Svetlana Trofimova
- Department of Foot and Ankle Surgery, Neuroorthopaedics and Systemic Disorders, Pediatric Orthopedic Institute N.A. H. Turner, Parkovaya Str., 64-68, Pushkin, Saint, Petersburg, Russia
| | - Mohammad Shboul
- Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Guseyn Rustamov
- Department of Pediatric Orthopedic and Trauma Surgery, State hospital of Republic of Dagestan, Makhachkala, Russian Federation, Russia
| | - Wiam Dwera
- The Béchir-Hamza Children's Hospital or Bab Saadoun, Tunis, Tunisia
| | - Katharina Sigl
- Head of the Muscuol-Skeletal Group Ordens-Klinikum, Linz, Austria
| | - Vladimir Kenis
- Department of Foot and Ankle Surgery, Neuroorthopaedics and Systemic Disorders, Pediatric Orthopedic Institute N.A. H. Turner, Parkovaya Str., 64-68, Pushkin, Saint, Petersburg, Russia
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4
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Cheng B, Liu Y, Zhao Y, Li Q, Liu Y, Wang J, Chen Y, Zhang M. The role of anthrax toxin protein receptor 1 as a new mechanosensor molecule and its mechanotransduction in BMSCs under hydrostatic pressure. Sci Rep 2019; 9:12642. [PMID: 31477767 PMCID: PMC6718418 DOI: 10.1038/s41598-019-49100-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 08/16/2019] [Indexed: 02/06/2023] Open
Abstract
Anthrax toxin protein receptor (ANTXR) 1 has many similarities to integrin and is regarded in some respects as a single-stranded integrin protein. However, it is not clear whether ANTXR1 responds to mechanical signals secondary to the activation of integrins or whether it is a completely new, independent and previously undiscovered mechanosensor that responds to an undefined subset of mechanical signaling molecules. Our study demonstrates that ANTXR1 is a novel mechanosensor on the cell membrane, acting independently from the classical mechanoreceptor molecule integrinβ1. We show that bone marrow stromal cells (BMSCs) respond to the hydrostatic pressure towards chondrogenic differentiation partly through the glycogen synthase kinase (GSK) 3β/β-Catenin signaling pathway, which can be partly regulated by ANTXR1 and might be related to the direct binding between ANTXR1 and low-density lipoprotein receptor-related protein (LRP) 5/6. In addition, ANTXR1 specifically activates Smad2 and upregulates Smad4 expression to facilitate the transport of activated Smad2 to the nucleus to regulate chondrogenesis, which might be related to the direct binding between ANTXR1 and Actin/Fascin1. We also demonstrate that ANTXR1 binds to some extent with integrinβ1, but this interaction does not affect the expression and function of either protein under pressure. Thus, we conclude that ANTXR1 plays a crucial role in BMSC mechanotransduction and controls specific signaling pathways that are distinct from those of integrin to influence the chondrogenic responses of BMSCs under hydrostatic pressure.
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Affiliation(s)
- Baixiang Cheng
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China
| | - Yanzheng Liu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China
| | - Ying Zhao
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China
| | - Qiang Li
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China
| | - Yanli Liu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China
| | - Junjun Wang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China
| | - Yongjin Chen
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China.
| | - Min Zhang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, No.145 West Changle Road, Xi'an, 710032, China.
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5
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Abstract
The anthrax toxin receptors-capillary morphogenesis gene 2 (CMG2) and tumor endothelial marker 8 (TEM8)-were identified almost 20 years ago, although few studies have moved beyond their roles as receptors for the anthrax toxins to address their physiological functions. In the last few years, insight into their endogenous roles has come from two rare diseases: hyaline fibromatosis syndrome, caused by mutations in CMG2, and growth retardation, alopecia, pseudo-anodontia, and optic atrophy (GAPO) syndrome, caused by loss-of-function mutations in TEM8. Although CMG2 and TEM8 are highly homologous at the protein level, the difference in disease symptoms points to variations in the physiological roles of the two anthrax receptors. Here, we focus on the similarities between these receptors in their ability to regulate extracellular matrix homeostasis, angiogenesis, cell migration, and skin elasticity. In this way, we shed light on how mutations in these two related proteins cause such seemingly different diseases and we highlight the existing knowledge gaps that could form the focus of future studies.
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Affiliation(s)
- Oksana A. Sergeeva
- Global Health Institute, School of Life Sciences, EPFL, Lausanne, Switzerland
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6
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Zhang LC, Shao Y, Gao LH, Liu J, Xi YY, Xu Y, Wu C, Chen W, Chen HP, Wang YL, Duan HF, Hu XW. TEM8 functions as a receptor for uPA and mediates uPA-stimulated EGFR phosphorylation. Cell Commun Signal 2018; 16:62. [PMID: 30241478 PMCID: PMC6151050 DOI: 10.1186/s12964-018-0272-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/06/2018] [Indexed: 02/07/2023] Open
Abstract
Background TEM8 is a cell membrane protein predominantly expressed in tumor endothelium, which serves as a receptor for the protective antigen (PA) of anthrax toxin. However, the physiological ligands for TEM8 remain unknown. Results Here we identified uPA as an interacting partner of TEM8. Binding of uPA stimulated the phosphorylation of TEM8 and augmented phosphorylation of EGFR and ERK1/2. Finally, TEM8-Fc, a recombinant fusion protein comprising the extracellular domain of human TEM8 linked to the Fc portion of human IgG1, efficiently abrogated the interaction between uPA and TEM8, blocked uPA-induced migration of HepG2 cells in vitro and inhibited the growth and metastasis of human MCF-7 xenografts in vivo. uPA, TEM8 and EGFR overexpression and ERK1/2 phosphorylation were found co-located on frozen cancer tissue sections. Conclusions Taken together, our data provide evidence that TEM8 is a novel receptor for uPA, which may play a significant role in the regulation of tumor growth and metastasis. Electronic supplementary material The online version of this article (10.1186/s12964-018-0272-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lian-Cheng Zhang
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China.,Department of Operational Medicine, Tianjin Institute of Environmental and Operational Medicine, Tianjin, 300050, China
| | - Yong Shao
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China
| | - Li-Hua Gao
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China
| | - Jin Liu
- Key Laboratory of Experimental Hematology, Beijing Institute of Radiation Medicine (BIRM), No. 27, Taiping Road, Haidian District, Beijing, 100850, China
| | - Yong-Yi Xi
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China
| | - Yin Xu
- Key Laboratory of Experimental Hematology, Beijing Institute of Radiation Medicine (BIRM), No. 27, Taiping Road, Haidian District, Beijing, 100850, China
| | - Chutse Wu
- Key Laboratory of Experimental Hematology, Beijing Institute of Radiation Medicine (BIRM), No. 27, Taiping Road, Haidian District, Beijing, 100850, China
| | - Wei Chen
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China
| | - Hui-Peng Chen
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China.
| | - You-Liang Wang
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China.
| | - Hai-Feng Duan
- Key Laboratory of Experimental Hematology, Beijing Institute of Radiation Medicine (BIRM), No. 27, Taiping Road, Haidian District, Beijing, 100850, China.
| | - Xian-Wen Hu
- Laboratory of Cell Engineering, Beijing Institute of Biotechnology (BIB), No. 20, Dongdajie Street, Fengtai District, Beijing, 100071, China.
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7
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Jia Z, Ackroyd C, Han T, Agrawal V, Liu Y, Christensen K, Dominy B. Effects from metal ion in tumor endothelial marker 8 and anthrax protective antigen: BioLayer Interferometry experiment and molecular dynamics simulation study. J Comput Chem 2017; 38:1183-1190. [PMID: 28437008 DOI: 10.1002/jcc.24768] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 01/08/2017] [Accepted: 01/14/2017] [Indexed: 11/09/2022]
Abstract
One of the anthrax receptors, tumor endothelial marker 8 (TEM8), is reported to be a potential anticancer target due to its over-expression during tumor angiogenesis. To extend our BioLayer Interferometry study in PA-TEM8 binding, we present a computational approach to reveal the role of an integral metal ion on receptor structure and binding thermodynamics. We estimated the interaction energy between PA and TEM8 using computer simulation. Consistent with experimental study, computational results indicate the metal ion in TEM8 contributes significantly to the binding affinity, and PA-TEM8 binding is more favorable in the presence of Mg2+ than Ca2+ . Further, computational analysis suggests that the differences in PA-TEM8 binding affinity are comparable to the closely related integrin proteins. The conformation change, which linked to changes in activity of integrins, was not found in TEM8. In the present of Mg2+ , TEM8 remains in a conformation analogous to an integrin open (high-affinity) conformation. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Zhe Jia
- Clemson University Department of Chemistry, 309 Hunter Lab Clemson University, Clemson, South Carolina, 29634
| | - Christine Ackroyd
- Department of Chemistry and Biochemistry, C205 BNSN, Brigham Young University, Provo, Utah, 84602
| | - Tingting Han
- Clemson University Department of Chemistry, 309 Hunter Lab Clemson University, Clemson, South Carolina, 29634
| | - Vibhor Agrawal
- Clemson University Department of Chemistry, 309 Hunter Lab Clemson University, Clemson, South Carolina, 29634
| | - Yinling Liu
- Clemson University Department of Chemistry, 309 Hunter Lab Clemson University, Clemson, South Carolina, 29634
| | - Kenneth Christensen
- Department of Chemistry and Biochemistry, C205 BNSN, Brigham Young University, Provo, Utah, 84602
| | - Brian Dominy
- Clemson University Department of Chemistry, 309 Hunter Lab Clemson University, Clemson, South Carolina, 29634
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8
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Hu K, Olsen BR, Besschetnova TY. Cell autonomous ANTXR1-mediated regulation of extracellular matrix components in primary fibroblasts. Matrix Biol 2016; 62:105-114. [PMID: 28011198 DOI: 10.1016/j.matbio.2016.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 12/06/2016] [Accepted: 12/09/2016] [Indexed: 12/28/2022]
Abstract
Our previous studies of Antxr1 knockout mice suggested that fibrotic skin abnormalities in these mice are associated with increased VEGF signaling. Here, based on studies of primary fibroblasts isolated from skin of Antx1+/+ and Antxr1-/- mice at embryonic stage E17.5 and postnatal day P49, we conclude that increased Col1a1 and Fn1 expression in Antxr1-deficient fibroblasts is partly mediated by a cell-autonomous ANTXR1-dependent mechanism. In turn, this may act in parallel with VEGF-dependent regulation of collagen type I and fibronectin production. We demonstrate that shRNA mediated knockdown of VEGF in Antxr1-/- fibroblasts reduces Col1a1 and Fn1 expression to below control levels, and these are restored by exogenous addition of recombinant VEGF. In addition, the increase in protein levels of collagen type I and fibronectin in mutant cells is blocked by VEGF neutralizing antibody. However, expressing the longest isoform of ANTXR1 (sv1) in mutant fibroblasts decreases levels of Ctgf, Col1a1 and Fn1 transcripts, but has no effect on VEGF expression. Taken together, our data suggest that the increased matrix production in Antxr1- deficient fibroblasts primarily occurs via a CTGF-dependent pathway and that other ANTXR1-associated mechanisms contribute to VEGF-dependent increase of collagen type I and fibronectin expression. Our findings provide a basis for further studies of novel ANTXR1-dependent connective tissue homeostatic control mechanisms in healthy individuals, patients with organ fibrosis, and patients with GAPO syndrome.
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Affiliation(s)
- Kai Hu
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States
| | - Bjorn R Olsen
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States; Department of Cell Biology, Harvard Medical School, United States
| | - Tatiana Y Besschetnova
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States; Department of Oral and Maxillofacial Surgery/Skeletal Biology Research Center, Massachusetts General Hospital and Harvard School of Dental Medicine, Boston, MA, United States.
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9
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Motta VN, Markle JGM, Gulban O, Mortin-Toth S, Liao KC, Mogridge J, Steward CA, Danska JS. Identification of the inflammasome Nlrp1b as the candidate gene conferring diabetes risk at the Idd4.1 locus in the nonobese diabetic mouse. THE JOURNAL OF IMMUNOLOGY 2015; 194:5663-73. [PMID: 25964492 DOI: 10.4049/jimmunol.1400913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 04/13/2015] [Indexed: 11/19/2022]
Abstract
Type 1 diabetes in the NOD mouse model has been linked to >30 insulin-dependent diabetes (Idd) susceptibility loci. Idd4 on chromosome 11 consists of two subloci, Idd4.1 and Idd4.2. Using congenic analysis of alleles in NOD and NOD-resistant (NOR) mice, we previously defined Idd4.1 as an interval containing >50 genes that controlled expression of genes in the type 1 IFN pathway. In this study, we report refined mapping of Idd4.1 to a 1.1-Mb chromosomal region and provide genomic sequence analysis and mechanistic evidence supporting its role in innate immune regulation of islet-directed autoimmunity. Genetic variation at Idd4.1 was mediated by radiation-sensitive hematopoietic cells, and type 1 diabetes protection conferred by the NOR allele was abrogated in mice treated with exogenous type 1 IFN-β. Next generation sequence analysis of the full Idd4.1 genomic interval in NOD and NOR strains supported Nlrp1b as a strong candidate gene for Idd4.1. Nlrp1b belongs to the Nod-like receptor (NLR) gene family and contributes to inflammasome assembly, caspase-1 recruitment, and release of IL-1β. The Nlrp1b of NOR was expressed as an alternative spliced isoform that skips exon 9, resulting in a premature stop codon predicted to encode a truncated protein. Functional analysis of the truncated NOR Nlrp1b protein demonstrated that it was unable to recruit caspase-1 and process IL-1β. Our data suggest that Idd4.1-dependent protection from islet autoimmunity is mediated by differences in type 1 IFN- and IL-1β-dependent immune responses resulting from genetic variation in Nlrp1b.
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Affiliation(s)
- Vinicius N Motta
- Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Janet G M Markle
- Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada; Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Omid Gulban
- Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Steven Mortin-Toth
- Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Kuo-Chien Liao
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Jeremy Mogridge
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Charles A Steward
- Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom; and
| | - Jayne S Danska
- Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada; Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
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10
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Dennis MK, Mogridge J. A protective antigen mutation increases the pH threshold of anthrax toxin receptor 2-mediated pore formation. Biochemistry 2014; 53:2166-71. [PMID: 24641616 PMCID: PMC3985898 DOI: 10.1021/bi5000756] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Anthrax toxin protective antigen
(PA) binds cellular receptors
and self-assembles into oligomeric prepores. A prepore converts to
a protein translocating pore after it has been transported to an endosome
where the low pH triggers formation of a membrane-spanning β-barrel
channel. Formation of this channel occurs after some PA–receptor
contacts are broken to allow pore formation, while others are retained
to preserve receptor association. The interaction between PA and anthrax
toxin receptor 1 (ANTXR1) is weaker than its interaction with ANTXR2
such that the pH threshold of ANTXR1-mediated pore formation is higher
by 1 pH unit. Here we examine receptor-specific differences in toxin
binding and pore formation by mutating PA residue G342 that selectively
abuts ANTXR2. Mutation of G342 to valine, leucine, isoleucine, or
tryptophan increased the amount of PA bound to ANTXR1-expressing cells
and decreased the amount of PA bound to ANTXR2-expressing cells. The
more conservative G342A mutation did not affect the level of binding
to ANTXR2, but ANTXR2-bound PA-G342A prepores exhibited a pH threshold
higher than that of wild-type prepores. Mixtures of wild-type PA and
PA-G342A were functional in toxicity assays, and the pH threshold
of ANTXR2-mediated pore formation was dictated by the relative amounts
of the two proteins in the hetero-oligomers. These results suggest
that PA subunits within an oligomer do not have to be triggered simultaneously
for a productive membrane insertion event to occur.
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Affiliation(s)
- Melissa K Dennis
- Department of Laboratory Medicine and Pathobiology, University of Toronto , Toronto, Ontario M5S 1A8, Canada
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11
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Simon NC, Barbieri JT. Bacillus cereus Certhrax ADP-ribosylates vinculin to disrupt focal adhesion complexes and cell adhesion. J Biol Chem 2014; 289:10650-10659. [PMID: 24573681 DOI: 10.1074/jbc.m113.500710] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacillus cereus is often associated with mild to moderate gastroenteritis; however, some recent isolates cause inhalational anthrax-like diseases and death. These potential emerging human pathogens express multiple virulence factors. B. cereus strain G9241 expresses anthrax toxin, several polysaccharide capsules, and the novel ADP-ribosyltransferase, Certhrax. In this study, we show that Certhrax ADP-ribosylates Arg-433 of vinculin, a protein that coordinates actin cytoskeleton and extracellular matrix interactions. ADP-ribosylation of vinculin disrupted focal adhesion complexes and redistributed vinculin to the cytoplasm. Exogenous vinculin rescued these phenotypes. This provides a mechanism for strain G9241 to breach host barrier defenses and promote bacterial growth and spread. Certhrax is the first bacterial toxin to add a post-translational modification to vinculin to disrupt the actin cytoskeleton.
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Affiliation(s)
- Nathan C Simon
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Joseph T Barbieri
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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12
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Jeong SY, Martchenko M, Cohen SN. Calpain-dependent cytoskeletal rearrangement exploited for anthrax toxin endocytosis. Proc Natl Acad Sci U S A 2013; 110:E4007-15. [PMID: 24085852 PMCID: PMC3801034 DOI: 10.1073/pnas.1316852110] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The protective antigen component of Bacillus anthracis toxins can interact with at least three distinct proteins on the host cell surface, capillary morphogenesis gene 2 (CMG2), tumor endothelial marker 8, and β1-integrin, and, with the assistance of other host proteins, enters targeted cells by receptor-mediated endocytosis. Using an antisense-based phenotypic screen, we discovered the role of calpains in this process. We show that functions of a ubiquitous Ca(2+)-dependent cysteine protease, calpain-2, and of the calpain substrate talin-1 are exploited for association of anthrax toxin and its principal receptor, CMG2, with higher-order actin filaments and consequently for toxin entry into host cells. Down-regulated expression of calpain-2 or talin-1, or pharmacological interference with calpain action, did not affect toxin binding but reduced endocytosis and increased the survival of cells exposed to anthrax lethal toxin. Adventitious expression of wild-type talin-1 promoted toxin endocytosis and lethality, whereas expression of a talin-1 mutant (L432G) that is insensitive to calpain cleavage did not. Disruption of talin-1, which links integrin-containing focal adhesion complexes to the actin cytoskeleton, facilitated association of toxin bound to its principal cell-surface receptor, CMG2, with higher-order actin filaments undergoing dynamic disassembly and reassembly during endocytosis. Our results reveal a mechanism by which a bacterial toxin uses constitutively occurring calpain-mediated cytoskeletal rearrangement for internalization.
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Affiliation(s)
| | | | - Stanley N. Cohen
- Departments of Genetics and
- Medicine, Stanford University School of Medicine, Stanford, CA 94305
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13
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Vargas M, Karamsetty R, Leppla SH, Chaudry GJ. Broad expression analysis of human ANTXR1/TEM8 transcripts reveals differential expression and novel splizce variants. PLoS One 2012; 7:e43174. [PMID: 22912819 PMCID: PMC3422265 DOI: 10.1371/journal.pone.0043174] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 07/20/2012] [Indexed: 01/25/2023] Open
Abstract
Tumor endothelial marker 8 (TEM8; ANTXR1) is one of two anthrax toxin receptors; the other is capillary morphogenesis gene 2 protein (CMG2; ANTXR2). TEM8 shows enhanced expression in certain tumor endothelia, and is thought to be a player in tumor vasculature formation. However, a comprehensive expression profile of individual TEM8 variants in normal or cancerous tissues is lacking. In this work we carried out an extensive analysis of all splice variants of human TEM8 in 12 digestive tissues, and 8 each fetal and adult tissues, 6 of them cognate pairs. Using variant-specific primers, we first ascertained the status of full-length transcripts by nested PCR. We then carried out quantitative analysis of each transcript by real-time PCR. Three splice variants of TEM8 were reported before, two single-pass integral membrane forms (V1 and V2) and one secreted (V3). Our analysis has revealed two new variants, one encoding a membrane-bound form of the receptor and the other secreted, which we have designated V4 and V5, respectively. All tissues had V1, V2, V3, and V4, but only prostate had V5. Real-time PCR revealed that all variants are present at different levels in various tissues. V3 appeared the most abundant of all. To ascertain its functionality for anthrax toxin, we expressed the newly identified form V4 in a receptor-negative host cell, and included V1 and V2 for comparison. Cytotoxicity, toxin binding, and internalization assays showed V4 to be as efficient a receptor as V1 and V2.
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Affiliation(s)
- Micaela Vargas
- Cell and Molecular Biology Program, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Raghavendra Karamsetty
- Cell and Molecular Biology Program, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, The Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - G. Jilani Chaudry
- Cell and Molecular Biology Program, Department of Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
- * E-mail:
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14
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Bann JG. Anthrax toxin protective antigen--insights into molecular switching from prepore to pore. Protein Sci 2012; 21:1-12. [PMID: 22095644 DOI: 10.1002/pro.752] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The protective antigen is a key component of the anthrax toxin, as it allows entry of the enzymatic components edema factor and lethal factor into the host cell, through the formation of a membrane spanning pore. This event is absolutely critical for the pathogenesis of anthrax, and although we have yet to understand the mechanism of pore formation, recent developments have provided key insights into how this process may occur. Based on the available data, a model is proposed for the kinetic steps for protective antigen conversion from prepore to pore. In this model, the driving force for pore formation is the formation of the phi (ϕ)-clamp, a region that forms a leak-free seal around the translocating polypeptide. Formation of the ϕ-clamp elicits movements within the prepore that provide steric freedom for the subsequent conformational changes required to form the membrane spanning pore.
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Affiliation(s)
- James G Bann
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA.
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15
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Trescos Y, Tournier JN. Cytoskeleton as an emerging target of anthrax toxins. Toxins (Basel) 2012; 4:83-97. [PMID: 22474568 PMCID: PMC3317109 DOI: 10.3390/toxins4020083] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 01/21/2012] [Accepted: 01/26/2012] [Indexed: 01/29/2023] Open
Abstract
Bacillus anthracis, the agent of anthrax, has gained virulence through its exotoxins produced by vegetative bacilli and is composed of three components forming lethal toxin (LT) and edema toxin (ET). So far, little is known about the effects of these toxins on the eukaryotic cytoskeleton. Here, we provide an overview on the general effects of toxin upon the cytoskeleton architecture. Thus, we shall discuss how anthrax toxins interact with their receptors and may disrupt the interface between extracellular matrix and the cytoskeleton. We then analyze what toxin molecular effects on cytoskeleton have been described, before discussing how the cytoskeleton may help the pathogen to corrupt general cell processes such as phagocytosis or vascular integrity.
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Affiliation(s)
- Yannick Trescos
- Unité Interactions Hôte-Agents pathogènes, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, BP 87, 24 avenue des Maquis du Grésivaudan 38702 La Tronche Cedex, France;
- Ecole du Val-de-Grâce, 1 place Alphonse Lavéran, 75005 Paris, France
| | - Jean-Nicolas Tournier
- Unité Interactions Hôte-Agents pathogènes, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, BP 87, 24 avenue des Maquis du Grésivaudan 38702 La Tronche Cedex, France;
- Ecole du Val-de-Grâce, 1 place Alphonse Lavéran, 75005 Paris, France
- Author to whom correspondence should be addressed; ; Tel.: +33-4-76636850; Fax: +33-4-76636917
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16
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Garlick KM, Batty S, Mogridge J. Binding of filamentous actin to anthrax toxin receptor 1 decreases its association with protective antigen. Biochemistry 2012; 51:1249-56. [PMID: 22303962 DOI: 10.1021/bi2016469] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
ANTXR1 is a type I membrane protein that binds the protective antigen (PA) component of anthrax toxin. The cytosolic domain of ANTXR1 has a novel actin-binding region that influences the interaction of the ectodomain with PA. Here, we have investigated features of the cytosolic domain of ANTXR1 that reduce the association of the receptor with PA. We mutated a stretch of conserved acidic amino acids adjacent to the actin-binding region and found that the mutation increased the affinity for monomeric actin in vitro. ANTXR1 bearing this mutation exhibited increased association with the cytoskeleton and bound less PA compared to the wild-type receptor, confirming the inverse correlation between the two interactions. To determine whether binding of actin is sufficient to regulate the ectodomain, we replaced the actin-binding region of ANTXR1 with that from the yeast protein abp140 and with the WH2 domain of WAVE2. Although both of these domains bound monomeric actin in vitro, only the sequence from abp140 reduced binding of PA to a hybrid receptor. The actin binding regions of ANTXR1 and abp140, but not the WH2 domain, colocalized with actin stress fibers, which suggested that filamentous actin regulates ANTXR1. Consistent with this notion, disruption of actin filaments using latrunculin A increased the amount of PA bound to cells. This work provides evidence that cytoskeletal dynamics regulate ANTXR1 function.
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Affiliation(s)
- Kristopher M Garlick
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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17
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Deuquet J, Lausch E, Superti-Furga A, van der Goot FG. The dark sides of capillary morphogenesis gene 2. EMBO J 2012; 31:3-13. [PMID: 22215446 PMCID: PMC3252584 DOI: 10.1038/emboj.2011.442] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/07/2011] [Indexed: 11/08/2022] Open
Abstract
Capillary morphogenesis gene 2 (CMG2) is a type I membrane protein involved in the homeostasis of the extracellular matrix. While it shares interesting similarities with integrins, its exact molecular role is unknown. The interest and knowledge about CMG2 largely stems from the fact that it is involved in two diseases, one infectious and one genetic. CMG2 is the main receptor of the anthrax toxin, and knocking out this gene in mice renders them insensitive to infection with Bacillus anthracis spores. On the other hand, mutations in CMG2 lead to a rare but severe autosomal recessive disorder in humans called Hyaline Fibromatosis Syndrome (HFS). We will here review what is known about the structure of CMG2 and its ability to mediate anthrax toxin entry into cell. We will then describe the limited knowledge available concerning the physiological role of CMG2. Finally, we will describe HFS and the consequences of HFS-associated mutations in CMG2 at the molecular and cellular level.
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Affiliation(s)
- Julie Deuquet
- Ecole Polytechnique Fédérale de Lausanne, Institute of Global Health, Lausanne, Switzerland
| | - Ekkehart Lausch
- Department of Pediatrics, University of Freiburg, Freiburg, Germany
| | - Andrea Superti-Furga
- Division of Molecular Pediatrics, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
| | - F Gisou van der Goot
- Ecole Polytechnique Fédérale de Lausanne, Institute of Global Health, Lausanne, Switzerland
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18
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Cai C, Che J, Xu L, Guo Q, Kong Y, Fu L, Xu J, Cheng Y, Chen W. Tumor endothelium marker-8 based decoys exhibit superiority over capillary morphogenesis protein-2 based decoys as anthrax toxin inhibitors. PLoS One 2011; 6:e20646. [PMID: 21674060 PMCID: PMC3107238 DOI: 10.1371/journal.pone.0020646] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 05/06/2011] [Indexed: 01/06/2023] Open
Abstract
Anthrax toxin is the major virulence factor produced by Bacillus anthracis. The toxin consists of three protein subunits: protective antigen (PA), lethal factor, and edema factor. Inhibition of PA binding to its receptors, tumor endothelium marker-8 (TEM8) and capillary morphogenesis protein-2 (CMG2) can effectively block anthrax intoxication, which is particularly valuable when the toxin has already been overproduced at the late stage of anthrax infection, thus rendering antibiotics ineffectual. Receptor-like agonists, such as the mammalian cell-expressed von Willebrand factor type A (vWA) domain of CMG2 (sCMG2), have demonstrated potency against the anthrax toxin. However, the soluble vWA domain of TEM8 (sTEM8) was ruled out as an anthrax toxin inhibitor candidate due to its inferior affinity to PA. In the present study, we report that L56A, a PA-binding-affinity-elevated mutant of sTEM8, could inhibit anthrax intoxication as effectively as sCMG2 in Fisher 344 rats. Additionally, pharmacokinetics showed that L56A and sTEM8 exhibit advantages over sCMG2 with better lung-targeting and longer plasma retention time, which may contribute to their enhanced protective ability in vivo. Our results suggest that receptor decoys based on TEM8 are promising anthrax toxin inhibitors and, together with the pharmacokinetic studies in this report, may contribute to the development of novel anthrax drugs.
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Affiliation(s)
- Chenguang Cai
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jinjing Che
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Long Xu
- Laboratory of protein engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Qiang Guo
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yirong Kong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ling Fu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Junjie Xu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (JX) (JX); (YC) (YC); (WC) (WC)
| | - Yuanguo Cheng
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (JX) (JX); (YC) (YC); (WC) (WC)
| | - Wei Chen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (JX) (JX); (YC) (YC); (WC) (WC)
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19
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Cryan LM, Rogers MS. Targeting the anthrax receptors, TEM-8 and CMG-2, for anti-angiogenic therapy. Front Biosci (Landmark Ed) 2011; 16:1574-88. [PMID: 21196249 DOI: 10.2741/3806] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The anthrax toxin receptors tumor endothelial marker-8 (TEM-8) and capillary morphogenesis gene-2 (CMG-2) are responsible for allowing entry of anthrax toxin into host cells. These receptors were first discovered due to their enhanced expression on endothelial cells undergoing blood vessel growth or angiogenesis in model systems. Inhibition of angiogenesis is an important strategy for current anti-cancer therapies and treatment of retinal diseases. Functional roles for TEM-8 and CMG-2 in angiogenesis have recently emerged. TEM-8 appears to regulate endothelial cell migration and tubule formation whereas a role for CMG-2 in endothelial proliferation has been documented. TEM-8 and CMG-2 bind differentially to extracellular matrix proteins including collagen I, collagen IV and laminin and these properties may be responsible for their apparent roles in regulating endothelial cell behavior during angiogenesis. TEM-8-binding moieties have also been suggested to be useful in selectively targeting anti-angiogenic and anti-tumorigenic therapies to tumor endothelium. Additionally, studies of modified forms of lethal toxin (LeTx) have demonstrated that targeted inhibition of MAPKs within tumor vessels may represent an efficacious anti-angiogenic strategy.
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Affiliation(s)
- Lorna M Cryan
- Department of Surgery, Children's Hospital Boston, Boston, MA 02115, USA
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20
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Yang MY, Chaudhary A, Seaman S, Dunty J, Stevens J, Elzarrad MK, Frankel AE, St Croix B. The cell surface structure of tumor endothelial marker 8 (TEM8) is regulated by the actin cytoskeleton. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:39-49. [PMID: 21129411 DOI: 10.1016/j.bbamcr.2010.11.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 11/17/2010] [Accepted: 11/19/2010] [Indexed: 01/01/2023]
Abstract
Tumor endothelial marker 8 (TEM8) is an integrin-like cell surface protein upregulated on tumor blood vessels and a potential vascular target for cancer therapy. Here, we found that the ability of an anti-TEM8 antibody, clone SB5, to recognize the extracellular domain of TEM8 on the cell surface depends on other host-cell factors. By taking advantage of SB5's ability to distinguish different forms of cell surface TEM8, we identified alpha-smooth muscle actin and transgelin, an actin binding protein, as intracellular factors able to alter TEM8 cell surface structure. Overexpression of either of these proteins in cells converted TEM8 from an SB5-exposed to an SB5-masked form and protected cells from SB5-saporin immunotoxins. Because the predominant form of TEM8 on the cell surface is not recognized by SB5, we also developed a new monoclonal antibody, called AF334, which is able to recognize both the SB5-exposed and the SB5-masked forms of TEM8. AF334-saporin selectively killed TEM8-positive cells independent of TEM8 cell surface structure. These studies reveal that TEM8 exists in different forms at the cell surface, a structure dependent on interactions with components of the actin cytoskeleton, and should aid in the rational design of the most effective diagnostic and therapeutic anti-TEM8 monoclonal antibodies.
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Affiliation(s)
- Mi Young Yang
- National Cancer Institute, Frederick, MD 21702-1201, USA
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21
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Ramey JD, Villareal VA, Ng C, Ward SC, Xiong JP, Clubb RT, Bradley KA. Anthrax toxin receptor 1/tumor endothelial marker 8: mutation of conserved inserted domain residues overrides cytosolic control of protective antigen binding. Biochemistry 2010; 49:7403-10. [PMID: 20690680 DOI: 10.1021/bi100887w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Anthrax toxin receptor 1 (ANTXR1)/tumor endothelial marker 8 (TEM8) is one of two known proteinaceous cell surface anthrax toxin receptors. A metal ion dependent adhesion site (MIDAS) present in the integrin-like inserted (I) domain of ANTXR1 mediates the binding of the anthrax toxin subunit, protective antigen (PA). Here we provide evidence that single point mutations in the I domain can override regulation of ANTXR1 ligand-binding activity mediated by intracellular signals. A previously reported MIDAS mutant of ANTXR1 (T118A) was found to retain normal metal ion binding and secondary structure but failed to bind PA, consistent with a locked inactive state. Conversely, mutation of a conserved I domain phenylalanine residue to a tryptophan (F205W) increased the proportion of cell-surface ANTXR1 that bound PA, consistent with a locked active state. Interestingly, the K(D) and total amount of PA bound by the isolated ANTXR1 I domain were not affected by the F205W mutation, indicating that ANTXR1 is preferentially found in the active state in the absence of inside-out signaling. Circular dichroism (CD) spectroscopy and (1)H-(15)N heteronuclear single-quantum coherence (HSQC) nuclear magnetic resonance (NMR) revealed that structural changes between T118A, F205W, and WT I domains were minor despite a greater than 10(3)-fold difference in their abilities to bind toxin. Regulation of toxin binding has important implications for the design of toxin inhibitors and for the targeting of ANTXR1 for antitumor therapies.
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Affiliation(s)
- Jordan D Ramey
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California 90095, USA
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22
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Abrami L, Bischofberger M, Kunz B, Groux R, van der Goot FG. Endocytosis of the anthrax toxin is mediated by clathrin, actin and unconventional adaptors. PLoS Pathog 2010; 6:e1000792. [PMID: 20221438 PMCID: PMC2832758 DOI: 10.1371/journal.ppat.1000792] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 01/26/2010] [Indexed: 11/21/2022] Open
Abstract
The anthrax toxin is a tripartite toxin, where the two enzymatic subunits require the third subunit, the protective antigen (PA), to interact with cells and be escorted to their cytoplasmic targets. PA binds to cells via one of two receptors, TEM8 and CMG2. Interestingly, the toxin times and triggers its own endocytosis, in particular through the heptamerization of PA. Here we show that PA triggers the ubiquitination of its receptors in a β-arrestin-dependent manner and that this step is required for clathrin-mediated endocytosis. In addition, we find that endocytosis is dependent on the heterotetrameric adaptor AP-1 but not the more conventional AP-2. Finally, we show that endocytosis of PA is strongly dependent on actin. Unexpectedly, actin was also found to be essential for efficient heptamerization of PA, but only when bound to one of its 2 receptors, TEM8, due to the active organization of TEM8 into actin-dependent domains. Endocytic pathways are highly modular systems. Here we identify some of the key players that allow efficient heptamerization of PA and subsequent ubiquitin-dependent, clathrin-mediated endocytosis of the anthrax toxin. Bacillus anthracis is the bacterium responsible for the anthrax disease. Its virulence is mainly due to 2 factors, the anthrax toxin and the anti-phagocytic capsule. This toxin is composed of three independent polypeptide chains. Two of these have enzymatic activity and are responsible for the effects of the toxin. The third has no activity but is absolutely required to bring the 2 enzymatic subunits into the cell where they act. If one blocks entry into the cells, one blocks the effects of these toxins, which is why it is important to understand how the toxin enters into the cell at the molecular level. Here we identified various molecules that are involved in efficiently bringing the toxin into the cell. First, we found that the actin cytoskeleton plays an important role in organizing one of the two anthrax toxin receptors at the cell surface. Second, we found a cytosolic protein, β-arrestin, that is required to modify the intracellular part of the toxin receptor, to allow uptake. Finally, we directly show, for the first time, that anthrax toxin uptake is mediated by the so-called clathrin-dependent pathway, a very modular entry pathway, but that the toxin utilizes this pathway in an unconventional way.
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Affiliation(s)
- Laurence Abrami
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Faculty of Life Sciences, Lausanne, Switzerland
| | - Mirko Bischofberger
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Faculty of Life Sciences, Lausanne, Switzerland
| | - Béatrice Kunz
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Faculty of Life Sciences, Lausanne, Switzerland
| | - Romain Groux
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Faculty of Life Sciences, Lausanne, Switzerland
| | - F. Gisou van der Goot
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Faculty of Life Sciences, Lausanne, Switzerland
- * E-mail:
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23
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Van Der Goot G, Young JA. Receptors of anthrax toxin and cell entry. Mol Aspects Med 2009; 30:406-12. [PMID: 19732789 PMCID: PMC2783407 DOI: 10.1016/j.mam.2009.08.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Accepted: 08/24/2009] [Indexed: 11/29/2022]
Abstract
Anthrax toxin-receptor interactions are critical for toxin delivery to the host cell cytoplasm. This review summarizes what is known about the molecular details of the protective antigen (PA) toxin subunit interaction with either the ANTXR1 and ANTXR2 cellular receptors, and how receptor-type can dictate the low pH threshold of PA pore formation. The roles played by cellular factors in regulating the endocytosis of toxin-receptor complexes is also discussed.
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Affiliation(s)
- Gisou Van Der Goot
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, SV-AI extension, Station 15, 1015 Lausanne, Switzerland,
| | - John A.T. Young
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037,
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24
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Garlick KM, Mogridge J. Direct interaction between anthrax toxin receptor 1 and the actin cytoskeleton. Biochemistry 2009; 48:10577-81. [PMID: 19817382 DOI: 10.1021/bi9015296] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The protective antigen component of anthrax toxin binds the I domain of the anthrax toxin receptors, ANTXR1 and ANTXR2, in a manner akin to how integrins bind their ligands. The I domains of integrins and ANTXR1 both have high- and low-affinity conformations, and the cytosolic tails of these receptors associate with the actin cytoskeleton. The association of ANTXR1 with the cytoskeleton correlates with weakened binding to PA, although a mechanistic explanation for this observation is lacking. Here, we identified a segment in the cytoplasmic tail of ANTXR1 required for its association with the cytoskeleton. We synthesized a 60-mer peptide based on this segment and demonstrated a direct interaction between the peptide and beta-actin, indicating that in contrast to integrins, ANTXR1 does not use an adaptor to bind the cytoskeleton. This peptide orders actin filaments into arrays, demonstrating an actin bundling activity that is novel for a membrane protein.
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Affiliation(s)
- Kristopher M Garlick
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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25
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Ha SD, Ham B, Mogridge J, Saftig P, Lin S, Kim SO. Cathepsin B-mediated autophagy flux facilitates the anthrax toxin receptor 2-mediated delivery of anthrax lethal factor into the cytoplasm. J Biol Chem 2009; 285:2120-9. [PMID: 19858192 DOI: 10.1074/jbc.m109.065813] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Anthrax lethal toxin (LeTx) is a virulence factor secreted by Bacillus anthracis and has direct cytotoxic effects on most cells once released into the cytoplasm. The cytoplasmic delivery of the proteolytically active component of LeTx, lethal factor (LF), is carried out by the transporter component, protective antigen, which interacts with either of two known surface receptors known as anthrax toxin receptor (ANTXR) 1 and 2. We found that the cytoplasmic delivery of LF by ANTXR2 was mediated by cathepsin B (CTSB) and required lysosomal fusion with LeTx-containing endosomes. Also, binding of protective antigen to ANXTR1 or -2 triggered autophagy, which facilitated the cytoplasmic delivery of ANTXR2-associated LF. We found that whereas cells treated with the membrane-permeable CTSB inhibitor CA074-Me- or CTSB-deficient cells had no defect in fusion of LC3-containing autophagic vacuoles with lysosomes, autophagic flux was significantly delayed. These results suggested that the ANTXR2-mediated cytoplasmic delivery of LF was enhanced by CTSB-dependent autophagic flux.
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Affiliation(s)
- Soon-Duck Ha
- Department of Microbiology and Immunology, Siebens-Drake Research Institute, University of Western Ontario, London, Ontario N6G2V4, Canada
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26
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Kintzer AF, Thoren KL, Sterling HJ, Dong KC, Feld GK, Tang II, Zhang TT, Williams ER, Berger JM, Krantz BA. The protective antigen component of anthrax toxin forms functional octameric complexes. J Mol Biol 2009; 392:614-29. [PMID: 19627991 PMCID: PMC2742380 DOI: 10.1016/j.jmb.2009.07.037] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/11/2009] [Accepted: 07/13/2009] [Indexed: 01/07/2023]
Abstract
The assembly of bacterial toxins and virulence factors is critical to their function, but the regulation of assembly during infection has not been studied. We begin to address this question using anthrax toxin as a model. The protective antigen (PA) component of the toxin assembles into ring-shaped homooligomers that bind the two other enzyme components of the toxin, lethal factor (LF) and edema factor (EF), to form toxic complexes. To disrupt the host, these toxic complexes are endocytosed, such that the PA oligomer forms a membrane-spanning channel that LF and EF translocate through to enter the cytosol. Using single-channel electrophysiology, we show that PA channels contain two populations of conductance states, which correspond to two different PA pre-channel oligomers observed by electron microscopy-the well-described heptamer and a novel octamer. Mass spectrometry demonstrates that the PA octamer binds four LFs, and assembly routes leading to the octamer are populated with even-numbered, dimeric and tetrameric, PA intermediates. Both heptameric and octameric PA complexes can translocate LF and EF with similar rates and efficiencies. Here, we report a 3.2-A crystal structure of the PA octamer. The octamer comprises approximately 20-30% of the oligomers on cells, but outside of the cell, the octamer is more stable than the heptamer under physiological pH. Thus, the PA octamer is a physiological, stable, and active assembly state capable of forming lethal toxins that may withstand the hostile conditions encountered in the bloodstream. This assembly mechanism may provide a novel means to control cytotoxicity.
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Affiliation(s)
- Alexander F. Kintzer
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A.,California Institute for Quantitative Biomedical Research (QB3), University of California, Berkeley, CA, 94720, U.S.A
| | - Katie L. Thoren
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A
| | - Harry J. Sterling
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A
| | - Ken C. Dong
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A
| | - Geoffrey K. Feld
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A
| | - Iok I. Tang
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A
| | - Teri T. Zhang
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, U.S.A
| | - Evan R. Williams
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A.,California Institute for Quantitative Biomedical Research (QB3), University of California, Berkeley, CA, 94720, U.S.A
| | - James M. Berger
- California Institute for Quantitative Biomedical Research (QB3), University of California, Berkeley, CA, 94720, U.S.A.,Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, U.S.A
| | - Bryan A. Krantz
- Department of Chemistry, University of California, Berkeley, CA, 94720, U.S.A.,California Institute for Quantitative Biomedical Research (QB3), University of California, Berkeley, CA, 94720, U.S.A.,Department of Molecular & Cell Biology, University of California, Berkeley, CA, 94720, U.S.A.,To whom correspondence should be addressed. University of California, Berkeley 492 Stanley Hall, #3220 Berkeley, CA 94720−3220 1−510−666−2788 (B.A.K.)
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Expression of Nlrp1b inflammasome components in human fibroblasts confers susceptibility to anthrax lethal toxin. Infect Immun 2009; 77:4455-62. [PMID: 19651869 DOI: 10.1128/iai.00276-09] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Anthrax lethal toxin causes macrophages and dendritic cells from some mouse strains to undergo caspase-1-dependent cell death. Central to this process is the NOD-like receptor Nlrp1b (Nalp1b), which detects intoxication and then self-associates to form a complex, termed an inflammasome, that is capable of activating the procaspase-1 zymogen. The nature of the signal detected directly by Nlrp1b is not known, and the mechanisms of inflammasome assembly are poorly understood. Here, we demonstrate that transfection of human fibroblasts with plasmids encoding murine Nlrp1b and procaspase-1 was sufficient to confer susceptibility to lethal toxin-mediated death on the cells. As has been observed in murine macrophages, the enzymatic activities of lethal toxin and the proteasome were both required for activation of the Nlrp1b inflammasome and this activation led to prointerleukin-1 beta processing. Release of interleukin-1beta from cells was not dependent on cell lysis, as its secretion was not affected by an osmoprotectant that prevented the appearance of lactate dehydrogenase in the culture medium. We generated constitutively active mutants of Nlrp1b by making amino-terminal deletions to the protein and observed that the ability to activate procaspase-1 was dependent on the CARD domain, which bound procaspase-1, and a region adjacent to the CARD domain that promoted self-association. Our results demonstrate that lethal toxin can activate Nlrp1b in a nonmyeloid cell line and are consistent with work that suggests that activation induces proximity of procaspase-1.
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