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Archana CA, Sekar YS, Suresh KP, Subramaniam S, Sagar N, Rani S, Anandakumar J, Pandey RK, Barman NN, Patil SS. Investigating the Influence of ANTXR2 Gene Mutations on Protective Antigen Binding for Heightened Anthrax Resistance. Genes (Basel) 2024; 15:426. [PMID: 38674361 PMCID: PMC11049084 DOI: 10.3390/genes15040426] [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: 02/23/2024] [Revised: 03/14/2024] [Accepted: 03/18/2024] [Indexed: 04/28/2024] Open
Abstract
Bacillus anthracis is the bacterium responsible for causing the zoonotic disease called anthrax. The disease presents itself in different forms like gastrointestinal, inhalation, and cutaneous. Bacterial spores are tremendously adaptable, can persist for extended periods and occasionally endanger human health. The Anthrax Toxin Receptor-2 (ANTXR2) gene acts as membrane receptor and facilitates the entry of the anthrax toxin into host cells. Additionally, mutations in the ANTXR2 gene have been linked to various autoimmune diseases, including Hyaline Fibromatosis Syndrome (HFS), Ankylosing Spondylitis (AS), Juvenile Hyaline Fibromatosis (JHF), and Infantile Systemic Hyalinosis (ISH). This study delves into the genetic landscape of ANTXR2, aiming to comprehend its associations with diverse disorders, elucidate the impacts of its mutations, and pinpoint minimal non-pathogenic mutations capable of reducing the binding affinity of the ANTXR2 gene with the protective antigen. Recognizing the pivotal role of single-nucleotide polymorphisms (SNPs) in shaping genetic diversity, we conducted computational analyses to discern highly deleterious and tolerated non-synonymous SNPs (nsSNPs) in the ANTXR2 gene. The Mutpred2 server determined that the Arg465Trp alteration in the ANTXR2 gene leads to altered DNA binding (p = 0.22) with a probability of a deleterious mutation of 0.808; notably, among the identified deleterious SNPs, rs368288611 (Arg465Trp) stands out due to its significant impact on altering the DNA-binding ability of ANTXR2. We propose these SNPs as potential candidates for hypertension linked to the ANTXR2 gene, which is implicated in blood pressure regulation. Noteworthy among the tolerated substitutions is rs200536829 (Ala33Ser), recognized as less pathogenic; this highlights its potential as a valuable biomarker, potentially reducing side effects on the host while also reducing binding with the protective antigen protein. Investigating these SNPs holds the potential to correlate with several autoimmune disorders and mitigate the impact of anthrax disease in humans.
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Affiliation(s)
- Chamalapura Ashwathama Archana
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru 560064, India; (C.A.A.); (Y.S.S.); (N.S.); (S.R.); (J.A.); (S.S.P.)
| | - Yamini Sri Sekar
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru 560064, India; (C.A.A.); (Y.S.S.); (N.S.); (S.R.); (J.A.); (S.S.P.)
| | - Kuralayanapalya Puttahonnappa Suresh
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru 560064, India; (C.A.A.); (Y.S.S.); (N.S.); (S.R.); (J.A.); (S.S.P.)
| | | | - Ningegowda Sagar
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru 560064, India; (C.A.A.); (Y.S.S.); (N.S.); (S.R.); (J.A.); (S.S.P.)
| | - Swati Rani
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru 560064, India; (C.A.A.); (Y.S.S.); (N.S.); (S.R.); (J.A.); (S.S.P.)
| | - Jayashree Anandakumar
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru 560064, India; (C.A.A.); (Y.S.S.); (N.S.); (S.R.); (J.A.); (S.S.P.)
| | - Rajan Kumar Pandey
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Solna, Sweden;
| | - Nagendra Nath Barman
- College of Veterinary Science, Assam Agricultural University (AAU), Guwahati 781022, India;
| | - Sharanagouda S. Patil
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru 560064, India; (C.A.A.); (Y.S.S.); (N.S.); (S.R.); (J.A.); (S.S.P.)
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Huang X, Zhang L, Luo W, Zeng Y, Li X, Yang N, Huang W, Ding BS. Endothelial anthrax toxin receptor 2 plays a protective role in liver fibrosis. Front Cell Dev Biol 2024; 11:1278968. [PMID: 38322497 PMCID: PMC10844529 DOI: 10.3389/fcell.2023.1278968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 12/18/2023] [Indexed: 02/08/2024] Open
Abstract
Hepatocellular carcinoma is one of the leading cancers worldwide and is a potential consequence of fibrosis. Therefore, the identification of key cellular and molecular mechanisms involved in liver fibrosis is an important goal for the development of new strategies to control liver-related diseases. Here, single-cell RNA sequencing data (GSE136103 and GES181483) of clinical liver non-parenchymal cells were analyzed to identify cellular and molecular mechanisms of liver fibrosis. The proportion of endothelial subpopulations in cirrhotic livers was significantly higher than that in healthy livers. Gene ontology and gene set enrichment analysis of differentially expressed genes in the endothelial subgroups revealed that extracellular matrix (ECM)-related pathways were significantly enriched. Since anthrax toxin receptor 2 (ANTXR2) interacts with the ECM, the expression of ANTXR2 in the liver endothelium was analyzed. ANTXR2 expression in the liver endothelium of wild-type (WT) mice significantly decreased after a 4-time sequential injection of carbon tetrachloride (CCl4) to induce liver fibrosis. Next, conditional knockout mice selectively lacking Antxr2 in endothelial cells were generated. After endothelial-specific Antxr2 knockout mice were subjected to the CCl4 model, the degree of liver fibrosis in the knockout group was significantly more severe than that in the control group. In addition, ANTXR2 in human umbilical vein endothelial cells promoted matrix metalloproteinase 2 (MMP2) activation to degrade the ECM in vitro. Finally, endothelial-specific overexpression of Antxr2 alleviated the development of liver fibrosis following adeno-associated virus treatment. Collectively, these results suggested that endothelial ANTXR2 plays a protective role in liver fibrosis. This function of ANTXR2 may be achieved by promoting MMP2 activation to degrade the ECM.
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Affiliation(s)
| | | | | | | | | | | | | | - Bi-Sen Ding
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second University Hospital, Sichuan University, Chengdu, China
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3
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Yin L, Thaker H. Cancer Drug Delivery Systems Using Bacterial Toxin Translocation Mechanisms. Bioengineering (Basel) 2023; 10:813. [PMID: 37508840 PMCID: PMC10376142 DOI: 10.3390/bioengineering10070813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/16/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
Recent advances in targeted cancer therapy hold great promise for both research and clinical applications and push the boundaries in finding new treatments for various currently incurable cancers. However, these therapies require specific cell-targeting mechanisms for the efficient delivery of drug cargo across the cell membrane to reach intracellular targets and avoid diffusion to unwanted tissues. Traditional drug delivery systems suffer from a limited ability to travel across the barriers posed by cell membranes and, therefore, there is a need for high doses, which are associated with adverse reactions and safety concerns. Bacterial toxins have evolved naturally to specifically target cell subtypes via their receptor binding module, penetrating the cell membrane efficiently through the membrane translocation process and then successfully delivering the toxic cargo into the host cytosol. They have, thus, been harnessed for the delivery of various drugs. In this review, we focus on bacterial toxin translocation mechanisms and recent progress in the targeted delivery systems of cancer therapy drugs that have been inspired by the receptor binding and membrane translocation processes of the anthrax toxin protective antigen, diphtheria toxin, and Pseudomonas exotoxin A. We also discuss the challenges and limitations of these studies that should be addressed before bacterial toxin-based drug delivery systems can become a viable new generation of drug delivery approaches in clinical translation.
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Affiliation(s)
- Linxiang Yin
- Department of Urology, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Surgery, Harvard Medical School, Boston, MA 02115, USA
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Hatim Thaker
- Department of Urology, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Surgery, Harvard Medical School, Boston, MA 02115, USA
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
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Anwar MU, Sergeeva OA, Abrami L, Mesquita FS, Lukonin I, Amen T, Chuat A, Capolupo L, Liberali P, D'Angelo G, van der Goot FG. ER-Golgi-localized proteins TMED2 and TMED10 control the formation of plasma membrane lipid nanodomains. Dev Cell 2022; 57:2334-2346.e8. [PMID: 36174556 DOI: 10.1016/j.devcel.2022.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/24/2022] [Accepted: 09/08/2022] [Indexed: 11/03/2022]
Abstract
To promote infections, pathogens exploit host cell machineries such as structural elements of the plasma membrane. Studying these interactions and identifying molecular players are ideal for gaining insights into the fundamental biology of the host cell. Here, we used the anthrax toxin to screen a library of 1,500 regulatory, cell-surface, and membrane trafficking genes for their involvement in the intoxication process. We found that endoplasmic reticulum (ER)-Golgi-localized proteins TMED2 and TMED10 are required for toxin oligomerization at the plasma membrane of human cells, an essential step dependent on localization to cholesterol-rich lipid nanodomains. Biochemical, morphological, and mechanistic analyses showed that TMED2 and TMED10 are essential components of a supercomplex that operates the exchange of both cholesterol and ceramides at ER-Golgi membrane contact sites. Overall, this study of anthrax intoxication led to the discovery that lipid compositional remodeling at ER-Golgi interfaces fully controls the formation of functional membrane nanodomains at the cell surface.
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Affiliation(s)
- Muhammad U Anwar
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Oksana A Sergeeva
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Laurence Abrami
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Francisco S Mesquita
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Ilya Lukonin
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland
| | - Triana Amen
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Audrey Chuat
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Laura Capolupo
- Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Prisca Liberali
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland
| | - Giovanni D'Angelo
- Institute of Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
| | - F Gisou van der Goot
- Global Health Institute, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
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5
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Choochuen P, Laochareonsuk W, Tanaanantarak P, Kanjanapradit K, Sangkhathat S. Juvenile Hyaline Fibromatosis: Report of a Case with a Novel ANTXR2 Gene Mutation. AMERICAN JOURNAL OF CASE REPORTS 2022; 23:e935921. [PMID: 35752930 PMCID: PMC9245060 DOI: 10.12659/ajcr.935921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 05/18/2022] [Accepted: 04/26/2022] [Indexed: 11/09/2022]
Abstract
BACKGROUND Juvenile hyaline fibromatosis is a rare autosomal recessive disorder with unknown prevalence characterized by abnormal development of hyalinized fibrous tissue usually in the skin, mucosa, bone, and often the internal organs. Here, we report the case of a 7-year-old girl from a family with ANTXR2 mutation confirming JHF. CASE REPORT The girl presented with multiple painless soft-tissue swellings affecting the ears, forehead, and scalp. Excisional biopsies of the masses reported positive immunohistochemical staining for collagen type VI in the extracellular matrix area, which indicated collagen VI accumulation. Genetic analysis was performed using whole-exome sequencing. The variants were further validated using Sanger sequencing in trio-based approach. We identified a novel mutation, c.1273_1293delinsTCTTGTGGGTTTGGCT in exon 15 of ANTXR2 gene, leading to a frameshift of the amino acid from codon 425 to all the rest of the amino acid chain (p.Pro425Serfs). The change of an encoded protein interrupted lysosome-mediated degradation of collagen VI. This finding was compatible with her parents whose genetic tests were both positive for the same heterogenous deletion/insertion mutation. The patient was treated with surgical excision of the tumor masses, which had to be repeated several times due to recurrences. CONCLUSIONS This novel mutation in exon 15 of the ANTXR2 gene may help improve understanding of genotype-phenotype correlations for this syndrome and provide the basis for diagnostic testing. A multidisciplinary team approach including genetic molecular testing is required for an accurate diagnosis and management of JHF for conducting genetic counseling for affected families as a part of holistic management.
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Affiliation(s)
- Pongsakorn Choochuen
- Department of Biomedical Sciences and Biomedical Engineering, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand
| | - Wison Laochareonsuk
- Department of Biomedical Sciences and Biomedical Engineering, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand
- Translational Medicine Research Center, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand
| | - Pattama Tanaanantarak
- Department of Radiology, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand
| | - Kanet Kanjanapradit
- Department of Pathology, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand
| | - Surasak Sangkhathat
- Translational Medicine Research Center, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand
- Department of Surgery, Faculty of Medicine, Prince of Songkla University, Hatyai, Songkhla, Thailand
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6
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Choate LA, Barshad G, McMahon PW, Said I, Rice EJ, Munn PR, Lewis JJ, Danko CG. Multiple stages of evolutionary change in anthrax toxin receptor expression in humans. Nat Commun 2021; 12:6590. [PMID: 34782625 PMCID: PMC8592990 DOI: 10.1038/s41467-021-26854-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/18/2021] [Indexed: 11/09/2022] Open
Abstract
The advent of animal husbandry and hunting increased human exposure to zoonotic pathogens. To understand how a zoonotic disease may have influenced human evolution, we study changes in human expression of anthrax toxin receptor 2 (ANTXR2), which encodes a cell surface protein necessary for Bacillus anthracis virulence toxins to cause anthrax disease. In immune cells, ANTXR2 is 8-fold down-regulated in all available human samples compared to non-human primates, indicating regulatory changes early in the evolution of modern humans. We also observe multiple genetic signatures consistent with recent positive selection driving a European-specific decrease in ANTXR2 expression in multiple tissues affected by anthrax toxins. Our observations fit a model in which humans adapted to anthrax disease following early ecological changes associated with hunting and scavenging, as well as a second period of adaptation after the rise of modern agriculture.
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Affiliation(s)
- Lauren A Choate
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Gilad Barshad
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Pierce W McMahon
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Iskander Said
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Edward J Rice
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Paul R Munn
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - James J Lewis
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA.
| | - Charles G Danko
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA.
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA.
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7
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Liu W, Nestorovich EM. Anthrax toxin channel: What we know based on over 30 years of research. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183715. [PMID: 34332985 DOI: 10.1016/j.bbamem.2021.183715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
Protective antigen channel is the central component of the deadly anthrax exotoxin responsible for binding and delivery of the toxin's enzymatic lethal and edema factor components into the cytosol. The channel, which is more than three times longer than the lipid bilayer membrane thickness and has a 6-Å limiting diameter, is believed to provide a sophisticated unfoldase and translocase machinery for the foreign protein transport into the host cell cytosol. The tripartite toxin can be reengineered, one component at a time or collectively, to adapt it for the targeted cancer therapeutic treatments. In this review, we focus on the biophysical studies of the protective antigen channel-forming activity, small ion transport properties, enzymatic factor translocation, and blockage comparing it with the related clostridial binary toxin channels. We address issues linked to the anthrax toxin channel structural dynamics and lipid dependence, which are yet to become generally recognized as parts of the toxin translocation machinery.
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Affiliation(s)
- Wenxing Liu
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA.
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Meng L, Yuan W, Chi H, Han R, Zhang Y, Pan X, Meng J, Liu Y, Song J, Zhong J, Liu X. Genetic deletion of CMG2 exacerbates systemic-to-pulmonary shunt-induced pulmonary arterial hypertension. FASEB J 2021; 35:e21421. [PMID: 33749907 DOI: 10.1096/fj.202000299r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 12/30/2020] [Accepted: 01/21/2021] [Indexed: 11/11/2022]
Abstract
Pulmonary arterial hypertension (PAH) secondary to congenital heart disease (CHD-PAH) with systemic-to-pulmonary shunt (SPS) is characterized by proliferative vascular remodeling. Capillary morphogenesis gene-2 (CMG2) plays a key role in cell proliferation and apoptosis. This study aimed to determine the role of CMG2 in the pathogenesis of SPS-induced PAH. CMG2 levels were significantly downregulated in pulmonary arterioles from patients with Eisenmenger syndrome and rats with SPS-induced PAH. CMG2 was highly expressed in several cells including human pulmonary arterial smooth muscle cells (HPASMCs). CMG2-/- rats exhibited more severe PAH and pulmonary vascular remodeling than wild-type rats when exposed to SPS for 8 weeks. Overexpression of CMG2 significantly inhibited proliferation and promoted apoptosis of HPASMCs, while knockdown of CMG2 promoted cell proliferation and inhibited cell apoptosis. Next-generation sequencing and subsequent validation results suggested that PI3K-AKT was the most prominent signaling pathway regulated by differentially expressed genes (DEGs) in CMG2-/- rat lungs. Our work identified a novel role for CMG2 in SPS-induced PAH based on the findings that CMG2 deficiency exacerbates SPS-induced vascular remodeling in the development of PAH, indicating that CMG2 might act as a potential target for the treatment of CHD-PAH.
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Affiliation(s)
- Liukun Meng
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Wen Yuan
- Medical Research Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Hongjie Chi
- Heart Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Ruijuan Han
- Department of Cardiology, Baotou Central hospital, Inner Mongolia, China
| | - Yeping Zhang
- Heart Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Xiangbin Pan
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Jian Meng
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Ying Liu
- Heart Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Jiawei Song
- Heart Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Jiuchang Zhong
- Heart Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Xiaoyan Liu
- Medical Research Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China.,Heart Center & Beijing Key Laboratory of Hypertension Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
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9
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Machen AJ, Fisher MT, Freudenthal BD. Anthrax toxin translocation complex reveals insight into the lethal factor unfolding and refolding mechanism. Sci Rep 2021; 11:13038. [PMID: 34158520 PMCID: PMC8219829 DOI: 10.1038/s41598-021-91596-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/27/2021] [Indexed: 11/09/2022] Open
Abstract
Translocation is essential to the anthrax toxin mechanism. Protective antigen (PA), the binding component of this AB toxin, forms an oligomeric pore that translocates lethal factor (LF) or edema factor, the active components of the toxin, into the cell. Structural details of the translocation process have remained elusive despite their biological importance. To overcome the technical challenges of studying translocation intermediates, we developed a method to immobilize, transition, and stabilize anthrax toxin to mimic important physiological steps in the intoxication process. Here, we report a cryoEM snapshot of PApore translocating the N-terminal domain of LF (LFN). The resulting 3.3 Å structure of the complex shows density of partially unfolded LFN near the canonical PApore binding site. Interestingly, we also observe density consistent with an α helix emerging from the 100 Å β barrel channel suggesting LF secondary structural elements begin to refold in the pore channel. We conclude the anthrax toxin β barrel aids in efficient folding of its enzymatic payload prior to channel exit. Our hypothesized refolding mechanism has broader implications for pore length of other protein translocating toxins.
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Affiliation(s)
- Alexandra J Machen
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Mark T Fisher
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
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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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11
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Tatulian SA, Kandel N. Membrane Pore Formation by Peptides Studied by Fluorescence Techniques. Methods Mol Biol 2019; 2003:449-464. [PMID: 31218629 DOI: 10.1007/978-1-4939-9512-7_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Pore formation in cellular membranes by pathogen-derived proteins is a mechanism utilized by a set of microbes to exert their cytotoxic effect. On the other hand, the host cells have developed a defense mechanism to produce antimicrobial peptides to kill the pathogens by a similar, membrane perforation mechanism. Furthermore, certain endogenous proteins or peptides kill the parent cells through membrane permeabilization. Analysis of the molecular details of membrane pore formation is often conducted using artificial systems, such as bilayer lipid membranes and synthetic peptides. This chapter describes two fluorescence-based methods to study peptide-induced membrane leakage. One method involves preparation of lipid vesicles loaded with a fluorophore (e.g., calcein or carboxyfluorescein) at a self-quenching concentration. If the externally added peptide forms relatively large pores (≥1 nm in diameter), the fluorophore leaks out and undergoes dequenching, resulting in time-dependent increase in fluorescence. The other method is designed to monitor smaller pores (<1 nm in diameter). It involves preparation of vesicles in a Ca2+-less buffer, containing a Ca2+-dependent fluorophore, such as Quin-2. Removal of external Quin-2 by a desalting column and addition of an appropriate concentration of CaCl2 externally sequesters Quin-2 and Ca2+ ions by the vesicle membrane. Addition of the pore-forming peptide to these vesicles results in membrane permeabilization, Ca2+ influx and binding to Quin-2. In both cases, the kinetics of the increase of fluorescence and its equilibrium levels allow quantitative analysis of the pore formation mechanism.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL, USA.
| | - Nabin Kandel
- Department of Physics, University of Central Florida, Orlando, FL, USA
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12
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Evans DJ, Wasinger AM, Brey RN, Dunleavey JM, St Croix B, Bann JG. Seneca Valley Virus Exploits TEM8, a Collagen Receptor Implicated in Tumor Growth. Front Oncol 2018; 8:506. [PMID: 30460197 PMCID: PMC6232524 DOI: 10.3389/fonc.2018.00506] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/16/2018] [Indexed: 12/25/2022] Open
Abstract
Recent studies reveal that Seneca Valley Virus (SVV) exploits tumor endothelial marker 8 (TEM8) for cellular entry, the same surface receptor pirated by bacterial-derived anthrax toxin. This observation is particularly significant as SVV is a known oncolytic virus which selectively infects and kills tumor cells, particularly those of neuroendocrine origin. TEM8 is a transmembrane glycoprotein that is preferentially upregulated in some tumor cell and tumor-associated stromal cell populations. Both TEM8 and SVV have been evaluated for targeting of tumors of multiple origins, but the connection between the two was previously unknown. Here, we review currently understood interactions between TEM8 and SVV, anthrax protective antigen (PA), and collagen VI, a native binding partner of TEM8, with an emphasis on potential therapeutic directions moving forward.
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Affiliation(s)
- David J Evans
- Department of Chemistry, Wichita State University, Wichita, KS, United States
| | - Alexa M Wasinger
- Department of Chemistry, Wichita State University, Wichita, KS, United States
| | | | - James M Dunleavey
- Tumor Angiogenesis Unit, National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD, United States
| | - Brad St Croix
- Tumor Angiogenesis Unit, National Cancer Institute (NCI), National Institutes of Health (NIH), Frederick, MD, United States
| | - James G Bann
- Department of Chemistry, Wichita State University, Wichita, KS, United States
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Harris JR, Soliakov A, Watkinson A, Lakey JH. Recombinant anthrax protective antigen: Observation of aggregation phenomena by TEM reveals specific effects of sterols. Micron 2016; 93:1-8. [PMID: 27883989 DOI: 10.1016/j.micron.2016.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 10/12/2016] [Indexed: 10/20/2022]
Abstract
Negatively stained transmission electron microscope images are presented that depict the aggregation of recombinant anthrax protective antigen (rPA83 monomer and the PA63 prepore oligomer) under varying in vitro biochemical conditions. Heat treatment (50°C) of rPA83 produced clumped fibrils, but following heating the PA63 prepore formed disordered aggregates. Freeze-thaw treatment of the PA63 prepore generated linear flexuous aggregates of the heptameric oligomers. Aqueous suspensions of cholesterol microcrystals were shown to bind small rPA83 aggregates at the edges of the planar bilayers. With PA63 a more discrete binding of the prepores to the crystalline cholesterol bilayer edges occurs. Sodium deoxycholate (NaDOC) treatment of rPA83 produced quasi helical fibrillar aggregate, similar but not identical to that produced by heat treatment. Remarkably, NaDOC treatment of the PA63 prepores induced transformation into pores, with a characteristic extended ß-barrel. The PA63 pores aggregated as dimers, that aggregated further as angular chains and closed structures in higher NaDOC concentrations. The significance of the sterol interaction is discussed in relation to its likely importance for PA action in vivo.
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Affiliation(s)
- J Robin Harris
- Institute of Zoology, University of Mainz, 55099 Mainz, Germany.
| | - Andrei Soliakov
- Fujifilm Diosynth Biotechnologies, Belasis Avenue, Billingham TS23 1LH, UK
| | - Allan Watkinson
- Envigo, Wooley Road, Alcon bury, Huntingdon, Cambridgeshire PE28 4HS, UK
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK
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Augmenting the Efficacy of Immunotoxins and Other Targeted Protein Toxins by Endosomal Escape Enhancers. Toxins (Basel) 2016; 8:toxins8070200. [PMID: 27376327 PMCID: PMC4963833 DOI: 10.3390/toxins8070200] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/14/2016] [Accepted: 06/17/2016] [Indexed: 12/18/2022] Open
Abstract
The toxic moiety of almost all protein-based targeted toxins must enter the cytosol of the target cell to mediate its fatal effect. Although more than 500 targeted toxins have been investigated in the past decades, no antibody-targeted protein toxin has been approved for tumor therapeutic applications by the authorities to date. Missing efficacy can be attributed in many cases to insufficient endosomal escape and therefore subsequent lysosomal degradation of the endocytosed toxins. To overcome this drawback, many strategies have been described to weaken the membrane integrity of endosomes. This comprises the use of lysosomotropic amines, carboxylic ionophores, calcium channel antagonists, various cell-penetrating peptides of viral, bacterial, plant, animal, human and synthetic origin, other organic molecules and light-induced techniques. Although the efficacy of the targeted toxins was typically augmented in cell culture hundred or thousand fold, in exceptional cases more than million fold, the combination of several substances harbors new problems including additional side effects, loss of target specificity, difficulties to determine the therapeutic window and cell type-dependent variations. This review critically scrutinizes the chances and challenges of endosomal escape enhancers and their potential role in future developments.
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