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Byerly CD, Zhu B, Warwick PA, Patterson LL, Pittner NA, McBride JW. Ehrlichia chaffeensis TRP120 ubiquitinates tumor suppressor APC to modulate Hippo and Wnt signaling. Front Cell Dev Biol 2024; 12:1327418. [PMID: 38562145 PMCID: PMC10982408 DOI: 10.3389/fcell.2024.1327418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 03/05/2024] [Indexed: 04/04/2024] Open
Abstract
Ehrlichia chaffeensis: TRP120 is a multifunctional effector that acts as a ligand mimic to activate evolutionary conserved eukaryotic signaling pathways Notch, Wnt, Hedgehog and Hippo. In addition, TRP120 is also a HECT E3 ubiquitin ligase known to ubiquitinate several host cell regulatory proteins (FBW7, PCGF5 and ENO-1) for degradation. We previously determined that TRP120 ubiquitinates the Notch negative regulator, FBW7, to maintain Notch signaling and promote infection. In this study, we investigated a potential mechanism used by Ehrlichia chaffeensis to maintain Hippo and Wnt signaling by ubiquitinating the tumor suppressor, adenomatous polyposis coli (APC), a negative regulator of Wnt and Hippo signaling. We determined that APC was rapidly degraded during E. chaffeensis infection despite increased APC transcription. Moreover, RNAi knockdown of APC significantly increased E. chaffeensis infection and coincided with increased active Yap and β-catenin in the nucleus. We observed strong nuclear colocalization between TRP120 and APC in E. chaffeensis-infected THP-1 cells and after ectopic expression of TRP120 in HeLa cells. Additionally, TRP120 interacted with both APC full length and truncated isoforms via co-immunoprecipitation. Further, TRP120 ubiquitination of APC was demonstrated in vitro and confirmed by ectopic expression of a TRP120 HECT Ub ligase catalytic site mutant. This study identifies APC as a TRP120 HECT E3 Ub ligase substrate and demonstrates that TRP120 ligase activity promotes ehrlichial infection by degrading tumor suppressor APC to positively regulate Hippo and Wnt signaling.
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Affiliation(s)
| | | | | | | | | | - Jere W. McBride
- Departments of Pathology, Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases, Sealy Institute for Vaccine Sciences and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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Byerly CD, Patterson LL, Pittner NA, Solomon RN, Patel JG, Rogan MR, McBride JW. Ehrlichia Wnt SLiM ligand mimic deactivates the Hippo pathway to engage the anti-apoptotic Yap-GLUT1-BCL-xL axis. Infect Immun 2023; 91:e0008523. [PMID: 37530530 PMCID: PMC10501218 DOI: 10.1128/iai.00085-23] [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: 03/02/2023] [Accepted: 06/03/2023] [Indexed: 08/03/2023] Open
Abstract
Ehrlichia chaffeensis TRP120 effector has evolved short linear motif (SLiM) ligand mimicry to repurpose multiple evolutionarily conserved cellular signaling pathways, including Wnt, Notch, and Hedgehog. In this investigation, we demonstrate that E. chaffeensis and recombinant TRP120 deactivate Hippo signaling, resulting in the activation of Hippo transcription coactivator Yes-associated protein (Yap). Moreover, a homologous 6 amino acid (QDVASH) SLiM shared by TRP120 and Wnt3a/5a ligands phenocopied Yap and β-catenin activation induced by E. chaffeensis, rTRP120, and Wnt5a. Similar Hippo gene expression profiles were also stimulated by E. chaffeensis, rTRP120, SLiM, and Wnt5a. Single siRNA knockdown of Hippo transcription co-activator/factors, Yap, and transcriptional enhanced associate domain (TEAD) significantly decreased E. chaffeensis infection. Yap activation was abolished in THP-1 Wnt Frizzled-5 (Fzd5) receptor knockout cells (KO), demonstrating Fzd5 receptor dependence. In addition, the TRP120-Wnt-SLiM antibody blocked Hippo deactivation (Yap activation). Expression of anti-apoptotic Hippo target gene SLC2A1 (encodes glucose transporter 1; GLUT1) was upregulated by E. chaffeensis and corresponded to increased levels of GLUT1. Conversely, siRNA knockdown of SLC2A1 significantly inhibited infection. Higher GLUT1 levels correlated with increased B cell lymphoma-extra large (BCL-xL) and decreased BCL2-associated X, apoptosis regulator (Bax) levels. Moreover, blocking Yap activation with the inhibitor Verteporfin induced apoptosis that corresponded to significant reductions in GLUT1 and BCL-xL levels and activation of Bax and Caspase-3 and -9. This study identifies a novel shared Wnt/Hippo SLiM ligand mimic and demonstrates that E. chaffeensis deactivates the Hippo pathway to engage the anti-apoptotic Yap-GLUT1-BCL-xL axis.
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Affiliation(s)
- Caitlan D. Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - LaNisha L. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nicholas A. Pittner
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Regina N. Solomon
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jignesh G. Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Madison R. Rogan
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
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Patterson LL, Byerly CD, Solomon R, Pittner N, Bui DC, Patel J, McBride JW. Ehrlichia Notch signaling induction promotes XIAP stability and inhibits apoptosis. Infect Immun 2023; 91:e0000223. [PMID: 37594275 PMCID: PMC10501217 DOI: 10.1128/iai.00002-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 06/07/2023] [Indexed: 08/19/2023] Open
Abstract
Ehrlichia chaffeensis has evolved multiple strategies to evade innate defenses of the mononuclear phagocyte. Recently, we reported the E. chaffeensis tandem repeat protein (TRP)120 effector functions as a Notch ligand mimetic and a ubiquitin ligase that degrades the nuclear tumor suppressor, F-box and WD repeat domain-containing 7, a negative regulator of Notch. The Notch intracellular domain (NICD) is known to inhibit apoptosis primarily by interacting with X-linked inhibitor of apoptosis protein (XIAP) to prevent degradation. In this study, we determined that E. chaffeensis activation of Notch signaling increases XIAP levels, thereby inhibiting apoptosis through both the intrinsic and executioner pathways. Increased NICD and XIAP levels were detected during E. chaffeensis infection and after TRP120 Notch ligand mimetic peptide treatment. Conversely, XIAP levels were reduced in the presence of Notch inhibitor DAPT. Cytoplasmic and nuclear colocalization of NICD and XIAP was observed during infection and a direct interaction was confirmed by co-immunoprecipitation. Procaspase levels increased temporally during infection, consistent with increased XIAP levels; however, knockdown (KD) of XIAP during infection significantly increased apoptosis and Caspase-3, -7, and -9 levels. Furthermore, treatment with SM-164, a second mitochondrial activator of caspases (Smac/DIABLO) antagonist, resulted in decreased procaspase levels and increased caspase activation, induced apoptosis, and significantly decreased infection. In addition, RNAi KD of XIAP also decreased infection and significantly increased apoptosis. Moreover, ectopic expression of TRP120 HECT Ub ligase catalytically defective mutant in HeLa cells decreased NICD and XIAP levels and increased caspase activation compared to HeLa cells with functional HECT Ub ligase catalytic activity (TRP120-WT). This investigation reveals a mechanism whereby E. chaffeensis modulates Notch signaling to stabilize XIAP and inhibit apoptosis.
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Affiliation(s)
- LaNisha L. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Caitlan D. Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Regina Solomon
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nicholas Pittner
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Duc Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jignesh Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
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Bui DC, Luo T, McBride JW. Type 1 secretion system and effectors in Rickettsiales. Front Cell Infect Microbiol 2023; 13:1175688. [PMID: 37256108 PMCID: PMC10225607 DOI: 10.3389/fcimb.2023.1175688] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/02/2023] [Indexed: 06/01/2023] Open
Abstract
Obligate intracellular bacteria in the order Rickettsiales are transmitted by arthropod vectors and cause life-threatening infections in humans and animals. While both type 1 and type 4 secretion systems (T1SS and T4SS) have been identified in this group, the most extensive studies of Rickettsiales T1SS and associated effectors have been performed in Ehrlichia. These studies have uncovered important roles for the T1SS effectors in pathobiology and immunity. To evade innate immune responses and promote intracellular survival, Ehrlichia and other related obligate pathogens secrete multiple T1SS effectors which interact with a diverse network of host targets associated with essential cellular processes. T1SS effectors have multiple functional activities during infection including acting as nucleomodulins and ligand mimetics that activate evolutionarily conserved cellular signaling pathways. In Ehrlichia, an array of newly defined major immunoreactive proteins have been identified that are predicted as T1SS substrates and have conformation-dependent antibody epitopes. These findings highlight the underappreciated and largely uncharacterized roles of T1SS effector proteins in pathobiology and immunity. This review summarizes current knowledge regarding roles of T1SS effectors in Rickettsiales members during infection and explores newly identified immunoreactive proteins as potential T1SS substrates and targets of a protective host immune response.
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Affiliation(s)
- Duc-Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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Gillespie JJ, Salje J. Orientia and Rickettsia: different flowers from the same garden. Curr Opin Microbiol 2023; 74:102318. [PMID: 37080115 DOI: 10.1016/j.mib.2023.102318] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 04/22/2023]
Abstract
Recent discoveries of basal extracellular Rickettsiales have illuminated divergent evolutionary paths to host dependency in later-evolving lineages. Family Rickettsiaceae, primarily comprised of numerous protist- and invertebrate-associated species, also includes human pathogens from two genera, Orientia and Rickettsia. Once considered sister taxa, these bacteria form distinct lineages with newly appreciated lifestyles and morphological traits. Contrasting other rickettsial human pathogens in Family Anaplasmataceae, Orientia and Rickettsia species do not reside in host-derived vacuoles and lack glycolytic potential. With only a few described mechanisms, strategies for commandeering host glycolysis to support cytosolic growth remain to be discovered. While regulatory systems for this unique mode of intracellular parasitism are unclear, conjugative transposons unique to Orientia and Rickettsia species provide insights that are critical for determining how these obligate intracellular pathogens overtake eukaryotic cytosol.
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Affiliation(s)
- Joseph J Gillespie
- Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, USA.
| | - Jeanne Salje
- Department of Biochemistry, Department of Pathology, and Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK.
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Byerly CD, Patterson LL, Pittner NA, Solomon RN, Patel JG, Rogan MR, McBride JW. Ehrlichia Wnt short linear motif ligand mimetic deactivates the Hippo pathway to engage the anti-apoptotic Yap-GLUT1-BCL-xL axis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.06.531456. [PMID: 36945589 PMCID: PMC10028901 DOI: 10.1101/2023.03.06.531456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Ehrlichia chaffeensis TRP120 effector has evolved short linear motif (SLiM) ligand mimicry to repurpose multiple evolutionarily conserved cellular signaling pathways including Wnt, Notch and Hedgehog. In this investigation, we demonstrate that E. chaffeensis and recombinant TRP120 deactivate Hippo signaling resulting in activation of Hippo transcription coactivator Yap and target gene expression. Moreover, a homologous 6 amino acid (QDVASH) SLiM shared by TRP120 and Wnt3a/5a ligands phenocopied Yap and β-catenin activation induced by E. chaffeensis, rTRP120 and Wnt5a. Similar Hippo gene expression profiles were also stimulated by E. chaffeensis, rTRP120, SLiM and Wnt5a. Single siRNA knockdown of Hippo transcription co-activator/factors (Yap and TEAD) significantly decreased E. chaffeensis infection. Yap activation was abolished in THP-1 Wnt Frizzled-5 (Fzd5) receptor knockout cells (KO), demonstrating Fzd5 receptor dependence. In addition, TRP120 Wnt-SLiM antibody blocked Hippo deactivation (Yap activation). Expression of anti-apoptotic Hippo target gene SLC2A1 (encodes glucose transporter 1; GLUT1) was upregulated by E. chaffeensis and corresponded to increased levels of GLUT1. Conversely, siRNA knockdown of SLC2A1 significantly inhibited infection. Higher GLUT1 levels correlated with increased BCL-xL and decreased Bax levels. Moreover, blocking Yap activation with the inhibitor Verteporfin induced apoptosis that corresponded to significant reductions in levels of GLUT1 and BCL-xL, and activation of Bax and Caspase-3 and -9. This study identifies a novel shared Wnt/Hippo SLiM ligand mimetic and demonstrates that E. chaffeensis deactivates the Hippo pathway to engage the anti-apoptotic Yap-GLUT1-BCL-xL axis.
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Affiliation(s)
- Caitlan D. Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - LaNisha L. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nicholas A. Pittner
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Regina N. Solomon
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jignesh G. Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Madison R. Rogan
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Department Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
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Pittner NA, Solomon RN, Bui DC, McBride JW. Ehrlichia effector SLiM-icry: Artifice of cellular subversion. Front Cell Infect Microbiol 2023; 13:1150758. [PMID: 36960039 PMCID: PMC10028187 DOI: 10.3389/fcimb.2023.1150758] [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: 01/24/2023] [Accepted: 02/23/2023] [Indexed: 03/09/2023] Open
Abstract
As an obligately intracellular bacterial pathogen that selectively infects the mononuclear phagocyte, Ehrlichia chaffeensis has evolved sophisticated mechanisms to subvert innate immune defenses. While the bacterium accomplishes this through a variety of mechanisms, a rapidly expanding body of evidence has revealed that E. chaffeensis has evolved survival strategies that are directed by the versatile, intrinsically disordered, 120 kDa tandem repeat protein (TRP120) effector. E. chaffeensis establishes infection by manipulating multiple evolutionarily conserved cellular signaling pathways through effector-host interactions to subvert innate immune defenses. TRP120 activates these pathways using multiple functionally distinct, repetitive, eukaryote-mimicking short linear motifs (SLiMs) located within the tandem repeat domain that have evolved in nihilo. Functionally, the best characterized TRP120 SLiMs mimic eukaryotic ligands (SLiM-icry) to engage pathway-specific host receptors and activate cellular signaling, thereby repurposing these pathways to promote infection. Moreover, E. chaffeensis TRP120 contains SLiMs that are targets of post-translational modifications such as SUMOylation in addition to many other validated SLiMs that are curated in the eukaryotic linear motif (ELM) database. This review will explore the extracellular and intracellular roles TRP120 SLiM-icry plays during infection - mediated through a variety of SLiMs - that enable E. chaffeensis to subvert mononuclear phagocyte innate defenses.
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Affiliation(s)
- Nicholas A. Pittner
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Regina N. Solomon
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Duc-Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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Akova Ölken E, Aszodi A, Taipaleenmäki H, Saito H, Schönitzer V, Chaloupka M, Apfelbeck M, Böcker W, Saller MM. SFRP2 Overexpression Induces an Osteoblast-like Phenotype in Prostate Cancer Cells. Cells 2022; 11:cells11244081. [PMID: 36552843 PMCID: PMC9777425 DOI: 10.3390/cells11244081] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/09/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Prostate cancer bone metastasis is still one of the most fatal cancer diagnoses for men. Survival of the circulating prostate tumor cells and their adaptation strategy to survive in the bone niche is the key point to determining metastasis in early cancer stages. The promoter of SFRP2 gene, encoding a WNT signaling modulator, is hypermethylated in many cancer types including prostate cancer. Moreover, SFRP2 can positively regulate osteogenic differentiation in vitro and in vivo. Here, we showed SFRP2 overexpression in the prostate cancer cell line PC3 induces an epithelial mesenchymal transition (EMT), increases the attachment, and modifies the transcriptome towards an osteoblast-like phenotype (osteomimicry) in a collagen 1-dependent manner. Our data reflect a novel molecular mechanism concerning how metastasizing prostate cancer cells might increase their chance to survive within bone tissue.
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Affiliation(s)
- Elif Akova Ölken
- Department of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), Ludwig-Maximilians-University (LMU) Hospital, Fraunhoferstraße 20, 82152 Planegg-Martinsried, Germany
| | - Attila Aszodi
- Department of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), Ludwig-Maximilians-University (LMU) Hospital, Fraunhoferstraße 20, 82152 Planegg-Martinsried, Germany
| | - Hanna Taipaleenmäki
- Institute of Musculoskeletal Medicine (IMM), Musculoskeletal University Center Munich (MUM), LMU Hospital, Fraunhoferstraße 20, 82152 Planegg-Martinsried, Germany
| | - Hiroaki Saito
- Institute of Musculoskeletal Medicine (IMM), Musculoskeletal University Center Munich (MUM), LMU Hospital, Fraunhoferstraße 20, 82152 Planegg-Martinsried, Germany
| | - Veronika Schönitzer
- Department of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), Ludwig-Maximilians-University (LMU) Hospital, Fraunhoferstraße 20, 82152 Planegg-Martinsried, Germany
| | - Michael Chaloupka
- Urologischen Klinik und Poliklinik, LMU Hospital, Marchioninistr 15, 81377 München, Germany
| | - Maria Apfelbeck
- Urologischen Klinik und Poliklinik, LMU Hospital, Marchioninistr 15, 81377 München, Germany
| | - Wolfgang Böcker
- Department of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), Ludwig-Maximilians-University (LMU) Hospital, Fraunhoferstraße 20, 82152 Planegg-Martinsried, Germany
| | - Maximilian Michael Saller
- Department of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), Ludwig-Maximilians-University (LMU) Hospital, Fraunhoferstraße 20, 82152 Planegg-Martinsried, Germany
- Correspondence: ; Tel.: +49-89-4400-55486
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Byerly CD, Mitra S, Patterson LL, Pittner NA, Velayutham TS, Paessler S, Veljkovic V, McBride JW. Ehrlichia SLiM ligand mimetic activates Hedgehog signaling to engage a BCL-2 anti-apoptotic cellular program. PLoS Pathog 2022; 18:e1010345. [PMID: 35576232 PMCID: PMC9135340 DOI: 10.1371/journal.ppat.1010345] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 05/26/2022] [Accepted: 04/21/2022] [Indexed: 11/19/2022] Open
Abstract
Ehrlichia chaffeensis (E. chaffeensis) has evolved eukaryotic ligand mimicry to repurpose multiple cellular signaling pathways for immune evasion. In this investigation, we demonstrate that TRP120 has a novel repetitive short linear motif (SLiM) that activates the evolutionarily conserved Hedgehog (Hh) signaling pathway to inhibit apoptosis. In silico analysis revealed that TRP120 has sequence and functional similarity with Hh ligands and a candidate Hh ligand SLiM was identified. siRNA knockdown of Hh signaling and transcriptional components significantly reduced infection. Co-immunoprecipitation and surface plasmon resonance demonstrated that rTRP120-TR interacted directly with Hh receptor Patched-2 (PTCH2). E. chaffeensis infection resulted in early upregulation of Hh transcription factor GLI-1 and regulation of Hh target genes. Moreover, soluble recombinant TRP120 (rTRP120) activated Hh and induced gene expression consistent with the eukaryotic Hh ligand. The TRP120-Hh-SLiM (NPEVLIKD) induced nuclear translocation of GLI-1 in THP-1 cells and primary human monocytes and induced a rapid and expansive activation of Hh pathway target genes. Furthermore, Hh activation was blocked by an α-TRP120-Hh-SLiM antibody. TRP120-Hh-SLiM significantly increased levels of Hh target, anti-apoptotic protein B-cell lymphoma 2 (BCL-2), and siRNA knockdown of BCL-2 dramatically inhibited infection. Blocking Hh signaling with the inhibitor Vismodegib, induced a pro-apoptotic cellular program defined by decreased mitochondria membrane potential, significant reductions in BCL-2, activation of caspase 3 and 9, and increased apoptotic cells. This study reveals a novel E. chaffeensis SLiM ligand mimetic that activates Hh signaling to maintain E. chaffeensis infection by engaging a BCL-2 anti-apoptotic cellular program.
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Affiliation(s)
- Caitlan D. Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Shubhajit Mitra
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - LaNisha L. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Nicholas A. Pittner
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Thangam S. Velayutham
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Slobodan Paessler
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Biomed Protection, LLC, Galveston, Texas, United States of America
| | - Veljko Veljkovic
- Biomed Protection, LLC, Galveston, Texas, United States of America
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
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10
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Patterson LL, Velayutham TS, Byerly CD, Bui DC, Patel J, Veljkovic V, Paessler S, McBride JW. Ehrlichia SLiM Ligand Mimetic Activates Notch Signaling in Human Monocytes. mBio 2022; 13:e0007622. [PMID: 35357214 PMCID: PMC9040721 DOI: 10.1128/mbio.00076-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 03/14/2022] [Indexed: 12/15/2022] Open
Abstract
Ehrlichia chaffeensis evades innate host defenses by reprogramming the mononuclear phagocyte through mechanisms that involve the exploitation of multiple evolutionarily conserved cellular signaling pathways, including Notch. This immune evasion strategy is directed in part by tandem repeat protein (TRP) effectors. Specifically, the TRP120 effector activates and regulates Notch signaling through interactions with the Notch receptor and the negative regulator, F-Box and WD repeat domain-containing 7 (FBW7). However, the specific molecular interactions and motifs required for E. chaffeensis TRP120-Notch receptor interaction and activation have not been defined. To investigate the molecular basis of TRP120 Notch activation, we compared TRP120 with endogenous canonical/noncanonical Notch ligands and identified a short region of sequence homology within the tandem repeat (TR) domain. TRP120 was predicted to share biological function with Notch ligands, and a function-associated sequence in the TR domain was identified. To investigate TRP120-Notch receptor interactions, colocalization between TRP120 and endogenous Notch-1 was observed. Moreover, direct interactions between full-length TRP120, the TRP120 TR domain containing the putative Notch ligand sequence, and the Notch receptor LBR were demonstrated. To molecularly define the TRP120 Notch activation motif, peptide mapping was used to identify an 11-amino acid short linear motif (SLiM) located within the TRP120 TR that activated Notch signaling and downstream gene expression. Peptide mutants of the Notch SLiM or anti-Notch SLiM antibody reduced or eliminated Notch activation and NICD nuclear translocation. This investigation reveals a novel molecularly defined pathogen encoded Notch SLiM mimetic that activates Notch signaling consistent with endogenous ligands. IMPORTANCE E. chaffeensis infects and replicates in mononuclear phagocytes, but how it evades innate immune defenses of this indispensable primary innate immune cell is not well understood. This investigation revealed the molecular details of a ligand mimicry cellular reprogramming strategy that involved a short linear motif (SLiM), which enabled E. chaffeensis to exploit host cell signaling to establish and maintain infection. E. chaffeensis TRP120 is a moonlighting effector that has been associated with cellular activation and other functions, including ubiquitin ligase activity. Herein, we identified and demonstrated that a SLiM present within each tandem repeat of TRP120 activated Notch signaling. Notch is an evolutionarily conserved signaling pathway responsible for many cell functions, including cell fate, development, and innate immunity. This study is significant because it revealed the first molecularly defined pathogen encoded SLiM that appears to have evolved de novo to mimic endogenous Notch ligands. Understanding Notch activation during E. chaffeensis infection provides a model to study pathogen exploitation of signaling pathways and will be useful in developing molecularly targeted countermeasures for inhibiting infection by a multitude of disease-causing pathogens that exploit cell signaling through molecular mimicry.
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Affiliation(s)
- LaNisha L. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | | | - Caitlan D. Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Duc Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jignesh Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | | | - Slobodan Paessler
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
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Moonlighting in Rickettsiales: Expanding Virulence Landscape. Trop Med Infect Dis 2022; 7:tropicalmed7020032. [PMID: 35202227 PMCID: PMC8877226 DOI: 10.3390/tropicalmed7020032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/05/2022] [Accepted: 02/17/2022] [Indexed: 12/22/2022] Open
Abstract
The order Rickettsiales includes species that cause a range of human diseases such as human granulocytic anaplasmosis (Anaplasma phagocytophilum), human monocytic ehrlichiosis (Ehrlichia chaffeensis), scrub typhus (Orientia tsutsugamushi), epidemic typhus (Rickettsia prowazekii), murine typhus (R. typhi), Mediterranean spotted fever (R. conorii), or Rocky Mountain spotted fever (R. rickettsii). These diseases are gaining a new momentum given their resurgence patterns and geographical expansion due to the overall rise in temperature and other human-induced pressure, thereby remaining a major public health concern. As obligate intracellular bacteria, Rickettsiales are characterized by their small genome sizes due to reductive evolution. Many pathogens employ moonlighting/multitasking proteins as virulence factors to interfere with multiple cellular processes, in different compartments, at different times during infection, augmenting their virulence. The utilization of this multitasking phenomenon by Rickettsiales as a strategy to maximize the use of their reduced protein repertoire is an emerging theme. Here, we provide an overview of the role of various moonlighting proteins in the pathogenicity of these species. Despite the challenges that lie ahead to determine the multiple potential faces of every single protein in Rickettsiales, the available examples anticipate this multifunctionality as an essential and intrinsic feature of these obligates and should be integrated into available moonlighting repositories.
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12
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Byerly CD, Patterson LL, McBride JW. Ehrlichia TRP effectors: moonlighting, mimicry and infection. Pathog Dis 2021; 79:6261440. [PMID: 33974702 PMCID: PMC8112483 DOI: 10.1093/femspd/ftab026] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 04/29/2021] [Indexed: 12/24/2022] Open
Abstract
Intracellular bacteria have evolved various strategies to evade host defense mechanisms. Remarkably, the obligately intracellular bacterium, Ehrlichia chaffeensis, hijacks host cell processes of the mononuclear phagocyte to evade host defenses through mechanisms executed in part by tandem repeat protein (TRP) effectors secreted by the type 1 secretion system. In the past decade, TRP120 has emerged as a model moonlighting effector, acting as a ligand mimetic, nucleomodulin and ubiquitin ligase. These defined functions illuminate the diverse roles TRP120 plays in exploiting and manipulating host cell processes, including cytoskeletal organization, vesicle trafficking, cell signaling, transcriptional regulation, post-translational modifications, autophagy and apoptosis. This review will focus on TRP effectors and their expanding roles in infection and provide perspective on Ehrlichia chaffeensis as an invaluable model organism for understanding infection strategies of obligately intracellular bacteria.
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Affiliation(s)
- Caitlan D Byerly
- Departments of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - LaNisha L Patterson
- Departments of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Jere W McBride
- Departments of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.,Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA.,Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA.,Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA.,Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA
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