1
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Thomas ME, Qi W, Walsh MP, Ma J, Westover T, Abdelhamed S, Ezzell LJ, Rolle C, Xiong E, Rosikiewicz W, Xu B, Loughran AJ, Pruett-Miller SM, Janke LJ, Klco JM. Functional characterization of cooperating MGA mutations in RUNX1::RUNX1T1 acute myeloid leukemia. Leukemia 2024; 38:991-1002. [PMID: 38454121 DOI: 10.1038/s41375-024-02193-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 03/09/2024]
Abstract
MGA (Max-gene associated) is a dual-specificity transcription factor that negatively regulates MYC-target genes to inhibit proliferation and promote differentiation. Loss-of-function mutations in MGA have been commonly identified in several hematological neoplasms, including acute myeloid leukemia (AML) with RUNX1::RUNX1T1, however, very little is known about the impact of these MGA alterations on normal hematopoiesis or disease progression. We show that representative MGA mutations identified in patient samples abolish protein-protein interactions and transcriptional activity. Using a series of human and mouse model systems, including a newly developed conditional knock-out mouse strain, we demonstrate that loss of MGA results in upregulation of MYC and E2F targets, cell cycle genes, mTOR signaling, and oxidative phosphorylation in normal hematopoietic cells, leading to enhanced proliferation. The loss of MGA induces an open chromatin state at promoters of genes involved in cell cycle and proliferation. RUNX1::RUNX1T1 expression in Mga-deficient murine hematopoietic cells leads to a more aggressive AML with a significantly shortened latency. These data show that MGA regulates multiple pro-proliferative pathways in hematopoietic cells and cooperates with the RUNX1::RUNX1T1 fusion oncoprotein to enhance leukemogenesis.
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Affiliation(s)
- Melvin E Thomas
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Wenqing Qi
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Michael P Walsh
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Jing Ma
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Tamara Westover
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Sherif Abdelhamed
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Lauren J Ezzell
- Graduate School of Biomedical Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Chandra Rolle
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Emily Xiong
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Wojciech Rosikiewicz
- Center for Applied Bioinformatics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Beisi Xu
- Center for Applied Bioinformatics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Allister J Loughran
- Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Shondra M Pruett-Miller
- Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Laura J Janke
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA
| | - Jeffery M Klco
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 342, Memphis, TN, 38105, USA.
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2
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Nishiguchi G, Mascibroda LG, Young SM, Caine EA, Abdelhamed S, Kooijman JJ, Miller DJ, Das S, McGowan K, Mayasundari A, Shi Z, Barajas JM, Hiltenbrand R, Aggarwal A, Chang Y, Mishra V, Narina S, Thomas M, Loughran AJ, Kalathur R, Yu K, Zhou S, Wang X, High AA, Peng J, Pruett-Miller SM, Daniels DL, Urh M, Shelat AA, Mullighan CG, Riching KM, Zaman GJR, Fischer M, Klco JM, Rankovic Z. Selective CK1α degraders exert antiproliferative activity against a broad range of human cancer cell lines. Nat Commun 2024; 15:482. [PMID: 38228616 PMCID: PMC10791743 DOI: 10.1038/s41467-024-44698-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 12/21/2023] [Indexed: 01/18/2024] Open
Abstract
Molecular-glue degraders are small molecules that induce a specific interaction between an E3 ligase and a target protein, resulting in the target proteolysis. The discovery of molecular glue degraders currently relies mostly on screening approaches. Here, we describe screening of a library of cereblon (CRBN) ligands against a panel of patient-derived cancer cell lines, leading to the discovery of SJ7095, a potent degrader of CK1α, IKZF1 and IKZF3 proteins. Through a structure-informed exploration of structure activity relationship (SAR) around this small molecule we develop SJ3149, a selective and potent degrader of CK1α protein in vitro and in vivo. The structure of SJ3149 co-crystalized in complex with CK1α + CRBN + DDB1 provides a rationale for the improved degradation properties of this compound. In a panel of 115 cancer cell lines SJ3149 displays a broad antiproliferative activity profile, which shows statistically significant correlation with MDM2 inhibitor Nutlin-3a. These findings suggest potential utility of selective CK1α degraders for treatment of hematological cancers and solid tumors.
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Affiliation(s)
- Gisele Nishiguchi
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Lauren G Mascibroda
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Sarah M Young
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Elizabeth A Caine
- Promega Corporation, 5430 East Cheryl Drive, Madison, WI, 53711, USA
| | - Sherif Abdelhamed
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | | | - Darcie J Miller
- Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Sourav Das
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Kevin McGowan
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Anand Mayasundari
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Zhe Shi
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Juan M Barajas
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Ryan Hiltenbrand
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Anup Aggarwal
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Yunchao Chang
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Vibhor Mishra
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Shilpa Narina
- Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Melvin Thomas
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Allister J Loughran
- Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Ravi Kalathur
- Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Kaiwen Yu
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Suiping Zhou
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Xusheng Wang
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Anthony A High
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Junmin Peng
- Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Shondra M Pruett-Miller
- Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Memphis, TN, 38105, USA
| | - Danette L Daniels
- Promega Corporation, 5430 East Cheryl Drive, Madison, WI, 53711, USA
| | - Marjeta Urh
- Promega Corporation, 5430 East Cheryl Drive, Madison, WI, 53711, USA
| | - Anang A Shelat
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Charles G Mullighan
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Kristin M Riching
- Promega Corporation, 5430 East Cheryl Drive, Madison, WI, 53711, USA
| | - Guido J R Zaman
- Oncolines B.V., Kloosterstraat 9, 5349 AB, Oss, The Netherlands
| | - Marcus Fischer
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA.
| | - Jeffery M Klco
- Department of Pathology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA.
| | - Zoran Rankovic
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA.
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3
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Florke Gee RR, Huber AD, Wu J, Bajpai R, Loughran AJ, Pruett-Miller SM, Chen T. The F-box-only protein 44 regulates pregnane X receptor protein level by ubiquitination and degradation. Acta Pharm Sin B 2023; 13:4523-4534. [PMID: 37969738 PMCID: PMC10638512 DOI: 10.1016/j.apsb.2023.07.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/24/2023] [Accepted: 06/13/2023] [Indexed: 11/17/2023] Open
Abstract
Pregnane X receptor (PXR) is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes [e.g., cytochrome P450 3A4 (CYP3A4)] and transporters. Although the regulation of PXR target genes is well-characterized, less is known about the regulation of PXR protein level. By screening an RNAi library, we identified the F-box-only protein 44 (FBXO44) as a novel E3 ligase for PXR. PXR abundance increases upon knockdown of FBXO44, and, inversely, decreases upon overexpression of FBXO44. Further analysis revealed that FBXO44 interacts with PXR, leading to its ubiquitination and proteasomal degradation, and we determined that the F-box associated domain of FBXO44 and the ligand binding domain of PXR are required for the functional interaction. In summary, FBXO44 regulates PXR protein abundance, which has downstream consequences for CYP3A4 levels and drug-drug interactions. The results of this study provide new insight into the molecular mechanisms that regulate PXR protein level and activity and suggest the importance of considering how modulating E3 ubiquitin ligase activities will affect PXR-mediated drug metabolism.
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Affiliation(s)
- Rebecca R. Florke Gee
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
- Graduate School of Biomedical Sciences, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Andrew D. Huber
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Richa Bajpai
- Center for Advanced Genome Engineering and Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Allister J. Loughran
- Center for Advanced Genome Engineering and Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Shondra M. Pruett-Miller
- Center for Advanced Genome Engineering and Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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4
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Mann B, Crawford JC, Reddy K, Lott J, Youn YH, Gao G, Guy C, Chou CH, Darnell D, Trivedi S, Bomme P, Loughran AJ, Thomas PG, Han YG, Tuomanen EI. Bacterial TLR2/6 Ligands Block Ciliogenesis, Derepress Hedgehog Signaling, and Expand the Neocortex. mBio 2023; 14:e0051023. [PMID: 37052506 PMCID: PMC10294647 DOI: 10.1128/mbio.00510-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 03/21/2023] [Indexed: 04/14/2023] Open
Abstract
Microbial components have a range of direct effects on the fetal brain. However, little is known about the cellular targets and molecular mechanisms that mediate these effects. Neural progenitor cells (NPCs) control the size and architecture of the brain and understanding the mechanisms regulating NPCs is crucial to understanding brain developmental disorders. We identify ventricular radial glia (vRG), the primary NPC, as the target of bacterial cell wall (BCW) generated during the antibiotic treatment of maternal pneumonia. BCW enhanced proliferative potential of vRGs by shortening the cell cycle and increasing self-renewal. Expanded vRGs propagated to increase neuronal output in all cortical layers. Remarkably, Toll-like receptor 2 (TLR2), which recognizes BCW, localized at the base of primary cilia in vRGs and the BCW-TLR2 interaction suppressed ciliogenesis leading to derepression of Hedgehog (HH) signaling and expansion of vRGs. We also show that TLR6 is an essential partner of TLR2 in this process. Surprisingly, TLR6 alone was required to set the number of cortical neurons under healthy conditions. These findings suggest that an endogenous signal from TLRs suppresses cortical expansion during normal development of the neocortex and that BCW antagonizes that signal through the TLR2/cilia/HH signaling axis changing brain structure and function. IMPORTANCE Fetal brain development in early gestation can be impacted by transplacental infection, altered metabolites from the maternal microbiome, or maternal immune activation. It is less well understood how maternal microbial subcomponents that cross the placenta, such as bacterial cell wall (BCW), directly interact with fetal neural progenitors and neurons and affect development. This scenario plays out in the clinic when BCW debris released during antibiotic therapy of maternal infection traffics to the fetal brain. This study identifies the direct interaction of BCW with TLR2/6 present on the primary cilium, the signaling hub on fetal neural progenitor cells (NPCs). NPCs control the size and architecture of the brain and understanding the mechanisms regulating NPCs is crucial to understanding brain developmental disorders. Within a window of vulnerability before the appearance of fetal immune cells, the BCW-TLR2/6 interaction results in the inhibition of ciliogenesis, derepression of Sonic Hedgehog signaling, excess proliferation of neural progenitors, and abnormal cortical architecture. In the first example of TLR signaling linked to Sonic Hedgehog, BCW/TLR2/6 appears to act during fetal brain morphogenesis to play a role in setting the total cell number in the neocortex.
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Affiliation(s)
- Beth Mann
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Jeremy Chase Crawford
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Kavya Reddy
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Josi Lott
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Yong Ha Youn
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Geli Gao
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Cliff Guy
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Ching-Heng Chou
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Daniel Darnell
- Hartwell Center for Bioinformatics and Biotechnology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Sanchit Trivedi
- Hartwell Center for Bioinformatics and Biotechnology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Perrine Bomme
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Allister J. Loughran
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Paul G. Thomas
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Young-Goo Han
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Elaine I. Tuomanen
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
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5
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Narayanaswamy VP, Townsend SM, Loughran AJ, Wiesmann W, Baker S. Polycationic Glycopolymer Demonstrates Activity Against Persisters and Biofilms of Non-tuberculosis Mycobacteria Cystic Fibrosis Clinical Isolates in vitro. Front Microbiol 2022; 13:821820. [PMID: 35265060 PMCID: PMC8900536 DOI: 10.3389/fmicb.2022.821820] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 01/31/2022] [Indexed: 01/15/2023] Open
Abstract
Non-tuberculosis Mycobacterium (NTM) is a group of opportunistic pathogens associated with pulmonary infections that are difficult to diagnose and treat. Standard treatment typically consists of prolonged combination antibiotic therapy. Antibiotic resistance and the role of biofilms in pathogen communities, such as NTM persister cells, is an important unmet challenge that leads to increased toxicity, frequent relapse, poor clinical management, and an extended treatment period. Infection recurrence and relapse are not uncommon among individuals with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD), where thick mucus supports bacterial biofilm production and impairs mucociliary clearance. The study evaluates a membrane-active cationic glycopolymer [poly (acetyl, arginyl) glucosamine (PAAG)] being developed to support the safe and effective treatment of NTM biofilm infections. PAAG shows antibacterial activity against a wide range of pathogenic bacteria at concentrations non-toxic to human epithelial cells. Time-kill curves demonstrated PAAG’s rapid bactericidal potential at concentrations as low as 1X MIC against all NTM strains tested and compared to the standard of care. PAAG treatment prevents persister formation and eradicates antibiotic-induced persister cells in planktonic NTM cultures below the limit of detection (10 colony-forming unit (CFU)/ml). Further, PAAG showed the ability to penetrate and disperse NTM biofilms formed by both rapidly and slowly growing strains, significantly reducing the biofilm biomass (p < 0.0001) compared to the untreated NTM biofilms. Microscopical examination confirmed PAAG’s ability to disrupt and disperse mycobacterial biofilms. A single PAAG treatment resulted in up to a 25-fold reduction in live-labeled NTM and a 78% reduction in biofilm thickness. Similar to other polycationic molecules, PAAG’s bactericidal and antibiofilm activities employ rapid permeabilization of the outer membrane of the NTM strains, and subsequently, reduce the membrane potential even at concentrations as low as 50 μg/ml (p < 0.001). The outcomes of these in vitro analyses suggest the importance of this polycationic glycopolymer, PAAG, as a potential therapeutic agent for opportunistic NTM infections.
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Affiliation(s)
| | | | | | | | - Shenda Baker
- Synedgen, Inc., Claremont, CA, United States.,Synspira Therapeutics, Inc., Framingham, MA, United States
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6
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Garcia BA, McDaniel MS, Loughran AJ, Johns JD, Narayanaswamy V, Fernandez Petty C, Birket SE, Baker SM, Barnaby R, Stanton BA, Foote JB, Rowe SM, Swords WE. Poly (acetyl, arginyl) glucosamine disrupts Pseudomonas aeruginosa biofilms and enhances bacterial clearance in a rat lung infection model. Microbiology (Reading) 2022; 168. [PMID: 35077346 PMCID: PMC8914243 DOI: 10.1099/mic.0.001121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Pseudomonas aeruginosa is a common opportunistic pathogen that can cause chronic infections in multiple disease states, including respiratory infections in patients with cystic fibrosis (CF) and non-CF bronchiectasis. Like many opportunists, P. aeruginosa forms multicellular biofilm communities that are widely thought to be an important determinant of bacterial persistence and resistance to antimicrobials and host immune effectors during chronic/recurrent infections. Poly (acetyl, arginyl) glucosamine (PAAG) is a glycopolymer that has antimicrobial activity against a broad range of bacterial species, and also has mucolytic activity, which can normalize the rheological properties of cystic fibrosis mucus. In this study, we sought to evaluate the effect of PAAG on P. aeruginosa bacteria within biofilms in vitro, and in the context of experimental pulmonary infection in a rodent infection model. PAAG treatment caused significant bactericidal activity against P. aeruginosa biofilms, and a reduction in the total biomass of preformed P. aeruginosa biofilms on abiotic surfaces, as well as on the surface of immortalized cystic fibrosis human bronchial epithelial cells. Studies of membrane integrity indicated that PAAG causes changes to P. aeruginosa cell morphology and dysregulates membrane polarity. PAAG treatment reduced infection and consequent tissue inflammation in experimental P. aeruginosa rat infections. Based on these findings we conclude that PAAG represents a novel means to combat P. aeruginosa infection, and may warrant further evaluation as a therapeutic.
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Affiliation(s)
- Bryan A Garcia
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, Medical University of South Carolina, Charleston, SC, USA.,Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Melissa S McDaniel
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Allister J Loughran
- Synedgen, Inc., Claremont, CA, USA.,St Jude Children's Research Hospital, Memphis, TN, USA
| | - J Dixon Johns
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | | | - Susan E Birket
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Cell Developmental and Integrative Physiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Shenda M Baker
- Synedgen, Inc., Claremont, CA, USA.,Synspira Therapeutics, Inc., Framingham, MA, USA
| | - Roxanna Barnaby
- Dartmouth Cystic Fibrosis Research Center, New Hanover, NH, USA
| | - Bruce A Stanton
- Dartmouth Cystic Fibrosis Research Center, New Hanover, NH, USA
| | - Jeremy B Foote
- Comparative Pathology Laboratory, at University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Steven M Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Cell Developmental and Integrative Physiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - W Edward Swords
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
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7
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Byrum S, Loughran AJ, Beenken KE, Orr LM, Storey AJ, Mackintosh SG, Edmondson RD, Tackett AJ, Smeltzer MS. Label-Free Proteomic Approach to Characterize Protease-Dependent and -Independent Effects of sarA Inactivation on the Staphylococcus aureus Exoproteome. J Proteome Res 2018; 17:3384-3395. [PMID: 30209945 PMCID: PMC6209314 DOI: 10.1021/acs.jproteome.8b00288] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The staphylococcal accessory regulator A ( sarA) impacts the extracellular accumulation of Staphylococcus aureus virulence factors at the level of intracellular production and extracellular protease-mediated degradation. We previously used a proteomics approach that measures protein abundance of all proteoforms to demonstrate that mutation of sarA results in increased levels of extracellular proteases and assesses the impact of this on the accumulation of S. aureus exoproteins. Our previous approach was limited as it did not take into account that large, stable proteolytic products from a given protein could result in false negatives when quantified by total proteoforms. Here, our goal was to use an expanded proteomics approach utilizing a dual quantitative method for measuring abundance at both the total proteoform and full-length exoprotein levels to alleviate these false negatives and thereby provide for characterization of protease-dependent and -independent effects of sarA mutation on the S. aureus exoproteome. Proteins present in conditioned medium from overnight, stationary phase cultures of the USA300 strain LAC, an isogenic sarA mutant, and a sarA mutant unable to produce any of the known extracellular proteases ( sarA/protease) were resolved using one-dimensional gel electrophoresis. Quantitative proteomic comparisons of sarA versus sarA/protease mutants identified proteins that were cleaved in a protease-dependent manner owing to mutation of sarA, and comparisons of sarA/protease mutant versus the LAC parent strain identified proteins in which abundance was altered in a sarA mutant in a protease-independent manner. Furthermore, the proteins uniquely identified by the full-length data analysis approach eliminated false negatives observed in the total proteoform analysis. This expanded approach provided for a more comprehensive analysis of the impact of mutating sarA on the S. aureus exoproteome.
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Affiliation(s)
- Stephanie
D. Byrum
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States,Arkansas
Children’s Research Institute, 13 Children’s Way, Little Rock, Arkansas 72202, United States
| | - Allister J. Loughran
- Department
of Microbiology and Immunology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Karen E. Beenken
- Department
of Microbiology and Immunology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Lisa M. Orr
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Aaron J. Storey
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Samuel G. Mackintosh
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Ricky D. Edmondson
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Alan J. Tackett
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States,Arkansas
Children’s Research Institute, 13 Children’s Way, Little Rock, Arkansas 72202, United States,E-mail:
| | - Mark S. Smeltzer
- Department
of Microbiology and Immunology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States,E-mail: , Phone: (501) 686-7958
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8
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Narayanaswamy VP, Keagy LL, Duris K, Wiesmann W, Loughran AJ, Townsend SM, Baker S. Novel Glycopolymer Eradicates Antibiotic- and CCCP-Induced Persister Cells in Pseudomonas aeruginosa. Front Microbiol 2018; 9:1724. [PMID: 30123191 PMCID: PMC6085434 DOI: 10.3389/fmicb.2018.01724] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 07/11/2018] [Indexed: 11/13/2022] Open
Abstract
Antibiotic treatments often fail to completely eradicate a bacterial infection, leaving behind an antibiotic-tolerant subpopulation of intact bacterial cells called persisters. Persisters are considered a major cause for treatment failure and are thought to greatly contribute to the recalcitrance of chronic infections. Pseudomonas aeruginosa infections are commonly associated with elevated levels of drug-tolerant persister cells, posing a serious threat to human health. This study represents the first time a novel large molecule polycationic glycopolymer, poly (acetyl, arginyl) glucosamine (PAAG), has been evaluated against antibiotic and carbonyl cyanide m-chlorophenylhydrazone induced P. aeruginosa persisters. PAAG eliminated eliminated persisters at concentrations that show no significant cytotoxicity on human lung epithelial cells. PAAG demonstrated rapid bactericidal activity against both forms of induced P. aeruginosa persister cells resulting in complete eradication of the in vitro persister cells within 24 h of treatment. PAAG demonstrated greater efficacy against persisters in vitro than antibiotics currently being used to treat persistent chronic infections such as tobramycin, colistin, azithromycin, aztreonam, and clarithromycin. PAAG caused rapid permeabilization of the cell membrane and caused significant membrane depolarization in persister cells. PAAG efficacy against these bacterial subpopulations suggests it may have substantial therapeutic potential for eliminating recurrent P. aeruginosa infections.
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9
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Rom JS, Atwood DN, Beenken KE, Meeker DG, Loughran AJ, Spencer HJ, Lantz TL, Smeltzer MS. Impact of Staphylococcus aureus regulatory mutations that modulate biofilm formation in the USA300 strain LAC on virulence in a murine bacteremia model. Virulence 2017; 8:1776-1790. [PMID: 28910576 PMCID: PMC5810510 DOI: 10.1080/21505594.2017.1373926] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Staphylococcus aureus causes acute and chronic forms of infection, the latter often associated with formation of a biofilm. It has previously been demonstrated that mutation of atl, codY, rot, sarA, and sigB limits biofilm formation in the USA300 strain LAC while mutation of agr, fur, and mgrA has the opposite effect. Here we used a murine sepsis model to assess the impact of these same loci in acute infection. Mutation of agr, atl, and fur had no impact on virulence, while mutation of mgrA and rot increased virulence. In contrast, mutation of codY, sarA, and sigB significantly attenuated virulence. Mutation of sigB resulted in reduced accumulation of AgrA and SarA, while mutation of sarA resulted in reduced accumulation of AgrA, but this cannot account for the reduced virulence of sarA or sigB mutants because the isogenic agr mutant was not attenuated. Indeed, as assessed by accumulation of alpha toxin and protein A, all of the mutants we examined exhibited unique phenotypes by comparison to an agr mutant and to each other. Attenuation of the sarA, sigB and codY mutants was correlated with increased production of extracellular proteases and global changes in extracellular protein profiles. These results suggest that the inability to repress the production of extracellular proteases plays a key role in attenuating the virulence of S. aureus in acute as well as chronic, biofilm-associated infections, thus opening up the possibility that strategies aimed at the de-repression of protease production could be used to broad therapeutic advantage. They also suggest that the impact of codY, sarA, and sigB on protease production occurs via an agr-independent mechanism.
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Affiliation(s)
- Joseph S Rom
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Danielle N Atwood
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Karen E Beenken
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Daniel G Meeker
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Allister J Loughran
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Horace J Spencer
- b Department of Biostatistics , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Tamara L Lantz
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Mark S Smeltzer
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA.,c Department of Orthopaedic Surgery , University of Arkansas for Medical Sciences , Little Rock , AR , USA.,d Department of Pathology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
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10
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Abstract
Bacterial or viral infection of the mother during the course of pregnancy can cross the placenta and actively infect the fetus. However, especially for bacteria, it is more common for mothers to experience an infection that can be treated without overt fetal infection. In this setting, it is less well understood what the risk to fetal development is, particularly in terms of neurological development. This research highlight reviews recent findings indicating that bacterial components generated during infection of the mother can cross the placenta and activate the fetal innate immune system resulting in changes in the course of brain development and subsequent progression to postnatal cognitive disorders. Bacterial cell wall is a ubiquitous bacterial PAMP (pathogen-associated molecular pattern) known to activate inflammation through the stimulation of TLR2. Cell wall is released from bacteria during antibiotic treatment and new work shows that embryos exposed to cell wall from the mother demonstrate anomalous proliferation of neuronal precursor cells in a TLR2 dependent manner. Such proliferation increases the neuronal density of the cortical plate and alters brain architecture. Although there is no fetal death, subsequent cognitive development is significantly impaired. This model system suggests that bacterial infection of the mother and its treatment can impact fetal brain development and requires greater understanding to potentially eliminate a risk factor for cognitive disorders such as autism.
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Affiliation(s)
- Allister J Loughran
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Elaine I Tuomanen
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
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11
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Meeker DG, Jenkins SV, Miller EK, Beenken KE, Loughran AJ, Powless A, Muldoon TJ, Galanzha EI, Zharov VP, Smeltzer MS, Chen J. Synergistic Photothermal and Antibiotic Killing of Biofilm-Associated Staphylococcus aureus Using Targeted Antibiotic-Loaded Gold Nanoconstructs. ACS Infect Dis 2016; 2:241-250. [PMID: 27441208 PMCID: PMC4945994 DOI: 10.1021/acsinfecdis.5b00117] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Indexed: 12/12/2022]
Abstract
Resistance to conventional antibiotics is a growing public health concern that is quickly outpacing the development of new antibiotics. This has led the Infectious Diseases Society of America (IDSA) to designate Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species as "ESKAPE pathogens" on the basis of the rapidly decreasing availability of useful antibiotics. This emphasizes the urgent need for alternative therapeutic strategies to combat infections caused by these and other bacterial pathogens. In this study, we used Staphylococcus aureus (S. aureus) as a proof-of-principle ESKAPE pathogen to demonstrate that an appropriate antibiotic (daptomycin) can be incorporated into polydopamine-coated gold nanocages (AuNC@PDA) and that daptomycin-loaded AuNC@PDA can be conjugated to antibodies targeting a species-specific surface protein (staphylococcal protein A; Spa) as a means of achieving selective delivery of the nanoconstructs directly to the bacterial cell surface. Targeting specificity was confirmed by demonstrating a lack of binding to mammalian cells, reduced photothermal and antibiotic killing of the Spa-negative species Staphylococcus epidermidis, and reduced killing of S. aureus in the presence of unconjugated anti-Spa antibodies. We demonstrate that laser irradiation at levels within the current safety standard for use in humans can be used to achieve both a lethal photothermal effect and controlled release of the antibiotic, thus resulting in a degree of therapeutic synergy capable of eradicating viable S. aureus cells. The system was validated using planktonic bacterial cultures of both methicillin-sensitive and methicillin-resistant S. aureus strains and subsequently shown to be effective in the context of an established biofilm, thus indicating that this approach could be used to facilitate the effective treatment of intrinsically resistant biofilm infections.
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Affiliation(s)
- Daniel G. Meeker
- Department
of Microbiology & Immunology, University
of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - Samir V. Jenkins
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Emily K. Miller
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Karen E. Beenken
- Department
of Microbiology & Immunology, University
of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - Allister J. Loughran
- Department
of Microbiology & Immunology, University
of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - Amy Powless
- Department of
Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Timothy J. Muldoon
- Department of
Biomedical Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Ekaterina I. Galanzha
- Phillips Classic Laser and Nanomedicine Laboratories, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - Vladimir P. Zharov
- Phillips Classic Laser and Nanomedicine Laboratories, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - Mark S. Smeltzer
- Department
of Microbiology & Immunology, University
of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - Jingyi Chen
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
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12
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Atwood DN, Loughran AJ, Courtney AP, Anthony AC, Meeker DG, Spencer HJ, Gupta RK, Lee CY, Beenken KE, Smeltzer MS. Comparative impact of diverse regulatory loci on Staphylococcus aureus biofilm formation. Microbiologyopen 2015; 4:436-51. [PMID: 25810138 PMCID: PMC4475386 DOI: 10.1002/mbo3.250] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 02/06/2015] [Indexed: 01/01/2023] Open
Abstract
The relative impact of 23 mutations on biofilm formation was evaluated in the USA300, methicillin-resistant strain LAC. Mutation of sarA, atl, codY, rsbU, and sigB limited biofilm formation in comparison to the parent strain, but the limitation imposed by mutation of sarA was greater than that imposed by mutation of any of these other genes. The reduced biofilm formation of all mutants other than the atl mutant was correlated with increased levels of extracellular proteases. Mutation of fur- and mgrA-enhanced biofilm formation but in LAC had no impact on protease activity, nuclease activity, or accumulation of the polysaccharide intercellular adhesin (PIA). The increased capacity of these mutants to form a biofilm was reversed by mutation of sarA, and this was correlated with increased protease production. Mutation of sarA, mgrA, and sigB had the same phenotypic effect in the methicillin-sensitive strain UAMS-1, but mutation of codY increased rather than decreased biofilm formation. As with the UAMS-1 mgrA mutant, this was correlated with increased production of PIA. Examination of four additional clinical isolates suggests that the differential impact of codY on biofilm formation may be a conserved characteristic of methicillin-resistant versus methicillin-sensitive strains.
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Affiliation(s)
- Danielle N Atwood
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Allister J Loughran
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Ashleah P Courtney
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Allison C Anthony
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Daniel G Meeker
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Horace J Spencer
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Ravi Kr Gupta
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Chia Y Lee
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Karen E Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Mark S Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.,Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas.,Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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13
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Loughran AJ, Atwood DN, Anthony AC, Harik NS, Spencer HJ, Beenken KE, Smeltzer MS. Impact of individual extracellular proteases on Staphylococcus aureus biofilm formation in diverse clinical isolates and their isogenic sarA mutants. Microbiologyopen 2014; 3:897-909. [PMID: 25257373 PMCID: PMC4263513 DOI: 10.1002/mbo3.214] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/07/2014] [Accepted: 08/15/2014] [Indexed: 01/01/2023] Open
Abstract
We demonstrate that the purified Staphylococcus aureus extracellular proteases aureolysin, ScpA, SspA, and SspB limit biofilm formation, with aureolysin having the greatest impact. Using protease-deficient derivatives of LAC, we confirmed that this is due to the individual proteases themselves. Purified aureolysin, and to a lesser extent ScpA and SspB, also promoted dispersal of an established biofilm. Mutation of the genes encoding these proteases also only partially restored biofilm formation in an FPR3757 sarA mutant and had little impact on restoring virulence in a murine bacteremia model. In contrast, eliminating the production of all of these proteases fully restored both biofilm formation and virulence in a sarA mutant generated in the closely related USA300 strain LAC. These results confirm an important role for multiple extracellular proteases in S. aureus pathogenesis and the importance of sarA in repressing their production. Moreover, purified aureolysin limited biofilm formation in 14 of 15 methicillin-resistant isolates and 11 of 15 methicillin-susceptible isolates, while dispersin B had little impact in UAMS-1, LAC, or 29 of 30 contemporary isolates of S. aureus. This suggests that the role of sarA and its impact on protease production is important in diverse strains of S. aureus irrespective of their methicillin resistance status.
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Affiliation(s)
- Allister J Loughran
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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14
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Beenken KE, Mrak LN, Zielinska AK, Atwood DN, Loughran AJ, Griffin LM, Matthews KA, Anthony AM, Spencer HJ, Skinner RA, Post GR, Lee CY, Smeltzer MS. Impact of the functional status of saeRS on in vivo phenotypes of Staphylococcus aureus sarA mutants. Mol Microbiol 2014; 92:1299-312. [PMID: 24779437 DOI: 10.1111/mmi.12629] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2014] [Indexed: 12/24/2022]
Abstract
We investigated the in vivo relevance of the impact of sarA and saeRS on protease production using derivatives of the USA300 strain LAC. The results confirmed that mutation of saeRS or sarA reduces virulence in a bacteremia model to a comparable degree. However, while eliminating protease production restored virulence in the sarA mutant, it had little impact in the saeRS mutant. Additionally, constitutive activation of saeRS (saeRS(C)) enhanced the virulence of LAC and largely restored virulence in the isogenic sarA mutant. Based on these results, together with our analysis of the representative virulence factors alpha toxin, protein A (Spa), and extracellular nucleases, we propose a model in which the attenuation of saeRS mutants is defined primarily by decreased production of such factors, while constitutive activation of saeRS increases virulence, and reverses the attenuation of sarA mutants, because it results in both increased production and decreased protease-mediated degradation of these same factors. This regulatory balance was also apparent in a murine model of catheter-associated infection, with the results suggesting that the impact of saeRS on nuclease production plays an important role during the early stages of these infections that is partially offset by increased protease production in sarA mutants.
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Affiliation(s)
- Karen E Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
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