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Singh R, Gholipourmalekabadi M, Shafikhani SH. Animal models for type 1 and type 2 diabetes: advantages and limitations. Front Endocrinol (Lausanne) 2024; 15:1359685. [PMID: 38444587 PMCID: PMC10912558 DOI: 10.3389/fendo.2024.1359685] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/05/2024] [Indexed: 03/07/2024] Open
Abstract
Diabetes mellitus, commonly referred to as diabetes, is a group of metabolic disorders characterized by chronic elevation in blood glucose levels, resulting from inadequate insulin production, defective cellular response to extracellular insulin, and/or impaired glucose metabolism. The two main types that account for most diabetics are type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), each with their own pathophysiological features. T1D is an autoimmune condition where the body's immune system attacks and destroys the insulin-producing beta cells in the pancreas. This leads to lack of insulin, a vital hormone for regulating blood sugar levels and cellular glucose uptake. As a result, those with T1D depend on lifelong insulin therapy to control their blood glucose level. In contrast, T2DM is characterized by insulin resistance, where the body's cells do not respond effectively to insulin, coupled with a relative insulin deficiency. This form of diabetes is often associated with obesity, sedentary lifestyle, and/or genetic factors, and it is managed with lifestyle changes and oral medications. Animal models play a crucial role in diabetes research. However, given the distinct differences between T1DM and T2DM, it is imperative for researchers to employ specific animal models tailored to each condition for a better understanding of the impaired mechanisms underlying each condition, and for assessing the efficacy of new therapeutics. In this review, we discuss the distinct animal models used in type 1 and type 2 diabetes mellitus research and discuss their strengths and limitations.
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Affiliation(s)
- Raj Singh
- Department of Medicine, Division of Hematology, Oncology, & Cell Therapy, Rush University Medical Center, Chicago, IL, United States
| | - Mazaher Gholipourmalekabadi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
- Department of Medical Biotechnology, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Sasha H Shafikhani
- Department of Medicine, Division of Hematology, Oncology, & Cell Therapy, Rush University Medical Center, Chicago, IL, United States
- Cancer Center, Rush University Medical Center, Chicago, IL, United States
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2
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Roy R, Mahmud F, Zayas J, Kuzel TM, Reiser J, Shafikhani SH. Reduced Bioactive Microbial Products (Pathogen-Associated Molecular Patterns) Contribute to Dysregulated Immune Responses and Impaired Healing in Infected Wounds in Mice with Diabetes. J Invest Dermatol 2024; 144:387-397.e11. [PMID: 37619833 PMCID: PMC10840742 DOI: 10.1016/j.jid.2023.08.004] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/11/2023] [Accepted: 08/01/2023] [Indexed: 08/26/2023]
Abstract
Diabetic chronic ulcers are plagued with persistent nonresolving inflammation. However, diabetic wound environment early after injury suffers from inadequate inflammatory responses due to reductions in proinflammatory cytokines levels. Diabetic neutrophils have known impairments in bactericidal functions. We hypothesized that reduced bacterial killing by diabetic neutrophils, due to their bactericidal functional impairments, results in reduced bioactive bacterial products, known as pathogen-associated molecular patterns, which in turn contribute to reduced signaling through toll-like receptors, leading to inadequate production of proinflammatory cytokines in infected diabetic wound early after injury. We tested our hypothesis in db/db type 2 obese diabetic mouse wound infection model with Pseudomonas aeruginosa. Our data indicate that despite substantially higher levels of infection, toll-like receptor 4-mediated signaling is reduced in diabetic wounds early after injury owing to reduced bioactive levels of lipopolysaccharide. We further demonstrate that topical treatment with lipopolysaccharide enhances toll-like receptor 4 signaling, increases proinflammatory cytokine production, restores leukocyte trafficking, reduces infection burden, and stimulates healing in diabetic wounds. We posit that lipopolysaccharide may be a viable therapeutic option for the treatment of diabetic foot ulcers if it is applied topically after the surgical debridement process, which is intended to reset chronic ulcers into acute fresh wounds.
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Affiliation(s)
- Ruchi Roy
- Division of Hematology, Oncology and Cell Therapy, Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Foyez Mahmud
- Division of Hematology, Oncology and Cell Therapy, Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Janet Zayas
- Division of Hematology, Oncology and Cell Therapy, Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA; Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, Illinois, USA
| | - Timothy M Kuzel
- Division of Hematology, Oncology and Cell Therapy, Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA; Cancer Center, Rush University Medical Center, Chicago, Illinois, USA
| | - Jochen Reiser
- Division of Hematology, Oncology and Cell Therapy, Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Sasha H Shafikhani
- Division of Hematology, Oncology and Cell Therapy, Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA; Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, Illinois, USA; Cancer Center, Rush University Medical Center, Chicago, Illinois, USA.
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Mony MP, Harmon KA, Hess R, Dorafshar AH, Shafikhani SH. An Updated Review of Hypertrophic Scarring. Cells 2023; 12:cells12050678. [PMID: 36899815 PMCID: PMC10000648 DOI: 10.3390/cells12050678] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [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: 12/20/2022] [Revised: 02/01/2023] [Accepted: 02/08/2023] [Indexed: 02/24/2023] Open
Abstract
Hypertrophic scarring (HTS) is an aberrant form of wound healing that is associated with excessive deposition of extracellular matrix and connective tissue at the site of injury. In this review article, we provide an overview of normal (acute) wound healing phases (hemostasis, inflammation, proliferation, and remodeling). We next discuss the dysregulated and/or impaired mechanisms in wound healing phases that are associated with HTS development. We next discuss the animal models of HTS and their limitations, and review the current and emerging treatments of HTS.
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Affiliation(s)
- Manjula P. Mony
- Department of Surgery, Division of Plastic & Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Kelly A. Harmon
- Department of Surgery, Division of Plastic & Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Ryan Hess
- Department of Surgery, Division of Plastic & Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Amir H. Dorafshar
- Department of Surgery, Division of Plastic & Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sasha H. Shafikhani
- Department of Medicine, Division of Hematology and Oncology and Cell Therapy, Rush University Medical Center, Chicago, IL 60612, USA
- Cancer Center, Rush University Medical Center, Chicago, IL 60612, USA
- Correspondence:
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4
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Wood SJ, Goldufsky JW, Seu MY, Dorafshar AH, Shafikhani SH. Pseudomonas aeruginosa Cytotoxins: Mechanisms of Cytotoxicity and Impact on Inflammatory Responses. Cells 2023; 12:cells12010195. [PMID: 36611990 PMCID: PMC9818787 DOI: 10.3390/cells12010195] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/01/2022] [Accepted: 12/01/2022] [Indexed: 01/05/2023] Open
Abstract
Pseudomonas aeruginosa is one of the most virulent opportunistic Gram-negative bacterial pathogens in humans. It causes many acute and chronic infections with morbidity and mortality rates as high as 40%. P. aeruginosa owes its pathogenic versatility to a large arsenal of cell-associated and secreted virulence factors which enable this pathogen to colonize various niches within hosts and protect it from host innate immune defenses. Induction of cytotoxicity in target host cells is a major virulence strategy for P. aeruginosa during the course of infection. P. aeruginosa has invested heavily in this strategy, as manifested by a plethora of cytotoxins that can induce various forms of cell death in target host cells. In this review, we provide an in-depth review of P. aeruginosa cytotoxins based on their mechanisms of cytotoxicity and the possible consequences of their cytotoxicity on host immune responses.
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Affiliation(s)
- Stephen J. Wood
- Department of Medicine, Division of Hematology, Oncology and Cell Therapy, Rush University Medical Center, Chicago, IL 60612, USA
- Department of Surgery, Division of Plastic and Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Josef W. Goldufsky
- Department of Medicine, Division of Hematology, Oncology and Cell Therapy, Rush University Medical Center, Chicago, IL 60612, USA
| | - Michelle Y. Seu
- Department of Surgery, Division of Plastic and Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Amir H. Dorafshar
- Department of Surgery, Division of Plastic and Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sasha H. Shafikhani
- Department of Medicine, Division of Hematology, Oncology and Cell Therapy, Rush University Medical Center, Chicago, IL 60612, USA
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL 60612, USA
- Cancer Center, Rush University Medical Center, Chicago, IL 60612, USA
- Correspondence:
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Roy R, Zayas J, Singh SK, Delgado K, Wood SJ, Mohamed MF, Frausto DM, Estupinian R, Giurini EF, Kuzel TM, Zloza A, Reiser J, Shafikhani SH. Overriding impaired FPR chemotaxis signaling in diabetic neutrophil stimulates infection control in murine diabetic wound. eLife 2022; 11:72071. [PMID: 35112667 PMCID: PMC8846594 DOI: 10.7554/elife.72071] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 07/09/2021] [Accepted: 02/01/2022] [Indexed: 11/19/2022] Open
Abstract
Infection is a major co-morbidity that contributes to impaired healing in diabetic wounds. Although impairments in diabetic neutrophils have been blamed for this co-morbidity, what causes these impairments and whether they can be overcome, remain largely unclear. Diabetic neutrophils, isolated from diabetic individuals, exhibit chemotaxis impairment but this peculiar functional impairment has been largely ignored because it appears to contradict the clinical findings which blame excessive neutrophil influx as a major impediment to healing in chronic diabetic ulcers. Here, we report that exposure to glucose in diabetic range results in impaired chemotaxis signaling through the formyl peptide receptor (FPR) in neutrophils, culminating in reduced chemotaxis and delayed neutrophil trafficking in the wound of Leprdb (db/db) type two diabetic mice, rendering diabetic wound vulnerable to infection. We further show that at least some auxiliary receptors remain functional under diabetic conditions and their engagement by the pro-inflammatory cytokine CCL3, overrides the requirement for FPR signaling and substantially improves infection control by jumpstarting the neutrophil trafficking toward infection, and stimulates healing in diabetic wound. We posit that CCL3 may have therapeutic potential for the treatment of diabetic foot ulcers if it is applied topically after the surgical debridement process which is intended to reset chronic ulcers into acute fresh wounds.
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Affiliation(s)
- Ruchi Roy
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Janet Zayas
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Sunil K Singh
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago, Chicago, United States
| | - Kaylee Delgado
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Stephen J Wood
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, United States
| | - Mohamed F Mohamed
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Dulce M Frausto
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Ricardo Estupinian
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Eileena F Giurini
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Timothy M Kuzel
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Andrew Zloza
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, United States
| | - Sasha H Shafikhani
- Department of Medicine, Rush University Medical Center, Chicago, United States
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Mahmud F, Roy R, Mohamed MF, Aboonabi A, Moric M, Ghoreishi K, Bayat M, Kuzel TM, Reiser J, Shafikhani SH. Therapeutic evaluation of immunomodulators in reducing surgical wound infection. FASEB J 2022; 36:e22090. [PMID: 34907595 PMCID: PMC9058973 DOI: 10.1096/fj.202101019r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 11/10/2021] [Accepted: 11/23/2021] [Indexed: 01/03/2023]
Abstract
Despite many advances in infection control practices, including prophylactic antibiotics, surgical site infections (SSIs) remain a significant cause of morbidity, prolonged hospitalization, and death worldwide. Our innate immune system possesses a multitude of powerful antimicrobial strategies which make it highly effective in combating bacterial, fungal, and viral infections. However, pathogens use various stealth mechanisms to avoid the innate immune system, which in turn buy them time to colonize wounds and damage tissues at surgical sites. We hypothesized that immunomodulators that can jumpstart and activate innate immune responses at surgical sites, would likely reduce infection at surgical sites. We used three immunomodulators; fMLP (formyl-Methionine-Lysine-Proline), CCL3 (MIP-1α), and LPS (Lipopolysaccharide), based on their documented ability to elicit strong inflammatory responses; in a surgical wound infection model with Pseudomonas aeruginosa to evaluate our hypothesis. Our data indicate that one-time topical treatment with these immunomodulators at low doses significantly increased proinflammatory responses in infected and uninfected surgical wounds and were as effective, (or even better), than a potent prophylactic antibiotic (Tobramycin) in reducing P. aeruginosa infection in wounds. Our data further show that immunomodulators did not have adverse effects on tissue repair and wound healing processes. Rather, they enhanced healing in both infected and uninfected wounds. Collectively, our data demonstrate that harnessing the power of the innate immune system by immunomodulators can significantly boost infection control and potentially stimulate healing. We propose that topical treatment with these immunomodulators at the time of surgery may have therapeutic potential in combating SSI, alone or in combination with prophylactic antibiotics.
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Affiliation(s)
- Foyez Mahmud
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA,Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Ruchi Roy
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA,Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Mohamed F. Mohamed
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA,Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Anahita Aboonabi
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA,Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Mario Moric
- Department of Anesthesiology, Rush University Medical Center, Chicago, IL, USA
| | | | - Mohammad Bayat
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Science, Tehran, Iran,Price Institute of Surgical Research, University of Louisville and Noveratech LLC. of Louisville, Louisville, KY, USA
| | - Timothy M. Kuzel
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA,Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Sasha H. Shafikhani
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA,Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA,Cancer Center, Rush University Medical Center, Chicago, IL, USA,To whom correspondence should be addressed:
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7
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Mohamed MF, Wood SJ, Roy R, Reiser J, Kuzel TM, Shafikhani SH. Pseudomonas aeruginosa ExoT induces G1 cell cycle arrest in melanoma cells. Cell Microbiol 2021; 23:e13339. [PMID: 33821556 PMCID: PMC8277761 DOI: 10.1111/cmi.13339] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [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: 11/02/2020] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 12/19/2022]
Abstract
Recently, we demonstrated that Pseudomonas aeruginosa Exotoxin T (ExoT) employs two distinct mechanisms to induce potent apoptotic cytotoxicity in a variety of cancer cell lines. We further demonstrated that it can significantly reduce tumour growth in an animal model for melanoma. During these studies, we observed that melanoma cells that were transfected with ExoT failed to undergo mitosis, regardless of whether they eventually succumbed to ExoT-induced apoptosis or survived in ExoT's presence. In this report, we sought to investigate ExoT's antiproliferative activity in melanoma. We delivered ExoT into B16 melanoma cells by bacteria (to show necessity) and by transfection (to show sufficiency). Our data indicate that ExoT exerts a potent antiproliferative function in melanoma cells. We show that ExoT causes cell cycle arrest in G1 interphase in melanoma cells by dampening the G1/S checkpoint proteins. Our data demonstrate that both domains of ExoT; (the ADP-ribosyltransferase (ADPRT) domain and the GTPase activating protein (GAP) domain); contribute to ExoT-induced G1 cell cycle arrest in melanoma. Finally, we show that the ADPRT-induced G1 cell cycle arrest in melanoma cells likely involves the Crk adaptor protein. Our data reveal a novel virulence function for ExoT and further highlight the therapeutic potential of ExoT against cancer.
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Affiliation(s)
- Mohamed F. Mohamed
- Department of Medicine/ Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
- Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Beni-Suef University, Egypt
| | - Stephen J. Wood
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL, USA
| | - Ruchi Roy
- Department of Medicine/ Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Jochen Reiser
- Department of Medicine/ Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Timothy M. Kuzel
- Department of Medicine/ Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
| | - Sasha H. Shafikhani
- Department of Medicine/ Division of Hematology/Oncology/Cell Therapy, Rush University Medical Center, Chicago, IL, USA
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL, USA
- Cancer Center, Rush University Medical Center, Chicago, IL, USA
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Kaminski A, Gupta KH, Goldufsky JW, Lee HW, Gupta V, Shafikhani SH. Pseudomonas aeruginosa ExoS Induces Intrinsic Apoptosis in Target Host Cells in a Manner That is Dependent on its GAP Domain Activity. Sci Rep 2018; 8:14047. [PMID: 30232373 PMCID: PMC6145893 DOI: 10.1038/s41598-018-32491-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 09/03/2018] [Indexed: 11/08/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes serious infections in immunocompromised individuals and cystic fibrosis patients. ExoS and ExoT are two homologous bifunctional Type III Secretion System (T3SS) virulence factors that induce apoptosis in target host cells. They possess a GTPase Activating Protein (GAP) domain at their N-termini, which share ~76% homology, and an ADP-ribosyltransferase (ADPRT) domain at their C-termini, which target non-overlapping substrates. Both the GAP and the ADPRT domains contribute to ExoT's cytotoxicity in target epithelial cells, whereas, ExoS-induced apoptosis is reported to be primarily due to its ADPRT domain. In this report, we demonstrate that ExoS/GAP domain is both necessary and sufficient to induce mitochondrial apoptosis. Our data demonstrate that intoxication with ExoS/GAP domain leads to enrichment of Bax and Bim into the mitochondrial outer-membrane, disruption of mitochondrial membrane and release of and cytochrome c into the cytosol, which activates initiator caspase-9 and effector caspase-3, that executes cellular death. We posit that the contribution of the GAP domain in ExoS-induced apoptosis was overlooked in prior studies due to its slower kinetics of cytotoxicity as compared to ADPRT. Our data clarify the field and reveal a novel virulence function for ExoS/GAP as an inducer of apoptosis.
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Affiliation(s)
- Amber Kaminski
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL, USA
| | - Kajal H Gupta
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL, USA
| | - Josef W Goldufsky
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL, USA
| | - Ha Won Lee
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Vineet Gupta
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Sasha H Shafikhani
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA.
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL, USA.
- Cancer Center, Rush University Medical Center, Chicago, IL, USA.
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9
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Kohlhapp FJ, Huelsmann EJ, Lacek AT, Schenkel JM, Lusciks J, Broucek JR, Goldufsky JW, Hughes T, Zayas JP, Dolubizno H, Sowell RT, Kühner R, Burd S, Kubasiak JC, Nabatiyan A, Marshall S, Bommareddy PK, Li S, Newman JH, Monken CE, Shafikhani SH, Marzo AL, Guevara-Patino JA, Lasfar A, Thomas PG, Lattime EC, Kaufman HL, Zloza A. Non-oncogenic Acute Viral Infections Disrupt Anti-cancer Responses and Lead to Accelerated Cancer-Specific Host Death. Cell Rep 2017; 17:957-965. [PMID: 27760326 DOI: 10.1016/j.celrep.2016.09.068] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 01/07/2016] [Accepted: 09/21/2016] [Indexed: 02/07/2023] Open
Abstract
In light of increased cancer prevalence and cancer-specific deaths in patients with infections, we investigated whether infections alter anti-tumor immune responses. We report that acute influenza infection of the lung promotes distal melanoma growth in the dermis and leads to accelerated cancer-specific host death. Furthermore, we show that during influenza infection, anti-melanoma CD8+ T cells are shunted from the tumor to the infection site, where they express high levels of the inhibitory receptor programmed cell death protein 1 (PD-1). Immunotherapy to block PD-1 reverses this loss of anti-tumor CD8+ T cells from the tumor and decreases infection-induced tumor growth. Our findings show that acute non-oncogenic infection can promote cancer growth, raising concerns regarding acute viral illness sequelae. They also suggest an unexpected role for PD-1 blockade in cancer immunotherapy and provide insight into the immune response when faced with concomitant challenges.
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Affiliation(s)
- Frederick J Kohlhapp
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA; Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - Erica J Huelsmann
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Andrew T Lacek
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Jason M Schenkel
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jevgenijs Lusciks
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA; Department of Internal Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Joseph R Broucek
- Department of General Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Josef W Goldufsky
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Tasha Hughes
- Department of General Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Janet P Zayas
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Hubert Dolubizno
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Ryan T Sowell
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Regina Kühner
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sarah Burd
- University of Oxford, Oxford OX1 2JD, UK
| | - John C Kubasiak
- Department of General Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Arman Nabatiyan
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA; Department of Internal Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sh'Rae Marshall
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA
| | - Praveen K Bommareddy
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA
| | - Shengguo Li
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA
| | - Jenna H Newman
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA
| | - Claude E Monken
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA; Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - Sasha H Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Amanda L Marzo
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA; Department of Internal Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Jose A Guevara-Patino
- Department of Surgery, Immunology Institute, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL 60153, USA
| | - Ahmed Lasfar
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA; Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Paul G Thomas
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Edmund C Lattime
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA; Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - Howard L Kaufman
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA; Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - Andrew Zloza
- Section of Surgical Oncology, Division of Surgical Oncology Research, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA; Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA.
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10
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Gupta KH, Goldufsky JW, Wood SJ, Tardi NJ, Moorthy GS, Gilbert DZ, Zayas JP, Hahm E, Altintas MM, Reiser J, Shafikhani SH. Apoptosis and Compensatory Proliferation Signaling Are Coupled by CrkI-Containing Microvesicles. Dev Cell 2017. [PMID: 28633020 DOI: 10.1016/j.devcel.2017.05.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Apoptosis has been implicated in compensatory proliferation signaling (CPS), whereby dying cells induce proliferation in neighboring cells as a means to restore homeostasis. The nature of signaling between apoptotic cells and their neighboring cells remains largely unknown. Here we show that a fraction of apoptotic cells produce and release CrkI-containing microvesicles (distinct from exosomes and apoptotic bodies), which induce proliferation in neighboring cells upon contact. We provide visual evidence of CPS by videomicroscopy. We show that purified vesicles in vitro and in vivo are sufficient to stimulate proliferation in other cells. Our data demonstrate that CrkI inactivation by ExoT bacterial toxin or by mutagenesis blocks vesicle formation in apoptotic cells and inhibits CPS, thus uncoupling apoptosis from CPS. We further show that c-Jun amino-terminal kinase (JNK) plays a pivotal role in mediating vesicle-induced CPS in recipient cells. CPS could have important ramifications in diseases that involve apoptotic cell death.
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Affiliation(s)
- Kajal H Gupta
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Josef W Goldufsky
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Stephen J Wood
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Nicholas J Tardi
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Gayathri S Moorthy
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Douglas Z Gilbert
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Janet P Zayas
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Eunsil Hahm
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sasha H Shafikhani
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA; Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA; Cancer Center, Rush University Medical Center, Chicago, IL 60612, USA.
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11
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Kroin JS, Li J, Goldufsky JW, Gupta KH, Moghtaderi M, Buvanendran A, Shafikhani SH. Perioperative high inspired oxygen fraction therapy reduces surgical site infection with Pseudomonas aeruginosa in rats. J Med Microbiol 2016; 65:738-744. [PMID: 27302326 DOI: 10.1099/jmm.0.000295] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Surgical site infection (SSI) remains one of the most important causes of healthcare-associated infections, accounting for ~17 % of all hospital-acquired infections. Although short-term perioperative treatment with high fraction of inspired oxygen (FiO2) has shown clinical benefits in reducing SSI in colorectal resection surgeries, the true clinical benefits of FiO2 therapy in reducing SSI remain unclear because randomized controlled trials on this topic have yielded disparate results and inconsistent conclusions. To date, no animal study has been conducted to determine the efficacy of short-term perioperative treatments with high (FiO2>60 %) versus low (FiO2<40 %) oxygen in reducing SSI. In this report, we designed a rat model for muscle surgery to compare the effectiveness of short-term perioperative treatments with high (FiO2=80 %) versus a standard low (FiO2=30 %) oxygen in reducing SSI with Pseudomonas aeruginosa - one of the most prevalent Gram-negative pathogens, responsible for nosocomial SSIs. Our data demonstrate that 5 h perioperative treatment with 80 % FiO2 is significantly more effective in reducing SSI with P. aeruginosa compared to 30 % FiO2 treatment. We further show that whilst 80 % FiO2 treatment does not affect neutrophil infiltration into P. aeruginosa-infected muscles, neutrophils in the 80 % FiO2-treated and infected animal group are significantly more activated than neutrophils in the 30 % FiO2-treated and infected animal group, suggesting that high oxygen perioperative treatment reduces SSI with P. aeruginosa by enhancing neutrophil activation in infected wounds.
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Affiliation(s)
- Jeffrey S Kroin
- Department of Anesthesiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Jinyuan Li
- Department of Anesthesiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Josef W Goldufsky
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Kajal H Gupta
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Masoomeh Moghtaderi
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Asokumar Buvanendran
- Department of Anesthesiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sasha H Shafikhani
- Rush University Cancer Center, Rush University Medical Center, Chicago, IL 60612, USA.,Department of Internal Medicine, Rush University Medical Center, Chicago, IL 60612, USA.,Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
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12
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Wood SJ, Goldufsky JW, Bello D, Masood S, Shafikhani SH. Pseudomonas aeruginosa ExoT Induces Mitochondrial Apoptosis in Target Host Cells in a Manner That Depends on Its GTPase-activating Protein (GAP) Domain Activity. J Biol Chem 2015; 290:29063-73. [PMID: 26451042 DOI: 10.1074/jbc.m115.689950] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa is the most common cause of hospital-acquired pneumonia and a killer of immunocompromised patients. We and others have demonstrated that the type III secretion system (T3SS) effector protein ExoT plays a pivotal role in facilitating P. aeruginosa pathogenesis. ExoT possesses an N-terminal GTPase-activating protein (GAP) domain and a C-terminal ADP-ribosyltransferase (ADPRT) domain. Because it targets multiple non-overlapping cellular targets, ExoT performs several distinct virulence functions for P. aeruginosa, including induction of apoptosis in a variety of target host cells. Both the ADPRT and the GAP domain activities contribute to ExoT-induced apoptosis. The ADPRT domain of ExoT induces atypical anoikis by transforming an innocuous cellular protein, Crk, into a cytotoxin, which interferes with integrin survival signaling. However, the mechanism underlying the GAP-induced apoptosis remains unknown. In this study, we demonstrate that the GAP domain activity is both necessary and sufficient to induce mitochondrial (intrinsic) apoptosis. We show that intoxication with GAP domain results in: (i) JNK1/2 activation; (ii) substantial increases in the mitochondrial levels of activated pro-apoptotic proteins Bax and Bid, and to a lesser extent Bim; (iii) loss of mitochondrial membrane potential and cytochrome c release; and (iv) activation of initiator caspase-9 and executioner caspase-3. Further, GAP-induced apoptosis is partially mediated by JNK1/2, but it is completely dependent on caspase-9 activity. Together, the ADPRT and the GAP domains make ExoT into a highly versatile and potent cytotoxin, capable of inducing multiple forms of apoptosis in target host cells.
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Affiliation(s)
| | | | | | - Sara Masood
- From the Department of Immunology/Microbiology
| | - Sasha H Shafikhani
- From the Department of Immunology/Microbiology, Department of Internal Medicine, and Cancer Center, Rush University Medical Center, Chicago, Illinois 60612
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13
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Kroin JS, Buvanendran A, Li J, Moric M, Im HJ, Tuman KJ, Shafikhani SH. Short-term glycemic control is effective in reducing surgical site infection in diabetic rats. Anesth Analg 2015; 120:1289-96. [PMID: 25695673 DOI: 10.1213/ane.0000000000000650] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Patients and animals with diabetes exhibit enhanced vulnerability to bacterial surgical infections. Despite multiple retrospective studies demonstrating the benefits associated with glycemic control in reducing bacterial infection after cardiac surgery, there are fewer guidelines on the use of glycemic control for noncardiac surgeries. In the current study, we investigated whether long-term (begun 2 weeks before surgery) or immediate (just before surgery) glycemic controls, continued postoperatively, can reduce surgical site infection in type 1 diabetic-induced rats. METHODS Rats were injected with streptozotocin to induce type 1 diabetes. Four groups of animals underwent surgery and thigh muscle Staphylococcus aureus bacteria challenge (1 × 10 colony forming units) at the time of surgery. Group 1 diabetic rats received insulin treatment just before surgery and continued until the end of study (short-term glycemic control group). Group 2 diabetic rats received insulin treatment 2 weeks before surgery and continued until the end of study (long-term glycemic control). Group 3 diabetic rats received no insulin treatment (no glycemic control group). Group 4 nondiabetic rats served as a healthy control group. Rats were euthanized at 3 or 6 days after surgery. Blood glucose and muscle bacterial burden were measured at 3 or 6 days after surgery. RESULTS Glycemic control was achieved in both long- and short-term insulin-treated diabetic rats. Compared with untreated diabetic rats, the bacterial burden in muscle was significantly lower in both groups of glycemic controlled diabetic rats at 3 (all P < 0.003) and 6 (all P < 0.0001) days after surgery. CONCLUSIONS A short-term glycemic control regimen, initiated just before surgery and bacterial exposure, was as effective in reducing surgical site infection as a long-term glycemic control in type 1 diabetic rats. These data suggest that immediately implementing glycemic control in type 1 diabetic surgical patients before undergoing noncardiac surgery may decrease the risk of infection.
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Affiliation(s)
- Jeffrey S Kroin
- From the *Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois; †Department of Biochemistry, Rush University Medical Center, Chicago, Illinois; and ‡Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois
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14
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Goldufsky J, Wood SJ, Jayaraman V, Majdobeh O, Chen L, Qin S, Zhang C, DiPietro LA, Shafikhani SH. Pseudomonas aeruginosa uses T3SS to inhibit diabetic wound healing. Wound Repair Regen 2015; 23:557-64. [PMID: 25912785 DOI: 10.1111/wrr.12310] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 04/22/2015] [Indexed: 12/16/2022]
Abstract
Diabetic foot ulcers are responsible for more hospitalizations than any other complication of diabetes. Bacterial infection is recognized as an important factor associated with impaired healing in diabetic ulcers. Pseudomonas aeruginosa is the most frequently detected Gram-negative pathogen in diabetic ulcers. P. aeruginosa infection has been shown to impair healing in diabetic wounds in a manner that correlates with its ability to form biofilm. While the majority of infections in diabetic ulcers are biofilm associated, 33% of infections are nonbiofilm in nature. P. aeruginosa is the most prevalent Gram-negative pathogen in all diabetic wound types, which suggests that the deleterious impact of P. aeruginosa on healing in diabetic wounds goes beyond its ability to form biofilm and likely involves other factors. The Type III Secretion System (T3SS) virulence structure is required for the pathogenesis of all P. aeruginosa clinical isolates, suggesting that it may also play a role in the inhibition of wound repair in diabetic skin ulcers. We evaluated the role of T3SS in mediating P. aeruginosa-induced tissue damage in the wounds of diabetic mice. Our data demonstrate that P. aeruginosa establishes a robust and persistent infection in diabetic wounds independent of its ability to form biofilm and causes severe wound damage in a manner that primarily depends on its T3SS.
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Affiliation(s)
- Josef Goldufsky
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois
| | - Stephen J Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois
| | - Vijayakumar Jayaraman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois
| | - Omar Majdobeh
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois
| | - Lin Chen
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois
| | - Shanshan Qin
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois
| | - Chunxiang Zhang
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois
| | - Luisa A DiPietro
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois
| | - Sasha H Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois.,Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois.,Cancer Center, Rush University Medical Center Chicago, Illinois
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15
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Wood S, Goldufsky J, Shafikhani SH. Pseudomonas aeruginosa ExoT Induces Atypical Anoikis Apoptosis in Target Host Cells by Transforming Crk Adaptor Protein into a Cytotoxin. PLoS Pathog 2015; 11:e1004934. [PMID: 26020630 PMCID: PMC4447348 DOI: 10.1371/journal.ppat.1004934] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 05/04/2015] [Indexed: 11/19/2022] Open
Abstract
Previously, we demonstrated that Pseudomonas aeruginosa ExoT induces potent apoptosis in host epithelial cells in a manner that primarily depends on its ADP-ribosyltransferase domain (ADPRT) activity. However, the mechanism underlying ExoT/ADPRT-induced apoptosis remains undetermined. We now report that ExoT/ADPRT disrupts focal adhesion sites, activates p38β and JNK, and interferes with integrin-mediated survival signaling; causing atypical anoikis. We show that ExoT/ADPRT-induced anoikis is mediated by the Crk adaptor protein. We found that Crk-/- knockout cells are significantly more resistant to ExoT-induced apoptosis, while Crk-/- cells complemented with Crk are rendered sensitive to ExoT-induced apoptosis. Moreover, a dominant negative (DN) mutant form of Crk phenocopies ExoT-induced apoptosis both kinetically and mechanistically. Crk is generally believed to be a component of focal adhesion (FA) and its role in cellular survival remains controversial in that it has been found to be either pro-survival or pro-apoptosis. Our data demonstrate that although Crk is recruited to FA sites, its function is likely not required for FA assembly or for survival per se. However, when modified by ExoT or by mutagenesis, it can be transformed into a cytotoxin that induces anoikis by disrupting FA sites and interfering with integrin survival signaling. To our knowledge, this is the first example whereby a bacterial toxin exerts its cytotoxicity by subverting the function of an innocuous host cellular protein and turning it against the host cell.
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Affiliation(s)
- Stephen Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Josef Goldufsky
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Sasha H. Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, United States of America
- Cancer Center, Rush University Medical Center, Chicago, Illinois, United States of America
- * E-mail:
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16
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Goldufsky J, Wood S, Hajihossainlou B, Rehman T, Majdobeh O, Kaufman HL, Ruby CE, Shafikhani SH. Pseudomonas aeruginosa exotoxin T induces potent cytotoxicity against a variety of murine and human cancer cell lines. J Med Microbiol 2015; 64:164-73. [PMID: 25627204 DOI: 10.1099/jmm.0.000003-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In patients with malignancy, the major barrier to achieving complete response is emergence of resistance to current chemotherapeutic agents. One of the major mechanisms by which tumour cells become resistant to therapies is by altering cellular drug targets through mutations and/or deletions. Resistance by this mechanism is achieved more easily if the drug has limited cellular targets and/or processes. We hypothesized that as Pseudomonas aeruginosa exotoxin T (ExoT) targets six proteins that are required for cancer cell survival and proliferation, it is highly unlikely for cancer cells to develop resistance to this toxin. We assessed ExoT's cytotoxicity against multiple invasive and highly resistant tumour cell lines in order to evaluate its potential as a chemotherapeutic agent. Our data demonstrated that ExoT induced potent cytotoxicity in all tumour cell lines that we examined. Collectively, our data highlighted the potential of ExoT as a possible chemotherapeutic candidate for the treatment of cancer.
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Affiliation(s)
- Joe Goldufsky
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Stephen Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Behnam Hajihossainlou
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Tooba Rehman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Omar Majdobeh
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | | | - Carl E Ruby
- Department of Surgery, Rush University Medical Center, Chicago, IL, USA Sarepta Therapeutics, Corvallis, OR, USA
| | - Sasha H Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA Rush University Cancer Center, Rush University Medical Center, Chicago, IL, USA
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17
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Goldufsky J, Wood S, Hajihossainlou B, Rehman T, Majdobeh O, Kaufman HL, Ruby CE, Shafikhani SH. Pseudomonas aeruginosa exotoxin T induces potent cytotoxicity against a variety of murine and human cancer cell lines. J Med Microbiol 2015. [DOI: 10.1099/jmm.0.000003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Joe Goldufsky
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Stephen Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Behnam Hajihossainlou
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Tooba Rehman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | - Omar Majdobeh
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
| | | | - Carl E. Ruby
- Sarepta Therapeutics, Corvallis, OR, USA
- Department of Surgery, Rush University Medical Center, Chicago, IL, USA
| | - Sasha H. Shafikhani
- Rush University Cancer Center, Rush University Medical Center, Chicago, IL, USA
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL, USA
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18
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Wood S, Jayaraman V, Huelsmann EJ, Bonish B, Burgad D, Sivaramakrishnan G, Qin S, DiPietro LA, Zloza A, Zhang C, Shafikhani SH. Pro-inflammatory chemokine CCL2 (MCP-1) promotes healing in diabetic wounds by restoring the macrophage response. PLoS One 2014; 9:e91574. [PMID: 24618995 PMCID: PMC3950222 DOI: 10.1371/journal.pone.0091574] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 02/13/2014] [Indexed: 01/13/2023] Open
Abstract
Prior studies suggest that the impaired healing seen in diabetic wounds derives from a state of persistent hyper-inflammation characterized by harmful increases in inflammatory leukocytes including macrophages. However, such studies have focused on wounds at later time points (day 10 or older), and very little attention has been given to the dynamics of macrophage responses in diabetic wounds early after injury. Given the importance of macrophages for the process of healing, we studied the dynamics of macrophage response during early and late phases of healing in diabetic wounds. Here, we report that early after injury, the diabetic wound exhibits a significant delay in macrophage infiltration. The delay in the macrophage response in diabetic wounds results from reduced Chemokine (C-C motif) ligand 2 (CCL2) expression. Importantly, one-time treatment with chemoattractant CCL2 significantly stimulated healing in diabetic wounds by restoring the macrophage response. Our data demonstrate that, rather than a hyper-inflammatory state; the early diabetic wound exhibits a paradoxical and damaging decrease in essential macrophage response. Our studies suggest that the restoration of the proper kinetics of macrophage response may be able to jumpstart subsequent healing stages. CCL2 chemokine-based therapy may be an attractive strategy to promote healing in diabetic wounds.
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Affiliation(s)
- Stephen Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Vijayakumar Jayaraman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Erica J. Huelsmann
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
- Rush University Cancer Center, Rush University Medical Center, Chicago, Illinois, United States of America
- Developmental Center for AIDS Research, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Brian Bonish
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
- Department of Dermatology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Derick Burgad
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Gayathri Sivaramakrishnan
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Shanshan Qin
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Luisa A. DiPietro
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Andrew Zloza
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
- Rush University Cancer Center, Rush University Medical Center, Chicago, Illinois, United States of America
- Developmental Center for AIDS Research, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Chunxiang Zhang
- Department of Pharmacology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Sasha H. Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
- Rush University Cancer Center, Rush University Medical Center, Chicago, Illinois, United States of America
- * E-mail:
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19
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Wood S, Pithadia R, Rehman T, Zhang L, Plichta J, Radek KA, Forsyth C, Keshavarzian A, Shafikhani SH. Chronic alcohol exposure renders epithelial cells vulnerable to bacterial infection. PLoS One 2013; 8:e54646. [PMID: 23358457 PMCID: PMC3554638 DOI: 10.1371/journal.pone.0054646] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 12/13/2012] [Indexed: 12/15/2022] Open
Abstract
Despite two centuries of reports linking alcohol consumption with enhanced susceptibility to bacterial infections and in particular gut-derived bacteria, there have been no studies or model systems to assess the impact of long-term alcohol exposure on the ability of the epithelial barrier to withstand bacterial infection. It is well established that acute alcohol exposure leads to reduction in tight and adherens junctions, which in turn leads to increases in epithelial cellular permeability to bacterial products, leading to endotoxemia and a variety of deleterious effects in both rodents and human. We hypothesized that reduced fortification at junctional structures should also reduce the epithelial barrier’s capacity to maintain its integrity in the face of bacterial challenge thus rendering epithelial cells more vulnerable to infection. In this study, we established a cell-culture based model system for long-term alcohol exposure to assess the impact of chronic alcohol exposure on the ability of Caco-2 intestinal epithelial cells to withstand infection when facing pathogenic bacteria under the intact or wounded conditions. We report that daily treatment with 0.2% ethanol for two months rendered Caco-2 cells far more susceptible to wound damage and cytotoxicity caused by most but not all bacterial pathogens tested in our studies. Consistent with acute alcohol exposure, long-term ethanol exposure also adversely impacted tight junction structures, but in contrast, it did not affect the adherens junction. Finally, alcohol-treated cells partially regained their ability to withstand infection when ethanol treatment was ceased for two weeks, indicating that alcohol’s deleterious effects on cells may be reversible.
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Affiliation(s)
- Stephen Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Ravi Pithadia
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Tooba Rehman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Lijuan Zhang
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Jennifer Plichta
- Department of Surgery, Burn and Shock Trauma Institute, Loyola University Chicago, Health Sciences Campus, Maywood, Illinois, United States of America
| | - Katherine A. Radek
- Department of Surgery, Burn and Shock Trauma Institute, Loyola University Chicago, Health Sciences Campus, Maywood, Illinois, United States of America
| | - Christopher Forsyth
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Ali Keshavarzian
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Sasha H. Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, Illinois, United States of America
- * E-mail:
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20
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Mahmood F, Hakimiyan A, Jayaraman V, Wood S, Sivaramakrishnan G, Rehman T, Reuhs BL, Chubinskaya S, Shafikhani SH. A novel human antimicrobial factor targets Pseudomonas aeruginosa through its type III secretion system. J Med Microbiol 2013; 62:531-539. [PMID: 23288430 DOI: 10.1099/jmm.0.051227-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Pseudomonas aeruginosa is an important opportunistic bacterial pathogen. Despite its metabolic and virulence versatility, it has not been shown to infect articular joints, which are areas that are rarely infected with bacteria in general. We hypothesized that articular joints possess antimicrobial activity that limits bacterial survival in these environments. We report that cartilages secrete a novel antimicrobial factor, henceforth referred to as the cartilage-associated antimicrobial factor (CA-AMF), with potent antimicrobial activity. Importantly, CA-AMF exhibited significantly more antimicrobial activity against P. aeruginosa strains with a functional type III secretion system (T3SS). We propose that CA-AMF represents a new class of human antimicrobial factors in innate immunity, one which has evolved to selectively target pathogenic bacteria among the beneficial and commensal microflora. The T3SS is the first example, to the best of our knowledge, of a pathogen-specific molecular target in this antimicrobial defence system.
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Affiliation(s)
- Fareeha Mahmood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Arnavaz Hakimiyan
- Department of Food Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Vijayakumar Jayaraman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Stephen Wood
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | | | - Tooba Rehman
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Bradley L Reuhs
- Department of Food Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Susanna Chubinskaya
- Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA
| | - Sasha H Shafikhani
- Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612, USA
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21
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Abstract
Cytokinesis is the final stage of cell division in which the daughter cells separate. Although a growing body of evidence suggests that cell migration-induced traction forces may be required to provide physical assistance for daughter cells to dissociate during abscission, the role of cell migration in cytokinesis has not been directly elucidated. Recently, we have demonstrated that Crk and paxillin, which are pivotal components of the cell migration machinery, localize to the midbody and are essential for the abscission. These findings provided an important link between the cell migration and cytokinesis machineries and prompted us to dissect the role of cell migration in cytokinesis. We show that cell migration controls the kinetics of cleavage furrowing, midbody extension and abscission and coordinates proper subcellular redistribution of Crk and syntaxin-2 to the midbody after ingression.
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Affiliation(s)
- Stephen Wood
- Department of Immunology, Rush University Medical Center; Chicago, IL USA
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22
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Abstract
The final stages in mammalian cytokinesis are poorly understood. Previously, we reported that the ADP-ribosyltransferase activity of Pseudomonas aeruginosa type III secreted toxin ExoT inhibits late stages of cytokinesis. Given that Crk adaptor proteins are the major substrates of ExoT ADP-ribosyltransferase activity, we tested the involvement of Crk in cytokinesis. We report that the focal adhesion-associated proteins, Crk and paxillin are essential for completion of cytokinesis. When their function is absent, the cytoplasmic bridge fails to resolve and the daughter cells fuse to form a binucleated cell. During cytokinesis, Crk is required for syntaxin-2 recruitment to the midbody, while paxillin is required for both Crk and syntaxin-2 localization to this compartment. Our data demonstrate that the subcellular localization and the activity of RhoA and citron K, which are essential for early stages of cytokinesis, are not dependent on paxillin, Crk or syntaxin-2. These studies reveal a novel role for Crk and paxillin in cytokinesis and suggest that focal adhesion complex, as a unit, may partake in this fundamental cellular process.
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Affiliation(s)
- Sasha H Shafikhani
- Department of Medicine, University of California, San Francisco, California, USA
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23
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Shafikhani SH, Morales C, Engel J. The Pseudomonas aeruginosa type III secreted toxin ExoT is necessary and sufficient to induce apoptosis in epithelial cells. Cell Microbiol 2008; 10:994-1007. [PMID: 18053004 PMCID: PMC10952005 DOI: 10.1111/j.1462-5822.2007.01102.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [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] [Indexed: 11/26/2022]
Abstract
Type III secreted (T3SS) effectors are important virulence factors in acute infections caused by Pseudomonas aeruginosa. PA103, a well-studied human lung isolate, encodes and secretes two effectors, ExoU and ExoT. ExoU is a potent cytotoxin that causes necrotic cell death. In addition, PA103 can induce cell death in macrophages in an ExoU-independent but T3SS-dependent manner. We now demonstrate that ExoT is both necessary and sufficient to cause apoptosis in HeLa cells and that it activates the mitochondrial/cytochrome c-dependent apoptotic pathway. We further show that ExoT induction of cell death is primarily dependent on its ADP ribosyltransferase domain activity. Our data also indicate that the T3SS apparatus can cause necrotic cell death, which is effectively blocked by ExoT, suggesting that P. aeruginosa may have evolved strategies to prevent T3SS-induced necrosis.
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Affiliation(s)
- Sasha H. Shafikhani
- Department of Medicine, University of California, San Francisco, CA 94143, USA
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143, USA
| | - Christina Morales
- Department of Medicine, University of California, San Francisco, CA 94143, USA
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143, USA
| | - Joanne Engel
- Department of Medicine, University of California, San Francisco, CA 94143, USA
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143, USA
- Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, CA 94143, USA
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24
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Shafikhani SH, Engel J. Pseudomonas aeruginosa type III-secreted toxin ExoT inhibits host-cell division by targeting cytokinesis at multiple steps. Proc Natl Acad Sci U S A 2006; 103:15605-10. [PMID: 17030800 PMCID: PMC1622869 DOI: 10.1073/pnas.0605949103] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [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] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that requires preexisiting epithelial injury to cause acute infections. We report that P. aeruginosa inhibits mammalian cytokinesis in a type III secretion system and exotoxin T (ExoT)-dependent manner. ExoT is a bifunctional type III secretion system effector protein that contains an N-terminal GTPase-activating protein domain and a C-terminal ADP-ribosyl transferase domain. Each of its domains inhibits cytokinesis in a kinetically, morphologically, and mechanistically distinct manner. The GTPase-activating protein-mediated inhibition of cytokinesis occurs early, likely as a consequence of its inhibitory effect on RhoA. The ADP-ribosyl transferase domain inhibits late steps of cytokinesis by blocking syntaxin-2 localization to the midbody, an event essential for completion of cytokinesis. These findings provide an example of a bacterial pathogen targeting cytokinesis.
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Affiliation(s)
| | - Joanne Engel
- *Division of Infectious Diseases, Department of Medicine and
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
- To whom correspondence should be addressed. E-mail:
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25
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Abstract
We have shown previously that Spo0A approximately P-dependent sinIR operon expression was substantially down-regulated in abrB null mutant backgrounds. In this report, we show that loss of function mutations in abrB also cause phosphorelay gene expression to be down regulated. abrB null mutations caused diminished vegetative growth-associated sporulation and resulted in a significant reduction in sporulation frequencies at T(24). These mutants, however, sporulated at wild-type levels at T(48), indicating that sporulation timing was affected. The rvtA11 mutation in spo0A, a deletion mutation in spo0E, and a null mutation in hpr ( scoC) rescued sporulation and Spo0A approximately P-dependent gene expression in an abrB mutant background. These data indicate that AbrB and Spo0E may comprise a checkpoint system that regulates the progression of sporulation, allowing exploration of alternate cell states prior to the irrevocable commitment to sporulation.
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Affiliation(s)
- Sasha H Shafikhani
- Department of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, CA 94704, USA.
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26
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Shafikhani SH, Núnez E, Leighton T. Corrigendum to: âHpr (ScoC) and the phosphorelay couple cell cycle and sporulation in Bacillus subtilisâ [FEMS Microbiol. Lett. 231 (2003) 99â110]. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09531.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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27
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Shafikhani SH, Núñez E, Leighton T. Hpr (ScoC) and the phosphorelay couple cell cycle and sporulation inBacillus subtilis. FEMS Microbiol Lett 2004; 231:99-110. [PMID: 14769473 DOI: 10.1016/s0378-1097(03)00936-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Revised: 12/01/2003] [Accepted: 12/07/2003] [Indexed: 11/25/2022] Open
Abstract
Bacillus subtilis sporulation is a developmental process that culminates in the formation of a highly resistant and persistent endospore. Inhibiting DNA synthesis prior to the completion of the final round of DNA replication blocks sporulation at an early stage. Conditions that prevent compartmentalization of gene expression, i.e. inhibition of asymmetric septum formation or chromosome partitioning, also block sporulation at an early stage. Multiple mechanisms including a RecA-dependent, a RecA-independent, and the soj-spo0J operon have been implicated in signal transduction, connecting DNA replication and chromosome partitioning to the onset of sporulation in B. subtilis. We suggest that a single mechanism involving Hpr (ScoC) and Sda couple cell cycle signaling to sporulation initiation. We show that transcription of phosphorelay sensory chain genes is adversely affected by post-exponential perturbation of the cell cycle. DNA replication arrest by chemical treatments, such as hydroxyphenylazouracil, hydroxyurea, nalidixic acid, and through genetic means using dnaA1ts and dnaB19ts temperature-sensitive mutants caused substantial down-regulation of spo0F and kinA expression and elevated the expression of spo0A and spo0H (sigH). Despite the elevation in spo0A expression, Spo0A approximately P-dependent sinI expression was substantially down-regulated indicating that in vivo Spo0A approximately P levels may be diminished. Similar alterations in gene expression patterns were observed in an ftsA279ts mutant background, indicating that cytokinesis and sporulation may also be coupled by a similar mechanism. Loss of function mutation in hpr (scoC) restored sporulation in a dnaA1ts mutant, blocked the DNA replication arrest induction of spo0A expression and restored expression of spo0F, kinA and sinI. Moreover, hpr expression was up-regulated in response to DNA replication arrest. The increase in hpr expression required Sda. These results suggest a role for Hpr (ScoC) in mediating the coupling of cell cycle events to the onset of sporulation.
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Affiliation(s)
- Sasha H Shafikhani
- Department of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, 401 Barker Hall, University of California, Berkeley, CA 94720, USA
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28
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Abstract
Sporulation in Bacillus subtilis can be triggered by carbon catabolite limitation. Conversely, carbon source excess can repress the production of extracellular enzymes, motility, and sporulation. Recent studies have implicated a pH-sensing mechanism, involving AbrB, the TCA cycle, Spo0K, and sigmaH in controlling the catabolite repression of sporulation gene expression. In an accompanying paper, we demonstrate that the AbrB-dependent pH-sensing mechanism may not be the only means by which carbon catabolites affect sporulation. In the studies reported here, we have examined the molecular basis underlying the catabolite repression phenotype of mutations in the hpr (scoC), rpoD (crsA47), and spo0A (rvtA11) loci. Loss of function mutations in hpr (scoC) restored sporulation gene expression and sporulation in the presence of excess catabolite(s), suggesting that Hpr (ScoC) has a pivotal role in mediating catabolite repression. Moreover, hpr gene expression increased substantially in the presence of excess catabolite(s), further supporting the involvement of Hpr (ScoC) in the carbon catabolite response system. We suggest that alterations in the phosphorelay response to catabolites may be one mechanism by which catabolite-resistant mutants such as crsA and rvtA are able to sporulate in the presence of excess glucose.
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Affiliation(s)
- Sasha H Shafikhani
- Department of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720, USA
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29
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Abstract
In response to nutrient limitations, Bacillus subtilis cells undergo a series of morphological and genetic changes that culminate in the formation of endospores. Conversely, excess catabolites inhibit sporulation. It has been demonstrated previously that excess catabolites caused a decrease in culture medium pH in a process that required functional AbrB. Culture medium acidification was also shown to inhibit sigmaH-dependent sporulation gene expression. The studies reported here investigate the effects of AbrB-mediated pH sensing on B. subtilis developmental competence. We have found that neither addition of a pH stabilizer, MOPS (pH 7.5), nor null mutations in abrB blocked catabolite repression of sporulation. Moreover, catabolite-induced culture medium acidification was observed in cultures of catabolite-resistant sporulation mutants, crsA47, rvtA11, and hpr-16, despite their efficient sporulation. These results suggest that AbrB-mediated pH sensing is not the only mechanism regulating catabolite repression of sporulation. The AbrB pathway may function to channel cells toward genetic competence, as opposed to other postexponential differentiation pathways.
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Affiliation(s)
- Sasha H Shafikhani
- Department of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, 401 Barker Hall, University of California, Berkeley, CA 94720, USA
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30
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Abstract
The expression of many gene products required during the early stages of Bacillus subtilis sporulation is regulated by sinIR operon proteins. Transcription of sinIR from the P1 promoter is induced at the end of exponential growth. In vivo transcription studies suggest that P1 induction is repressed by the transition-state regulatory protein Hpr and is induced by the phosphorylated form of Spo0A. In vitro DNase I footprinting studies confirmed that Hpr, AbrB, and Spo0A are trans-acting transcriptional factors that bind to the P1 promoter region of sinIR. We have also determined that the P1 promoter is transcribed in vitro by the major vegetative sigma factor, final sigma(A), form of RNA polymerase.
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Affiliation(s)
- Sasha H Shafikhani
- Department of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720, USA
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