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Yao Y, Gupta D, Yelon D. The MEK-ERK signaling pathway promotes maintenance of cardiac chamber identity. Development 2024; 151:dev202183. [PMID: 38293792 PMCID: PMC10911121 DOI: 10.1242/dev.202183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 01/21/2024] [Indexed: 02/01/2024]
Abstract
Ventricular and atrial cardiac chambers have unique structural and contractile characteristics that underlie their distinct functions. The maintenance of chamber-specific features requires active reinforcement, even in differentiated cardiomyocytes. Previous studies in zebrafish have shown that sustained FGF signaling acts upstream of Nkx factors to maintain ventricular identity, but the rest of this maintenance pathway remains unclear. Here, we show that MEK1/2-ERK1/2 signaling acts downstream of FGF and upstream of Nkx factors to promote ventricular maintenance. Inhibition of MEK signaling, like inhibition of FGF signaling, results in ectopic atrial gene expression and reduced ventricular gene expression in ventricular cardiomyocytes. FGF and MEK signaling both influence ventricular maintenance over a similar timeframe, when phosphorylated ERK (pERK) is present in the myocardium. However, the role of FGF-MEK activity appears to be context-dependent: some ventricular regions are more sensitive than others to inhibition of FGF-MEK signaling. Additionally, in the atrium, although endogenous pERK does not induce ventricular traits, heightened MEK signaling can provoke ectopic ventricular gene expression. Together, our data reveal chamber-specific roles of MEK-ERK signaling in the maintenance of ventricular and atrial identities.
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Affiliation(s)
- Yao Yao
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Deepam Gupta
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Deborah Yelon
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
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2
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Mao A, Li Z, Ning G, Zhou Z, Wei C, Li J, He X, Wang Q. Sclerotome-derived PDGF signaling functions as a niche cue responsible for primitive erythropoiesis. Development 2023; 150:dev201807. [PMID: 37882745 PMCID: PMC10690055 DOI: 10.1242/dev.201807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 10/19/2023] [Indexed: 10/27/2023]
Abstract
Primitive erythropoiesis serves a vital role in embryonic development, generating primitive red blood cells responsible for transportation of oxygen throughout the body. Although diverse niche factors are known to function in definitive hematopoiesis, the microenvironment contributing to primitive hematopoiesis remains largely elusive. Here, we report that platelet-derived growth factor (PDGF) signaling is required for erythroid progenitor differentiation in zebrafish. Ablating pdgfαa (also known as pdgfaa) and pdgfαb (also known as pdgfab) or blocking PDGF signaling with an inhibitor impairs erythroid progenitor differentiation, thus resulting in a significant decrease in the number of erythrocytes. We reveal that pdgfαb is expressed in sclerotomal cells, and that its receptor genes, pdgfra and pdgfrb, are expressed in the adjacent erythroid progenitor cells. Sclerotome-specific overexpression of pdgfαb effectively restores primitive erythropoiesis in pdgfαa-/-;pdgfαb-/- mutant embryos. In addition, we have defined ERK1/2 signaling as a downstream pathway of PDGF signaling during embryonic erythropoiesis. Taken together, our findings indicate that PDGF signaling derived from sclerotome functions as a niche cue for primitive erythropoiesis.
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Affiliation(s)
- Aihua Mao
- Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, Guangdong 515063, China
| | - Zhuyun Li
- Innovation Centre of Ministry of Education for Development and Diseases, Sixth Affiliated Hospital, School of Medicine, South China University of Technology, Guangzhou 510006, China
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guozhu Ning
- Affiliated Hospital of Guangdong Medical University and Key Laboratory of Zebrafish Model for Development and Disease, Guangdong Medical University, Zhanjiang 524001, China
| | - Zhengrong Zhou
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chiju Wei
- Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, Guangdong 515063, China
| | - Jianchao Li
- Innovation Centre of Ministry of Education for Development and Diseases, Sixth Affiliated Hospital, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Xinyu He
- Innovation Centre of Ministry of Education for Development and Diseases, Sixth Affiliated Hospital, School of Medicine, South China University of Technology, Guangzhou 510006, China
| | - Qiang Wang
- Innovation Centre of Ministry of Education for Development and Diseases, Sixth Affiliated Hospital, School of Medicine, South China University of Technology, Guangzhou 510006, China
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3
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Liu J, Zhu C, Ning G, Yang L, Cao Y, Huang S, Wang Q. Chemokine signaling links cell-cycle progression and cilia formation for left-right symmetry breaking. PLoS Biol 2019; 17:e3000203. [PMID: 31430272 PMCID: PMC6716676 DOI: 10.1371/journal.pbio.3000203] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 08/30/2019] [Accepted: 08/06/2019] [Indexed: 11/19/2022] Open
Abstract
Zebrafish dorsal forerunner cells (DFCs) undergo vigorous proliferation during epiboly and then exit the cell cycle to generate Kupffer's vesicle (KV), a ciliated organ necessary for establishing left-right (L-R) asymmetry. DFC proliferation defects are often accompanied by impaired cilia elongation in KV, but the functional and molecular interaction between cell-cycle progression and cilia formation remains unknown. Here, we show that chemokine receptor Cxcr4a is required for L-R laterality by controlling DFC proliferation and KV ciliogenesis. Functional analysis revealed that Cxcr4a accelerates G1/S transition in DFCs and stabilizes forkhead box j1a (Foxj1a), a master regulator of motile cilia, by stimulating Cyclin D1 expression through extracellular regulated MAP kinase (ERK) 1/2 signaling. Mechanistically, Cyclin D1-cyclin-dependent kinase (CDK) 4/6 drives G1/S transition during DFC proliferation and phosphorylates Foxj1a, thereby disrupting its association with proteasome 26S subunit, non-ATPase 4b (Psmd4b), a 19S regulatory subunit. This prevents the ubiquitin (Ub)-independent proteasomal degradation of Foxj1a. Our study uncovers a role for Cxcr4 signaling in L-R patterning and provides fundamental insights into the molecular linkage between cell-cycle progression and ciliogenesis.
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Affiliation(s)
- Jingwen Liu
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Chengke Zhu
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Key Laboratory of Aquatics Science of Chongqing, College of Animal Science in Rongchang Campus, Southwest University, Chongqing, China
| | - Guozhu Ning
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Liping Yang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Yu Cao
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Sizhou Huang
- Development and Regeneration Key Laboratory of Sichuan Province, Department of Anatomy and Histology and Embryology, Chengdu Medical College, Chengdu, China
- * E-mail: (SH); (QW)
| | - Qiang Wang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
- * E-mail: (SH); (QW)
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4
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Cui X, Xu W, Neupane P, Weiser-Schlesinger A, Weng R, Pockros B, Li Y, Moayeri M, Leppla SH, Fitz Y, Eichacker PQ. Bacillus anthracis lethal toxin, but not edema toxin, increases pulmonary artery pressure and permeability in isolated perfused rat lungs. Am J Physiol Heart Circ Physiol 2019; 316:H1076-H1090. [PMID: 30767685 DOI: 10.1152/ajpheart.00685.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although lethal toxin (LT) and edema toxin (ET) contribute to lethality during Bacillus anthracis infection, whether they increase vascular permeability and the extravascular fluid accumulation characterizing this infection is unclear. We employed an isolated perfused Sprague-Dawley rat lung model to investigate LT and ET effects on pulmonary vascular permeability. Lungs (n ≥ 6 per experimental group) were isolated, ventilated, suspended from a force transducer, and perfused. Lung weight and pulmonary artery (Ppa) and left atrial pressures were measured over 4 h, after which pulmonary capillary filtration coefficients (Kf.c) and lung wet-to-dry weight ratios (W/D) were determined. When compared with controls, LT increased Ppa over 4 h and Kf.c and W/D at 4 h (P < 0.0001). ET decreased Ppa in a significant trend (P = 0.09) but did not significantly alter Kf.c or W/D (P ≥ 0.29). Edema toxin actually blocked LT increases in Ppa but not LT increases in Kf.c and W/D. When Ppa was maintained at control levels, LT still increased Kf.c and W/D (P ≤ 0.004). Increasing the dose of each toxin five times significantly increased and a toxin-directed monoclonal antibody decreased the effects of each toxin (P ≤ 0.05). Two rho-kinase inhibitors (GSK269962 and Y27632) decreased LT increases in Ppa (P ≤ 0.02) but actually increased Kf.c and W/D in LT and control lungs (P ≤ 0.05). A vascular endothelial growth factor receptor inhibitor (ZM323881) had no significant effect (P ≥ 0.63) with LT. Thus, LT but not ET can increase pulmonary vascular permeability independent of increased Ppa and could contribute to pulmonary fluid accumulation during anthrax infection. However, pulmonary vascular dilation with ET could disrupt protective hypoxic vasoconstriction. NEW & NOTEWORTHY The most important findings from the present study are that Bacillus anthracis lethal toxin increases pulmonary artery pressure and pulmonary permeability independently in the isolated rat lung, whereas edema toxin decreases the former and does not increase permeability. Each effect could be a basis for organ dysfunction in patients with this lethal infection. These findings further support the need for adjunctive therapies that limit the effects of both toxins during infection.
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Affiliation(s)
- Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Wanying Xu
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Pranita Neupane
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Andie Weiser-Schlesinger
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Ray Weng
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Benjamin Pockros
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, Maryland
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, Maryland
| | - Yvonne Fitz
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
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5
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Suffredini DA, Cui X, Xu W, Li Y, Eichacker PQ. The Potential Pathogenic Contributions of Endothelial Barrier and Arterial Contractile Dysfunction to Shock Due to B. anthracis Lethal and Edema Toxins. Toxins (Basel) 2017; 9:toxins9120394. [PMID: 29210983 PMCID: PMC5744114 DOI: 10.3390/toxins9120394] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 11/24/2017] [Accepted: 11/29/2017] [Indexed: 01/22/2023] Open
Abstract
Shock with B. anthracis infection is particularly resistant to conventional cardiovascular support and its mortality rate appears higher than with more common bacterial pathogens. As opposed to many bacteria that lack exotoxins directly depressing hemodynamic function, lethal and edema toxin (LT and ET respectively) both cause shock and likely contribute to the high lethality rate with B. anthracis. Selective inhibition of the toxins is protective in infection models, and administration of either toxin alone in animals produces hypotension with accompanying organ injury and lethality. Shock during infection is typically due to one of two mechanisms: (i) intravascular volume depletion related to disruption of endothelial barrier function; and (ii) extravasation of fluid and/or maladaptive dilation of peripheral resistance arteries. Although some data suggests that LT can produce myocardial dysfunction, growing evidence demonstrates that it may also interfere with endothelial integrity thereby contributing to the extravasation of fluid that helps characterize severe B. anthracis infection. Edema toxin, on the other hand, while known to produce localized tissue edema when injected subcutaneously, has potent vascular relaxant effects that could lead to pathologic arterial dilation. This review will examine recent data supporting a role for these two pathophysiologic mechanisms underlying the shock LT and ET produce. Further research and a better understanding of these mechanisms may lead to improved management of B. anthracis in patients.
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Affiliation(s)
- Dante A Suffredini
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Wanying Xu
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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6
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Kelly ML, Astsaturov A, Rhodes J, Chernoff J. A Pak1/Erk signaling module acts through Gata6 to regulate cardiovascular development in zebrafish. Dev Cell 2014; 29:350-9. [PMID: 24823378 DOI: 10.1016/j.devcel.2014.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 01/31/2014] [Accepted: 04/01/2014] [Indexed: 01/12/2023]
Abstract
Proper neural crest development and migration is critical during embryonic development, but the molecular mechanisms regulating this process remain incompletely understood. Here, we show that the protein kinase Erk, which plays a central role in a number of key developmental processes in vertebrates, is regulated in the developing neural crest by p21-activated protein kinase 1 (Pak1). Furthermore, we show that activated Erk signals by phosphorylating the transcription factor Gata6 on a conserved serine residue to promote neural crest migration and proper formation of craniofacial structures, pigment cells, and the outflow tract of the heart. Our data suggest an essential role for Pak1 as an Erk activator, and Gata6 as an Erk target, during neural crest development.
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Affiliation(s)
- Mollie L Kelly
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA; Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, PA 19102, USA
| | - Artyom Astsaturov
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Jennifer Rhodes
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Jonathan Chernoff
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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7
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Liu J, Cai C, Guo Q, Zhang J, Dong D, Li G, Fu L, Xu J, Chen W. Secretory expression and efficient purification of recombinant anthrax toxin lethal factor with full biological activity in E. coli. Protein Expr Purif 2013; 89:56-61. [DOI: 10.1016/j.pep.2013.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 02/18/2013] [Accepted: 02/19/2013] [Indexed: 11/29/2022]
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D'Agnillo F, Williams MC, Moayeri M, Warfel JM. Anthrax lethal toxin downregulates claudin-5 expression in human endothelial tight junctions. PLoS One 2013; 8:e62576. [PMID: 23626836 PMCID: PMC3633853 DOI: 10.1371/journal.pone.0062576] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 03/22/2013] [Indexed: 01/22/2023] Open
Abstract
Vascular leakage pathologies such as pleural effusion and hemorrhage are hallmarks of anthrax pathogenesis. We previously reported that anthrax lethal toxin (LT), the major virulence factor of anthrax, reduces barrier function in cultured primary human microvascular endothelial cells. Here, we show that LT-induced barrier dysfunction is accompanied by the reduced expression of the endothelial tight junction (TJ) protein claudin-5 but no change in the expression of other TJ components occludin, ZO-1, ZO-2, or the adherens junction (AJ) protein VE-cadherin. The downregulation of claudin-5 correlated temporally and dose-dependently with the reduction of transendothelial electrical resistance. LT-induced loss of claudin-5 was independent of cell death and preceded the appearance of actin stress fibers and altered AJ morphology. Pharmacological inhibition of MEK-1/2, two kinases that are proteolytically inactivated by LT, showed a similar reduction in claudin-5 expression. We found that LT reduced claudin-5 mRNA levels but did not accelerate the rate of claudin-5 degradation. Mice challenged with LT also showed significant reduction in claudin-5 expression. Together, these findings support a possible role for LT disruption of endothelial TJs in the vascular leakage pathologies of anthrax.
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Affiliation(s)
- Felice D'Agnillo
- Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, United States of America.
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Impaired function of the Tie-2 receptor contributes to vascular leakage and lethality in anthrax. Proc Natl Acad Sci U S A 2012; 109:10024-9. [PMID: 22665799 DOI: 10.1073/pnas.1120755109] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The anthrax lethal toxin (LT) enters host cells and enzymatically cleaves MAPKKs or MEKs. How these molecular events lead to death from anthrax remains poorly understood, but published reports suggest a direct effect of LT on vascular permeability. We have found that LT challenge in mice disrupts signaling through Tie-2, a tonically activated receptor tyrosine kinase in the endothelium. Genetic manipulations favoring Tie-2 activation enhanced interendothelial junctional contacts, prevented vascular leakage, and promoted survival following a lethal dose of LT. Cleavage of MEK1/2 was necessary for LT to induce endothelial barrier dysfunction, and activated Tie-2 signaled through the uncleaved fraction of MEKs to prevent LT's effects on the endothelium. Finally, primates infected with toxin-secreting Bacillus anthracis bacilli developed a rapid and marked imbalance in the endogenous ligands that signal Tie-2, similar to that seen in LT-challenged mice. Our results show that B. anthracis LT blunts signaling through Tie-2, thereby weakening the vascular barrier and contributing to lethality of the disease. Measurement of circulating Tie-2 ligands and manipulation of Tie-2 activity may represent future prognostic and therapeutic avenues for humans exposed to B. anthracis.
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Barochia AV, Cui X, Sun J, Li Y, Solomon SB, Migone TS, Subramanian GM, Bolmer SD, Eichacker PQ. Protective antigen antibody augments hemodynamic support in anthrax lethal toxin shock in canines. J Infect Dis 2012; 205:818-29. [PMID: 22223857 DOI: 10.1093/infdis/jir834] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Anthrax-associated shock is closely linked to lethal toxin (LT) release and is highly lethal despite conventional hemodynamic support. We investigated whether protective antigen-directed monoclonal antibody (PA-mAb) treatment further augments titrated hemodynamic support. METHODS AND RESULTS Forty sedated, mechanically ventilated, instrumented canines challenged with anthrax LT were assigned to no treatment (controls), hemodynamic support alone (protocol-titrated fluids and norepinephrine), PA-mAb alone (administered at start of LT infusion [0 hours] or 9 or 12 hours later), or both, and observed for 96 hours. Although all 8 controls died, 2 of 8 animals receiving hemodynamic support alone survived (median survival times 65 vs 85 hours, respectively; P = .03). PA-mAb alone at 0 hour improved survival (5 of 5 animals survived), but efficacy decreased progressively with delayed treatment (9 hours, 2 of 3 survived; 12 hours, 0 of 4 survived) (P = .004 comparing survival across treatment times). However, combined treatment increased survival irrespective of PA-mAb administration time (0 hours, 4 of 5 animals; 9 hours, 3 of 3 animals; and 12 hours, 4 of 5 animals survived) (P = .95 comparing treatment times). Compared to hemodynamic support alone, when combined over PA-mAb treatment times (0, 9, and 12 hours), combination therapy produced higher survival (P = .008), central venous pressures, and left ventricular ejection fractions, and lower heart rates, norepinephrine requirements and fluid retention (P ≤ .03). CONCLUSIONS PA-mAb may augment conventional hemodynamic support during anthrax LT-associated shock.
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Affiliation(s)
- Amisha V Barochia
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
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11
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Fevurly RD, Hasso S, Fye A, Fishman SJ, Chan J. Novel zebrafish model reveals a critical role for MAPK in lymphangiogenesis. J Pediatr Surg 2012; 47:177-82. [PMID: 22244413 PMCID: PMC3662220 DOI: 10.1016/j.jpedsurg.2011.10.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Accepted: 10/08/2011] [Indexed: 01/08/2023]
Abstract
PURPOSE Lymphatic disorders are poorly understood with few animal models. We designed a novel assay to measure lymphatic development using transgenic zebrafish with fluorescently labeled endothelial cells. Two major branches of the vascular endothelial growth factor receptor (VEGFR) signaling pathway were examined: the MAPK and PI3K pathways. METHODS Direct visualization of lymphatic development was performed in control embryos or under chemical inhibition. Treatment involved a 6-hour pulse of inhibitor at 3 days postfertilization. Fish were analyzed for the presence of the thoracic duct (TD) at 4 days postfertilization (n > 100 specimens). RESULTS Thoracic duct formation was prevented using selective inhibitors against kinases (MAPK, PI3K/TOR, or VEGFR). These kinases were important for TD formation because the lymphatic vessel failed to form in most of treated animals. Remarkably, MAPK pathway inhibition most robustly reduced lymphangiogenesis, demonstrated by a lack of lymphatic endothelial cells. CONCLUSION We conclude that MAPK pathway function downstream of the VEGFRs is crucial at the early stages of TD development. This study provides a novel animal model and a potential target pathway for further investigation. We suggest further examination of MAPK pathway deregulation as a potential mechanism underlying lymphatic disease in humans.
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12
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Hicks CW, Cui X, Sweeney DA, Li Y, Barochia A, Eichacker PQ. The potential contributions of lethal and edema toxins to the pathogenesis of anthrax associated shock. Toxins (Basel) 2011; 3:1185-202. [PMID: 22069762 PMCID: PMC3202877 DOI: 10.3390/toxins3091185] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 09/08/2011] [Accepted: 09/09/2011] [Indexed: 12/22/2022] Open
Abstract
Outbreaks of Bacillus anthracis in the US and Europe over the past 10 years have emphasized the health threat this lethal bacteria poses even for developed parts of the world. In contrast to cutaneous anthrax, inhalational disease in the US during the 2001 outbreaks and the newly identified injectional drug use form of disease in the UK and Germany have been associated with relatively high mortality rates. One notable aspect of these cases has been the difficulty in supporting patients once shock has developed. Anthrax bacilli produce several different components which likely contribute to this shock. Growing evidence indicates that both major anthrax toxins may produce substantial cardiovascular dysfunction. Lethal toxin (LT) can alter peripheral vascular function; it also has direct myocardial depressant effects. Edema toxin (ET) may have even more pronounced peripheral vascular effects than LT, including the ability to interfere with the actions of conventional vasopressors. Additionally, ET also appears capable of interfering with renal sodium and water retention. Importantly, the two toxins exert their actions via quite different mechanisms and therefore have the potential to worsen shock and outcome in an additive fashion. Finally, both toxins have the ability to inhibit host defense and microbial clearance, possibly contributing to the very high bacterial loads noted in patients dying with anthrax. This last point is clinically relevant since emerging data has begun to implicate other bacterial components such as anthrax cell wall in the shock and organ injury observed with infection. Taken together, accumulating evidence regarding the potential contribution of LT and ET to anthrax-associated shock supports efforts to develop adjunctive therapies that target both toxins in patients with progressive shock.
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Affiliation(s)
- Caitlin W. Hicks
- Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44195, USA;
- Howard Hughes Medical Institute-National Institutes of Health Research Scholar, National Institutes of Health, Bethesda, MD 20814, USA
| | - Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
| | - Daniel A. Sweeney
- Medical Intensivist Program, Washington Hospital, Fremont, CA 94538, USA;
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
| | - Amisha Barochia
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
| | - Peter Q. Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
- Author to whom correspondence should be addressed; ; Tel.: +1-301-496-9320; Fax: +1-301-402-1213
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13
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Guichard A, Nizet V, Bier E. New insights into the biological effects of anthrax toxins: linking cellular to organismal responses. Microbes Infect 2011; 14:97-118. [PMID: 21930233 DOI: 10.1016/j.micinf.2011.08.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/30/2011] [Accepted: 08/30/2011] [Indexed: 12/15/2022]
Abstract
The anthrax toxins lethal toxin (LT) and edema toxin (ET) are essential virulence factors produced by Bacillus anthracis. These toxins act during two distinct phases of anthrax infection. During the first, prodromal phase, which is often asymptomatic, anthrax toxins act on cells of the immune system to help the pathogen establish infection. Then, during the rapidly progressing (or fulminant) stage of the disease bacteria disseminate via a hematological route to various target tissues and organs, which are typically highly vascularized. As bacteria proliferate in the bloodstream, LT and ET begin to accumulate rapidly reaching a critical threshold level that will cause death even when the bacterial proliferation is curtailed by antibiotics. During this final phase of infection the toxins cause an increase in vascular permeability and a decrease in function of target organs including the heart, spleen, kidney, adrenal gland, and brain. In this review, we examine the various biological effects of anthrax toxins, focusing on the fulminant stage of the disease and on mechanisms by which the two toxins may collaborate to cause cardiovascular collapse. We discuss normal mechanisms involved in maintaining vascular integrity and based on recent studies indicating that LT and ET cooperatively inhibit membrane trafficking to cell-cell junctions we explore several potential mechanisms by which the toxins may achieve their lethal effects. We also summarize the effects of other potential virulence factors secreted by B. anthracis and consider the role of toxic factors in the evolutionarily recent emergence of this devastating disease.
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Affiliation(s)
- Annabel Guichard
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0349, USA
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Abstract
Bacillus anthracis infection is rare in developed countries. However, recent outbreaks in the United States and Europe and the potential use of the bacteria for bioterrorism have focused interest on it. Furthermore, although anthrax was known to typically occur as one of three syndromes related to entry site of (i.e., cutaneous, gastrointestinal, or inhalational), a fourth syndrome including severe soft tissue infection in injectional drug users is emerging. Although shock has been described with cutaneous anthrax, it appears much more common with gastrointestinal, inhalational (5 of 11 patients in the 2001 outbreak in the United States), and injectional anthrax. Based in part on case series, the estimated mortalities of cutaneous, gastrointestinal, inhalational, and injectional anthrax are 1%, 25 to 60%, 46%, and 33%, respectively. Nonspecific early symptomatology makes initial identification of anthrax cases difficult. Clues to anthrax infection include history of exposure to herbivore animal products, heroin use, or clustering of patients with similar respiratory symptoms concerning for a bioterrorist event. Once anthrax is suspected, the diagnosis can usually be made with Gram stain and culture from blood or surgical specimens followed by confirmatory testing (e.g., PCR or immunohistochemistry). Although antibiotic therapy (largely quinolone-based) is the mainstay of anthrax treatment, the use of adjunctive therapies such as anthrax toxin antagonists is a consideration.
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Affiliation(s)
- Daniel A Sweeney
- Medical Intensivist Program, Washington Hospital, Fremont, California, USA
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Hasso S, Chan J. Chemical Approaches to Angiogenesis in Development and Regeneration. Methods Cell Biol 2011; 101:181-95. [DOI: 10.1016/b978-0-12-387036-0.00008-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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