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Progulske-Fox A, Chukkapalli SS, Getachew H, Dunn WA, Oliver JD. VBNC, previously unrecognized in the life cycle of Porphyromonas gingivalis?. J Oral Microbiol 2022; 14:1952838. [PMID: 35035782 PMCID: PMC8759725 DOI: 10.1080/20002297.2021.1952838] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Bacteria are exposed to stresses during their growth and multiplication in their ecological systems to which they respond in multiple ways as expert survivalists. One such response mechanism is to convert to a viable but not culturable (VBNC) state. As the name indicates, bacteria in the VBNC state have lost their ability to grow on routine growth medium. A large number of bacteria including many pathogenic species have been reported to be able to enter a VBNC state. VBNC differs from culturable cells in various physiological properties which may result in changes in chemical resistance, adhesion, cellular morphology, metabolism, gene expression, membrane and cell wall composition and/or virulence. The ability of VBNC bacteria to return to the culturable state or resuscitate, when the stressor is removed poses a considerable threat to public health. There have been few publications that overtly describe the ability of oral pathogenic species to enter the VBNC state. However, the presence of VBNCs among oral pathogens such as Porphyromonas gingivalis in human chronic infections may be an important virulence factor and have severe implications for therapy. In this review, we intend to i) define and summarize the significance of the VBNC state in general and ii) discuss the VBNC state of oral bacteria with regard to P. gingivalis. Future studies focused on this phenomenon of intraoral VBNC would provide novel molecular insights on the virulence and persistence of oral pathogens during chronic infections and identify potential novel therapies.
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Affiliation(s)
- A Progulske-Fox
- Department of Oral Biology, Center for Molecular Microbiology, University of Florida, Gainesville, FL, USA.,Center for Molecular Microbiology, University of Florida, Gainesville, FL, USA
| | - S S Chukkapalli
- Department of Oral Biology, Center for Molecular Microbiology, University of Florida, Gainesville, FL, USA.,Center for Molecular Microbiology, University of Florida, Gainesville, FL, USA
| | - H Getachew
- Department of Oral Biology, Center for Molecular Microbiology, University of Florida, Gainesville, FL, USA.,Center for Molecular Microbiology, University of Florida, Gainesville, FL, USA
| | - W A Dunn
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL, USA
| | - J D Oliver
- Department of Biological Sciences, University of North Carolina, Charlotte, NC, USA
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2
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Weingarten-Gabbay S, Klaeger S, Sarkizova S, Pearlman LR, Chen DY, Gallagher KME, Bauer MR, Taylor HB, Dunn WA, Tarr C, Sidney J, Rachimi S, Conway HL, Katsis K, Wang Y, Leistritz-Edwards D, Durkin MR, Tomkins-Tinch CH, Finkel Y, Nachshon A, Gentili M, Rivera KD, Carulli IP, Chea VA, Chandrashekar A, Bozkus CC, Carrington M, Bhardwaj N, Barouch DH, Sette A, Maus MV, Rice CM, Clauser KR, Keskin DB, Pregibon DC, Hacohen N, Carr SA, Abelin JG, Saeed M, Sabeti PC. Profiling SARS-CoV-2 HLA-I peptidome reveals T cell epitopes from out-of-frame ORFs. Cell 2021; 184:3962-3980.e17. [PMID: 34171305 PMCID: PMC8173604 DOI: 10.1016/j.cell.2021.05.046] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 04/21/2021] [Accepted: 05/27/2021] [Indexed: 01/23/2023]
Abstract
T cell-mediated immunity plays an important role in controlling SARS-CoV-2 infection, but the repertoire of naturally processed and presented viral epitopes on class I human leukocyte antigen (HLA-I) remains uncharacterized. Here, we report the first HLA-I immunopeptidome of SARS-CoV-2 in two cell lines at different times post infection using mass spectrometry. We found HLA-I peptides derived not only from canonical open reading frames (ORFs) but also from internal out-of-frame ORFs in spike and nucleocapsid not captured by current vaccines. Some peptides from out-of-frame ORFs elicited T cell responses in a humanized mouse model and individuals with COVID-19 that exceeded responses to canonical peptides, including some of the strongest epitopes reported to date. Whole-proteome analysis of infected cells revealed that early expressed viral proteins contribute more to HLA-I presentation and immunogenicity. These biological insights, as well as the discovery of out-of-frame ORF epitopes, will facilitate selection of peptides for immune monitoring and vaccine development.
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Affiliation(s)
- Shira Weingarten-Gabbay
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Susan Klaeger
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | | | - Leah R Pearlman
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Da-Yuan Chen
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Kathleen M E Gallagher
- Cellular Immunotherapy Program and Cancer Center, Massachusetts General Hospital, Charlestown, MA 02129, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Matthew R Bauer
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Harvard Program in Biological and Biomedical Sciences, Harvard Medical School, Boston, MA 02115, USA
| | - Hannah B Taylor
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | | | - John Sidney
- Center for Infectious Disease and Vaccine Research, La Jolla Institute for Immunology (LJI), La Jolla, CA 92037, USA
| | - Suzanna Rachimi
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Hasahn L Conway
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Katelin Katsis
- Cellular Immunotherapy Program and Cancer Center, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Yuntong Wang
- Repertoire Immune Medicines, Cambridge, MA 02139, USA
| | | | | | - Christopher H Tomkins-Tinch
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Yaara Finkel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Aharon Nachshon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Matteo Gentili
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Keith D Rivera
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Isabel P Carulli
- Translational Immunogenomics Laboratory, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Vipheaviny A Chea
- Translational Immunogenomics Laboratory, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Abishek Chandrashekar
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Cansu Cimen Bozkus
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
| | - Mary Carrington
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA; Basic Science Program, Frederick National Laboratory for Cancer Research in the Laboratory of Integrative Cancer Immunology, National Cancer Institute, Bethesda, MD, USA
| | - Nina Bhardwaj
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
| | - Dan H Barouch
- Harvard Medical School, Boston, MA 02115, USA; Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA, USA; Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA; Massachusetts Consortium on Pathogen Readiness, Boston, MA, USA
| | - Alessandro Sette
- Center for Infectious Disease and Vaccine Research, La Jolla Institute for Immunology (LJI), La Jolla, CA 92037, USA; Department of Medicine, Division of Infectious Diseases and Global Public Health, University of California, San Diego (UCSD), La Jolla, CA 92037, USA
| | - Marcela V Maus
- Cellular Immunotherapy Program and Cancer Center, Massachusetts General Hospital, Charlestown, MA 02129, USA; Harvard Medical School, Boston, MA 02115, USA; Klarman Cell Observatory, Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA; Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Karl R Clauser
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Derin B Keskin
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Translational Immunogenomics Laboratory, Dana-Farber Cancer Institute, Boston, MA, USA; Health Informatics Lab, Metropolitan College, Boston University, Boston, MA, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | | | - Nir Hacohen
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Center for Cancer Research, Massachusetts General Hospital, Boston, MA, USA
| | - Steven A Carr
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Mohsan Saeed
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA; National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA.
| | - Pardis C Sabeti
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Massachusetts Consortium on Pathogen Readiness, Boston, MA, USA; Department of Immunology and Infectious Disease, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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3
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Reyes L, Getachew H, Dunn WA, Progulske-Fox A. Porphyromonas gingivalis W83 traffics via ICAM1 in microvascular endothelial cells and alters capillary organization in vivo. J Oral Microbiol 2020; 12:1742528. [PMID: 32341760 PMCID: PMC7170297 DOI: 10.1080/20002297.2020.1742528] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 01/16/2023] Open
Abstract
Objective: Microvascular dysfunction is a feature of periodontal disease. P. gingivalis, one of the most common oral bacteria present in gingival tissue biofilms, has also been identified in the gingival capillaries of patients with chronic periodontitis. We sought to determine the effect of P. gingivalis W83 infection on microvascular endothelium in vivo and in vitro. Methods and Results: Interdental papillae of rats with P. gingivalis-induced alveolar bone loss had a more dilated and denser subepithelial capillary network than uninfected controls. P. gingivalis W83 was detected in the epithelial layers, the subepithelial connective tissue matrix, and subgingival capillaries. P. gingivalis invaded human dermal microvascular endothelial cells (HD-MVECS) and persisted up termination (24 h). Colocalization analysis at 2.5, 6, and 24 h post-inoculation showed that 79-88% of internalized bacteria were in ICAM-1 positive endosomes, and 10-39% were in Rab5, Rab7, or LAMP1 positive compartments, but never in autophagosomes. Antibody-based blockade of ICAM-1 significantly reduced W83 invasion in HD-MVECS. P. gingivalis infected HD-MVECS were unable to form vascular networks in Matrigel. Conclusions: P. gingivalis perturbs microvascular endothelial function and invasion of these cells via ICAM-1 may be important for microbial persistence within tissues.
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Affiliation(s)
- L Reyes
- Department of Pathobiological Sciences, University of Wisconsin - Madison, School of Veterinary Medicine, Madison, WI, USA
| | - H Getachew
- Department of Oral Biology, College of Dentistry, Center for Molecular Microbiology University of Florida, Gainesville, FL, USA
| | - W A Dunn
- Department of Oral Biology, College of Dentistry, Center for Molecular Microbiology University of Florida, Gainesville, FL, USA.,Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL, USA
| | - A Progulske-Fox
- Department of Oral Biology, College of Dentistry, Center for Molecular Microbiology University of Florida, Gainesville, FL, USA
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4
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Imrie L, Le Bihan T, O'Toole Á, Hickner PV, Dunn WA, Weise B, Rund SSC. Genome annotation improvements from cross-phyla proteogenomics and time-of-day differences in malaria mosquito proteins using untargeted quantitative proteomics. PLoS One 2019; 14:e0220225. [PMID: 31356616 PMCID: PMC6663012 DOI: 10.1371/journal.pone.0220225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [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: 10/24/2018] [Accepted: 07/11/2019] [Indexed: 12/12/2022] Open
Abstract
The malaria mosquito, Anopheles stephensi, and other mosquitoes modulate their biology to match the time-of-day. In the present work, we used a non-hypothesis driven approach (untargeted proteomics) to identify proteins in mosquito tissue, and then quantified the relative abundance of the identified proteins from An. stephensi bodies. Using these quantified protein levels, we then analyzed the data for proteins that were only detectable at certain times-of-the day, highlighting the need to consider time-of-day in experimental design. Further, we extended our time-of-day analysis to look for proteins which cycle in a rhythmic 24-hour ("circadian") manner, identifying 31 rhythmic proteins. Finally, to maximize the utility of our data, we performed a proteogenomic analysis to improve the genome annotation of An. stephensi. We compare peptides that were detected using mass spectrometry but are 'missing' from the An. stephensi predicted proteome, to reference proteomes from 38 other primarily human disease vector species. We found 239 such peptide matches and reveal that genome annotation can be improved using proteogenomic analysis from taxonomically diverse reference proteomes. Examination of 'missing' peptides revealed reading frame errors, errors in gene-calling, overlapping gene models, and suspected gaps in the genome assembly.
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Affiliation(s)
- Lisa Imrie
- SynthSys–Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Thierry Le Bihan
- SynthSys–Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Rapid Novor, Kitchener, Ontario, Canada
| | - Áine O'Toole
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Paul V. Hickner
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - W. Augustine Dunn
- Boston Children's Hospital, Boston, Massachusetts, United States of America
| | - Benjamin Weise
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Samuel S. C. Rund
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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5
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Ouahed J, Gordon W, Canavan JB, Zhou H, Du S, von Schack D, Phillips K, Wang L, Dunn WA, Field M, Friel S, Griffith A, Evans S, Tollefson S, Carrellas M, Cao B, Merker A, Bousvaros A, Shouval DS, Hung K, Lepsy C, Afzelius L, Korzenik JR, Snapper SB. Mucosal Gene Expression in Pediatric and Adult Patients With Ulcerative Colitis Permits Modeling of Ideal Biopsy Collection Strategy for Transcriptomic Analysis. Inflamm Bowel Dis 2018; 24:2565-2578. [PMID: 30085215 PMCID: PMC6265054 DOI: 10.1093/ibd/izy242] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Indexed: 12/13/2022]
Abstract
BACKGROUND Transcriptional profiling has been performed on biopsies from ulcerative colitis patients. Limitations in prior studies include the variability introduced by inflammation, anatomic site of biopsy, extent of disease, and medications. We sought to more globally understand the variability of gene expression from patients with ulcerative colitis to advance our understanding of its pathogenesis and to guide clinical study design. METHODS We performed transcriptional profiling on 13 subjects, including pediatric and adult patients from 2 hospital sites. For each patient, we collected 6 biopsies from macroscopically inflamed tissue and 4 biopsies from macroscopically healthy-appearing tissue. Isolated RNA was used for microarray gene expression analysis utilizing Affymetrix Human Primeview microarrays. Ingenuity pathway analysis was used to assess over-representation of gene ontology and biological pathways. RNAseq was also performed, and differential analysis was assessed to compare affected vs unaffected samples. Finally, we modeled the minimum number of biopsies required to reliably detect gene expression across different subject numbers. RESULTS Transcriptional profiles co-clustered independently of the hospital collection site, patient age, sex, and colonic location, which parallels prior gene expression findings. A small set of genes not previously described was identified. Our modeling analysis reveals the number of biopsies and patients per cohort to yield reliable results in clinical studies. CONCLUSIONS Key findings include concordance, including some expansion, of previously published gene expression studies and similarity among different age groups. We also established a reliable statistical model for biopsy collection for future clinical studies.
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Affiliation(s)
- Jodie Ouahed
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - William Gordon
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts
| | - James B Canavan
- Department of Medicine, Harvard Medical School, Boston, Massachusetts,Division of Gastroenterology, Hepatology and Endoscopy, Brigham & Women’s Hospital, Boston, Massachusetts
| | - Huanyu Zhou
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts
| | - Sarah Du
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts
| | - David von Schack
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts
| | | | - Lu Wang
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts
| | - W Augustine Dunn
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Michael Field
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts
| | - Shelby Friel
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts
| | - Alexandra Griffith
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts
| | - Spencer Evans
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts
| | - Sophia Tollefson
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts
| | - Madeline Carrellas
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham & Women’s Hospital, Boston, Massachusetts
| | - Bonnie Cao
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham & Women’s Hospital, Boston, Massachusetts
| | - Ami Merker
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham & Women’s Hospital, Boston, Massachusetts
| | - Athos Bousvaros
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Dror S Shouval
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Edmond and Lily Safra Children’s Hospital, Sheba Medical Center, Tel Hashomer, Israel,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - BCH IBD Center
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts
| | | | - Kenneth Hung
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts
| | | | - Lovisa Afzelius
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts
| | - Joshua R Korzenik
- Department of Medicine, Harvard Medical School, Boston, Massachusetts,Division of Gastroenterology, Hepatology and Endoscopy, Brigham & Women’s Hospital, Boston, Massachusetts
| | - Scott B Snapper
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts,Division of Gastroenterology, Hepatology and Endoscopy, Brigham & Women’s Hospital, Boston, Massachusetts,Address correspondence to: Scott B. Snapper, MD, PhD, 300 Longwood Ave, Enders 601, Boston, MA 02115 ()
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6
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Sallis BF, Erkert L, Moñino-Romero S, Acar U, Wu R, Konnikova L, Lexmond WS, Hamilton MJ, Dunn WA, Szepfalusi Z, Vanderhoof JA, Snapper SB, Turner JR, Goldsmith JD, Spencer LA, Nurko S, Fiebiger E. An algorithm for the classification of mRNA patterns in eosinophilic esophagitis: Integration of machine learning. J Allergy Clin Immunol 2018; 141:1354-1364.e9. [PMID: 29273402 PMCID: PMC6425755 DOI: 10.1016/j.jaci.2017.11.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [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: 06/22/2017] [Revised: 11/17/2017] [Accepted: 11/30/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND Diagnostic evaluation of eosinophilic esophagitis (EoE) remains difficult, particularly the assessment of the patient's allergic status. OBJECTIVE This study sought to establish an automated medical algorithm to assist in the evaluation of EoE. METHODS Machine learning techniques were used to establish a diagnostic probability score for EoE, p(EoE), based on esophageal mRNA transcript patterns from biopsies of patients with EoE, gastroesophageal reflux disease and controls. Dimensionality reduction in the training set established weighted factors, which were confirmed by immunohistochemistry. Following weighted factor analysis, p(EoE) was determined by random forest classification. Accuracy was tested in an external test set, and predictive power was assessed with equivocal patients. Esophageal IgE production was quantified with epsilon germ line (IGHE) transcripts and correlated with serum IgE and the Th2-type mRNA profile to establish an IGHE score for tissue allergy. RESULTS In the primary analysis, a 3-class statistical model generated a p(EoE) score based on common characteristics of the inflammatory EoE profile. A p(EoE) ≥ 25 successfully identified EoE with high accuracy (sensitivity: 90.9%, specificity: 93.2%, area under the curve: 0.985) and improved diagnosis of equivocal cases by 84.6%. The p(EoE) changed in response to therapy. A secondary analysis loop in EoE patients defined an IGHE score of ≥37.5 for a patient subpopulation with increased esophageal allergic inflammation. CONCLUSIONS The development of intelligent data analysis from a machine learning perspective provides exciting opportunities to improve diagnostic precision and improve patient care in EoE. The p(EoE) and the IGHE score are steps toward the development of decision trees to define EoE subpopulations and, consequently, will facilitate individualized therapy.
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Affiliation(s)
- Benjamin F. Sallis
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Medicine, Harvard Medical School, Medical
University of Vienna
| | - Lena Erkert
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna
| | - Sherezade Moñino-Romero
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Pediatrics and Adolescent Medicine, Medical
University of Vienna
| | - Utkucan Acar
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Medicine, Harvard Medical School, Medical
University of Vienna
| | - Rina Wu
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna
| | - Liza Konnikova
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Medicine, Harvard Medical School, Medical
University of Vienna
| | - Willem S. Lexmond
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Medicine, Harvard Medical School, Medical
University of Vienna
| | - Matthew J. Hamilton
- Department of Medicine, Harvard Medical School, Medical
University of Vienna.,Department of Pathology, Medical University of
Vienna.,Division of Gastroenterology, Hepatology, and Endoscopy,
Brigham and Women’s Hospital; Medical University of Vienna
| | - W. Augustine Dunn
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Medicine, Harvard Medical School, Medical
University of Vienna
| | - Zsolt Szepfalusi
- Department of Pediatrics and Adolescent Medicine, Medical
University of Vienna
| | - Jon A. Vanderhoof
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna
| | - Scott B. Snapper
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Medicine, Harvard Medical School, Medical
University of Vienna
| | - Jerrold R. Turner
- Department of Pathology, Medical University of
Vienna.,Division of Gastroenterology, Hepatology, and Endoscopy,
Brigham and Women’s Hospital; Medical University of Vienna
| | - Jeffrey D. Goldsmith
- Department of Pathology, Boston Children’s Hospital,
Medical University of Vienna
| | - Lisa A. Spencer
- Department of Medicine, Harvard Medical School, Medical
University of Vienna.,Department of Medicine, Division of Allergy and
Inflammation, Beth Israel Deaconess Medical Center, Boston, Medical University of
Vienna
| | - Samuel Nurko
- Department of Pediatrics, Division of Gastroenterology,
Hepatology and Nutrition, Medical University of Vienna.,Department of Medicine, Harvard Medical School, Medical
University of Vienna
| | - Edda Fiebiger
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston, Mass; Department of Medicine, Harvard Medical School, Boston, Mass.
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7
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Vannini L, Augustine Dunn W, Reed TW, Willis JH. Changes in transcript abundance for cuticular proteins and other genes three hours after a blood meal in Anopheles gambiae. Insect Biochem Mol Biol 2014; 44:33-43. [PMID: 24269292 PMCID: PMC3970321 DOI: 10.1016/j.ibmb.2013.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/24/2013] [Accepted: 11/05/2013] [Indexed: 05/03/2023]
Abstract
Numerous studies have examined changes in transcript levels after Anopheles gambiae takes a blood meal. Marinotti et al. (2006) used microarrays and reported massive changes in transcript levels 3 h after feeding (BF3h) compared to non-blood fed (NBF). We were intrigued by the number of transcripts for structural cuticular proteins (CPs) that showed such major differences in levels and employed paired-end (50 bp) RNA-seq technology to compare whole body transcriptomes from 5-day-old females NBF and BF3h. We detected transcripts for the majority of CPs (164/243) but levels of only 12 were significantly altered by the blood meal. While relative transcript levels of NBF females were somewhat similar to the microarray data, there were major differences in BF3h animals, resulting in levels of many transcripts, both for CPs and other genes changing in the opposite direction. We compared our data also to other studies done with both microarrays and RNA-seq. Findings were consistent that a small number of CP genes have transcripts that persist even in 5-day-old adults. Some of these transcripts showed diurnal rhythms (Rund et al., 2013; Rinker et al., 2013). In situ hybridization revealed that transcripts for several of these CP genes were found exclusively or predominantly in the eye. Transcripts other than for CPs that changed in response to blood-feeding were predominantly expressed in midgut and Malpighian tubules. Even in these tissues, genes responsible for proteins with similar functions, such as immunity or digestion, responded differently, with transcript levels for some rising and others falling. These data demonstrate that genes coding for some CPs are dynamic in expression even in adults and that the response to a blood meal is rapid and precisely orchestrated.
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Affiliation(s)
- Laura Vannini
- University of Georgia, Cellular Biology, Athens, GA 30602, USA.
| | - W Augustine Dunn
- University of California Irvine, Molecular Biology and Biochemistry, Irvine, CA 92697, USA.
| | - Tyler W Reed
- University of Georgia, Cellular Biology, Athens, GA 30602, USA.
| | - Judith H Willis
- University of Georgia, Cellular Biology, Athens, GA 30602, USA.
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Bonizzoni M, Dunn WA, Campbell CL, Olson KE, Marinotti O, James AA. Complex modulation of the Aedes aegypti transcriptome in response to dengue virus infection. PLoS One 2012; 7:e50512. [PMID: 23209765 PMCID: PMC3507784 DOI: 10.1371/journal.pone.0050512] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [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: 07/05/2012] [Accepted: 10/22/2012] [Indexed: 12/23/2022] Open
Abstract
Dengue fever is the most important arboviral disease world-wide, with Aedes aegypti being the major vector. Interactions between the mosquito host and dengue viruses (DENV) are complex and vector competence varies among geographically-distinct Ae. aegypti populations. Additionally, dengue is caused by four antigenically-distinct viral serotypes (DENV1–4), each with multiple genotypes. Each virus genotype interacts differently with vertebrate and invertebrate hosts. Analyses of alterations in mosquito transcriptional profiles during DENV infection are expected to provide the basis for identifying networks of genes involved in responses to viruses and contribute to the molecular-genetic understanding of vector competence. In addition, this knowledge is anticipated to support the development of novel disease-control strategies. RNA-seq technology was used to assess genome-wide changes in transcript abundance at 1, 4 and 14 days following DENV2 infection in carcasses, midguts and salivary glands of the Ae. aegypti Chetumal strain. DENV2 affected the expression of 397 Ae. aegypti genes, most of which were down-regulated by viral infection. Differential accumulation of transcripts was mainly tissue- and time-specific. Comparisons of our data with other published reports reveal conservation of functional classes, but limited concordance of specific mosquito genes responsive to DENV2 infection. These results indicate the necessity of additional studies of mosquito-DENV interactions, specifically those focused on recently-derived mosquito strains with multiple dengue virus serotypes and genotypes.
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Affiliation(s)
- Mariangela Bonizzoni
- Program in Public Health, University of California Irvine, Irvine, California, United States of America
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - W. Augustine Dunn
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, United States of America
- Institute for Genomics and Bioinformatics, University of California Irvine, Irvine, California, United States of America
| | - Corey L. Campbell
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Ken E. Olson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Osvaldo Marinotti
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, United States of America
| | - Anthony A. James
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, United States of America
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, United States of America
- * E-mail:
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Bonizzoni M, Dunn WA, Campbell CL, Olson KE, Marinotti O, James AA. Strain Variation in the Transcriptome of the Dengue Fever Vector, Aedes aegypti. G3 (Bethesda) 2012; 2:103-14. [PMID: 22384387 PMCID: PMC3276191 DOI: 10.1534/g3.111.001107] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 11/15/2011] [Indexed: 11/18/2022]
Abstract
Studies of transcriptome dynamics provide a basis for understanding functional elements of the genome and the complexity of gene regulation. The dengue vector mosquito, Aedes aegypti, exhibits great adaptability to diverse ecological conditions, is phenotypically polymorphic, and shows variation in vectorial capacity to arboviruses. Previous genome sequencing showed richness in repetitive DNA and transposable elements that can contribute to genome plasticity. Population genetic studies revealed a varying degree of worldwide genetic polymorphism. However, the extent of functional genetic polymorphism across strains is unknown. The transcriptomes of three Ae. aegypti strains, Chetumal (CTM), Rexville D-Puerto Rico (Rex-D) and Liverpool (LVP), were compared. CTM is more susceptible than Rex- D to infection by dengue virus serotype 2. A total of 4188 transcripts exhibit either no or small variation (<2-fold) among sugar-fed samples of the three strains and between sugar- and blood-fed samples within each strain, corresponding most likely to genes encoding products necessary for vital functions. Transcripts enriched in blood-fed mosquitoes encode proteins associated with catalytic activities, molecular transport, metabolism of lipids, carbohydrates and amino acids, and functions related to blood digestion and the progression of the gonotropic cycle. Significant qualitative and quantitative differences were found in individual transcripts among strains including differential representation of paralogous gene products. The majority of immunity-associated transcripts decreased in accumulation after a bloodmeal and the results are discussed in relation to the different susceptibility of CTM and Rex-D mosquitoes to DENV2 infection.
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Affiliation(s)
| | - W. Augustine Dunn
- Department of Molecular Biology and Biochemistry, and
- Institute for Genomics and Bioinformatics, University of California, Irvine, California 92697
| | | | - Ken E. Olson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523
| | | | - Anthony A. James
- Department of Molecular Biology and Biochemistry, and
- Department of Microbiology and Molecular Genetics, University of California, California, Irvine 92697
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10
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Abstract
Little is known about endosomal pathway proteins involved in arthropod-borne virus (arbovirus) assembly and cell-to-cell spread in vector mosquitoes. UNC93A and synaptic vesicle-2 (SV2) proteins are involved in intracellular transport in mammals. They show amino acid sequence conservation from mosquitoes to humans, and their transcripts are highly enriched in Aedes aegypti during arbovirus infection. Transient gene silencing of SV2 or UNC93A in mosquitoes infected with the recombinant alphavirus Sindbis MRE16-enhanced green fluorescent protein (SINV; family Togaviridae) resulted in the accumulation of viral positive- and negative-strand RNA, congregation of virus envelope antigen in intracellular networks, and reduced virus dissemination outside of the midgut. Further, UNC93A silencing, but not SV2 silencing, resulted in a 10-fold reduction in viral titres at 4 days post-infection. Together, these data support a role for UNC93A and SV2 in virus assembly or budding. Cis-regulatory elements (CREs) were identified at the 5'-ends of genes from the original data set in which SV2 and UNC93A were identified. Common CREs at the 5'-end genomic regions of a subset of enriched transcripts support the hypothesis that UNC93A transcription may be co-regulated with that of other ion transport and endosomal trafficking proteins.
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Affiliation(s)
- C L Campbell
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
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Bonizzoni M, Dunn WA, Campbell CL, Olson KE, Dimon MT, Marinotti O, James AA. RNA-seq analyses of blood-induced changes in gene expression in the mosquito vector species, Aedes aegypti. BMC Genomics 2011; 12:82. [PMID: 21276245 PMCID: PMC3042412 DOI: 10.1186/1471-2164-12-82] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 01/28/2011] [Indexed: 11/29/2022] Open
Abstract
Background Hematophagy is a common trait of insect vectors of disease. Extensive genome-wide transcriptional changes occur in mosquitoes after blood meals, and these are related to digestive and reproductive processes, among others. Studies of these changes are expected to reveal molecular targets for novel vector control and pathogen transmission-blocking strategies. The mosquito Aedes aegypti (Diptera, Culicidae), a vector of Dengue viruses, Yellow Fever Virus (YFV) and Chikungunya virus (CV), is the subject of this study to look at genome-wide changes in gene expression following a blood meal. Results Transcriptional changes that follow a blood meal in Ae. aegypti females were explored using RNA-seq technology. Over 30% of more than 18,000 investigated transcripts accumulate differentially in mosquitoes at five hours after a blood meal when compared to those fed only on sugar. Forty transcripts accumulate only in blood-fed mosquitoes. The list of regulated transcripts correlates with an enhancement of digestive activity and a suppression of environmental stimuli perception and innate immunity. The alignment of more than 65 million high-quality short reads to the Ae. aegypti reference genome permitted the refinement of the current annotation of transcript boundaries, as well as the discovery of novel transcripts, exons and splicing variants. Cis-regulatory elements (CRE) and cis-regulatory modules (CRM) enriched significantly at the 5'end flanking sequences of blood meal-regulated genes were identified. Conclusions This study provides the first global view of the changes in transcript accumulation elicited by a blood meal in Ae. aegypti females. This information permitted the identification of classes of potentially co-regulated genes and a description of biochemical and physiological events that occur immediately after blood feeding. The data presented here serve as a basis for novel vector control and pathogen transmission-blocking strategies including those in which the vectors are modified genetically to express anti-pathogen effector molecules.
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Affiliation(s)
- Mariangela Bonizzoni
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California, USA
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12
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Abranches J, Zeng L, Bélanger M, Rodrigues PH, Simpson-Haidaris PJ, Akin D, Dunn WA, Progulske-Fox A, Burne RA. Invasion of human coronary artery endothelial cells by Streptococcus mutans OMZ175. ACTA ACUST UNITED AC 2009; 24:141-5. [PMID: 19239641 DOI: 10.1111/j.1399-302x.2008.00487.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Dissemination of oral bacteria into the bloodstream has been associated with eating, oral hygiene, and dental procedures; including tooth extraction, endodontic treatment, and periodontal surgery. Recently, studies identified Streptococcus mutans, the primary etiological agent of dental caries, as the most prevalent bacterial species found in clinical samples from patients who underwent heart valve and atheromatous plaque surgery. METHODS By using antibiotic protection assays, we tested the capacity of 14 strains of S. mutans to invade primary human coronary artery endothelial cells (HCAEC). RESULTS Serotype e strain B14 and serotype f strain OMZ175 of S. mutans were able to efficiently invade HCAEC. Among the tested strains, serotype f S. mutans OMZ175 was the most invasive, whereas strains of serotype c S. mutans, the most prevalent serotype in dental plaque, were not invasive. Based on its high invasion rate, we further investigated the invasive properties of serotype f OMZ175. Using transmission electron microscopy and antibiotic protection assays we demonstrate that S. mutans OMZ175 is capable of attaching to the HCAEC surface, entering the cells and surviving in HCAEC for at least 29 h. DISCUSSION Our findings highlight a potential role for S. mutans in the pathogenesis of certain cardiovascular diseases.
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Affiliation(s)
- J Abranches
- Center for Oral Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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Togawa T, Dunn WA, Emmons AC, Nagao J, Willis JH. Developmental expression patterns of cuticular protein genes with the R&R Consensus from Anopheles gambiae. Insect Biochem Mol Biol 2008; 38:508-19. [PMID: 18405829 PMCID: PMC2416445 DOI: 10.1016/j.ibmb.2007.12.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 12/17/2007] [Accepted: 12/19/2007] [Indexed: 05/03/2023]
Abstract
CPR proteins are the largest cuticular protein family in arthropods. The whole genome sequence of Anopheles gambiae revealed 156 genes that code for proteins with the R&R Consensus and named CPRs. This protein family can be divided into RR-1 and RR-2 subgroups, postulated to contribute to different regions of the cuticle. We determined the temporal expression patterns of these genes throughout post-embryonic development by means of real-time qRT-PCR. Based on expression profiles, these genes were grouped into 21 clusters. Most of the genes were expressed with sharp peaks at single or multiple periods associated with molting. Genes coding for RR-1 and RR-2 proteins were found together in several co-expression clusters. Twenty-five genes were expressed exclusively at one metamorphic stage. Five out of six X-linked genes showed equal expression in males and females, supporting the presence of a gene dosage compensation system in A. gambiae. Many RR-2 genes are organized into sequence clusters whose members are extremely similar to each other and generally closely associated on a chromosome. Most genes in each sequence cluster are expressed with the same temporal expression pattern and at the same level, suggesting a shared mechanism to regulate their expression.
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Affiliation(s)
| | | | | | | | - Judith H. Willis
- Corresponding author: Judith H. Willis, Tel: +1-706-542-0802; Fax: +1-706-542-4271, E-mail:
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Togawa T, Augustine Dunn W, Emmons AC, Willis JH. CPF and CPFL, two related gene families encoding cuticular proteins of Anopheles gambiae and other insects. Insect Biochem Mol Biol 2007; 37:675-88. [PMID: 17550824 DOI: 10.1016/j.ibmb.2007.03.011] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 03/16/2007] [Accepted: 03/20/2007] [Indexed: 05/15/2023]
Abstract
Cuticular proteins (CPs) are structural proteins of insects as well as other arthropods. Several CP families have been described, among them a small family defined by a 51 amino acid motif [Andersen, S.O., Rafn, K., Roepstorff, P., 1997. Sequence studies of proteins from larval and pupal cuticle of the yellow meal worm, Tenebrio molitor. Insect Biochem. Mol. Biol. 27, 121-131]. We identified four proteins of this family in Anopheles gambiae that we have named CPF. We have also identified CPFs from other insects by searching databases. Alignment of these CPF proteins showed that the conserved region is only 44 aa long and revealed another conserved motif at the C-terminus. A dendrogram divided the CPF proteins into four groups, one basal and three specialized. We also identified several proteins of another CP family, CPFL, which has similarities to CPFs. CPFs and CPFLs share some protein motifs. Expression studies with real-time qRT-PCR of the A. gambiae CPFs and CPFLs showed that the four CPFs and one CPFL gene are expressed just before pupal or adult ecdysis, suggesting that they are components of the outer layer of pupal and adult cuticles. The other CPFLs appear to contribute to larval cuticle. Recombinant CPF proteins did not bind to chitin in the assay we used.
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Affiliation(s)
- Toru Togawa
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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15
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He N, Botelho JMC, McNall RJ, Belozerov V, Dunn WA, Mize T, Orlando R, Willis JH. Proteomic analysis of cast cuticles from Anopheles gambiae by tandem mass spectrometry. Insect Biochem Mol Biol 2007; 37:135-46. [PMID: 17244542 DOI: 10.1016/j.ibmb.2006.10.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 10/26/2006] [Accepted: 10/31/2006] [Indexed: 05/13/2023]
Abstract
Identification of authenticated cuticular proteins has been based on isolation and sequencing of individual proteins extracted from cleaned cuticles. These data facilitated classification of sequences from conceptual translation of cDNA or genomic sequences. The question arises whether such putative cuticular proteins actually are incorporated into the cuticle. This paper describes the profiling of cuticular proteins from Anopheles gambiae starting with cuticle cleaned by the insect itself in the course of molting. Proteins extracted from cast larval head capsules and cast pupal cuticles were fractionated by 1D SDS gel electrophoresis. Large gel slices were reduced, carbamidomethylated and digested with trypsin. The pellet remaining after SDS extraction was also treated with trypsin. The resulting peptides were separated on a C18 column and then analyzed by tandem mass spectrometry. Two-hundred-ninety-five peptides from putative cuticular proteins were identified; these corresponded to a minimum of 69 and a maximum of 119 different proteins. Each is reported as an authentic Anopheles cuticular protein for the first time. In addition to members of two known cuticular protein families, members of additional families likely to be structural components of the cuticle were identified. Furthermore, other peptides were identified that can be attributed to molting fluid, muscle and sclerotizing agents.
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Affiliation(s)
- Ningjia He
- The Key Laboratory of Sericulture, Southwest University, Chongqing 400715, PR China
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16
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Guan J, Stromhaug PE, George MD, Habibzadegah-Tari P, Bevan A, Dunn WA, Klionsky DJ. Cvt18/Gsa12 is required for cytoplasm-to-vacuole transport, pexophagy, and autophagy in Saccharomyces cerevisiae and Pichia pastoris. Mol Biol Cell 2001; 12:3821-38. [PMID: 11739783 PMCID: PMC60758 DOI: 10.1091/mbc.12.12.3821] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.5] [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: 11/11/2022] Open
Abstract
Eukaryotic cells have the ability to degrade proteins and organelles by selective and nonselective modes of micro- and macroautophagy. In addition, there exist both constitutive and regulated forms of autophagy. For example, pexophagy is a selective process for the regulated degradation of peroxisomes by autophagy. Our studies have shown that the differing pathways of autophagy have many molecular events in common. In this article, we have identified a new member in the family of autophagy genes. GSA12 in Pichia pastoris and its Saccharomyces cerevisiae counterpart, CVT18, encode a soluble protein with two WD40 domains. We have shown that these proteins are required for pexophagy and autophagy in P. pastoris and the Cvt pathway, autophagy, and pexophagy in S. cerevisiae. In P. pastoris, Gsa12 appears to be required for an early event in pexophagy. That is, the involution of the vacuole or extension of vacuole arms to engulf the peroxisomes does not occur in the gsa12 mutant. Consistent with its role in vacuole engulfment, we have found that this cytosolic protein is also localized to the vacuole surface. Similarly, Cvt18 displays a subcellular localization that distinguishes it from the characterized proteins required for cytoplasm-to-vacuole delivery pathways.
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Affiliation(s)
- J Guan
- Department of Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA
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17
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18
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Abstract
Cells are capable of adapting to changes in their environment by synthesizing needed proteins and degrading superfluous ones. Pichia pastoris synthesizes peroxisomal enzymes to grow in methanol medium. Upon adapting from methanol medium to one containing glucose, this yeast rapidly and selectively degrades peroxisomes by an autophagic process referred to as pexophagy. In this study, we have utilized a novel approach to identify genes required for this degradative pathway. Our approach involves the random integration of a vector containing the Zeocin resistance gene into the yeast genome by restriction enzyme-mediated integration. Cells unable to degrade peroxisomes during glucose adaptation were isolated, and the genes that were disrupted by the insertion of the vector were determined by sequencing. By using this approach, we have identified a number of genes required for glucose-induced selective autophagy of peroxisomes (GSA genes). We report here the characterization of Gsa11, a unique 208-kDa protein. We found that this protein is required for glucose-induced pexophagy and starvation-induced autophagy. Gsa11 is a cytosolic protein that becomes associated with one or more structures situated near the vacuole during glucose adaptation. The punctate localization of Gsa11 was not observed in gsa10, gsa12, gsa14, and gsa19 mutants. We have previously shown that Gsa9 appears to relocate from a compartment at the vacuole surface to regions between the vacuole and the peroxisomes being sequestered. In the gsa11 mutants, the vacuole only partially surrounded the peroxisomes, but Gsa9 was still distributed around the peroxisome cluster. This suggests that Gsa9 binds to the peroxisomes independent of the vacuole. The data also indicate that Gsa11 is not necessary for Gsa9 to interact with peroxisomes but acts at an intermediate event required for the vacuole to engulf the peroxisomes.
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Affiliation(s)
- P E Strømhaug
- Institute for Cancer Research, Department of Cell Biology, The Norwegian Radium Hospital, Montebello, N-0310 Oslo, Norway
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Abstract
Fenproporex is a sympathomimetic agent with a pharmacological profile similar to that of amphetamine. It is available in many countries throughout the world, but it is currently not available in the United States. Because of its stimulant effects, it has a great potential for abuse. To the best of our knowledge, there have been no literature reports of blood or serum concentrations found in therapeutic, toxic, or fatal cases. We report a case where fenproporex was a finding in the death of a young adult. Blood, urine, and gastric contents were analyzed. The following drug concentrations were found: 0.90 mg/L (inferior vena cava blood), 1.2 mg/L (urine), and 120 mg total (gastric) for fenproporex and 0.084 mg/L (inferior vena cava blood), 0.94 mg/L (urine), and 0.14 mg total (gastric) for amphetamine. In addition to the fenproporex, other medications detected and their blood concentrations found in this case were H diazepam (0.54 mg/L), nordiazepam (0.46 mg/L), diphenhydramine (0.12 mg/L), and gamma hydroxybutyric acid (GHB) (1100 mg/L).
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Affiliation(s)
- R R Bell
- Office of the Medical Examiner, District Six, Largo, Florida 33778, USA
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20
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Abstract
Porphyromonas gingivalis is a periodontal pathogen that also localizes to atherosclerotic plaques. Our previous studies demonstrated that P. gingivalis is capable of invading endothelial cells and that intracellular bacteria are contained in vacuoles that resemble autophagosomes. In this study, we have examined the trafficking of P. gingivalis 381 to the autophagic pathway. P. gingivalis 381 internalized by human coronary artery endothelial (HCAE) cells is located within vacuoles morphologically identical to autophagosomes. The progression of P. gingivalis 381 through intracellular vacuoles was analyzed by immunofluorescence microscopy. Vacuoles containing P. gingivalis colocalize with Rab5 and HsGsa7p early after internalization. At later times, P. gingivalis colocalizes with BiP and then progresses to a vacuole that contains BiP and lysosomal glycoprotein 120. Late endosomal markers and the lysosomal cathepsin L do not colocalize with P. gingivalis 381. The intracellular survival of P. gingivalis 381 decreases over 8 h in HCAE cells pretreated with the autophagy inhibitors 3-methyladenine and wortmannin. In addition, the vacuole containing P. gingivalis 381 lacks BiP but contains cathepsin L in the presence of wortmannin. These results suggest that P. gingivalis 381 evades the endocytic pathway to lysosomes and instead traffics to the autophagosome.
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Affiliation(s)
- B R Dorn
- Center for Molecular Microbiology, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
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21
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Lu M, Holliday LS, Zhang L, Dunn WA, Gluck SL. Interaction between aldolase and vacuolar H+-ATPase: evidence for direct coupling of glycolysis to the ATP-hydrolyzing proton pump. J Biol Chem 2001; 276:30407-13. [PMID: 11399750 DOI: 10.1074/jbc.m008768200] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.4] [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: 11/06/2022] Open
Abstract
Vacuolar H(+)-ATPases (V-ATPases) are essential for acidification of intracellular compartments and for proton secretion from the plasma membrane in kidney epithelial cells and osteoclasts. The cellular proteins that regulate V-ATPases remain largely unknown. A screen for proteins that bind the V-ATPase E subunit using the yeast two-hybrid assay identified the cDNA clone coded for aldolase, an enzyme of the glycolytic pathway. The interaction between E subunit and aldolase was confirmed in vitro by precipitation assays using E subunit-glutathione S-transferase chimeric fusion proteins and metabolically labeled aldolase. Aldolase was isolated associated with intact V-ATPase from bovine kidney microsomes and osteoclast-containing mouse marrow cultures in co-immunoprecipitation studies performed using an anti-E subunit monoclonal antibody. The interaction was not affected by incubation with aldolase substrates or products. In immunocytochemical assays, aldolase was found to colocalize with V-ATPase in the renal proximal tubule. In osteoclasts, the aldolase-V-ATPase complex appeared to undergo a subcellular redistribution from perinuclear compartments to the ruffled membranes following activation of resorption. In yeast cells deficient in aldolase, the peripheral V(1) domain of V-ATPase was found to dissociate from the integral membrane V(0) domain, indicating direct coupling of glycolysis to the proton pump. The direct binding interaction between V-ATPase and aldolase may be a new mechanism for the regulation of the V-ATPase and may underlie the proximal tubule acidification defect in hereditary fructose intolerance.
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Affiliation(s)
- M Lu
- Departments of Medicine and Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, Florida 32610, USA.
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22
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Abstract
Aldolase B is an abundant cytosolic protein found in all eukaryotic cells. Like many glycolytic enzymes, this protein was sequestered into lysosomes for degradation during nutrient starvation. We report here that the degradation of recombinant aldolase B was enhanced two-fold when rat and human hepatoma cells were starved for amino acid and serum. In addition, starvation-induced degradation of aldolase B was inhibited by chloroquine, an inhibitor of lysosomal proteinases and by 3-methyladenine, an inhibitor of autophagy. Aldolase B has three lysosomal targeting motifs (Q(12)KKEL, Q(58)FREL, and IKLDQ(111)) that have been proposed to interact with hsc73 thereby initiating its transport into lysosomes. In this study, we have mutated the essential glutamine residues in each of these hsc73-binding motifs in order to evaluate their roles in the lysosomal degradation of aldolase B during starvation. We have found that when glutamines 12 or 58 are mutated to asparagines enhanced degradation of aldolase B proceeded normally. However, when glutamine 111 was mutated to an asparagine or a threonine, starvation-induced degradation was completely suppressed. These mutations did not appear to alter the tertiary structure of aldolase B since enzymatic activity was not affected. Our results suggest that starvation-induced lysosomal degradation of aldolase B requires both autophagy and glutamine 111. We discuss the possible roles for autophagy and hsc73-mediated transport in the lysosomal sequestration of aldolase B.
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Affiliation(s)
- P P Susan
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Health Science Center, P.O. Box 100235, Gainesville, FL 32610-0525, USA
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23
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Abeliovich H, Dunn WA, Kim J, Klionsky DJ. Dissection of autophagosome biogenesis into distinct nucleation and expansion steps. J Cell Biol 2000; 151:1025-34. [PMID: 11086004 PMCID: PMC2174351 DOI: 10.1083/jcb.151.5.1025] [Citation(s) in RCA: 219] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2000] [Accepted: 10/13/2000] [Indexed: 11/22/2022] Open
Abstract
Rapamycin, an antifungal macrolide antibiotic, mimics starvation conditions in Saccharomyces cerevisiae through activation of a general G(0) program that includes widespread effects on translation and transcription. Macroautophagy, a catabolic membrane trafficking phenomenon, is a prominent part of this response. Two views of the induction of autophagy may be considered. In one, up-regulation of proteins involved in autophagy causes its induction, implying that autophagy is the result of a signal transduction mechanism leading from Tor to the transcriptional and translational machinery. An alternative hypothesis postulates the existence of a dedicated signal transduction mechanism that induces autophagy directly. We tested these possibilities by assaying the effects of cycloheximide and specific mutations on the induction of autophagy. We find that induction of autophagy takes place in the absence of de novo protein synthesis, including that of specific autophagy-related proteins that are up-regulated in response to rapamycin. We also find that dephosphorylation of Apg13p, a signal transduction event that correlates with the onset of autophagy, is also independent of new protein synthesis. Finally, our data indicate that autophagosomes that form in the absence of protein synthesis are significantly smaller than normal, indicating a role for de novo protein synthesis in the regulation of autophagosome expansion. Our results define the existence of a signal transduction-dependent nucleation step and a separate autophagosome expansion step that together coordinate autophagosome biogenesis.
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Affiliation(s)
- H Abeliovich
- University of Michigan, Department of Biology, Ann Arbor, Michigan 48109, USA
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Abstract
There is an emerging paradigm shift from coronary heart disease having a purely hereditary and nutritional causation to possibly having an infectious etiology. Recent epidemiological studies have shown a correlation between periodontal disease and coronary heart disease. However, to date, there is minimal information as to the possible disease mechanisms of this association. It is our hypothesis that invasion of the coronary artery cells by oral bacteria may start and/or exacerbate the inflammatory response in atherosclerosis. Since a few periodontal pathogens have been reported to invade oral epithelial tissues, we tested the ability of three putative periodontal pathogens-Eikenella corrodens, Porphyromonas gingivalis, and Prevotella intermedia-to invade human coronary artery endothelial cells and coronary artery smooth muscle cells. In this study we demonstrate by an antibiotic protection assay and electron microscopy that specific species and strains invade coronary artery cells at a significant level. Actin polymerization and eukaryotic protein synthesis in metabolically active cells were required since the corresponding inhibitors nearly abrogated invasion. Many intracellular P. gingivalis organisms were seen to be present in multimembranous vacuoles resembling autophagosomes by morphological analysis. This is the first report of oral microorganisms invading human primary cell cultures of the vasculature.
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Affiliation(s)
- B R Dorn
- Department of Oral Biology, College of Dentistry, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
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25
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Abstract
Cytosolic and peroxisomal enzymes necessary for methanol assimilation are synthesized when Pichia pastoris is grown in methanol. Upon adaptation from methanol to a glucose environment, these enzymes are rapidly and selectively sequestered and degraded within the yeast vacuole. Sequestration begins when the vacuole changes shape and surrounds the peroxisomes. The opposing membranes then fuse, engulfing the peroxisome. In this study, we have characterized a mutant cell line (glucose-induced selective autophagy), gsa7, which is defective in glucose-induced selective autophagy of peroxisomes, and have identified the GSA7 gene. Upon glucose adaptation, gsa7 cells were unable to degrade peroxisomal alcohol oxidase. We observed that the peroxisomes were surrounded by the vacuole, but complete uptake into the vacuole did not occur. Therefore, we propose that GSA7 is not required for initiation of autophagy but is required for bringing the opposing vacuolar membranes together for homotypic fusion, thereby completing peroxisome sequestration. By sequencing the genomic DNA fragment that complemented the gsa7 phenotype, we have found that GSA7 encodes a protein of 71 kDa (Gsa7p) with limited sequence homology to a family of ubiquitin-activating enzymes, E1. The knockout mutant gsa7Delta had an identical phenotype to gsa7, and both mutants were rescued by an epitope-tagged Gsa7p (Gsa7-hemagglutinin [HA]). In addition, a GSA7 homolog, APG7, a protein required for autophagy in Saccharomyces cerevisiae, was capable of rescuing gsa7. We have sequenced the human homolog of GSA7 and have shown many regions of identity between the yeast and human proteins. Two of these regions align to the putative ATP-binding domain and catalytic site of the family of ubiquitin activating enzymes, E1 (UBA1, UBA2, and UBA3). When either of these sites was mutated, the resulting mutants [Gsa7(DeltaATP)-HA and Gsa7(C518S)-HA] were unable to rescue gsa7 cells. We provide evidence to suggest that Gsa7-HA formed a thio-ester linkage with a 25-30 kDa protein. This conjugate was not observed in cells expressing Gsa7(DeltaATP)-HA or in cells expressing Gsa7(C518S)-HA. Our results suggest that this unique E1-like enzyme is required for homotypic membrane fusion, a late event in the sequestration of peroxisomes by the vacuole.
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Affiliation(s)
- W Yuan
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, Florida 32610, USA
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26
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Abstract
We have previously shown that stress-induced protein degradation requires a functional ubiquitin-activating enzyme and the autophagic-lysosomal pathway. In this study, we examined the occurrence of ubiquitin-protein conjugates that form during nutrient starvation. Kidney and liver epithelial cells respond to nutrient stress by enhancing autophagy and protein degradation. We have shown that this degradative response was more dramatic in nondividing cultures. In addition, the onset of autophagy was suppressed by pactamycin, cycloheximide, and puromycin. We observed an accumulation of ubiquitinated proteins coincident with the degradative response to amino acid starvation. The stress-induced protein ubiquitination was not affected by cycloheximide, indicating that protein synthesis was not required. The ubiquitinated proteins were localized to the cytosol and subcellular fractions enriched with autophagosomes and lysosomes. The incorporation of the ubiquitinated proteins into autolysosomes was dramatically reduced by 3-methyladenine, an inhibitor of autophagy. The evidence suggests that ubiquitinated proteins are sequestered by autophagy for degradation. We next set out to identify those primary ubiquitinated proteins at 60 kDa and 68 kDa. Polyclonal antibodies were prepared against these proteins that had been immunopurified from rat liver lysosomes. The antibodies prepared against those 68 kDa proteins also recognized a 40 kDa protein in cytosolic fractions. Internal amino acid sequences obtained from two cyanogen bromide fragments of this 40 kDa protein were shown to be identical to sequences in liver fructose1,6-bisphosphate aldolase B. Anti-Ub68 antibodies recognized purified aldolase A and aldolase B. Conversely, antibodies prepared against aldolase B recognized the 40 kDa aldolase as well as four to five high molecular weight forms, including a 68 kDa protein. Finally, we have shown that the degradation of aldolase B was enhanced during amino acid and serum starvation. This degradation was suppressed by chloroquine and 3-methyladenine, suggesting that aldolase B was being degraded within autolysosomes. We propose that aldolase B is ubiquitinated within the cytosol and then transported into autophagosomes and autolysosomes for degradation during nutrient stress.
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Affiliation(s)
- S E Lenk
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, USA
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27
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Yuan W, Tuttle DL, Shi YJ, Ralph GS, Dunn WA. Glucose-induced microautophagy in Pichia pastoris requires the alpha-subunit of phosphofructokinase. J Cell Sci 1997; 110 ( Pt 16):1935-45. [PMID: 9296392 DOI: 10.1242/jcs.110.16.1935] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [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: 11/20/2022] Open
Abstract
We have characterized biochemically, morphologically, and genetically two distinct pathways for the selective degradation of peroxisomes in Pichia pastoris. These pathways are independently regulated and analogous to microautophagy and macroautophagy that have been defined in mammalian cells. When P. pastoris is grown in methanol, cytosolic and peroxisomal enzymes necessary for methanol assimilation are synthesized. During adaptation from methanol to glucose, these enzymes are rapidly and selectively degraded within the yeast vacuole by microautophagy. We have isolated gsa mutants that are defective in glucose-induced selective autophagy of peroxisomes. In this study, we have shown that gsa1 is unable to sequester peroxisomes into the yeast vacuole. In addition, we provide evidence that the glucose-induced selective autophagy 1 (GSA1) protein is the alpha subunit of the phosphofructokinase enzyme complex encoded by PFK1. First, we can rescue the gsa1 mutant by transformation with a vector containing PFK1. Second, cellular levels of both PFK1 mRNA and phosphofructokinase activity are dramatically reduced in gsa1 when compared to the parental GS115. Third, a PFK1 knockout (delta pfk1) is unable to degrade alcohol oxidase during glucose adaptation. As observed in gsa1, the peroxisomes in delta pfk1 remain outside the vacuole during adaptation. Our data are consistent with the concept that PFK1 protein is required for an event upstream of vacuole degradation (i.e. signaling, selection, or sequestration). However, the degradation of peroxisomes does not require a catalytically active phosphofructokinase. The inability of delta pfk1 cells to degrade alcohol oxidase can be rescued by transformation with either normal PFK1 or mutant pfk1 whose catalytic site had been inactivated by a single amino acid mutation. We propose that PFK1 protein directly modulates glucose-induced microautophagy independent of its ability to metabolize glucose intermediates.
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Affiliation(s)
- W Yuan
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610, USA
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28
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Abstract
The budding yeast Pichia pastoris responds to methanolic media by synthesizing high levels of cytosolic enzymes (e.g. formate dehydrogenase) and peroxisomal enzymes (e.g. alcohol oxidase), which are necessary to assimilate this carbon source. Major alterations in cellular metabolism are initiated upon a shift in carbon source to ethanol or glucose. These alterations require the synthesis of new proteins and the rapid degradation of those enzymes no longer needed for methanol utilization. In this study, we have measured cytosolic and peroxisomal enzyme activities and examined the fate of morphologically distinct peroxisomes to assess the degradative response of this yeast during nutrient adaptation. Utilizing biochemical, morphological and genetic approaches, we have shown that there exist in P. pastoris at least two pathways for the sequestration of peroxisomes into the vacuole for degradation. The ethanol-induced pathway is independent of protein synthesis and includes an intermediate stage in which individual peroxisomes are sequestered into autophagosomes by wrapping membranes, which then fuse with the vacuole. This process is analogous to macroautophagy. The glucose-induced pathway invokes the engulfment of clusters of peroxisomes by finger-like protrusions of the vacuole by a process analogous to microautophagy. Unlike ethanol adaptation, glucose stimulated the degradation of formate dehydrogenase as well. Peroxisomes remained outside the vacuoles of glucose-adapted cycloheximide-treated normal cells, suggesting that protein synthesis is required for peroxisome entry into the yeast vacuole. Two complementary mutants (gsa1 and gsa2) that are unable to degrade peroxisomes or formate dehydrogenase during glucose adaptation were isolated. The mutated gene products appear to function in one or more events upstream of degradation within the vacuole, since ethanol-induced peroxisome degradation proceeded normally in these mutants and peroxisomes were found outside the vacuoles of glucose-adapted gsa2 cells. Mutants lacking vacuolar proteinases A and B were unable to degrade alcohol oxidase or formate dehydrogenase during ethanol or glucose adaptation. Peroxisomes were found to accumulate within the vacuoles of these proteinase mutants during adaptation. Combined, the results suggest that there exist in Pichia pastoris two independent pathways for the sequestration of peroxisomes into the vacuole, the site of degradation.
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Affiliation(s)
- D L Tuttle
- University of Florida College of Medicine, Department of Anatomy and Cell Biology, Gainesville 32610-0235, USA
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29
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Dunn WA, Raizada MK, Vogt ES, Brown EA. Growth factor-induced neurite growth in primary neuronal cultures of dogs with neuronal ceroid lipofuscinosis. Int J Dev Neurosci 1994; 12:185-96. [PMID: 7942092 DOI: 10.1016/0736-5748(94)90040-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [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: 01/28/2023] Open
Abstract
Neuronal ceroid lipofuscinosis (NCL) is a type of lysosomal storage disease resulting in the progressive deterioration of neuronal function. Little is known about the genetics, pathophysiology and biochemical basis of this disease. This is, in part, due to the complexity of the central nervous system and the lack of an in vitro model. In this report, we describe the conditions to establish neuronal cells in primary culture from the brains of newborn English setters with NCL, a canine model for this disease. Over 80% of the neuronal cells from normal dog brain establish well-developed interconnecting networks of long neurites. On the contrary, approximately 50% of the neurons cultured from NCL dog brains do not assemble neurites. Of those NCL neurons with processes, the neurites are routinely shorter and fewer in number than those seen in normal cultures. In addition, the characteristic inclusion bodies, pathological markers for this disease in vivo, are prevalent in the soma of cultured neuronal cells isolated from NCL dog brain. A time-dependent maturation of the inclusion bodies suggests a progression of the disease state in culture. The reduced ability of the NCL neurons to establish neurites prompted us to examine the effects of growth factors on neurite assembly. Our data show that insulin-like growth factor I, epidermal growth factor and platelet-derived growth factor are capable of stimulating neurite outgrowth of NCL neurons. We report the establishment and morphological characterization of neuronal cultures from normal and NCL dog brains. The abnormal morphology of cultured NCL neurons can, in part, be alleviated by supplementing the medium with growth factors. The results suggest that this cellular model of NCL will be useful to study the molecular and physiological mechanisms of NCL disease, as well as to test potential therapeutic agents and candidate genes.
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Affiliation(s)
- W A Dunn
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610
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30
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Woodard MH, Dunn WA, Laine RO, Malandro M, McMahon R, Simell O, Block ER, Kilberg MS. Plasma membrane clustering of system y+ (CAT-1) amino acid transporter as detected by immunohistochemistry. Am J Physiol 1994; 266:E817-24. [PMID: 8203520 DOI: 10.1152/ajpendo.1994.266.5.e817] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Transport of cationic amino acids in fully differentiated mammalian cells is mediated primarily by system y1+ [cationic amino acid transporter (CAT)-1 gene product]. Antibodies, prepared against synthetic peptide sequences predicted to be extracellular loops of the CAT-1 transporter protein, detected the transporter on the surface of cultured cells. In human fibroblasts, porcine pulmonary artery endothelial cells, and cultured rat hepatoma cells, the CAT-1 transporter protein was clustered in an apparent random pattern throughout the plasma membrane. In contrast, labeling of the fibroblasts with antibodies against the epidermal growth factor receptor or the GLUT-1 glucose transporter demonstrated a uniform staining pattern covering the entire cell surface. The CAT-1 antibody labeling was specific, as demonstrated by peptide inhibition and the lack of staining by preimmune serum. Furthermore, hepatocytes did not exhibit specific antibody binding consistent with the lack of system y1+ activity. Disruption of the microtubule assembly resulted in a reversible loss of the CAT-1 transporter clusters and a more generalized labeling of the cell body. The data demonstrate the existence of microdomains within the plasma membrane that contain the CAT-1 transporter protein.
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Affiliation(s)
- M H Woodard
- Department of Medicine, College of Medicine, University of Florida, Gainesville 32610-0245
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31
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Abstract
Lysosomes play a central role in the degradation of extracellular and intracellular macromolecules. These organelles contain hydrolytic enzymes capable of degrading proteins, proteoglycans, nucleic acids, and lipids. The mechanisms involved in the delivery of such intracellular compounds to the lysosome have been characterized in several recent studies. The sequestration of intracellular macromolecules for intralysosomal degradation can occur by crinophagy, hsc73-mediated carrier transport, or autophagy. The major route of delivery of cellular proteins and RNA into lysosomes is by autophagy. Furthermore, autophagy is regulated by nutrients and hormones, thus allowing the cell to adjust its degradative state to environmental changes.
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Affiliation(s)
- W A Dunn
- Department of Anatomy and Cell Biology, Box 100235, JHMHC, University of Florida College of Medicine, Gainesville, FL 32610, USA
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32
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Abstract
In this report we give details on an overdose fatality involving both digoxin and doxepin. There have been numerous reported fatalities, both accidental and suicidal, involving digoxin and many more reports of fatalities involving doxepin. We believe that this is the first time a fatality from this drug combination has been reported in the literature.
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Affiliation(s)
- W A Dunn
- Analytical Bio-Chemistries Incorporated, Feasterville, PA 19053
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Siek TJ, Dunn WA. Documentation of a doxylamine overdose death: quantitation by standard addition and use of three instrumental techniques. J Forensic Sci 1993; 38:713-20. [PMID: 8515223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To answer the question, "Is this death due to a drug overdose?" requires at least that the drug be unequivocally identified and a blood concentration reliably determined. The approach taken in this case as standard addition technique and use of three different chromatographic techniques-high performance liquid chromatography (HPLC), high performance thin-layer chromatography (HP-TLC) and gas chromatography/mass spectrometry (GC/MS). Each of the chromatographies was carried out on the same extract by splitting the residue three ways. HPLC provided a quantitative result which was 1.2 mg/L in blood and HP-TLC and GC/MS confirmed this result with additional quantitative data, information about two metabolites (nordoxylamine and dinordoxylamine) and conclusive identification. Blood nordoxylamine was 0.52 mg/L and doxylamine plus metabolites in urine was 25 mg/L.
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Affiliation(s)
- T J Siek
- Analytic Bio-Chemistries, Feasterville, PA
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34
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Tuttle DL, Lewin AS, Dunn WA. Selective autophagy of peroxisomes in methylotrophic yeasts. Eur J Cell Biol 1993; 60:283-90. [PMID: 8330626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The methylotrophic yeasts Pichia pastoris and Hansenula polymorpha respond to a methanol substrate by synthesizing peroxisomal enzymes resulting in the formation of large peroxisomes. When the carbon source was changed from methanol to glucose, we observed a rapid loss of peroxisomes. In this comparative study, we utilized biochemical and morphological techniques to characterize the loss of peroxisomes in these yeasts. We used metabolic labeling and chase procedures to evaluate whether this loss was due to suppressed synthesis or enhanced degradation. The synthesis of alcohol oxidase was depressed 10-fold when cultures grown in methanol attained stationary growth. However, no further reduction of synthesis was observed upon transfer of these cultures to glucose medium. In stationary phase cultures maintained in methanol, two peroxisomal proteins, alcohol oxidase and dihydroxyacetone synthase, were degraded with a half-life of over 3 h. However, within 3 h of glucose repression, as much as 80% of the radiolabeled peroxisomal proteins were lost from both yeasts. This glucose-mediated degradative event appeared to be specific for peroxisomal proteins, since mitochondrial proteins were stable. Ultrastructural examination of both yeasts revealed that glucose induced the sequestration of peroxisomes into the yeast vacuole, the presumed site of degradation. These results suggest that peroxisome loss during glucose repression is due to a selective, enhanced degradation of whole peroxisomes by autophagic mechanisms.
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Affiliation(s)
- D L Tuttle
- University of Florida College of Medicine, Department of Anatomy and Cell Biology, Gainesville 32610-0235
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35
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Chegini N, Rossi MJ, Schultz GS, Dunn WA, Masterson BJ. Cellular distribution of epidermal growth factor, transforming growth factor-α, and epidermal growth factor receptor in fascia and peritoneum during healing in the rat: an autoradiographic and immunohistochemical study. Wound Repair Regen 1993; 1:28-40. [PMID: 17147706 DOI: 10.1046/j.1524-475x.1993.10108.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The presence and cellular distribution of epidermal growth factor (EGF), TGF-alpha, and EGF-R were determined in the rat fascial and peritoneal tissue during healing of an incisional injury by means of immunohistochemistry and autoradiographic techniques. The immunostaining intensity for EGF in the regenerating wound area was substantially higher during the first 14 days, then decreased to near prewound levels during 14 to 35 days after surgery. Within the wound area, the most intense immunostaining occurred with inflammatory cells, followed by fascial striated muscle and arterioles, whereas fibroblasts in the regenerating area contained very low immunostaining intensity. The immunostaining pattern for TGF-alpha with the use of three separate polyclonal antibodies that were directed against the amino and carboxy termini of TGF-alpha precursor and a fragment of the mature 50-amino-acid form of TGF-alpha was similar to that seen with EGF and persisted until 28 days after injury. However, fibroblasts in the regenerating area immunostained intensely for TGF-alpha but not for EGF. Quantitative autoradiography of iodine 125-labeled EGF binding and immunohistochemical studies of the EGF-R with monoclonal antibodies that were directed against the extracellular binding domain of EGF-R demonstrated the presence of specific EGF-R in regenerating fascial and peritoneal tissue. Net grain density (100 microm(2)), representing specific binding of (125)I-EGF, was calculated for different cell types in the wound. The grain density over fascial striated muscle, migratory fibroblasts and peritoneal fibroblasts increased by two and one half, three, and four times, respectively, at 7 days and decreased to the values in adjacent unwounded tissue by 21 days after injury (p < 0.05). Immunostaining for the EGF-R generated similar patterns, which persisted for 14 days after injury. The grain density and immunostaining for EGF-R over the arterioles in the wound did not change during the course of healing and was similar to that of the uninjured regions. In summary, these observations indicate that the local levels of EGF, TGF-alpha, and EGF-R increase during the early phases of healing in fascial and peritoneal injury, which suggests a role for these growth factors in the normal mechanism of fascial/peritoneal wound healing and fibrous adhesion formation.
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Affiliation(s)
- N Chegini
- Department of Obstetrics and Gynecology, University of Florida, Gainesville, Fla, USA
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36
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Lenk SE, Bhat D, Blakeney W, Dunn WA. Effects of streptozotocin-induced diabetes on rough endoplasmic reticulum and lysosomes of rat liver. Am J Physiol 1992; 263:E856-62. [PMID: 1443117 DOI: 10.1152/ajpendo.1992.263.5.e856] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the absence of amino acids and insulin, ribosome-free regions of the rough endoplasmic reticulum (RER) invaginate to form an autophagosome, which matures into an autolysosome (W. A. Dunn, Jr., J. Cell Biol. 110: 1923-1933, 1990). In this study, biochemical and morphological methods were used to examine the structure and integrity of the RER and the lysosome-vacuolar system in livers of untreated (normal serum insulin) and streptozotocin (STZ)-treated (depressed serum insulin) fed and fasted rats. Degradation of endogenous proteins was increased by 70% in STZ-treated animals. Proteolysis was further enhanced when these animals were deprived of food for 24 h. These alterations in protein turnover were accompanied by increases in the fractional volume of autophagic vacuoles and in the hepatic amounts of three lysosomal hydrolases. These effects of STZ were prevented on administration of insulin. In addition, there was an insulin-dependent 50% loss of RER surface area in livers from STZ-treated rats. This loss of structural RER was accompanied by comparable decreases in the cellular amounts of two RER membrane proteins and one luminal protein, suggesting that the RER was degraded as a unit. Additional losses of RER were observed when STZ-treated rats were fasted. Furthermore, the hepatic amounts of two serum proteins decreased, suggesting the functional capacity of the RER was reduced. Combined, the data suggest that in STZ-induced diabetes the losses in RER are related to enhanced autophagy.
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Affiliation(s)
- S E Lenk
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610-0235
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Nakagawa Y, Purushotham KR, Wang PL, Fischer JE, Dunn WA, Schneyer CA, Humphreys-Beher MG. Alterations in the subcellular distribution of p21ras-GTPase activating protein in proliferating rat acinar cells. Biochem Biophys Res Commun 1992; 187:1172-9. [PMID: 1382416 DOI: 10.1016/0006-291x(92)91320-p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [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: 12/26/2022]
Abstract
Rat parotid acinar cells undergo transient proliferation in response to chronic administration of the beta-adrenergic agonist isoproterenol or epidermal growth factor (EGF). Treatment with these agents caused an increase in tyrosine phosphorylation of p21ras-GTPase activating protein (GAP). This phosphorylation event was accompanied by a redistribution of the protein from the plasma membrane to internal membrane compartments. Separation of subcellular membranes revealed increased GAP associated with a low density population of vesicles concomitant with growth stimulation as well as to the nuclear membrane, but not the nucleoplasm. Upon cessation of hyperplasia induced by isoproterenol, phosphorylated GAP present in the plasma membrane returned to control cell levels.
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Affiliation(s)
- Y Nakagawa
- Department of Oral Biology, University of Florida, Gainesville 32610
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38
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Abstract
We evaluated the role of cytoskeletal elements in the degradation of endogenous proteins via autophagy using biochemical and morphological techniques. In the absence of exogenous amino acids, degradation of endogenous proteins was enhanced in cultured normal rat kidney cells. This enhanced degradative state was accompanied by a 4-fold increase in the occurrence of autophagic vacuoles. In the presence of drugs that induce the depolymerization of microfilaments (cytochalasins B and D) or microtubules (nocodazole), protein degradation was not enhanced in nutrient-deprived cells. Although these drugs had similar inhibitory effects on the protein degradation, their effect on autophagy differed. Cytochalasins B and D interfered with the formation of the autophagosome. In cells treated with these drugs, the fractional volume represented by autophagic vacuoles was not substantially increased despite nutrient depletion. On the contrary, nocodazole appeared to have no effect on the formation of autophagosomes. Instead, this drug suppressed the delivery of hydrolytic enzymes, thereby resulting in an accumulation of acidic autophagic vacuoles containing undegraded cellular components.
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Affiliation(s)
- A Aplin
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610-0235
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39
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Lenk SE, Dunn WA, Trausch JS, Ciechanover A, Schwartz AL. Ubiquitin-activating enzyme, E1, is associated with maturation of autophagic vacuoles. J Biophys Biochem Cytol 1992; 118:301-8. [PMID: 1321157 PMCID: PMC2290057 DOI: 10.1083/jcb.118.2.301] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The ubiquitin-activating enzyme, E1, is required for initiating a multi-step pathway for the covalent linkage of ubiquitin to target proteins. A CHO cell line containing a mutant thermolabile E1, ts20, has been shown to be defective in stress-induced degradation of proteins at restrictive temperature (Gropper et al., 1991. J. Biol. Chem. 266:3602-3610). Parental E36 cells responded to restrictive temperature by stimulating lysosome-mediated protein degradation twofold. Such a response was not observed in ts20 cells. The absence of accelerated degradation in these cells at 39.5 degrees C was accompanied by an accumulation of autolysosomes. The fractional volume of these degradative autophagic vacuoles was at least sixfold greater than that observed for either E36 cells at 30.5 degrees or 39.5 degrees C, or ts20 cells at 30.5 degrees C. These vacuoles were acidic and contained both acid phosphatase and cathepsin L, but, unlike the autolysosomes observed in E36 cells, ubiquitin-conjugated proteins were conspicuously absent. Combined, our results suggest that in ts20 cells, which are unable to generate ubiquitin-protein conjugates due to heat inactivation of E1, the formation and maturation of autophagosomes into autolysosomes is normal, but the conversion of autolysosomes into residual bodies is disrupted.
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Affiliation(s)
- S E Lenk
- Department of Anatomy, University of Florida Health Science Center, Gainesville 32610
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40
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Villa A, Sharp AH, Racchetti G, Podini P, Bole DG, Dunn WA, Pozzan T, Snyder SH, Meldolesi J. The endoplasmic reticulum of Purkinje neuron body and dendrites: molecular identity and specializations for Ca2+ transport. Neuroscience 1992; 49:467-77. [PMID: 1331857 DOI: 10.1016/0306-4522(92)90111-e] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [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: 12/26/2022]
Abstract
Immunofluorescence and immunogold labeling, together with sucrose gradient separation and Western blot analysis of microsomal subfractions, were employed in parallel to probe the endoplasmic reticulum in the cell body and dendrites of rat cerebellar Purkinje neurons. Two markers, previously investigated in non-nerve cells, the membrane protein p91 (calnexin) and the lumenal protein BiP, were found to be highly expressed and widely distributed to the various endoplasmic reticulum sections of Purkinje neurons, from the cell body to dendrites and dendritic spines. An antibody (denominated anti-rough-surfaced endoplasmic reticulum), which recognized two membrane proteins, p14 and p40, revealed a similar immunogold labeling pattern. However, centrifugation results consistent with a widespread distribution were obtained for p14 only, while p40 was concentrated in the rough microsome-enriched subfractions. The areas enriched in the inositol 1,4,5-triphosphate receptor and thus presumably specialized in Ca2+ transport (stacks of multiple smooth-surfaced cisternae; the dendritic spine apparatus) also exhibited labeling for BiP and p91, and were positive for the anti-rough-surfaced endoplasmic reticulum antibody (presumably via the p14 antigen). Additional antibodies, that yielded inadequate immunocytochemical signals, were employed only by Western blotting of the microsomal subfractions, while the ryanodine receptor was studied by specific binding. The latter receptor and the Ca2+ ATPase, known in other species to be concentrated in Purkinje neurons, exhibited bimodal distributions with a peak in the light and another in the heavy subfractions. A similar distribution was also observed with another lumenal protein, protein disulfide isomerase. Taken as a whole, the results that we have obtained suggest the existence in the endoplasmic reticulum of Purkinje neurons of two levels of organization; the first identified by widespread, probably general markers (BiP, p91, possibly p14 and others), the second by specialization markers, such as the inositol 1,4,5-triphosphate receptor and, possibly, p40, which appear restricted to areas where specific functions appear to be localized.
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Affiliation(s)
- A Villa
- Department of Pharmacology, CNR Cytopharmacology and B. Ceccarelli Centers, S. Raffaele Scientific Institute, Milano, Italy
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Purushotham KR, Dunn WA, Schneyer CA, Humphreys-Beher MG. A novel mechanism for isoprenaline-stimulated proliferation of rat parotid acinar cells involving the epidermal growth factor receptor and cell surface galactosyltransferase. Biochem J 1992; 284 ( Pt 3):767-76. [PMID: 1622394 PMCID: PMC1132605 DOI: 10.1042/bj2840767] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [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: 12/27/2022]
Abstract
Chronic injections of epidermal growth factor (EGF) or the beta-adrenergic receptor agonist isoprenaline resulted in rat parotid gland hypertrophy and hyperplasia. Introduction of a polyclonal antibody to EGF or the EGF-receptor (EGF-R) caused a specific retardation of acinar cell proliferation when injected along with the growth factor. Meanwhile, only the antibody to EGF-R caused a dose-dependent retardation of proliferation on co-administration with isoprenaline both in vivo and in vitro. The antibody injected alone had no effect on cell growth. When cells were incubated in the presence of EGF, plasma membranes from isoprenaline-treated and control animals showed phosphorylation of the EGF-R tyrosine moieties and transient increases in membrane-associated phospholipase C gamma. Isoprenaline did not stimulate phosphorylation of the EGF-R in isolated plasma membranes. However, activation of the phosphotyrosine-signalling pathway could be duplicated by incubating isoprenaline-treated acinar cells, but not control cells, with bovine galactosyltransferase. Immunopurified EGF-R demonstrated variations in reactivity with two different lectins after treatment of the cells with the beta-agonist as well as increased galactosyltransferase substrate capacity in vitro. In addition, incubation of intact acinar cells and isolated plasma-membrane fractions from isoprenaline-treated rats with UDP-[14C]galactose resulted in an increased incorporation of label into the EGF-R. The results suggest that the carbohydrate moiety of the EGF-R has been altered in isoprenaline-treated animals allowing galactosyltransferase now to recognize this receptor. This interaction may in part mediate proliferation of parotid acinar cells. Indeed, we have previously shown that an antibody to galactosyltransferase is capable of blocking isoprenaline-mediated acinar cell proliferation in vivo [Humphreys-Beher, Schneyer, Kidd & Marchase (1987) J. Biol. Chem. 262, 11706-11713].
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Affiliation(s)
- K R Purushotham
- Department of Oral Biology, University of Florida, Gainesville 32610
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Roitelman J, Olender EH, Bar-Nun S, Dunn WA, Simoni RD. Immunological evidence for eight spans in the membrane domain of 3-hydroxy-3-methylglutaryl coenzyme A reductase: implications for enzyme degradation in the endoplasmic reticulum. J Biophys Biochem Cytol 1992; 117:959-73. [PMID: 1374417 PMCID: PMC2289486 DOI: 10.1083/jcb.117.5.959] [Citation(s) in RCA: 151] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We have raised two monospecific antibodies against synthetic peptides derived from the membrane domain of the ER glycoprotein 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate limiting enzyme in the cholesterol biosynthetic pathway. This domain, which was proposed to span the ER membrane seven times (Liscum, L., J. Finer-Moore, R. M. Stroud, K. L. Luskey, M. S. Brown, and J. L. Goldstein. 1985. J. Biol. Chem. 260:522-538), plays a critical role in the regulated degradation of the enzyme in the ER in response to sterols. The antibodies stain the ER of cells and immunoprecipitate HMG-CoA reductase and HMGal, a chimeric protein composed of the membrane domain of the reductase fused to Escherichia coli beta-galactosidase, the degradation of which is also accelerated by sterols. We show that the sequence Arg224 through Leu242 of HMG-CoA reductase (peptide G) faces the cytoplasm both in cultured cells and in rat liver, whereas the sequence Thr284 through Glu302 (peptide H) faces the lumen of the ER. This indicates that a sequence between peptide G and peptide H spans the membrane of the ER. Moreover, by epitope tagging with peptide H, we show that the loop segment connecting membrane spans 3 and 4 is sequestered in the lumen of the ER. These results demonstrate that the membrane domain of HMG-CoA reductase spans the ER eight times and are inconsistent with the seven membrane spans topological model. The approximate boundaries of the proposed additional transmembrane segment are between Lys248 and Asp276. Replacement of this 7th span in HMGal with the first transmembrane helix of bacteriorhodopsin abolishes the sterol-enhanced degradation of the protein, indicating its role in the regulated turnover of HMG-CoA reductase within the endoplasmic reticulum.
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Affiliation(s)
- J Roitelman
- Department of Biological Sciences, Stanford University, California 94305
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Lenk SE, Fisher DL, Dunn WA. Regulation of protein secretion by crinophagy in perfused rat liver. Eur J Cell Biol 1991; 56:201-9. [PMID: 1724960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We examined the secretion of three serum proteins, albumin (RSA), alpha 2 mu-globulin (alpha 2 mu G), and transferrin (Trf), in the isolated perfused liver. Within 4 h of perfusion, only 20 to 35% of previously synthesized proteins were secreted by the liver into the recirculating medium. Low temperature inhibited the secretion of alpha 2 mu G and Trf, but not RSA. The amount of RSA secreted by the liver increased twofold in the presence of leupeptin, a proteinase inhibitor, or primaquine, a weak base capable of neutralizing acidic compartments. Neither drug affected Trf secretion, while the release of alpha 2 mu G was enhanced threefold by primaquine treatment. Only 55 to 70% of the total amount of these serum proteins present in the liver at the onset of perfusion could be accounted for after 4 h of perfusion. Our evidence suggests that these losses are due to protein degradation. The degradation of RSA and alpha 2 mu G was inhibited at 15 degrees C and by both leupeptin and primaquine. Contrary, RSA degradation was not altered when livers were perfused at 20 degrees C. Morphological techniques combined with immunological probes were utilized to identify possible intracellular sites of RSA degradation. RSA and cathepsin L were colocalized to large vacuoles found near the cell periphery. Entry of RSA into these vacuoles occurred at 20 degrees C but not at 15 degrees C. Our results using perfused rat livers suggest that as much as 40% of hepatic serum proteins are degraded via fusion of secretory vesicles with lysosomes (e.g., crinophagy).
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Affiliation(s)
- S E Lenk
- Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville
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Simms JS, Chegini N, Williams RS, Rossi AM, Dunn WA. Identification of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor in surgically induced endometriosis in rats. Obstet Gynecol 1991; 78:850-7. [PMID: 1923211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The present immunohistochemical studies used polyclonal antibodies specific to epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and monoclonal antibodies to the extracellular binding domain of EGF receptor to elucidate their presence and cellular distribution in surgically induced endometriosis in the rat. Uterine segments were implanted in the mesenteric region adjacent to a blood vessel for a period of 4-6 weeks. During operative reexploration, the implanted tissues were intact, morphologically similar to the controls, and consisted of a cyst containing clear fluid and associated adhesion formation. All the uterine cell types immunostained with antibody to EGF. The highest immunostaining intensity was associated with inflammatory cells infiltrated among endometrial stromal cells, followed by luminal and glandular epithelial and stromal cells. The cysts consisted of an inner simple columnar epithelium, surrounded by several layers of smooth muscle and connective tissue. The cyst epithelial layer immunostained weakly, while the supporting wall stained moderately. The inflammatory cells found within the cyst cavity immunostained very intensely, comparable to those in the endometrium. The patterns of immunostaining for TGF-alpha and EGF receptor were similar to that observed for EGF. Myometrial smooth-muscle cells and endothelial and smooth-muscle cells of arterioles were also immunostained for EGF, TGF-alpha, and EGF receptor, but with lower intensity than that of the endometrium. These observations suggest that, like normal uterine tissue, endometrial implants produce EGF and TGF-alpha locally and contain receptors for EGF. These results imply a possible paracrine or autocrine role for growth factors in the establishment and/or maintenance of endometriotic tissue.
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Affiliation(s)
- J S Simms
- Department of Obstetrics and Gynecology, University of Florida, Gainesville
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Abstract
A colorimetric method for the screening of cyanide in biological specimens is presented. Cyanide in a 200-microL sample is diffused in a Conway 3 compartment dish into the center well where it catalyzes the reaction between p-nitrobenzaldehyde and o-dinitrobenzene. The resulting blue-violet color intensity is proportional to cyanide concentration. The reaction is specific for cyanide, and concentrations as low as 0.05 mg/L can readily be detected.
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Affiliation(s)
- W A Dunn
- Analytic Bio-Chemistries, Inc., Feasterville, Pennsylvania 19053
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Abstract
Autophagic vacuoles form within 15 min of perfusing a liver with amino acid-depleted medium. These vacuoles are bound by a "smooth" double membrane and do not contain acid phosphatase activity. In an attempt to identify the membrane source of these vacuoles, I have used morphological techniques combined with immunological probes to localize specific membrane antigens to the limiting membranes of newly formed or nascent autophagic vacuoles. Antibodies to three integral membrane proteins of the plasma membrane (CE9, HA4, and epidermal growth factor receptor) and one of the Golgi apparatus (sialyltransferase) did not label these vacuoles. Internalized epidermal growth factor and its membrane receptor were not found in nascent autophagic vacuoles but were present in lysosome-like degradative autophagic vacuoles. All these results suggested that autophagic vacuoles were not formed from plasma membrane, Golgi apparatus, or endosome constituents. Antisera prepared against integral membrane proteins (14, 25, and 40 kD) of the RER was found to label the inner and outer limiting membranes of almost all nascent autophagic vacuoles. In addition, ribophorin II was identified at the limiting membranes of many nascent autophagic vacuoles. Finally, secretory proteins, rat serum albumin and alpha 2u-globulin, were localized to the lumen of the RER and to the intramembrane space between the inner and outer membranes of some of these vacuoles. The results were consistent with the formation of autophagic vacuoles from ribosome-free regions of the RER.
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Affiliation(s)
- W A Dunn
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610
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Abstract
Data presented in the accompanying paper suggests nascent autophagic vacuoles are formed from RER (Dunn, W. A. 1990. J. Cell Biol. 110:1923-1933). In the present report, the maturation of newly formed or nascent autophagic vacuoles into degradative vacuoles was examined using morphological and biochemical methods combined with immunological probes. Within 15 min of formation, autophagic vacuoles acquired acid hydrolases and lysosomal membrane proteins, thus becoming degradative vacuoles. A previously undescribed type of autophagic vacuole was also identified having characteristics of both nascent and degradative vacuoles, but was different from lysosomes. This intermediate compartment contained only small amounts of cathepsin L in comparison to lysosomes and was bound by a double membrane, typical of nascent vacuoles. However, unlike nascent vacuoles vet comparable to degradative vacuoles, these vacuoles were acidic and contained the lysosomal membrane protein, lgp120, at the outer limiting membrane. The results were consistent with the stepwise acquisition of lysosomal membrane proteins and hydrolases. The presence of mannose-6-phosphate receptor in autophagic vacuoles suggested a possible role of this receptor in the delivery of newly synthesized hydrolases from the Golgi apparatus. However, tunicamycin had no significant effect on the amount of mature acid hydrolases present in a preparation of autophagic vacuoles isolated from a metrizamide gradient. Combined, the results suggested nascent autophagic vacuoles mature into degradative vacuoles in a stepwise fashion: (a) acquisition of lysosomal membrane proteins by fusing with a vesicle deficient in hydrolytic enzymes (e.g., prelysosome); (b) vacuole acidification; and (c) acquisition of hydrolases by fusing with preexisting lysosomes or Golgi apparatus-derived vesicles.
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Affiliation(s)
- W A Dunn
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610
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Wang SL, Shiverick KT, Ogilvie S, Dunn WA, Raizada MK. Characterization of epidermal growth factor receptors in astrocytic glial and neuronal cells in primary culture. Endocrinology 1989; 124:240-7. [PMID: 2783308 DOI: 10.1210/endo-124-1-240] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Studies characterized the structure and function of epidermal growth factor (EGF) receptors in astrocytic glial cells and neuronal cells in primary culture from neonatal rat brain. [125I]EGF binding to membranes prepared from glial and neuronal cultures was specific and dependent on protein concentration; however, glial preparations bound 5-fold more [125I]EGF per mg protein. Unlabeled EGF competed for binding to both glial and neuronal membranes with an IC50 of 5 nM, whereas insulin, insulin-like growth factor I, and nerve growth factor failed to compete. Scatchard plot analysis of binding data for glial cells yielded a curvilinear plot with dissociation constants of 7.12 nM for high affinity and 6.2 microM for low affinity sites. The higher level of binding in glial compared to neuronal membranes reflected a greater number of binding sites rather than differences in receptor affinity. In glial membranes, [125I]EGF covalently cross-linked to one major protein with a mol wt of 170,000, and EGF stimulated the phosphorylation of a 170,000 protein which was half-maximal at 20 nM. In contrast, neither covalent cross-linking nor receptor autophosphorylation could be detected in neuronal membranes. Culture of glial cells in the presence of EGF stimulated [35S]methionine incorporation into both cellular and secreted proteins, whereas no effect of EGF was observed in neuronal cultures. The addition of EGF to glial cultures produced a dose-dependent stimulation of [3H]thymidine incorporation as well as the multiplication of cells over a 6-day period. These observations show that functional EGF receptors in the neonatal brain are predominantly localized in glial cells.
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Affiliation(s)
- S L Wang
- Department of Pharmacology and Experimental Therapeutics, University of Florida, Gainesville 32610
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Abstract
Substantial amounts of epidermal growth factor (EGF) are cleared from the circulation by hepatocytes via receptor-mediated endocytosis and subsequently degraded within lysosomes. We have used a combined biochemical and morphological approach to examine the fate of the receptor after exposure to EGF. Polyclonal antibodies were prepared against the purified receptor and their specificity established by immunoprecipitation and immunoblotting techniques. The EGF receptor was then localized by immunofluorescence and immunoperoxidase techniques and quantified on immunoblots. In untreated livers, EGF receptor was restricted to the sinusoidal and lateral surfaces of hepatocytes. 2-4 min after exposure of cells to EGF, the receptor was found in small vesicles (i.e., coated vesicles) as well as larger vesicles and tubules at the cell periphery. By 15 min the receptor was found in multivesicular endosomes located near bile canaliculi. Exposure of hepatocytes to EGF also resulted in a rapid loss of receptor protein from total liver homogenates and a decrease in its half-life from 8.7 h in control livers to 2.5 h. This EGF-induced loss of receptors was not observed when lysosomal proteinases were inhibited by leupeptin or when endosome/lysosome fusion was prevented by low temperature (16 degrees C). In the presence of leupeptin, receptor could be detected in structures identified as lysosomes using acid-phosphatase cytochemistry. All these results suggested rapid internalization of EGF receptors in response to ligand and degradation within lysosomes. However, four times more ligand was degraded at 8 h than the number of high-affinity (Kd of 8-15 nM) EGF-binding sites lost, suggesting either (a) high-affinity receptors were recycled, and/or (b) more than 300,000 receptors were available for EGF uptake. We identified and characterized a latent pool of approximately 300,000 low-affinity receptors (Kd approximately 200 nM) that could be separated on sucrose gradients from the plasma membrane pool of approximately 300,000 high-affinity receptors (Kd of 8-15 nM). Despite the differences in their binding affinities, the high- and low-affinity receptors appeared to be structurally identical and were both EGF-dependent protein kinases. In addition, the dynamics of the low-affinity receptors were consistent with a functional role in EGF uptake and delivery to lysosomes.
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Dunn WA, Rettura G, Seifter E, Englard S. Carnitine biosynthesis from gamma-butyrobetaine and from exogenous protein-bound 6-N-trimethyl-L-lysine by the perfused guinea pig liver. Effect of ascorbate deficiency on the in situ activity of gamma-butyrobetaine hydroxylase. J Biol Chem 1984; 259:10764-70. [PMID: 6432788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The production of carnitine from peptide-bound 6-N-trimethyl-L-lysine (Lys(Me3)) or 4-N-trimethyl-aminobutyrate(gamma-butyrobetaine) perfused through isolated guinea pig livers was investigated. [Methyl-3H] Lys(Me3)-labeled agalacto-orosomucoid (AGOR) and asialofetuin were rapidly taken up and degraded by the perfused liver. Most of the free Lys(Me3) derived from Lys(Me3)-AGOR was released unmodified into the perfusion medium. However, Lys(Me3), arising from Lys(Me3)-asialofetuin was converted mostly to gamma-butyrobetaine and carnitine. gamma-Butyrobetaine added to the perfusion medium was hydroxylated to carnitine by the liver at a rate of 2.3 mumol/h. Guinea pigs maintained on an ascorbate-free diet for 17-60 days showed lowered ascorbate contents in all tissues measured and, coincidentally, a sharp reduction in carnitine levels in kidney, liver, and cardiac, and skeletal muscle. Carnitine production from [1,2,3,4-14C]gamma-butyrobetaine and [methyl-3H]Lys(Me3)-asialofetuin was reduced in perfused livers obtained from ascorbate-deficient guinea pigs. Although hydroxylation of gamma-butyrobetaine to carnitine was effectively depressed in the perfused isolated livers from ascorbate-deficient animals, hydroxylation of [methyl-3H]Lys(Me3) (derived from asialofetuin) to [methyl-3H]3-hydroxy-6-N-trimethyl-L-lysine was unaffected. Prior administration of ascorbate to the medium perfusing the isolated livers caused carnitine biosynthesis from all precursors examined to return to control values.
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