| Transgenic Leishmania model for delta-aminolevulinate-inducible monospecific uroporphyria: cytolytic phototoxicity initiated by singlet oxygen-mediated inactivation of proteins and its ablation by endosomal mobilization of cytosolic uroporphyrin. | |
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MedLine Citation:
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PMID: 18487349 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Inherent deficiencies of Leishmania in heme biosynthesis were genetically complemented for delta-aminolevulinate-inducible biosynthesis and accumulation of light-excitable uroporphyrin. The phototoxic flagellar immobilization and cytolysis phenotypes and porphyrin mobilization noted previously were further analyzed biochemically and cytologically to delineate the mechanism of phototoxicity and detoxification in this monoporphyric model. Under optimal conditions of induction for approximately 3 days, cells remained viable but became increasingly uroporphyric, peaking at > or =90% of the population by approximately day 2; thereafter, a small population of less porphyric or aporphyric cells emerged. On exposure to light, the flagella of porphyric cells were immobilized in milliseconds, and singlet oxygen became detectable in their lysates. Both photosensitive phenotypes increased proportionally with the cellular uroporphyric levels and were susceptible to inhibition by azide, but not by D-mannitol. Brief irradiation of the uroporphyric cells produced no appreciable protein degradation but inactivated cytosolic neomycin phosphotransferase and significantly bleached cytosolic green fluorescent protein, which was azide reversible. These cells were irreparably photodamaged, as indicated by their subsequent loss of membrane permeability and viability. This is the first in situ demonstration that early inactivation of functional proteins by singlet oxygen initiates the cytolytic phototoxicity in uroporphyria. Detoxification appears to involve endocytic/exocytic mobilization of uroporphyrin from cytosol to "porphyrinosomes" for its eventual extracellular expulsion. This is proposed as the sole mechanism of detoxification, since it is attributable to the reversion of porphyric to aporphyric cells during uroporphyrinogenesis and repeated cycles of this event plus photolysis selected no resistant mutants, only aporphyric clones of the parental phenotypes. Further characterization of the transport system for uroporphyrin in this model is expected to benefit not only our understanding of the cellular mechanism for disposal of toxic soluble wastes but also potentially the effective management of human uroporphyria and the use of uroporphyric Leishmania for vaccine/drug delivery. |
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Authors:
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Sujoy Dutta; Bala Krishna Kolli; Aihua Tang; Shigeru Sassa; Kwang-Poo Chang |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2008-05-16 |
Journal Detail:
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Title: Eukaryotic cell Volume: 7 ISSN: 1535-9786 ISO Abbreviation: Eukaryotic Cell Publication Date: 2008 Jul |
Date Detail:
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Created Date: 2008-07-09 Completed Date: 2008-08-28 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 101130731 Medline TA: Eukaryot Cell Country: United States |
Other Details:
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Languages: eng Pagination: 1146-57 Citation Subset: IM |
Affiliation:
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Department of Microbiology/Immunology, Chicago Medical School/Rosalind Franklin University, North Chicago, Illinois 60064, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Aminolevulinic Acid
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metabolism,
pharmacology* Animals Animals, Genetically Modified / genetics, metabolism Azides / pharmacology Biological Transport Cell Membrane Permeability / radiation effects Cell Survival / radiation effects Cytosol / metabolism* Flagella / drug effects, metabolism Humans Leishmania / drug effects, genetics, metabolism*, radiation effects Light Models, Animal Phenotype Photolysis Porphyrias / chemically induced, metabolism, therapy Proteins / metabolism* Singlet Oxygen / metabolism* Transport Vesicles / metabolism Uroporphyrins / genetics, metabolism*, pharmacokinetics |
| Grant Support | |
ID/Acronym/Agency:
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AI-20486/AI/NIAID NIH HHS; AI-68835/AI/NIAID NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Azides; 0/Proteins; 0/Uroporphyrins; 106-60-5/Aminolevulinic Acid; 17778-80-2/Singlet Oxygen |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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