A Study of Nramp1 function and targeting
A Study of Nramp1 function and targeting
Nramp1 is a member of a family of divalent cation transporters found in a variety of species. Mammalian Nramp1 is found exclusively in cells of haematopoietic lineage, namely monocytes/macrophages and polymorphonuclear leukocytes. Studies in mice have shown Nramp1 to confer resistance to a number of taxonomically and antigenically distinct organisms including Leishmania, Salmonella and Mycobacteria. It is recruited to phagolysosomes upon ingestion of bacteria where it is believed to affect the microenvironment within the phagolysosome. Two hypotheses have been formulated: one in which Nramp1 depletes the microenvironment of iron, starving the bacteria; and the other in which Nramp1 supplies iron for radical production and active attack of the bacteria.
Through the use of in vitro expression systems, induction studies in murine macrophages and sequence analysis, the following has been achieved. Nramp1 is regulated by its own substrate; iron, but also by oxygen derived radicals. In addition putative sites for this type of regulation have been identified in the promoter sequence.
Stable transfectant cell lines containing constitutively expressed Nramp1 grow at a slower rate compared to controls, as measured by cell staining and [3H]-thymidine uptake. These cell lines also show greater resistance to superoxide-induced stress, and attenuation of PKCbI protein levels, transcription of which is sensitive to labile iron pool concentrations. Together the results imply that Nramp1 may act to sequester iron in an intracellular vesicular system.
Lastly analysis of EGFP wildtype and mutant Nramp1 tagged proteins indicates that N-terminal phosphorylation of Nramp1 is not important in its targeting, as has been suggested. It is also shown that under an appropriate stimulus Nramp1 can translocate to the plasma membrane; the functional significance of this is discussed.
University of Southampton
Baker, Stephen Timothy
5b99afca-eb3c-46cf-afc9-133ee7196915
2002
Baker, Stephen Timothy
5b99afca-eb3c-46cf-afc9-133ee7196915
Baker, Stephen Timothy
(2002)
A Study of Nramp1 function and targeting.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Nramp1 is a member of a family of divalent cation transporters found in a variety of species. Mammalian Nramp1 is found exclusively in cells of haematopoietic lineage, namely monocytes/macrophages and polymorphonuclear leukocytes. Studies in mice have shown Nramp1 to confer resistance to a number of taxonomically and antigenically distinct organisms including Leishmania, Salmonella and Mycobacteria. It is recruited to phagolysosomes upon ingestion of bacteria where it is believed to affect the microenvironment within the phagolysosome. Two hypotheses have been formulated: one in which Nramp1 depletes the microenvironment of iron, starving the bacteria; and the other in which Nramp1 supplies iron for radical production and active attack of the bacteria.
Through the use of in vitro expression systems, induction studies in murine macrophages and sequence analysis, the following has been achieved. Nramp1 is regulated by its own substrate; iron, but also by oxygen derived radicals. In addition putative sites for this type of regulation have been identified in the promoter sequence.
Stable transfectant cell lines containing constitutively expressed Nramp1 grow at a slower rate compared to controls, as measured by cell staining and [3H]-thymidine uptake. These cell lines also show greater resistance to superoxide-induced stress, and attenuation of PKCbI protein levels, transcription of which is sensitive to labile iron pool concentrations. Together the results imply that Nramp1 may act to sequester iron in an intracellular vesicular system.
Lastly analysis of EGFP wildtype and mutant Nramp1 tagged proteins indicates that N-terminal phosphorylation of Nramp1 is not important in its targeting, as has been suggested. It is also shown that under an appropriate stimulus Nramp1 can translocate to the plasma membrane; the functional significance of this is discussed.
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Published date: 2002
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Local EPrints ID: 464846
URI: http://eprints.soton.ac.uk/id/eprint/464846
PURE UUID: 0e777ae4-0944-46ab-9b40-40a6f6dc681c
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Date deposited: 05 Jul 2022 00:04
Last modified: 16 Mar 2024 19:47
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Author:
Stephen Timothy Baker
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