Transcriptional control of Nramp1: a paradigm for the repressive action of c-Myc

2004 ◽  
Vol 32 (6) ◽  
pp. 1084-1086 ◽  
Author(s):  
A.S. Lapham ◽  
E.S. Phillips ◽  
C.H. Barton
Keyword(s):  
Transcriptional Control ◽  
Cell Activation ◽  
Zinc Finger Protein ◽  
Specific Binding ◽  
Divalent Cations ◽  
Natural Resistance ◽  
Finger Protein ◽  
Late Endosomes ◽  
Solute Carrier ◽  
Macrophage Protein

Slc11a1/Nramp1 (solute carrier family 11 member a1/murine natural resistance-associated macrophage protein 1 gene) encodes a divalent cation transporter that resides within lysosomes/late endosomes of macrophages. Nramp1 modulates the cellular distribution of divalent cations in response to cell activation by intracellular pathogens. Nramp1 expression is repressed and activated by the proto-oncogene c-Myc and Miz-1 (c-Myc-interacting zinc finger protein 1) respectively. Here we demonstrate, using a c-Myc mutant (V394D, Val394→Asp) that is incapable of binding Miz-1, that c-Myc repression of Nramp1 transcription is dependent on its interaction with Miz-1. An oligo pull-down assay demonstrates specific binding of recombinant Miz-1 to the Nramp1 Miz-1-binding site or initiator element(s), and Miz-1-dependent c-Myc recruitment.

Genetic analysis of SLC11A1 polymorphisms in multiple sclerosis patients

2004 ◽  
Vol 10 (6) ◽  
pp. 618-620 ◽  
Author(s):  
Manuel Comabella ◽  
Laura Altet ◽  
Francesc Peris ◽  
Pablo Villoslada ◽  
Armand Sánchez ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Natural Resistance ◽  
Bivalent Cation ◽  
Slc11a1 Gene ◽  
Late Endosomes ◽  
Solute Carrier ◽  
Macrophage Protein ◽  
Multiple Sclerosis Patients ◽  
Control Study

Solute carrier 11a1 (SLC11A1; formerly NRAMP1, where NRAMP stands for natural resistance-associated macrophage protein) is a proton/bivalent cation antiporter that localizes to late endosomes/lysosomes. SLC11A1 regulates macrophage functions that are of potential importance in the induction and/or maintenance of autoimmune diseases such as rheumatoid arthritis, type 1 diabetes and Crohn’s disease. We investigated SLC11A1 gene as a candidate gene for genetic susceptibility to multiple sclerosis (MS) in our population. Four SLC11A1 gene polymorphisms (5?GT repeat, D543N, 1729 -55del4 and 1729 -271del4) were analysed in a case-control study of 195 patients with MS and 125 control subjects. We found no evidence of association between SLC11A1 polymorphisms and MS susceptibility in the Spanish population.

scholarly journals Mycobacterium tuberculosis Expresses a Novel Ph-Dependent Divalent Cation Transporter Belonging to the Nramp Family

1999 ◽  
Vol 190 (5) ◽  
pp. 717-724 ◽  
Author(s):  
Daniel Agranoff ◽  
Irene M. Monahan ◽  
Joseph A. Mangan ◽  
Philip D. Butcher ◽  
Sanjeev Krishna
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Metal Ion ◽  
Divalent Cations ◽  
Natural Resistance ◽  
Xenopus Laevis Oocytes ◽  
Mrna Levels ◽  
Susceptibility To Infection ◽  
Reverse Transcription Pcr ◽  
Acidic Extracellular Ph ◽  
Macrophage Protein

Mammalian natural resistance–associated macrophage protein (Nramp) homologues are important determinants of susceptibility to infection by diverse intracellular pathogens including mycobacteria. Eukaryotic Nramp homologues transport divalent cations such as Fe2+, Mn2+, Zn2+, and Cu2+. Mycobacterium tuberculosis and Mycobacterium bovis (bacillus Calmette-Guérin [BCG]) also encode an Nramp homologue (Mramp). RNA encoding Mramp induces ∼20-fold increases in 65Zn2+ and 55Fe2+ uptake when injected into Xenopus laevis oocytes. Transport is dependent on acidic extracellular pH and is maximal between pH 5.5 and 6.5. Mramp-mediated 65Zn2+ and 55Fe2+ transport is abolished by an excess of Mn2+ and Cu2+, confirming that Mramp interacts with a broad range of divalent transition metal cations. Using semiquantitative reverse transcription PCR, we show that Mramp mRNA levels in M. tuberculosis are upregulated in response to increases in ambient Fe2+ and Cu2+ between <1 and 5 μM concentrations and that this upregulation occurs in parallel with mRNA for y39, a putative metal-transporting P-type ATPase. Using a quantitative ratiometric PCR technique, we demonstrate a fourfold decrease in Mramp/y39 mRNA ratios from organisms grown in 5–70 μM Cu2+. M. bovis BCG cultured axenically and within THP-1 cells also expresses mRNA encoding Mramp. Mramp exemplifies a novel prokaryotic class of metal ion transporter. Within phagosomes, Mramp and Nramp1 may compete for the same divalent cations, with implications for intracellular survival of mycobacteria.

Solute carrier 11a1 (Slc11a1; formerly Nramp1) regulates metabolism and release of iron acquired by phagocytic, but not transferrin-receptor-mediated, iron uptake

2002 ◽  
Vol 363 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Victoriano MULERO ◽  
Susan SEARLE ◽  
Jenefer M. BLACKWELL ◽  
Jeremy H. BROCK
Keyword(s):  
Iron Uptake ◽  
Interferon Γ ◽  
Natural Resistance ◽  
Null Alleles ◽  
Iron Release ◽  
Wild Type ◽  
Bivalent Cation ◽  
Insoluble Form ◽  
Solute Carrier ◽  
Macrophage Protein

Solute carrier 11a1 (Slc11a1; formerly Nramp1; where Nramp stands for natural-resistance-associated macrophage protein) is a proton/bivalent cation antiporter that localizes to late endosomes/lysosomes and controls resistance to pathogens. In the present study the role of Slc11a1 in iron turnover is examined in macrophages transfected with Slc11a1Gly169 (wild-type) or Slc11a1Asp169 (mutant = functional null) alleles. Following direct acquisition of transferrin (Tf)-bound iron via the Tf receptor, iron uptake and release was equivalent in wild-type and mutant macrophages and was not influenced by interferon-γ/lipopolysaccharide activation. Following phagocytosis of [59Fe]Tf—anti-Tf immune complexes, iron uptake was equivalent and up-regulated similarly with activation, but intracellular distribution was markedly different. In wild-type macrophages most iron was in the soluble (60%) rather than insoluble (12%) fraction, with 28% ferritin (Ft)-bound. With activation, the soluble component increased to 82% at the expense of Ft-bound iron (< 5%). In mutant macrophages, 40–50% of iron was in insoluble form, 50–60% was soluble and < 5% was Ft-bound. Western-blot analysis confirmed failure of mutant macrophages to degrade complexes 24h after phagocytic uptake. Confocal microscopy showed that complexes were within lysosome-associated membrane protein 1-positive vesicles in wild-type and mutant macrophages at 30min and 24h, implying failure in the degradative process in mature phagosomes in mutant macrophages. NO-mediated iron release was 2.4-fold higher in activated wild-type macrophages compared with mutant macrophages. Overall, our data suggest that iron acquired by phagocytosis and degradation is retained within the phagosomal compartment in wild-type macrophages, and that NO triggers iron release by direct secretion of phagosomal contents rather than via the cytoplasm.

scholarly journals Host Resistance to Intracellular Infection: Mutation of Natural Resistance-associated Macrophage Protein 1 (Nramp1) Impairs Phagosomal Acidification

1998 ◽  
Vol 188 (2) ◽  
pp. 351-364 ◽  
Author(s):  
David J. Hackam ◽  
Ori D. Rotstein ◽  
Wei-jian Zhang ◽  
Samantha Gruenheid ◽  
Philippe Gros ◽  
...  
Keyword(s):  
Integral Membrane Protein ◽  
Natural Resistance ◽  
Wild Type ◽  
Intracellular Parasites ◽  
Late Endosomes ◽  
Latex Beads ◽  
Buffering Power ◽  
Ratio Imaging ◽  
Macrophage Protein ◽  
Phagosomal Membrane

The mechanisms underlying the survival of intracellular parasites such as mycobacteria in host macrophages remain poorly understood. In mice, mutations at the Nramp1 gene (for natural resistance-associated macrophage protein), cause susceptibility to mycobacterial infections. Nramp1 encodes an integral membrane protein that is recruited to the phagosome membrane in infected macrophages. In this study, we used microfluorescence ratio imaging of macrophages from wild-type and Nramp1 mutant mice to analyze the effect of loss of Nramp1 function on the properties of phagosomes containing inert particles or live mycobacteria. The pH of phagosomes containing live Mycobacterium bovis was significantly more acidic in Nramp1- expressing macrophages than in mutant cells (pH 5.5 ± 0.06 versus pH 6.6 ± 0.05, respectively; P &lt;0.005). The enhanced acidification could not be accounted for by differences in proton consumption during dismutation of superoxide, phagosomal buffering power, counterion conductance, or in the rate of proton “leak”, as these were found to be comparable in wild-type and Nramp1-deficient macrophages. Rather, after ingestion of live mycobacteria, Nramp1-expressing cells exhibited increased concanamycin-sensitive H+ pumping across the phagosomal membrane. This was associated with an enhanced ability of phagosomes to fuse with vacuolar-type ATPase–containing late endosomes and/or lysosomes. This effect was restricted to live M. bovis and was not seen in phagosomes containing dead M. bovis or latex beads. These data support the notion that Nramp1 affects intracellular mycobacterial replication by modulating phagosomal pH, suggesting that Nramp1 plays a central role in this process.

scholarly journals Localisation of Nramp1 in macrophages: modulation with activation and infection

1998 ◽  
Vol 111 (19) ◽  
pp. 2855-2866 ◽  
Author(s):  
S. Searle ◽  
N.A. Bright ◽  
T.I. Roach ◽  
P.G. Atkinson ◽  
C.H. Barton ◽  
...  
Keyword(s):  
Macrophage Activation ◽  
Leishmania Major ◽  
Polyclonal Antibodies ◽  
Natural Resistance ◽  
Activated Macrophages ◽  
Wild Type ◽  
Late Endosomes ◽  
Gold Labelling ◽  
Macrophage Protein ◽  
Phagosome Fusion

The murine natural resistance-associated macrophage protein, Nramp1, has multiple pleiotropic effects on macrophage activation and regulates survival of intracellular pathogens including Leishmania, Salmonella and Mycobacterium species. Nramp1 acts as an iron transporter, but precisely how this relates to macrophage activation and/or pathogen survival remains unclear. To gain insight into function, anti-Nramp1 monoclonal and polyclonal antibodies are used here to localise Nramp1 following activation and infection. Confocal microscope analysis in uninfected macrophages demonstrates that both the mutant (infection-susceptible) and wild-type (infection-resistant) forms of the protein localise to the membranes of intracellular vesicular compartments. Gold labelling and electron microscopy defines these compartments more precisely as electron-lucent late endosomal and electron-dense lysosomal compartments, with Nramp1 colocalizing with Lamp1 and cathepsins D and L in both compartments, with macrosialin in late endosomes, and with BSA-5 nm gold in pre-loaded lysosomes. Nramp1 is upregulated with interferon-(gamma) and lipopolysaccaride treatment, coinciding with an increase in labelling in lysosomes relative to late endosomes and apparent dispersion of Nramp1-positive vesicles from a perinuclear location towards the periphery of the cytoplasm along the microtubular network. In both control and activated macrophages, expression of the protein is 3- to 4-fold higher in wild-type compared to mutant macrophages. In Leishmania major-infected macrophages, Nramp1 is observed in the membrane of the pathogen-containing phagosomes, which retain a perinuclear localization in resting macrophages. In Mycobacterium avium-infected resting and activated macrophages, Nramp1-positive vesicles migrated to converge, but not always fuse, with pathogen-containing phagosomes. The Nramp1 protein is thus located where it can have a direct influence on phagosome fusion and the microenvironment of the pathogen, as well as in the more general regulation of endosomal/lysosomal function in macrophages.

c-Myc represses the murine Nrampl promoter

2002 ◽  
Vol 30 (4) ◽  
pp. 774-777 ◽  
Author(s):  
H. Bowen ◽  
T. E. Biggs ◽  
S. T. Baker ◽  
E. Phillips ◽  
V. H. Perry ◽  
...  
Keyword(s):  
Binding Sites ◽  
Natural Resistance ◽  
Intracellular Pathogens ◽  
Flanking Sequence ◽  
Inhibitory Effects ◽  
Late Endosomes ◽  
E Box ◽  
Macrophage Protein ◽  
Iron Pool ◽  
Divalent Cation Transporter

The Nrampl (natural resistance-associated macrophage protein 1) gene modulates the growth of intracellular pathogens and encodes a divalent cation transporter within lysosomes/late endosomes of macrophages. Nrampl modulates the cytoplasmic iron pool. Wu, Polack and Dalla-Favera [(1999) Science 283, 676–679] showed reciprocal control of H-ferritin and IRP2 by c-Myc, and suggest that c-Myc regulates genes to increase cytoplasmic iron. A role for c-Myc in Nrampl regulation was evaluated. Co-transfection studies show that c-Myc represses Nrampl promoter function. Five non-canonical Myc-max binding sites (E-box) identified within the Nrampl 5′-flanking sequence are not responsible for the inhibitory effects of c-Myc on Nrampl expression. An initiator(s) adjacent to the transcriptioninitiation site is a candidate for the inhibition observed. Results are consistent with a role for Nrampl removing iron from the cytosol and antagonizing c-Myc function.

scholarly journals Natural Resistance to Intracellular Infections

2000 ◽  
Vol 192 (9) ◽  
pp. 1237-1248 ◽  
Author(s):  
Nada Jabado ◽  
Andrzej Jankowski ◽  
Samuel Dougaparsad ◽  
Virginie Picard ◽  
Sergio Grinstein ◽  
...  
Keyword(s):  
Divalent Cations ◽  
Fluorescence Emission ◽  
Integral Membrane Protein ◽  
Peritoneal Macrophages ◽  
Natural Resistance ◽  
Susceptibility To Infection ◽  
The Difference ◽  
Macrophage Protein ◽  
Phagosomal Membrane ◽  
Intracellular Infections

Mutations at the natural resistance–associated macrophage protein 1 (Nramp1) locus cause susceptibility to infection with antigenically unrelated intracellular pathogens. Nramp1 codes for an integral membrane protein expressed in the lysosomal compartment of macrophages, and is recruited to the membrane of phagosomes soon after the completion of phagocytosis. To define whether Nramp1 functions as a transporter at the phagosomal membrane, a divalent cation-sensitive fluorescent probe was designed and covalently attached to a porous particle. The resulting conjugate, zymosan–FF6, was ingested by macrophages and its fluorescence emission was recorded in situ after phagocytosis, using digital imaging. Quenching of the probe by Mn2+ was used to monitor the flux of divalent cations across the phagosomal membrane in peritoneal macrophages obtained from Nramp1-expressing (+/+) and Nramp1-deficient (−/−) macrophages. Phagosomes from Nramp1+/+ mice extrude Mn2+ faster than their Nramp−/− counterparts. The difference in the rate of transport is eliminated when acidification of the phagosomal lumen is dissipated, suggesting that divalent metal transport through Nramp1 is H+ dependent. These studies suggest that Nramp1 contributes to defense against infection by extrusion of divalent cations from the phagosomal space. Such cations are likely essential for microbial function and their removal from the phagosomal microenvironment impairs pathogenesis, resulting in enhanced bacteriostasis or bactericidal activity.

scholarly journals Application of a Glucose Dehydrogenase-Fused with Zinc Finger Protein to Label DNA Aptamers for the Electrochemical Detection of VEGF

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3878
Author(s):  
Jinhee Lee ◽  
Atsuro Tatsumi ◽  
Kaori Tsukakoshi ◽  
Ellie D. Wilson ◽  
Koichi Abe ◽  
...  
Keyword(s):  
Electrochemical Detection ◽  
Zinc Finger ◽  
Electrochemical Sensors ◽  
Zinc Finger Protein ◽  
Specific Binding ◽  
Glucose Dehydrogenase ◽  
Current Response ◽  
Finger Protein ◽  
Electrochemical Signal ◽  
Endothelial Growth Factor

Aptamer-based electrochemical sensors have gained attention in the context of developing a diagnostic biomarker detection method because of their rapid response, miniaturization ability, stability, and design flexibility. In such detection systems, enzymes are often used as labels to amplify the electrochemical signal. We have focused on glucose dehydrogenase (GDH) as a labeling enzyme for electrochemical detection owing to its high enzymatic activity, availability, and well-established electrochemical principle and platform. However, it is difficult and laborious to obtain one to one labeling of a GDH-aptamer complex with conventional chemical conjugation methods. In this study, we used GDH that was genetically fused to a DNA binding protein, i.e., zinc finger protein (ZF). Fused GDH can be attached to an aptamer spontaneously and site specifically in a buffer by exploiting the sequence-specific binding ability of ZF. Using such a fusion protein, we labeled a vascular endothelial growth factor (VEGF)-binding aptamer with GDH and detected the target electrochemically. As a result, upon the addition of glucose, the GDH labeled on the aptamer generated an amperometric signal, and the current response increased dependent on the VEGF concentration. Eventually, the developed electrochemical sensor proved to detect VEGF levels as low as 105 pM, thereby successfully demonstrating the concept of using ZF-fused GDH to enzymatically label aptamers.

scholarly journals Human genes in TB infection: their role in immune response

2016 ◽  
Vol 69 (1) ◽  
Author(s):  
D. Lykouras ◽  
F. Sampsonas ◽  
A. Kaparianos ◽  
K. Karkoulias ◽  
G. Tsoukalas ◽  
...  
Keyword(s):  
Immune Response ◽  
Innate Immune ◽  
Natural Resistance ◽  
Cell Mediated Immunity ◽  
Th1 Cell ◽  
Human Genes ◽  
Solute Carrier ◽  
Macrophage Protein ◽  
Ongoing Concern

Tuberculosis (TB) caused by the human pathogen Mycobacterium tuberculosis, is the leading cause of morbidity and mortality caused by infectious agents worldwide. Recently, there has been an ongoing concern about the clarification of the role of specific human genes and their polymorphisms involved in TB infection. In the vast majority of individuals, innate immune pathways and Thelper 1 (Th1) cell mediated immunity are activated resulting in the lysis of the bacterium. Firstly, PTPN22 R620W polymorphism is involved in the response to cases of infection. The Arg753Gln polymorphism in TLR-2 leads to a weaker response against the M. tuberculosis. The gene of the vitamin D receptor (VDR) has a few polymorphisms (BsmI, ApaI, Taq1, FokI) whose mixed genotypes alter the immune response. Solute carrier family 11 member (SLC11A1) is a proton/divalent cation antiporter that is more familiar by its former name NRAMP1 (natural resistance associated macrophage protein 1) and can affect M. tuberculosis growth. Polymorphisms of cytokines such as IL-10, IL-6, IFN-g, TNF-a, TGF-b1 can affect the immune response in various ways. Finally, a major role is played by M. tuberculosis antigens and the Ras-associated small GTP-ase 33A. As far as we know this is the first review that collates all these polymorphisms in order to give a comprehensive image of the field, which is currently evolving.

Sign in / Sign up

Export Citation Format

Share Document