NRAMP1 Research Articles

Correction: Pristane-Induced Arthritis Loci Interact with the Slc11a1 Gene to Determine Susceptibility in Mice Selected for High Inflammation

Correction: Pristane-Induced Arthritis Loci Interact with the Slc11a1 Gene to Determine Susceptibility in Mice Selected for High Inflammation

Up-regulation of the arginine vasotocin precursor gene from Paralichthys olivaceus: isolation and expression upon acute pathogen invasion

Arginine vasotocin (AVT) is a neurohypophysial hormone of non-mammal vertebrates functions in various physiological processes and homologous to mammal vasopressin. In this study, a full-length cDNA coding for a putative AVT precursor was isolated from flounder, Paralichthys olivaceus by rapid amplification of cDNA ends. It was 641 bp long, coding 153 amino acids, and consisted in 69 bp long 5′-untranslated region (UTR), 462 bp open reading frame and 110 bp 3′-UTR. The putative amino acid sequence of flounder AVT was determined, and compared with other AVTs from different species. Also, 1,447 bp of flounder AVT gene, corresponding to the isolated cDNA region with 2 introns within it, was isolated. Reverse transcription polymerase chain reaction result showed that flounder AVT was strongly expressed in the brain but not in the any other tissues examined, confirming it is brain-specific gene. Expression profile of the AVT, together with arylalkylamine N-acetyltransferase, heat shock protein 70, interferon-stimulated gene 15 and natural resistance-associated macrophage protein genes were surveyed from Streptococcus iniae infected flounders by real-time quantitative PCR. It revealed that flounder AVT is up-regulated under acute stress compared to the non-challenged control.

Pristane-Induced Arthritis Loci Interact with the Slc11a1 Gene to Determine Susceptibility in Mice Selected for High Inflammation

AIRmax (maximal inflammation) and AIRmin (minimal inflammation) mice show distinct susceptibilities to pristane-induced arthritis (PIA). The Slc11a1 gene, which regulates macrophage and neutrophil activity, is involved in this infirmity. AIRmaxSS mice homozygous for the non-functional Slc11a1 S (gly169asp) allele obtained by genotype-assisted crosses from AIRmax and AIRmin mice are more susceptible than mice homozygous for the Slc11a1 resistant (R) allele. The present work sought to identify the quantitative trait loci (QTL) regulating PIA and to examine the interactions of these QTL with Slc11a1 alleles in modulating PIA. Mice were given two ip injections of 0.5 mL pristane at 60 day intervals, and the incidence and severity of PIA was scored up to 160 days. Genome-wide linkage studies were performed to search for arthritis QTL in an F2 (AIRmax × AIRmin, n = 290) population. Significant arthritis QTL (LODscore>4) were detected on chromosomes 5 and 8, and suggestive QTL on chromosomes 7, 17 and 19. Global gene expression analyses performed on Affymetrix mouse 1.0 ST bioarrays (27k genes) using RNA from arthritic or control mice paws showed 419 differentially expressed genes between AIRmax and AIRmin mice and demonstrated significantly (P<0.001) over-represented genes related to inflammatory responses and chemotaxis. Up-regulation of the chemokine genes Cxcl1, Cxcl9, Cxcl5, Cxcl13 on chromosome 5 was higher in AIRmaxSS than in the other lines. Macrophage scavenger receptor 1 and hemeoxigenase (decycling) 1 genes on chromosome 8 were also expressed at higher levels in AIRmaxSS mice. Our results show that the gene expression profiles of the two arthritis QTL (on chromosomes 5 and 8) correlate with Slc11a1 alleles, resulting in enhanced AIRmaxSS mice susceptibility to PIA.

Molecular analysis of solute carrier family 11 member a1 (Slc11a1) gene in ruminants and non-ruminants using computational method

Solute carrier family 11 member a1 gene (Slc11a1) previously known as natural resistance-associated macrophage protein 1 (Nramp1) is a gene of member of family of metal ion-transport protein. The cellular expression is restricted to phagocytic cells. Slc11a1 delivers bivalent metal cations from the cytosol into acidic endosomal and lysosomal compartments where Fenon and Haber-Weiss reaction generates toxic antimicrobial radicals for direct antimicrobial activity against harmful microorganisms. The present study was undertaken with the objective of analyzing Slc11a1 gene to gain insight into the evolutionary proximity and divergence as well as the polymorphism of this gene in ruminants and non-ruminants including the attendant effects of the genetic variants on the function of the Slc11a1 protein. Thirty Slc11a1 gene sequences of 6 mammalian species classified as ruminant (goat, sheep, cattle, Bubalus bubalis and Bubalus carabanensis) and non-ruminant (swine and horse) animals were investigated. The length of the Slc11a1 gene varied from 448-2,357. There was substantial genetic variation and polymorphism in the aligned sequences of Slc11a1 gene within and across species. Functional analysis of non-synonymous mutations in cattle revealed that twenty five of the amino acid substitutions at the peptide binding region could be beneficial, (E36G), (T52A), (N161S) and (V248I) were likely to be beneficial while only (Q312K) was harmful. In horse, two of the amino acid mutations were harmful, two were likely to be harmful, one was undecided, four were likely beneficial and the rest twenty were beneficial. The phylogenetic trees showed some form of proximity and differentiation in Slc11a1 sequences within and across species. The present information on the polymorphism of Slc11a1 gene might be exploited in the search for association with disease resistance in Nigerian livestock species.

Comparative analyses of cadmium and zinc uptake correlated with changes in natural resistance-associated macrophage protein (NRAMP) expression in Solanum nigrum L. and Brassica rapa

Environmental context Soils contaminated with metals can pose both environmental and human health risks. This study showed that a common crop vegetable grown in the presence of cadmium and zinc readily accumulated these metals, and thus could be a source of toxicity when eaten. The work highlights potential health risks from consuming crops grown on contaminated soils. Abstract Ingestion of plants grown in heavy metal contaminated soils can cause toxicity because of metal accumulation. We compared Cd and Zn levels in Brassica rapa, a widely grown crop vegetable, with that of the hyperaccumulator Solanum nigrum L. Solanum nigrum contained 4 times more Zn and 12 times more Cd than B. rapa, relative to dry mass. In S. nigrum Cd and Zn preferentially accumulated in the roots whereas in B. rapa Cd and Zn were concentrated more in the shoots than in the roots. The different distribution of Cd and Zn in B. rapa and S. nigrum suggests the presence of distinct metal uptake mechanisms. We correlated plant metal content with the expression of a conserved putative natural resistance-associated macrophage protein (NRAMP) metal transporter in both plants. Treatment of both plants with either Cd or Zn increased expression of the NRAMP, with expression levels being higher in the roots than in the shoots. These findings provide insights into the molecular mechanisms of heavy metal processing by S. nigrum L. and the crop vegetable B. rapa that could assist in application of these plants for phytoremediation. These investigations also highlight potential health risks associated with the consumption of crops grown on contaminated soils.

OsNRAMP3 Is a Vascular Bundles-Specific Manganese Transporter That Is Responsible for Manganese Distribution in Rice

Manganese (Mn) is an essential trace element for plants. Recently, the genes responsible for uptake of Mn in plants were identified in Arabidopsis and rice. However, the mechanism of Mn distribution in plants has not been clarified. In the present study we identified a natural resistance-associated macrophage protein (NRAMP) family gene in rice, OsNRAMP3, involved in Mn distribution. OsNRAMP3 encodes a plasma membrane-localized protein and was specifically expressed in vascular bundles, especially in phloem cells. Yeast complementation assay showed that OsNRAMP3 is a functional Mn-influx transporter. When OsNRAMP3 was absent, rice plants showed high sensitivity to Mn deficiency. Serious necrosis appeared on young leaves and root tips of the OsNRAMP3 knockout line cultivated under low Mn conditions, and high Mn supplies could rescue this phenotype. However, the necrotic young leaves of the knockout line possessed similar levels of Mn to the wild type, suggesting that the necrotic appearance was caused by disturbed distribution of Mn but not a general Mn shortage. Additionally, compared with wild type, leaf Mn content in osnramp3 plants was mostly in older leaves. We conclude that OsNRAMP3 is a vascular bundle-localized Mn-influx transporter involved in Mn distribution and contributes to remobilization of Mn from old to young leaves.

Mechanism and Regulation of Mycobactin Fatty Acyl-AMP Ligase FadD33

Mycobacterial siderophores are critical components for bacterial virulence in the host. Pathogenic mycobacteria synthesize iron chelating siderophores named mycobactin and carboxymycobactin to extract intracellular macrophage iron. The two siderophores differ in structure only by a lipophilic aliphatic chain attached on the ε-amino group of the lysine mycobactin core, which is transferred by MbtK. Prior to acyl chain transfer, the lipophilic chain requires activation by a specific fatty acyl-AMP ligase FadD33 (also known as MbtM) and is then loaded onto phosphopantetheinylated acyl carrier protein (holo-MbtL) to form covalently acylated MbtL. We demonstrate that FadD33 prefers long chain saturated lipids and initial velocity studies showed that FadD33 proceeds via a Bi Uni Uni Bi ping-pong mechanism. Inhibition experiments suggest that, during the first half-reaction (adenylation), fatty acid binds first to the free enzyme, followed by ATP and the release of pyrophosphate to form the adenylate intermediate. During the second half-reaction (ligation), holo-MbtL binds to the enzyme followed by the release of products AMP and acylated MbtL. In addition, we characterized a post-translational regulation mechanism of FadD33 by the mycobacterial protein lysine acetyltransferase in a cAMP-dependent manner. FadD33 acetylation leads to enzyme inhibition, which can be reversed by the NAD(+)-dependent deacetylase, MSMEG_5175 (DAc1). To the best of our knowledge, this is the first time that bacterial siderophore synthesis has been shown to be regulated via post-translational protein acetylation.

Molecular cloning, characterization and expression of natural resistance associated macrophage protein (Nramp) gene cDNA from grass carp (Ctenopharyngodon idella)

Natural resistance associated macrophage protein(Nramp) family is a novel family of functional related proteins with innate resistance to intracellular parasites in mammals,which has the capacity of enhancing macro-phages that are meant to kill pathogens.However,few reports are available about the structure and function of Nramp in lower vertebrates such as teleosts.In this study,cDNA of Nramp gene was amplified from liver of grass carp(Ctenopharyngodon idella) by reverse transcription polymerase chain reaction(RT-PCR) and rapid amplifi-cation of cDNA ends(RACE).The full-length cDNA of Nramp gene was 3 158 bp,including a 155 bp 5′ terminal UTR,a 1 368 bp 3′ terminal UTR and a 1 635 bp open reading frame encoding a protein with 554 amino acid residues,which contained the signature features of the Nramp protein family: 12 transmembrane(TM) domains,a consensus transport motif(CTM) with 20 amino acid residues between the transmembrane domains 8 and 9.The deduced amino acid sequence of grass carp Nramp exhibited about 62.5% 90.2% homology with 16 other verte-brate Nramp sequences.Compared with the other fish's Nramps,the unique feature of grass carp Nramp was the presence of two iron-responsive regulatory-protein-binding sites(IRE) in 3 UTR and 5 UTR.Phylogenetic analy-sis revealed that the grass carp Nramp was clustered with other fish Nramps and was closer to Nramp2 of mam-mals.RT-PCR results of grass carp Nramp transcripts in different tissues indicated that the grass carp Nramp transcripts were highly abundant in head kidney and spleen and low in muscle and skin.The grass carp kidney cells(CIK) challenged with the grass carp reovirus(GCRV) could evidently elevate Nramp mRNA levels in cell cultures.

Expression in Arabidopsis and cellular localization reveal involvement of rice NRAMP, OsNRAMP1, in arsenic transport and tolerance

Irrigation of paddy fields to arsenic (As) containing groundwater leads to As accumulation in rice grains and causes serious health risk to the people worldwide. To reduce As intake via consumption of contaminated rice grain, identification of the mechanisms for As accumulation and detoxification in rice is a prerequisite. Herein, we report involvement of a member of rice NRAMP (Natural Resistance-Associated Macrophage Protein) transporter, OsNRAMP1, in As, in addition to cadmium (Cd), accumulation through expression in yeast and Arabidopsis. Expression of OsNRAMP1 in yeast mutant (fet3fet4) rescued iron (Fe) uptake and exhibited enhanced accumulation of As and Cd. Expression of OsNRAMP1 in Arabidopsis provided tolerance with enhanced As and Cd accumulation in root and shoot. Cellular localization revealed that OsNRAMP1 resides on plasma membrane of endodermis and pericycle cells and may assist in xylem loading for root to shoot mobilization. This is the first report demonstrating role of NRAMP in xylem mediated loading and enhanced accumulation of As and Cd in plants. We propose that genetic modification of OsNRAMP1 in rice might be helpful in developing rice with low As and Cd content in grain and minimize the risk of food chain contamination to these toxic metals.

Upregulation of the Host SLC11A1 Gene by Clostridium difficile Toxin B Facilitates Glucosylation of Rho GTPases and Enhances Toxin Lethality

Pseudomembranous enterocolitis associated with Clostridium difficile infection is an important cause of morbidity and mortality in patients being treated with antibiotics. Two closely related large protein toxins produced by C. difficile, TcdA and TcdB, which act identically but at different efficiencies to glucosylate low-molecular-weight Rho GTPases, underlie the microbe's pathogenicity. Using antisense RNA encoded by a library of human expressed sequence tags (ESTs), we randomly inactivated host chromosomal genes in HeLa cells and isolated clones that survived exposure to ordinarily lethal doses of TcdB. This phenotypic screening and subsequent analysis identified solute carrier family 11 member 1 (SLC11A1; formerly NRAMP1), a divalent cation transporter crucial to host defense against certain microbes, as an enhancer of TcdB lethality. Whereas SLC11A1 normally is poorly expressed in human cells of nonmyeloid lineage, TcdB increased SLC11A1 mRNA abundance in such cells through the actions of the RNA-binding protein HuR. We show that short hairpin RNA (shRNA) directed against SLC11A1 reduced TcdB glucosylation of small Rho GTPases and, consequently, toxin lethality. Consistent with the previously known role of SLC11A1 in cation transport, these effects were enhanced by elevation of Mn(2+) in media; conversely, they were decreased by treatment with a chelator of divalent cations. Our findings reveal an unsuspected role for SLC11A1 in determining C. difficile pathogenicity, demonstrate the novel ability of a bacterial toxin to increase its cytotoxicity, establish a mechanistic basis for these effects, and suggest a therapeutic approach to mitigate cell killing by C. difficile toxins A and B.

Functional analysis of bovine Nramp1 and production of transgenic cloned embryosin vitro

Natural resistance-associated macrophage protein 1 (Nramp1) plays an important role in restraining the growth of intracellular pathogens within macrophages. In this study, Nramp1 cDNA was cloned from Qinchuan cattle and its anti-bacterial activity was demonstrated as being able to significantly inhibit the growth of Salmonella abortusovis and Brucella abortus in macrophages. Calf fibroblasts stably transfected with pSP-NRAMP1-HA vector were used to reconstruct bovine embryos by somatic cell nuclear transfer (SCNT). Reconstructed embryos were maturated in vitro and the blastocyst formation rate (14.0%) was similar to that of control embryos (14.5%). Transgenic blastocysts were transplanted into 43 recipient cattle, of which 14 recipients became pregnant as evidenced by non-return estrus and by rectal palpation. One fetus was aborted after 6½ months of pregnancy and transgene integration was confirmed by semi-quantitative polymerase chain reaction. Together, this study showed that bovine Nramp1 retains biological function against the growth of intracellular bacteria and can be used to reconstruct embryos and produce Nramp1 transgenic cattle, which may benefit the animal and enhance their ability to prevent attack by intracellular pathogens.

Nitric Oxide Not Apoptosis Mediates Differential Killing of Mycobacterium bovis in Bovine Macrophages

To identify the resistance phenotype against Mycobacterium bovis in cattle, we used a bactericidal assay that has been considered a marker of this trait. Three of 24 cows (12.5%) were phenotyped as resistant and 21 as susceptible. Resistance of bovine macrophages (MΦ) to BCG challenge was evaluated for its association with SLC11A1 GT microsatellite polymorphisms within 3′UTR region. Twenty-three cows (95.8%) had a GT13 genotype, reported as resistant, consequently the SLC11A1polymorphism was not in agreement with our bactericidal assay results. MΦ of cows with resistant or susceptible phenotype were challenged in vitro with virulent M. bovis field strain or BCG, and nitric oxide production, bacterial killing and apoptosis induction were measured in resting and LPS-primed states. M. bovis field strain induced more apoptosis than BCG, although the difference was not significant. Resistant MΦ controlled better the replication of M. bovis (P<0.01), produced more nitric oxide (P<0.05) and were slightly more prone to undergo apoptosis than susceptible cells. LPS pretreatment of MΦ enhanced all the functional parameters analyzed. Inhibition of nitric oxide production with n G-monomethyl-L-arginine monoacetate enhanced replication of M. bovis but did not modify apoptosis rates in both resistant and susceptible MΦ. We conclude that nitric oxide production not apoptosis is a major determinant of macrophage resistance to M. bovis infection in cattle and that the influence of SLC11A1 gene 3′UTR polymorphism is not associated with this event.

Identification of a novel microRNA (miRNA) from rice that targets an alternatively spliced transcript of the Nramp6 (Natural resistance‐associated macrophage protein 6) gene involved in pathogen resistance

Plants have evolved efficient defence mechanisms to defend themselves from pathogen attack. Although many studies have focused on the transcriptional regulation of defence responses, less is known about the involvement of microRNAs (miRNAs) as post-transcriptional regulators of gene expression in plant immunity. This work investigates miRNAs that are regulated by elicitors from the blast fungus Magnaporthe oryzae in rice (Oryza sativa). Small RNA libraries were constructed from rice tissues and subjected to high-throughput sequencing for the identification of elicitor-responsive miRNAs. Target gene expression was examined by microarray analysis. Transgenic lines were used for the analysis of miRNA functioning in disease resistance. Elicitor treatment is accompanied by dynamic alterations in the expression of a significant number of miRNAs, including new members of annotated miRNAs. Novel miRNAs from rice are proposed. We report a new rice miRNA, osa-miR7695, which negatively regulates an alternatively spliced transcript of OsNramp6 (Natural resistance-associated macrophage protein 6). This novel miRNA experienced natural and domestication selection events during evolution, and its overexpression in rice confers pathogen resistance. This study highlights an miRNA-mediated regulation of OsNramp6 in disease resistance, whilst illustrating the existence of a novel regulatory network that integrates miRNA function and mRNA processing in plant immunity.

Solute Carrier 11A1 Is Expressed by Innate Lymphocytes and Augments Their Activation

Solute carrier 11A1 (SLC11A1) is a divalent ion transporter formerly known as the natural resistance-associated macrophage protein (NRAMP1) and the Bcg/Lsh/Ity locus. SLC11A1 was thought to be exclusively expressed in monocyte/macrophages and to have roles in phagosome maturation and cell activation. We characterized the expression of SLC11A1 in the majority of human and bovine γδ T cells and NK cells and in human CD3(+)CD45RO(+) T cells. Consistent with a role for iron-dependent inhibition of protein tyrosine phosphatases, SLC11A1(+) lymphocytes were more prone to activation and retained tyrosine phosphorylation. Transfection of SLC11A1 into a human γδ T cell-like line rendered the cells more prone to activation. Nonadherent splenocytes from wild-type mice expressed significantly greater IFN-γ compared with cells from Sv/129 (SLC11A1(-/-)) mice. Our data suggest that SLC11A1 has a heretofore unknown role in activation of a large subset of innate lymphocytes that are critical sources of IFN-γ. SLC11A1(+) animals have enhanced innate IFN-γ expression in response to Salmonella infection compared with SLC11A1(-) mice, which include commonly used inbred laboratory mice. Expression of SLC11A1 in innate lymphocytes and its role in augmenting their activation may account for inconsistencies in studies of innate lymphocytes in different animal models.

Genetic and functional evidence for a role for SLC11A1 in susceptibility to otitis media in early childhood in a Western Australian population

Otitis media (OM) is a common disease in early childhood characterised by inflammation of the middle ear. Susceptibility to recurrent acute OM (rAOM; ⩾3 episodes AOM in 6months) and chronic OM with effusion (COME; middle ear effusion ⩾3months) is 40–70% heritable. Three bacterial pathogens commonly associated with OM, Streptococcus pneumoniae (Sp), non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mc), have been observed within adenoids and as facultative intracellular pathogens that invade and survive in mononuclear cells. Case/pseudo-control conditional logistic regression analysis of variants in the SLC11A1 gene, initially identified for its role in resistance to intra-macrophage pathogens in mice, revealed association with OM at four polymorphisms (Pbest=0.025) in 531 families (660 affected children) from the Western Australian Family Study of Otitis Media. This included association at the functional promoter GTn polymorphism (rs34448891) with alleles that regulate high (allele 3; odds ratio=1.2, 95% CI 1.00–1.44, P=0.04) versus low (allele 2; odds ratio=0.83, 95% CI 0.69–0.99, P=0.04) SLC11A1 expression. Haplotype and stepwise conditional logistic regression analyses support a single genetic effect in the proximal region of SLC11A1, with the haplotype 3_C_C_G across rs34448891_rs2276631_rs3731865_rs2695343 significantly (P=0.008) over-transmitted to affected offspring. Stratified analysis showed no association with OM in children who had undergone adenoidectomy (296 children), whereas children with adenoids intact (364 children) showed improved significance at the GTn polymorphism (allele 3: odds ratio=1.38, 95% CI=1.10–1.75, P=0.006). Quantitative RT/PCR demonstrated high expression of SLC11A1 in mononuclear cells isolated from adenoid tissue, with a trend for decreased expression with increasing copies of GTn allele 2. Expression of SLC11A1 was enhanced at 12 (P=1.2×10−3) and 24h (P<1.0×10−4) after infection of Mono-Mac-6 cells with NTHi. This study identifies SLC11A1 as a novel candidate for OM susceptibility, particularly in children with adenoids intact. Further analysis in other cohorts is required to validate these observations.

Association of Mycobacterium avium subsp. paratuberculosis and SLC11A1 polymorphisms in Sardinian multiple sclerosis patients

Recent findings propose that Mycobacterium avium subsp. paratuberculosis (MAP) infection could act as risk factor in favoring multiple sclerosis (MS) progression. SLC11A1 is a gene associated with mycobacterial survival in the host and it may be involved in the induction and maintenance of autoimmune disease. In this preliminary study, 100 MS patients and 100 healthy controls (HCs) from Sardinia were enrolled. Eight single nucleotide polymorphisms (SNPs) in the SLC11A gene were searched by PCR RFLP-genotyping. IS900 specie specific PCR was undertaken to search for MAP presence. Indirect ELISA was performed to asses if MS patients displayed a stronger humoral response against MAP2694 protein compared to the HCs. Only rs2276631 SNP was associated with MS. MAP DNA was detected in 23 out of 100 MS patients (23%) and in 7 out of 100 HCs (7%). A strong humoral response against MAP2694 protein was detected in 36% of MS patients and only in 3% of HCs. A correlation between ELISA sero-positivity and the rs2276631 SNP was also found. Our preliminary results suggest that the Sardinian population might be prone to develop autoimmune disease due to polymorphisms in immunomodulating the SLC11A1 gene, which is important in the immune response against intracellular bacteria such as MAP.

The NRAMP1 polymorphism as a risk factor for tuberculous spondylitis.

In the present study, we analysed the association between the incidence of tuberculous spondylitis with the Natural Resistance Associated Macrophage Protein 1 (NRAMP1, also known as Solute Carrier Family 11a member1) polymorphism by studying the genetic segregation of this polymorphism and the incidence of the disease among members of the West Javanese population undergoing surgery for tuberculous spondylitis at our institution. We compared the distribution of NRAMP1 polymorphism at two specific sites, namely D543N, and 3'UTR, among subjects with pulmonary tuberculosis and tuberculous spondylitis. We found no significant differences in distribution of polymorphism between the two groups, or between pulmonary tuberculosis and tuberculous spondylitis compared to healthy subjects. However, a pattern emerged in that polymorphisms at the two sites seemed to be protective against development of tuberculous spondylitis in our study population. We concluded that in the West Javanese population, there is no association between NRAMP1 polymorphism with the propensity for development of pulmonary tuberculosis or tuberculous spondylitis. In fact, NRAMP1 may provide protection against the development of tuberculous spondylitis. tuberculous spondylitis, NRAMP1, polymorphism.

Cell-Type Specific Determinants of NRAMP1 Expression in Professional Phagocytes.

The Natural resistance-associated macrophage protein 1 (Nramp1 or Solute carrier 11 member 1, Slc11a1) transports divalent metals across the membrane of late endosomes and lysosomes in professional phagocytes. Nramp1 represents an ancient eukaryotic cell-autonomous defense whereas the gene duplication that yielded Nramp1 and Nramp2 predated the origin of Sarcopterygians (lobe-finned fishes and tetrapods). SLC11A1 genetic polymorphisms associated with human resistance to tuberculosis consist of potential regulatory variants. Herein, current knowledge of the regulation of SLC11A1 gene expression is reviewed and comprehensive analysis of ENCODE data available for hematopoietic cell-types suggests a hypothesis for the regulation of SLC11A1 expression during myeloid development and phagocyte functional polarization. SLC11A1 is part of a 34.6 kb CTCF-insulated locus scattered with predicted regulatory elements: a 3' enhancer, a large 5' enhancer domain and four elements spread around the transcription start site (TSS), including several C/EBP and PU.1 sites. SLC11A1 locus ends appear mobilized by ETS-related factors early during myelopoiesis; activation of both 5' and 3' enhancers in myelo-monocytic cells correlate with transcription factor binding at the TSS. Characterizing the corresponding cis/trans determinants functionally will establish the mechanisms involved and possibly reveal genetic variation that impacts susceptibility to infectious or immune diseases.

NRAMP1, VDR, HLA-DRB1, and HLA-DQB1 Gene Polymorphisms in Susceptibility to Tuberculosis among the Chinese Kazakh Population: A Case-Control Study

Background. To explore the potential role of natural-resistance-associated macrophage protein 1 (NRAMP1) gene, vitamin D receptor (VDR) gene, (human leukocyte antigen, (HLA-DRB1) HLA) -DRB1 gene, and HLA-DQB1 gene polymorphisms in susceptibility to tuberculosis (TB) in the Chinese Kazakh population. Methods. A case-control study was performed on the Chinese Kazak population. Genetic polymorphisms of NRAMP1 gene (3′UTR) and VDR gene (TaqI and FokI) were analysed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing analysis in TB patients and healthy controls. Genetic polymorphisms of HLA-DRB1 gene and HLA-DQB1 gene in the two groups were detected with polymerase chain reaction-sequence-specific primers (PCR-SSPs) technique and sequencing analysis. Results. There was statistically significant difference in the 3′UTR polymorphism between the TB patients and healthy controls in the Chinese Kazak population (P = 0.002; OR = 1.859; 95% CI = 1.182–2.926). Significant difference was observed in the FokI polymorphism between the TB patients and healthy controls (P = 0.001; OR = 1.530; 95% CI = 1.007–2.325). It does not disclose any significant association between the disease and TaqI (P > 0.05). Alleles HLA-DRB1∗04 and HLA-DQB1∗0201 occurred more frequently in patients than in controls (P = 0.011 and 0.002; OR = 1.889 and 1.802; 95% CI = 1.153–3.095 and 1.230–2.639, resp.). Conclusions. Polymorphisms in the NRAMP1 gene, VDR gene, HLA-DRB1 gene, and HLA-DQB1 gene are statistically associated with susceptibility to TB in the Chinese Kazakh population.

Relationship between NRAMP1 gene polymorphism and efficacy of BCG vaccine in helminth-infected populations

Infection of mothers with schistosomiasis and filariasis has been shown to influence infant responses to neonatal Bacille Calmette-Guérin (BCG) immunization. The genetic makeup of infants is also considered an important determinant for the activity of BCG vaccine. The effect of natural resistance-associated macrophage protein 1 (NRAMP1) gene polymorphism on the efficacy of BCG vaccine was examined in neonates with helminth-infected mothers (63 infants) and the results were compared with neonates of uninfected mothers (187 infants). After BCG vaccination, assessment of scar presence, tuberculin test, stool analysis, and IgE level was performed. Polymorphism of the NRAMP1 gene was investigated by PCR amplification followed by RFLP analysis. We found that patients with heterozygosity of intron 4 (GC) and/or maternal infection with helminth parasites showed reduced efficacy of BCG vaccine against tuberculosis.