Natural Resistance-associated Macrophage Protein Gene Research Articles

The natural resistance-associated macrophage protein gene in African Americans with sarcoidosis.

The histologic and clinical similarities between tuberculosis and sarcoidosis suggest a shared underlying pathophysiology. Human natural resistance-associated macrophage protein (NRAMP1), which is closely related to the mouse gene, has been associated with susceptibility to tuberculosis in some human populations. Given the importance of the Nramp1 gene in animal models of granulomatous disorders, the association with human tuberculosis, and the possible role of NRAMP1 in macrophage activation and function, we hypothesized that human NRAMP1 plays a role in susceptibility to sarcoidosis. We analyzed several NRAMP1 gene polymorphisms in a case-control study of 157 African American patients with sarcoidosis and 111 African American control subjects. Our results, in contrast to those in tuberculosis patients, showed that the less common genotypes were found more often in control subjects than in case patients (odds ratio, 0.48; 95% confidence interval, 0.28-0.81). In particular, one polymorphism, a (CA)(n) repeat in the immediate 5' region of the gene, was found to have a protective effect (P = 0. 014). Whereas NRAMP1 polymorphisms have been associated with increased susceptibility to tuberculosis, our results suggest that at least one NRAMP1 polymorphism may decrease susceptibility in sarcoidosis.

The natural resistance-associated macrophage protein gene is associated with Crohn's disease

Background. Identification of the genes causing inflammatory bowel disease (IBD) would enhance the understanding of and the treatment options for this disease. A hyperreactive immune response toward the intestinal flora has been implicated in the pathology of IBD. The natural resistance-associated macrophage protein (NRAMP) gene is believed to regulate macrophage function, especially the ability to fight intracellular pathogens. Genetic differences of NRAMP might, therefore, be associated with IBD. Methods. Two DNA markers (D2S434 and D2S1323) near NRAMP were polymerase chain reaction (PCR) amplified and genotyped with DNA from 103 patients with Crohn's disease, 85 patients with ulcerative colitis, and 98 control subjects. Clinical data were obtained for all patients. Comparisons were made by chi-squared analysis. Disease association with significant haplotypes was expressed as odds ratio. Results. Allele and genotype distributions were similar for both markers among all groups. Haplotype frequencies were different among Crohn's disease and control groups (p = 0.024). Two individual haplotypes of the patients with Crohn's disease were significant compared with control subjects: DA (p = 0.023; odds ratio, 0.5; 95% confidence interval, 0.3 to 0.9) and EA (p = 0.001; odds ratio, 3.5; 95% confidence interval, 1.6 to 3.2). The haplotype distribution was different within three age-of-onset groups of patients with Crohn's disease (p = 0.05). Conclusions. This study is the first to report an association between the NRAMP gene and Crohn's disease.

Expression of NRAMP1 molecule in human peripheral blood leukocytes

Natural resistance or susceptibility of host to infection with several intracellular pathogens, such as Mycobacterium, Salmonella and Leishmania, is controlled in mice by the expression of a single dominant gene locus designated Lsh/Ity/Bcg. Natural resistance-associated macrophage protein gene 1 ( Nramp1) was isolated as a candidate gene. Nramp1 gene encodes a 60 kDa polypeptide with 10–12 potential transmembrane domains and an evolutionary conserved consensus transport motif. The present study shows that the human NRAMP1 gene is expressed in all established hematopoietic cell lines examined, including monocytes/macrophages and B- and T-lymphocytes. In contrast, cell type-specific expressions are observed in human peripheral blood leukocytes. NRAMP1 expression is very low level in granulocytes. B- and T-lymphocytes are equivalent in the level of NRAMP1 expression. Notable expression of NRAMP1 gene can be detected in the monocyte population. These results have important implications for the host defence mechanisms and the pathogenesis of intracelluar pathogens which are recognized and ingested by the mononuclear phagocyte system including monocytes/macrophages.

Location of NRAMP1 molecule on the plasma membrane and its association with microtubules

Natural resistance to infection with intracellular parasites, such as Leishmania, Salmonella, and Mycobacterium, is controlled in mice by the expression of a single dominant gene locus designated Lsh/Ity/Bcg. Natural resistance-associated macrophage protein gene 1 ( NRAMP1) was isolated as a candidate gene. NRAMP1 encodes an M r 60 000 polypeptide with 10–12 potential transmembrane domains and an evolutionary conserved consensus transport motif. The present study shows that the human NRAMP1 molecule is expressed in all cell lineages of macrophage/monocyte and B- and T-lymphocytes. Immunohistochemical analysis using antihuman NRAMP1 antibody provides the direct evidence that the NRAMP1 molecule is located and distributed on the plasma membrane. An NRAMP1-glutathione S-transferase (GST) fusion protein was used to affinity-purify a protein, bound to the NH 2-terminal cytoplasmic domain of NRAMP1. It was found that the NRAMP1 molecule was associated with α- and β-tubulin of microtubules. These results suggest that NRAMP1 may function as a molecule, possessing the abilities of membrane-anchoring and microtubule-binding, for the microtubule-mediated transport of vesicles and be a new class of microtubule-associated proteins.

Structural analysis of human natural resistance-associated macrophage protein 1 promoter

Natural resistance-associated macrophage protein gene 1 ( Nramp1) was isolated as a candidate for the mouse gene locus Lsh/Ity/Bcg, which regulates macrophage activation for antimicrobial activity against intracellular pathogens. To investigate the structural and functional organization of the human homologue, NRAMP1, the overlapping genomic clones encompassing NRAMP1 were isolated. These clones spanned approximately 35 kb in size and the nucleotide sequence of 3779 bp of the 5′ flanking region has been determined. The transcription start site was mapped by primer extension analysis. A TATA box element and the transcription regulatory elements in the acute phase reaction were found.

Institutional Control Measures for Tuberculosis in the Era of Multiple Drug Resistance: ACCP/ATS Consensus Conference

Institutional Control Measures for Tuberculosis in the Era of Multiple Drug Resistance: ACCP/ATS Consensus Conference

Identification of natural resistance-associated macrophage protein in peripheral blood lymphocytes

Natural resistance-associated macrophage protein gene ( Nramp) was isolated from the gene locus Lsh/Ity/Bcg, which regulates macrophage activation for antimicrobial activity against intracellular pathogens. The deduced protein sequence encodes an integral membrane protein that has structural homology with known prokaryotic and eukaryotic transport systems. In the present study, a polyclonal antibody was raised with the synthetic peptide of the carboxy-terminal 17 amino acids of human Nramp. The protein product of the gene is apparently present in human peripheral blood lymphocyte (PBL) as a 60 kD a protein recognized by the antibody, which is consistent with the calculated molecular mass. Bacterial lipopolysaccharide or interferon-γ did not appear to stimulate the level of Nramp expression in PBL.

Isolation and Characterization of Human NRAMP cDNA

The mouse gene locus Lsh/Ity/Bcg regulates macrophage activation for antimicrobial activity against intracellular pathogens. A candidate gene, designated natural resistance-associated macrophage protein gene (Nramp), recently isolated from a mouse pre-B cell cDNA library, encodes an integral membrane protein that has structural homology with known prokaryotic and eukaryotic transport systems. In the present study, the cDNA for human Nramp was isolated by screening a human monocyte cDNA library. The cDNA was 2245 bp in length and coded for a protein of 483 amino acid residues with a molecular weight mass of 52.8 kDa. The deduced amino acid sequence was 89% homologous with that of mouse. Southern blot analysis indicated a single gene for Nramp counterpart in the human genome. Northern blot analysis revealed a single species of mRNA of approximately 2.5 kb.