12 research outputs found
Characterization of an Oct1 orthologue in the channel catfish, Ictalurus punctatus: A negative regulator of immunoglobulin gene transcription?
BACKGROUND: The enhancer (EĪ¼3') of the immunoglobulin heavy chain locus (IGH) of the channel catfish (Ictalurus punctatus) has been well characterized. The functional core region consists of two variant Oct transcription factor binding octamer motifs and one E-protein binding Ī¼E5 site. An orthologue to the Oct2 transcription factor has previously been cloned in catfish and is a functionally active transcription factor. This study was undertaken to clone and characterize the Oct1 transcription factor, which has also been shown to be important in driving immunoglobulin gene transcription in mammals. RESULTS: An orthologue of Oct1, a POU family transcription factor, was cloned from a catfish macrophage cDNA library. The inferred amino acid sequence of the catfish Oct1, when aligned with other vertebrate Oct1 sequences, revealed clear conservation of structure, with the POU specific subdomain of catfish Oct1 showing 96% identity to that of mouse Oct1. Expression of Oct1 was observed in clonal T and B cell lines and in all tissues examined. Catfish Oct1, when transfected into both mammalian (mouse) and catfish B cell lines, unexpectedly failed to drive transcription from three different octamer-containing reporter constructs. These contained a trimer of octamer motifs, a fish V(H )promoter, and the core region of the catfish EĪ¼3' IGH enhancer, respectively. This failure of catfish Oct1 to drive transcription was not rescued by human BOB.1, a co-activator of Oct transcription factors that stimulates transcription driven by catfish Oct2. When co-transfected with catfish Oct2, Oct1 reduced Oct2 driven transcriptional activation. Electrophoretic mobility shift assays showed that catfish Oct1 (native or expressed in vitro) bound both consensus and variant octamer motifs. Putative N- and C-terminal activation domains of Oct1, when fused to a Gal4 DNA binding domain and co-transfected with Gal4-dependent reporter constructs were transcriptionally inactive, which may be due in part to a lack of residues associated with activation domain function. CONCLUSION: An orthologue to mammalian Oct1 has been found in the catfish. It is similar to mammalian Oct1 in structure and expression. However, these results indicate that the physiological functions of catfish Oct1 differ from those of mammalian Oct1 and include negative regulation of transcription
A Functional Variant in ERAP1 Predisposes to Multiple Sclerosis
The ERAP1 gene encodes an aminopeptidase involved in antigen processing. A functional polymorphism in the gene (rs30187, Arg528Lys) associates with susceptibility to ankylosying spondylitis (AS), whereas a SNP in the interacting ERAP2 gene increases susceptibility to another inflammatory autoimmune disorder, Crohn's disease (CD). We analysed rs30187 in 572 Italian patients with CD and in 517 subjects suffering from multiple sclerosis (MS); for each cohort, an independent sex- and age-matched control group was genotyped. The frequency of the 528Arg allele was significantly higher in both disease cohorts compared to the respective control population (for CD, ORā=ā1.20 95%CI: 1.01ā1.43, pā=ā0.036; for RRMS, ORā=ā1.26; 95%CI: 1.04ā1.51, pā=ā0.01). Meta-analysis with the Wellcome Trust Cases Control Consortium GWAS data confirmed the association with MS (pmetaā=ā0.005), but not with CD. In AS, the rs30187 variant has a predisposing effect only in an HLA-B27 allelic background. It remains to be evaluated whether interaction between ERAP1 and distinct HLA class I alleles also affects the predisposition to MS, and explains the failure to provide definitive evidence for a role of rs30187 in CD. Results herein support the emerging concept that a subset of master-regulatory genes underlay the pathogenesis of autoimmunity
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Novel mechanism for estrogen receptor alpha modulation of murine lupus
Female sex is a risk factor for lupus. Sex hormones, sex chromosomes and hormone receptors are implicated in the pathogenic pathways in lupus. Estrogen receptor alpha (ERĪ±) knockout (KO) mice are used for defining hormone receptor effects in lupus. Prior studies of ERĪ± KO in lupus have conflicting results, likely due to sex hormone levels, different lupus strains and different ERĪ± KO constructs. Our objective was to compare a complete KO of ERĪ± vs. the original functional KO of ERĪ± (expressing a short ERĪ±) on disease expression and immune phenotype, while controlling sex hormone levels. We studied female lupus prone NZM2410 WT and ERĪ± mutant mice. All mice (nĀ =Ā 44) were ovariectomized (OVX) for hormonal control. Groups of each genotype were estrogen (E2)-repleted after OVX. We found that OVXed NZM mice expressing the truncated ERĪ± (ERĪ± short) had significantly reduced nephritis and prolonged survival compared to both wildtype and the complete ERĪ±KO (ERĪ± null) mice, but surprisingly only if E2-repleted. ERĪ± null mice were not protected regardless of E2 status. We observed significant differences in splenic B cells and dendritic cells and a decrease in cDC2 (CD11b+CD8ā) dendritic cells, without a concomitant decrease in cDC1 (CD11b-CD8a+) cells comparing ERĪ± short to ERĪ± null or WT mice. Our data support a protective role for the ERĪ± short protein. ERĪ± short is similar to an endogenously expressed ERĪ± variant (ERĪ±46). Modulating its expression/activity represents a potential approach for treating female-predominant autoimmune diseases.
ā¢NZM2410 mice expressing an ERĪ± short variant are protected from glomerulonephritis.ā¢The protective effect of ERĪ± āshortā requires estrogen, but not testosterone.ā¢B cells and dendritic cells are reduced in NZM mice expressing the ERĪ± short variant.ā¢CD8+CD11b- (cDC1s) are increased vs. CD8a-CD11b+ (cDC2s) cells in NZM ERĪ± short mice