Molecular cloning and characterization of a glucose transporter-related gene from Trypanosoma brucei

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Genetic variation in hepcidin expression and its implications for phenotypic differences in iron metabolism

At the core of iron homeostasis is hepcidin, a small acute phase antimicrobial peptide that now also appears to synchronously orchestrate the response of iron transporter and regulatory genes. In this perspective article, Drs Bayele and Srai discuss cis and trans acting factors that may influence hepcidin variation in humans and their potential role in iron metabolism control. See related papers on page 1293 and 1297

Tumour necrosis factor alpha downregulates human hemojuvelin expression via a novel response element within its promoter

Abstract Background Iron homeostasis is chiefly regulated by hepcidin whose expression is tightly controlled by inflammation, iron stores, and hypoxia. Hemojuvelin (HJV) is a bone morphogenetic protein co-receptor that has been identified as a main upstream regulator of hepcidin expression; HJV mutations are associated with a severe form of iron overload (Juvenile haemochromatosis). Currently however, there is no information on how HJV is regulated by inflammation. Methods To study the regulation of Hjv expression by inflammation and whether Hfe has a role in that regulation, control and LPS-injected wild type and Hfe KO mice were used. Moreover, human hepatoma cells (HuH7) were used to study the effect of IL-6 and TNF-α on HJV mRNA expression. Results Here we show that LPS repressed hepatic Hjv and BMPs, while it induced hepcidin 1 expression in wild-type and Hfe KO mice with no effect on hepatic pSMAD 1, 5, 8 protein levels. In addition, exogenous TNF-α (20 ng/mL) decreased HJV mRNA and protein expression to 40% of control with no effect on hepcidin mRNA expression in 24 hours. On the other hand, IL-6 induced hepcidin mRNA and protein expression with no effect on HJV mRNA expression levels. Moreover, using the HJV promoter-luciferase reporter fusion construct (HJVP1.2-luc), we showed that the basal luciferase activity of HJVP1.2-luc was inhibited by 33% following TNF-α treatment of HuH7 transfected cells suggesting that the TNF-α down-regulation is exerted at the transcriptional level. Additionally, mutation of a canonical TNF- alpha responsive element (TNFRE) within HJVP1.2-luc abolished TNF-α response suggesting that this TNFRE is functional. Conclusions From these results, we conclude that TNF-α suppresses HJV transcription possibly via a novel TNFRE within the HJV promoter. In addition, the results suggest that the proposed link between inflammation and BMP-SMAD signalling is independent of HJV and BMP ligands.</p

Intronic SNP rs3811647 of the human transferrin gene modulates its expression in hepatoma cells

Peer Reviewe

Intronic SNP rs3811647 of the human transferrin gene modulates its expression in hepatoma cells | El SNP intrónico rs3811647 del gen de la transferrina humano, modula su expresión en células hepáticas

Introduction: Transferrin (Tf) exerts a crucial function in the maintenance of systemic iron homeostasis. The expression of the Tf gene is controlled by transcriptional mechanism, although little is known about genetic factors influence. Objective: To study the role of rs3811647 in Tf expression using an in-vitro assay on hepatoma cells. Design and Methods: Hep3B cells were co-transfected with constructs containing A (VarA-Tf-luc) and G (VarGTf- luc) variants of rs3811647, using luciferase as a surrogate reporter of Tf expression. Results: Luciferase assays showed a higher intrinsic enhancer activity (p < 0.05) in the A compared with the G variant. In silico analysis of SNP rs3811647 showed that the A allele might constitute a binding site for the transcription factor glucocorticoid receptor (GR). Conclusion: The A allele of SNP rs3811647 increases Tf expression in a manner that might underlie inter-individual variation in serum transferrin levels observed in different population groups.This study was supported by Project AGL2009-11437.Peer Reviewe

Protein transduction by lipidic peptide dendrimers

We investigated the potential of a new family of lipidic peptide dendrimers in protein transduction into cultured cells. Dendrimer-protein interaction was determined by gel retardation assays using purified recombinant protein. To assess intracellular protein delivery, two marker proteins were used: recombinant firefly luciferase and a Cy3-labeled monoclonal antibody to the c-myc proto-oncogene. Protein delivery was determined by luciferase assays and fluorescence microscopy, respectively. While there was minimal delivery of luciferase or antibody in the absence of the dendrimers, the latter increased protein delivery substantially. Luciferase delivery was concentration and cell type-dependent; the efficiency of delivery also varied with the number of terminal amino groups on the dendrimers. In previous reports, we showed that these dendrimers could be used for gene and drug delivery; the data we report herein suggest that they may also be capable of intracellular protein delivery. This finding has important implications for the use of these dendrimers in protein therapeutics and vaccinology