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Background/Objectives: Iron (Fe) is a co-factor for enzymes of the developing brain necessitating sufficient supply. We investigated the effects of administering ferric derisomaltose/Fe isomaltoside (FDI) subcutaneously to Fe-deficient (ID) pregnant rats on cerebral and hepatic concentrations of essential metals and the expression of iron-relevant genes. Methods: Pregnant rats subjected to ID were injected with FDI on the day of mating (E0), 14 days into pregnancy (E14), or the day of birth (postnatal (P0)). The efficacy was evaluated by determination of cerebral and hepatic Fe, copper (Cu), and zinc (Zn) and gene expression of ferroportin, hepcidin, and ferritin H + L in pups on P0 and as adults on P70. Results: Females fed an ID diet (5.2 mg/kg Fe) had offspring with significantly lower cerebral and hepatic Fe compared to female controls fed a standard diet (158 mg/kg Fe). Cerebral Cu increased irrespective of supplying a standard diet or administering FDI combined with the standard diet. Hepatic hepcidin mRNA was significantly lower following ID. Cerebral hepcidin mRNA was hardly detectable irrespective of iron status. Conclusions: In conclusion, administering FDI subcutaneously to ID pregnant rats on E0 normalizes fetal cerebral and hepatic Fe. When applied at later gestational ages, supplementation with additional Fe to the offspring is needed to normalize cerebral and hepatic Fe. [ABSTRACT FROM AUTHOR]

Abstract Background Menkes disease (MD) is an X-linked, fatal neurodegenerative disorder of copper metabolism, caused by mutations in the ATP7A gene. Thirty-three Menkes patients in whom no mutation had been detected with standard diagnostic tools were screened for exon duplications in the ATP7A gene. Methods The ATP7A gene was screened for exon duplications using multiplex ligation-dependent probe amplification (MLPA). The expression level of ATP7A was investigated by real-time PCR and detailed analysis of the ATP7A mRNA was performed by RT-PCR followed by sequencing. In order to investigate whether the identified duplicated fragments originated from a single or from two different X-chromosomes, polymorphic markers located in the duplicated fragments were analyzed. Results Partial ATP7A gene duplication was identified in 20 unrelated patients including one patient with Occipital Horn Syndrome (OHS). Duplications in the ATP7A gene are estimated from our material to be the disease causing mutation in 4% of the Menkes disease patients. The duplicated regions consist of between 2 and 15 exons. In at least one of the cases, the duplication was due to an intra-chromosomal event. Characterization of the ATP7A mRNA transcripts in 11 patients revealed that the duplications were organized in tandem, in a head to tail direction. The reading frame was disrupted in all 11 cases. Small amounts of wild-type transcript were found in all patients as a result of exon-skipping events occurring in the duplicated regions. In the OHS patient with a duplication of exon 3 and 4, the duplicated out-of-frame transcript coexists with an almost equally represented wild-type transcript, presumably leading to the milder phenotype. Conclusions In general, patients with duplication of only 2 exons exhibit a milder phenotype as compared to patients with duplication of more than 2 exons. This study provides insight into exon duplications in the ATP7A gene.

Abstract Background PhiC31 integrase facilitates efficient integration of transgenes into human and mouse genomes and is considered for clinical gene therapy. However recent studies have shown that the enzyme can induce various chromosomal abnormalities in primary human embryonic cells and mammalian cell lines. The mechanisms involved are unknown, but it has been proposed that PhiC31 attachment sites in the host genome recombine leading to chromosomal translocations. Results We have studied possible effects of the PhiC31 integrase expression in human adult fibroblasts by karyotyping. All control cells were cytogenetically normal, whereas cells expressing PhiC31 integrase show chromosomal abnormalities confirming our previous results using primary embryonic fibroblasts. In order to study the early mechanisms involved we measured H2AX phosphorylation – a primary event in the response to DNA double-strand-breaks. Transient transfection with PhiC31 integrase encoding plasmids lead to an elevated number of cells positive for H2AX phosphorylation detected by immunofluorescence. Western blot analysis confirmed the upregulated H2AX phosphorylation, whereas markers for apoptosis as well as p53 and p21 were not induced. Cells transfected with plasmids encoding the Sleeping Beauty transposase remained cytogenetically normal, and in these cells less upregulation of H2AX phosphorylation could be detected. Conclusion In primary human fibroblasts expression of PhiC31 integrase leads to a DNA damage response and chromosomal aberrations.

Iron is required in a variety of essential processes in the body. In this review, we focus on iron transport in the brain and the role of the divalent metal transporter 1 (DMT1) vital for iron uptake in most cells. DMT1 locates to cellular membranes and endosomal membranes, where it is a key player in non-transferrin bound iron uptake and transferrinbound iron uptake, respectively. Four isoforms of DMT1 exist, and their respective characteristics involve a complex cell-specific regulatory machinery all controlling iron transport across these membranes. This complexity reflects the fine balance required in iron homeostasis, as this metal is indispensable in many cell functions but highly toxic when appearing in excess. DMT1 expression in the brain is prominent in neurons. Of serious dispute is the expression of DMT1 in non-neuronal cells. Recent studies imply that DMT1 does exist in endosomes of brain capillary endothelial cells denoting the blood-brain barrier. This supports existing evidence that iron uptake at the BBB occurs by means of transferrin-receptor mediated endocytosis followed by detachment of iron from transferrin inside the acidic compartment of the endosome and DMT1- mediated pumping iron into the cytosol. The subsequent iron transport across the abluminal membrane into the brain likely occurs by ferroportin. The virtual absent expression of transferrin receptors and DMT1 in glial cells, i.e., astrocytes, microglia and oligodendrocytes, suggest that the steady state uptake of iron in glia is much lower than in neurons and/or other mechanisms for iron uptake in these cell types prevail. [ABSTRACT FROM AUTHOR]

Menkes disease is an X-linked disorder of copper metabolism caused by mutations in the ATP7A gene. Whereas most of the patients exhibit a severe classical form, about 9% of the patients exhibit a milder form of Menkes disease. The mildest form is called occipital horn syndrome (OHS). Mutations in the ATP7A gene can be identified in 95-98% of the Menkes disease patients by standard screening techniques. Investigation of RNA isolated from the fibroblasts of eleven patients with no identified mutations was performed, and revealed inclusion of new pseudo-exons into the ATP7A mRNA from three unrelated patients: two patients with OHS and one patient with classical Menkes disease. The pseudo-exons were inserted between exons 10 and 11, between exons 16 and 17 and between exons 14 and 15 in the three patients, as a result of deep intronic mutations. This is the first time the activation of pseudo-exons is demonstrated in the ATP7A gene, and it demonstrates the usefulness of RNA analysis, in terms of revealing disease-causing mutations in noncoding regions. The fact that three different mutations cause disease by the activation of pseudo-exon inclusion also indicates that in Menkes disease this is an important mechanism, which has hitherto been overlooked. [ABSTRACT FROM AUTHOR]

Background: PhiC31 integrase facilitates efficient integration of transgenes into human and mouse genomes and is considered for clinical gene therapy. However recent studies have shown that the enzyme can induce various chromosomal abnormalities in primary human embryonic cells and mammalian cell lines. The mechanisms involved are unknown, but it has been proposed that PhiC31 attachment sites in the host genome recombine leading to chromosomal translocations. Results: We have studied possible effects of the PhiC31 integrase expression in human adult fibroblasts by karyotyping. All control cells were cytogenetically normal, whereas cells expressing PhiC31 integrase show chromosomal abnormalities confirming our previous results using primary embryonic fibroblasts. In order to study the early mechanisms involved we measured H2AX phosphorylation - a primary event in the response to DNA double-strand-breaks. Transient transfection with PhiC31 integrase encoding plasmids lead to an elevated number of cells positive for H2AX phosphorylation detected by immunofluorescence. Western blot analysis confirmed the upregulated H2AX phosphorylation, whereas markers for apoptosis as well as p53 and p21 were not induced. Cells transfected with plasmids encoding the Sleeping Beauty transposase remained cytogenetically normal, and in these cells less upregulation of H2AX phosphorylation could be detected. Conclusion: In primary human fibroblasts expression of PhiC31 integrase leads to a DNA damage response and chromosomal aberrations. [ABSTRACT FROM AUTHOR]