Hepcidin is a 25-amino acid peptide involved in iron homeostasis in mice and humans. It is produced in the liver from a larger precursor, and it is detectable in blood and urine. In contrast to the human genome, which contains only one copy of the gene, the mouse genome contains 2 highly similar hepcidin genes, hepc1 and hepc2, which are, however, considerably divergent at the level of the corresponding mature 25-amino acid peptide. This striking observation led us to ask whether hepc1 and hepc2 performed the same biologic activity with regard to iron metabolism in the mouse. We recently described the severe iron-deficient anemia phenotype in transgenic mice overexpressing hepc1 in the liver. Here we report that, in contrast to the hepc1-transgenic mice, none of the 7 founder hepc2-transgenic animals suffered from anemia. They all developed normally with hematologic parameters similar to the nontransgenic littermates. Hepc2 transgenic mRNA level was found to be very high for all lines compared with the level of hepc1 transgene mRNA necessary to produce severe anemia. These data provide evidence that hepc2 does not act on iron metabolism like hepc1 and give clues for the identification of amino acids important for the iron-regulatory action of the mature 25-amino acid peptide. IntroductionHepcidin, a liver-specific regulatory peptide, was recently demonstrated to play a key role in regulating iron homeostasis. Although not demonstrated, hepcidin is likely acting on iron metabolism by limiting intestinal iron absorption and iron release from macrophages (for reviews, see Nicolas et al 1 and Ganz 2 ). This function is fundamental for maintaining iron homeostasis, in particular to avoid accumulation of excess iron that leads to organ dysfunction. This is the case in hereditary hemochromatosis (HH), a prevalent genetic disorder of iron hyperabsorption leading to hyperferremia, tissue iron deposition, and complications including cirrhosis, hepatocellular carcinoma, heart disease, endocrinopathies, and diabetes (for review see Fleming and Sly 3 ). Most patients with HH are homozygous for a missense mutation C282Y in the atypical major histocompatibility complex (MHC) class I molecule HFE. 4 A more severe form of the disease, known as juvenile hemochromatosis (JH), is characterized by rapid iron loading and clinical presentation of hypogonadism and cardiomyopathy at a young age. 5 The major responsible gene is linked to chromosome 1q21 but it has not yet been identified. Recently, 2 families with homozygous mutations of the hepcidin gene on chromosome 19 have been reported. 6 The affected individuals presented all the clinical signs of JH, which highlights the irreplaceable regulatory role of hepcidin in maintaining iron balance in humans. In mice, complete hepcidin deficiency has also been reported to be associated with a severe iron overload phenotype. 7 Interestingly, along with the uncommon JH due to complete hepcidin deficiency, partial hepcidin deficiency has been described in the most common form of HFE-related ...

Electropermeabilization is a nonviral method used to transfer genes into living cells. Up to now, the mechanism is still to be elucidated. Since cell permeabilization, a prerequired for gene transfection, is triggerred by electric field, its characteristics should depend on its vectorial properties. The present investigation addresses the effect of pulse polarity and orientation on membrane permeabilization and gene delivery by electric pulses applied to cultured mammalian cells. This has been directly observed at the single-cell level by using digitized fluorescence microscopy. While cell permeabilization is only slightly affected by reversing the polarity of the electric pulses or by changing the orientation of pulses, transfection level increases are observed. These last effects are due to an increase in the cell membrane area where DNA interacts. Fluorescently labelled plasmids only interact with the electropermeabilized side of the cell facing the cathode. The plasmid interaction with the electropermeabilized cell surface is stable and is not affected by pulses of reversed polarities. Under such conditions, DNA interacts with the two sites of the cell facing the two electrodes. When changing both the pulse polarity and their direction, DNA interacts with the whole membrane cell surface. This is associated with a huge increase in gene expression. This present study demonstrates the relationship between the DNA/membrane surface interaction and the gene transfer efficiency, and it allows to define the experimental conditions to optimize the yield of transfection of mammalian cells.

Spinal muscular atrophy (SMA) is a recessive autosomal disorder characterized by degeneration of lower motor neurons caused by mutations of the survival motor neuron gene (SMN1). No curative treatment is known so far. Mutant mice carrying homozygous deletion of Smn exon 7 directed to neurons display skeletal muscle denervation, moderate loss of motor neuron cell bodies and severe axonal degeneration. These features, similar to those found in human SMA, strongly suggest the involvement of a dying back process of motor neurons and led us to test whether neurotrophic factors might have a protective role in SMA. We report here the therapeutic benefits of systemic delivery of cardiotrophin-1 (CT-1), a neurotrophic factor belonging to the IL-6 cytokine family. Intra-muscular injection of adenoviral vector expressing CT-1, even at very low dose, improves median survival, delays motor defect of mutant mice and exerts protective effect against loss of proximal motor axons and aberrant cytoskeletal organization of motor synaptic terminals. In spite of the severity of SMA phenotype in mutant mice, CT-1 is able to slow down disease progression. Neuroprotection could be regarded as valuable therapeutic approach in SMA.