Origin of fundus hyperautofluorescent spots and their role in retinal degeneration in a mouse model of Goldmann-Favre syndrome

Goldmann-Favre syndrome, also known as enhanced S-cone syndrome, is an inherited retinal degeneration disease in which a gain of photoreceptor cell types results in retinal dysplasia and degeneration. Although microglia have been implicated in the pathogenesis of many neurodegenerative diseases, the fundamental role of these cells in this disease is unknown. In the current study, sequential analyses suggest that microglia are recruited and appear after outer nuclear layer folding. By crossing rd7 mice (a model for hereditary retinal degeneration owing to Nr2e3 mutation) with mice carrying the macrophage Fas-induced apoptosis (Mafia) transgene, we generated double-mutant mice and studied the role of the resident retinal microglia. Microglial cells in these double-mutant mice express enhanced green fluorescent protein (EGFP) and a suicide gene that can trigger Fas-mediated apoptosis via systemic treatment with AP20187 (FK506 dimerizer). We demonstrated that more than 80% of the EGFP+ cells in retinas from rd7/rd7;Tg/Tg mice express Iba-1 (a microglial marker), and resident microglia are still present in the retina because AP20187 does not cross the blood-brain barrier. Hence, only circulating bone marrow (BM)-derived microglia are depleted. Depletion of circulating BM-derived microglia accelerates retinal degeneration in rd7 mice. An increased number of autofluorescent (AF) spots is a consequence of resident microglia proliferation, which in turn establishes an inflammatory cytokine milieu via the upregulation of IL-1β, IL-6 and TNFα expression. This inflammation is likely to accelerate retinal degeneration. This study not only identifies inflammation as a crucial step in the pathogenesis of retinal degeneration, but also highlights the involvement of specific cytokine genes that could serve as future treatment targets in retinal degenerations.

LHX2 regulates the neural differentiation of human embryonic stem cells via transcriptional modulation of PAX6 and CER1

The LIM homeobox 2 transcription factor Lhx2 is known to control crucial aspects of neural development in various species. However, its function in human neural development is still elusive. Here, we demonstrate that LHX2 plays a critical role in human neural differentiation, using human embryonic stem cells (hESCs) as a model. In hESC-derived neural progenitors (hESC-NPs), LHX2 was found to be expressed before PAX6, and co-expressed with early neural markers. Conditional ectopic expression of LHX2 promoted neural differentiation, whereas disruption of LHX2 expression in hESCs significantly impaired neural differentiation. Furthermore, we have demonstrated that LHX2 regulates neural differentiation at two levels: first, it promotes expression of PAX6 by binding to its active enhancers, and second, it attenuates BMP and WNT signaling by promoting expression of the BMP and WNT antagonist Cerberus 1 gene (CER1), to inhibit non-neural differentiation. These findings indicate that LHX2 regulates the transcription of downstream intrinsic and extrinsic molecules that are essential for early neural differentiation in human.

Parallel fabrication of magnetic tunnel junction nanopillars by nanosphere lithography

We present a new method for fabricating magnetic tunnel junction nanopillars that uses polystyrene nanospheres as a lithographic template. Unlike the common approaches, which depend on electron beam lithography to sequentially fabricate each nanopillar, this method is capable of patterning a large number of nanopillars simultaneously. Both random and ordered nanosphere patterns have been explored for fabricating high quality tunneling junctions with magnetoresistance in excess of 100%, employing ferromagnetic layers with both out-of-plane and in-plane easy axis. Novel voltage induced switching has been observed in these structures. This method provides a cost-effective way of rapidly fabricating a large number of tunnel junction nanopillars in parallel.

Pt magnetic polarization on Y3Fe5O12 and magnetotransport characteristics

Thin Pt films on an yttrium iron garnet (YIG = Y(3)Fe(5)O(12)) show ferromagneticlike transport properties, which may impact the functionality of Pt in spin current detection, but do not provide direct quantitative information on the Pt magnetization. We report magnetic x-ray magnetic circular dichroism measurements of YIG/Pt(1.5 nm) showing an average Pt moment of 0.054 μ(B) at 300 K and 0.076 μ(B) at 20 K. This observation indicates strong proximity effects and induced magnetic ordering in Pt on magnetic insulators and their contribution to the spin-related measurements should not be neglected. The transport characteristics also suggest considerable modifications in the Pt electronic structure due to magnetic ordering.

Endothelial progenitor cells derived from Wharton's jelly of the umbilical cord reduces ischemia-induced hind limb injury in diabetic mice by inducing HIF-1α/IL-8 expression

Peripheral arterial diseases, the major complication of diabetes, can result in lower limb amputation. Since endothelial progenitor cells (EPCs) are involved in neovascularization, the aim of this study was to examine whether EPCs isolated from Wharton's jelly (WJ-EPCs) of the umbilical cord, a rich source of mesenchymal stem cells, could reduce ischemia-induced hind limb injury in diabetic mice. We evaluated the effects of WJ-EPC transplantation on hind limb injury caused by femoral artery ligation in mice with streptozotocin (STZ)-induced diabetes. We found that the ischemic hind limb in mice with STZ-induced diabetes showed decreased blood flow and capillary density and increased cell apoptosis and that these effects were significantly inhibited by an injection of WJ-EPCs. In addition, hypoxia-inducible factor-1α (HIF-1α) and interleukin-8 (IL-8) were highly expressed in transplanted WJ-EPCs in the ischemic skeletal tissues and were present at high levels in hypoxia-treated cultured WJ-EPCs. Moreover, incubation of the NOR skeletal muscle cell line under hypoxic conditions in conditioned medium from EPCs cultured for 16 h under hypoxic conditions resulted in decreased expression of pro-apoptotic proteins and increased expression of anti-apoptotic proteins. The inhibition of HIF-1α or IL-8 expression by EPCs using HIF-1α siRNA or IL-8 siRNA, respectively, prevented this change in expression of apoptotic-related proteins. Wharton's jelly in the umbilical cord is a valuable source of EPCs, and transplantation of these EPCs represents an innovative therapeutic strategy for treating diabetic ischemic tissues. The HIF-1α/IL-8 signaling pathway plays a critical role in the protective effects of EPCs in the ischemic hind limb of diabetic mice.

Intrinsic spin Seebeck effect in Au/YIG

The acute magnetic proximity effects in Pt/YIG compromise the suitability of Pt as a spin current detector. We show that Au/YIG, with no anomalous Hall effect and a negligible magnetoresistance, allows the measurements of the intrinsic spin Seebeck effect with a magnitude much smaller than that in Pt/YIG. The experiment results are consistent with the spin polarized density functional calculations for Pt with a sizable and Au with a negligible magnetic moment near the interface with YIG.

Depletion of regulatory T lymphocytes reverses the imbalance between pro- and anti-tumor immunities via enhancing antigen-specific T cell immune responses

Background

The regulatory T cells (Tregs) can actively suppress the immune responses. However, literature about detailed changes of host effective and suppressive immunities before and after depletion of Tregs in ovarian carcinomas, is rare.

Materials and Methods

Ovarian cancer patients and the ascitogenic animal model were employed. Immunologic profiles with flow cytometric analyses, immunohistochemistric staining, RT-PCR, ELISA, and ELISPOT assays were performed. In vivo depletion of Treg cells with the mAb PC61was also performed in the animal model.

Results

The cytokines, including IL-4 (p = 0.017) and TNF-α (p = 0.046), significantly decreased while others such as TGF-β (p = 0.013), IL-6 (p = 0.016), and IL-10 (p = 0.018) were elevated in ascites of ovarian cancer patients, when the disease progressed to advanced stages. The ratio of CD8⁺ T cell/Treg cell in ascites was also lower in advanced diseases than in early diseases (advanced 7.37±0.64 vs. early 14.25±3.11, p = 0.037). The kinetic low-dose CD25 Ab depletion group had significantly lower intra-peritoneal tumor weight (0.20±0.03 g) than the sequential high-dose (0.69±0.06 g) and sequential low-dose (0.67±0.07 g) CD25 Ab deletion groups (p = 0.001) after 49 days of tumor challenge in the animal. The kinetic low-dose CD25 Ab depletion group generated the highest number of IFN-γ-secreting, mesothelin-specific T lymphocytes compared to the other groups (p<0.001).

Conclusions

The imbalance between effective and suppressive immunities becomes more severe as a tumor progresses. The depletion of Treg cells can correct the imbalance of immunologic profiles and generate potent anti-tumor effects. Targeting Treg cells can be a new strategy for the immunotherapy of ovarian carcinoma.

Unified formalism of Andreev reflection at a ferromagnet/superconductor interface

We present a unified formalism of Andreev reflection of a partial polarized current at a ferromagnet/superconductor interface instead of assuming a linear combination of unpolarized and polarized currents. The Andreev reflection is limited by the states of minority spins and the extra majority spins become evanescent wave. We further study the effects of spin polarization, inelastic scattering, and interfacial scattering on the Andreev reflection, normal reflection, and transmitted probabilities in equilibrium as well as under a bias. Our model, which reduces to those of Blonder, Tinkham, and Klapwijk, Mazin, and Dynes in three limiting cases, provides a significantly better description of the experimental results.

R26R-GR: a Cre-activable dual fluorescent protein reporter mouse

Green fluorescent protein (GFP) and its derivatives are the most widely used molecular reporters for live cell imagining. The development of organelle-specific fusion fluorescent proteins improves the labeling resolution to a higher level. Here we generate a R26 dual fluorescent protein reporter mouse, activated by Cre-mediated DNA recombination, labeling target cells with a chromatin-specific enhanced green fluorescence protein (EGFP) and a plasma membrane-anchored monomeric cherry fluorescent protein (mCherry). This dual labeling allows the visualization of mitotic events, cell shapes and intracellular vesicle behaviors. We expect this reporter mouse to have a wide application in developmental biology studies, transplantation experiments as well as cancer/stem cell lineage tracing.

Transport magnetic proximity effects in platinum

Platinum (Pt) metal, being nonmagnetic and with a strong spin-orbit coupling interaction, has been central in detecting the pure spin current and establishing most of the recent spin-based phenomena. Magnetotransport measurements, both electrical and thermal, conclusively show strong ferromagnetic characteristics in thin Pt films on the ferromagnetic insulator due to the magnetic proximity effects. The pure spin current phenomena measured by Pt, including the inverse spin Hall and the spin Seebeck effects, are thus contaminated and not exclusively established.

Suppression of extensive neurofilament phosphorylation rescues α-Internexin/peripherin-overexpressing PC12 cells from neuronal cell death

Intermediate filament (IF) overproduction induces abnormal accumulation of neuronal IF, which is a pathological indicator of some neurodegenerative disorders. In our study, α-Internexin- and peripherin-overexpressing PC12 cells (pINT-EGFP and pEGFP-peripherin) were used as models to study neuropathological pathways responsible for neurodegenerative diseases. Microarray data revealed that Cdk5-related genes were downregulated and Cdk5 regulatory subunit-associated protein 3 (GSK-3α and GSK-3β) were upregulated in pINT-EGFP cells. Increased expression of phosphorylated neurofilament and aberrant activation of Cdk5 and GSK-3β were detected in both pEGFP-peripherin and pINT-EGFP cells by Western blotting. In addition, pharmacological approaches to retaining viability of pINT-EGFP and pEGFP-peripherin cells were examined. Treatment with Cdk5 inhibitor and GSK-3β inhibitor significantly suppressed neuronal death. Dynamic changes of disaggregation of EGFP-peripherin and decrease in green fluorescence intensity were observed in pEGFP-peripherin and pINT-EGFP cells by confocal microscopy after GSK-3β inhibitor treatment. We conclude that inhibition of Cdk5 and GSK-3β suppresses neurofilament phosphorylation, slows down the accumulation of neuronal IF in the cytoplasm, and subsequently avoids damages to cell organelles. The results suggest that suppression of extensive neurofilament phosphorylation may be a potential strategy for ameliorating neuron death. The suppression of hyperphosphorylation of neuronal cytoskeletons with kinase inhibitors could be one of potential therapeutic treatments for neurodegenerative diseases.

Extended Skyrmion phase in epitaxial FeGe(111) thin films

The Skyrmion state in epitaxial B20 FeGe(111) thin films, determined by the topological Hall effect, is greatly extended in the phase diagram to cover all temperatures up to the Curie temperature T(C)≈271 K and over a wide magnetic field range that includes a zero magnetic field. The properties of the Skyrmion phase can be controlled and manipulated by the film thickness, which has a strong effect on the stabilization of Skyrmions.

A neuronal death model: overexpression of neuronal intermediate filament protein peripherin in PC12 cells

BACKGROUND

Abnormal accumulation of neuronal intermediate filament (IF) is a pathological indicator of some neurodegenerative disorders. However, the underlying neuropathological mechanisms of neuronal IF accumulation remain unclear. A stable clone established from PC12 cells overexpressing a GFP-Peripherin fusion protein (pEGFP-Peripherin) was constructed for determining the pathway involved in neurodegeneration by biochemical, cell biology, and electronic microscopy approaches. In addition, pharmacological approaches to preventing neuronal death were also examined.

RESULTS

Results of this study showed that TUNEL positive reaction could be detected in pEGFP-Peripherin cells. Swollen mitochondria and endoplasmic reticulum (ER) were seen by electron microscopy in pEGFP-Peripherin cells on day 8 of nerve growth factor (NGF) treatment. Peripherin overexpression not only led to the formation of neuronal IF aggregate but also causes aberrant neuronal IF phosphorylation and mislocation. Western blots showed that calpain, caspase-12, caspase-9, and caspase-3 activity was upregulated. Furthermore, treatment with calpain inhibitor significantly inhibited cell death.

CONCLUSIONS

These results suggested that the cytoplasmic neuronal IF aggregate caused by peripherin overexpression may induce aberrant neuronal IF phosphorylation and mislocation subsequently trapped and indirectly damaged mitochondria and ER. We suggested that the activation of calpain, caspase-12, caspase-9, and caspase-3 were correlated to the dysfunction of the ER and mitochondria in our pEGFP-Peripherin cell model. The present study suggested that pEGFP-Peripherin cell clones could be a neuronal death model for future studies in neuronal IFs aggregate associated neurodegeneration.

Intrinsic spin-dependent thermal transport

Most studies of spin caloritronic effects to date, including spin-Seebeck effect, utilize thin films on substrates. We use patterned ferromagnetic thin film to demonstrate the profound effect of a substrate on the spin-dependent thermal transport. With different sample patterns and on varying the direction of temperature gradient, both longitudinal and transverse thermal voltages exhibit asymmetric instead of symmetric spin dependence. This unexpected behavior is due to an out-of-plane temperature gradient imposed by the thermal conduction through the substrate and the mixture of anomalous Nernst effects. Only with substrate-free samples have we determined the intrinsic spin-dependent thermal transport with characteristics and field sensitivity similar to those of the anisotropic magnetoresistance effect.

Electric-field-assisted switching in magnetic tunnel junctions

The advent of spin transfer torque effect accommodates site-specific switching of magnetic nanostructures by current alone without magnetic field. However, the critical current density required for usual spin torque switching remains stubbornly high around 10(6)-10(7) A cm(-2). It would be fundamentally transformative if an electric field through a voltage could assist or accomplish the switching of ferromagnets. Here we report electric-field-assisted reversible switching in CoFeB/MgO/CoFeB magnetic tunnel junctions with interfacial perpendicular magnetic anisotropy, where the coercivity, the magnetic configuration and the tunnelling magnetoresistance can be manipulated by voltage pulses associated with much smaller current densities. These results represent a crucial step towards ultralow energy switching in magnetic tunnel junctions, and open a new avenue for exploring other voltage-controlled spintronic devices.

Human Pompe disease-induced pluripotent stem cells for pathogenesis modeling, drug testing and disease marker identification

Pompe disease is caused by autosomal recessive mutations in the acid alpha-glucosidase (GAA) gene, which encodes GAA. Although enzyme replacement therapy has recently improved patient survival greatly, the results in skeletal muscles and for advanced disease are still not satisfactory. Here, we report the derivation of Pompe disease-induced pluripotent stem cells (PomD-iPSCs) from two patients with different GAA mutations and their potential for pathogenesis modeling, drug testing and disease marker identification. PomD-iPSCs maintained pluripotent features and had low GAA activity and high glycogen content. Cardiomyocyte-like cells (CMLCs) differentiated from PomD-iPSCs recapitulated the hallmark Pompe disease pathophysiological phenotypes, including high levels of glycogen and multiple ultrastructural aberrances. Drug rescue assessment showed that exposure of PomD-iPSC-derived CMLCs to recombinant human GAA reversed the major pathologic phenotypes. Furthermore, l-carnitine treatment reduced defective cellular respiration in the diseased cells. By comparative transcriptome analysis, we identified glycogen metabolism, lysosome and mitochondria-related marker genes whose expression robustly correlated with the therapeutic effect of drug treatment in PomD-iPSC-derived CMLCs. Collectively, these results demonstrate that PomD-iPSCs are a promising in vitro disease model for the development of novel therapeutic strategies for Pompe disease.

Electric Tweezers

Electric tweezers utilize DC and AC electric fields through voltages applied on patterned electrodes to manipulate nanoentities suspended in a liquid. Nanowires with a large aspect ratio are particularly suitable for use in electric tweezers for patterning, assembling, and manipulation. Despite operating in the regime of extremely small particle Reynolds number (of order 10^-5), electric tweezers can manipulate nanowires with high precision to follow any prescribed trajectory, to rotate nanowires with controlled chirality, angular velocity and rotation angle, and to assemble nanowires to fabricate nanoelectromechanical system (NEMS) devices such as nanomotors and nano-oscillators. Electric tweezers have also been used to transport in a highly controlled manner drug-carrying functionalized nanowires for cell-specific drug delivery.

zVAD-induced autophagic cell death requires c-Src-dependent ERK and JNK activation and reactive oxygen species generation

The treatment of L929 fibrosarcoma cells with zVAD has been shown to induce necroptosis. However, whether autophagy is involved or not in this event remains controversial. In this study, we re-examined the role of autophagy in zVAD-induced cell death in L929 cells and further elucidated the signaling pathways triggered by caspase inhibition and contributing to autophagic death. First, we found that zVAD can stimulate LC3-II formation, autophagosome and autolysosome formation, and ROS accumulation. Antioxidants, beclin 1 or Atg5 silencing, and class III PtdIns3K inhibitors all effectively blocked ROS production and cell death, suggesting ROS accumulation downstream of autophagy contributes to cell necrosis. zVAD also stimulated PARP activation, and the PARP inhibitor DPQ can reduce zVAD-induced cell death, but did not affect ROS production, suggesting the increased ROS leads to PARP activation and cell death. Notably, our data also indicated the involvement of Src-dependent JNK and ERK in zVAD-induced ROS production and autophagic death. We found caspase 8 is associated with c-Src at the resting state, and upon zVAD treatment this association was decreased and accompanied by c-Src activation. In conclusion, we confirm the autophagic death in zVAD-treated L929 cells, and define a new molecular pathway in which Src-dependent ERK and JNK activation can link a signal from caspase inhibition to autophagy, which in turn induce ROS production and PARP activation, eventually leading to necroptosis. Thus, in addition to initiating proteolytic activity for cell apoptosis, inactivated caspase 8 also functions as a signaling molecule for autophagic death.

Neuronal degeneration in autonomic nervous system of Dystonia musculorum mice

Background

Dystonia musculorum (dt) is an autosomal recessive hereditary neuropathy with a characteristic uncoordinated movement and is caused by a defect in the bullous pemphigoid antigen 1 (BPAG1) gene. The neural isoform of BPAG1 is expressed in various neurons, including those in the central and peripheral nerve systems of mice. However, most previous studies on neuronal degeneration in BPAG1-deficient mice focused on peripheral sensory neurons and only limited investigation of the autonomic system has been conducted.

Methods

In this study, patterns of nerve innervation in cutaneous and iridial tissues were examined using general neuronal marker protein gene product 9.5 via immunohistochemistry. To perform quantitative analysis of the autonomic neuronal number, neurons within the lumbar sympathetic and parasympathetic ciliary ganglia were calculated. In addition, autonomic neurons were cultured from embryonic dt/dt mutants to elucidate degenerative patterns in vitro. Distribution patterns of neuronal intermediate filaments in cultured autonomic neurons were thoroughly studied under immunocytochemistry and conventional electron microscopy.

Results

Our immunohistochemistry results indicate that peripheral sensory nerves and autonomic innervation of sweat glands and irises dominated degeneration in dt/dt mice. Quantitative results confirmed that the number of neurons was significantly decreased in the lumbar sympathetic ganglia as well as in the parasympathetic ciliary ganglia of dt/dt mice compared with those of wild-type mice. We also observed that the neuronal intermediate filaments were aggregated abnormally in cultured autonomic neurons from dt/dt embryos.

Conclusions

These results suggest that a deficiency in the cytoskeletal linker BPAG1 is responsible for dominant sensory nerve degeneration and severe autonomic degeneration in dt/dt mice. Additionally, abnormally aggregated neuronal intermediate filaments may participate in neuronal death of cultured autonomic neurons from dt/dt mutants.

Hypoxic culture maintains self-renewal and enhances embryoid body formation of human embryonic stem cells

Hypoxic environment is theoretically more physiological for the growth of human embryonic stem (hES) cells. It has been reported that hypoxic culture maintained better undifferentiation of hES cells, but the effects on differentiation are less well established. The hES cells were thus cultured and compared in hypoxia (2% oxygen [O2]) and normoxia (21% O2). The data showed that the undifferentiated state of hES cells was maintained more favorably in hypoxia during prolonged culture. Most tested genes belonging to FGF, TGF-beta/GMP, and Wnt signaling pathways were enriched in undifferentiated hES cells and downregulated upon differentiation, accompanied with differential expression of FGFR1, FGFR2, and FRAT2 between hypoxia and normoxia. Higher P-Smad2/3 level was identified in hypoxia, favoring the maintenance of hES cells in undifferentiation. Bisulfite sequencing showed similar imprinting status between different O2 tensions at H19 differentially methylated region (DMR) and KvDMR loci. Embryoid body formation was enhanced in hypoxia accompanied with suppressed Sox17, Desmin, Gata4, Brachyury, and Cdx2 expression. We concluded that hypoxia improved self-renewal of hES cells through modulation of major signaling pathways and was also more efficient for differentiation to embryoid bodies, though they might present with suppressed expression of some lineage-specific genes across all the three embryonic germ layers and trophectoderm.

Krüppel-like transcription factor 4 contributes to maintenance of telomerase activity in stem cells

The zinc finger Krüppel-like transcription factor 4 (KLF4) has been implicated in cancer formation and stem cell regulation. However, the function of KLF4 in tumorigenesis and stem cell regulation are poorly understood due to limited knowledge of its targets in these cells. In this study, we have revealed a surprising link between KLF4 and regulation of telomerase that offers important insight into how KLF4 contributes to cancer formation and stem cell regulation. KLF4 sufficiently activated expression of the human telomerase catalytic subunit, human telomerase reverse transcriptase (hTERT), in telomerase-low alternative lengthening of telomeres (ALT), and fibroblast cells, while downregulation of KLF4 reduced its expression in cancerous and stem cells, which normally exhibits high expression. Furthermore, KLF4-dependent induction of hTERT was mediated by a KLF4 binding site in the proximal promoter region of hTERT. In human embryonic stem cells, expression of hTERT replaced KLF4 function to maintain their self-renewal. Therefore, our findings demonstrate that hTERT is one of the major targets of KLF4 in cancer and stem cells to maintain long-term proliferation potential.

Constraint-induced movement therapy as a paradigm of translational research in neurorehabilitation: Reviews and prospects

There is an increasing awareness about the importance of translation from basic scientific findings into practical application for efficiently improving human health, especially in the pharmaceutical industry. In the field of neurorehabilitation, however, the bench-to-bedside process continues to be developing, and thus most of the therapeutic interventions have encountered barriers during exploration of evidence-based effectiveness. Despite this immaturity, constraint-induced movement therapy (CIT), a well-evidenced treatment evolved from research in nonhuman primates, is suggested to be an ideal paradigm of translational research in the field of neurorehabilitation. This article reviews the evolvement of CIT with regards to its behavioral efficacy and neuroimaging evidence through the translation roadmap developed by the National Institutes of Health. We also discuss prospects for the application of combined interventions, such as stem cell therapy or pharmaceutical prescription, with appropriate screening of patients beforehand, as well as an efficient delivery mode after the treatment. To achieve such goals and consolidate evidenced-based neurorehabilitation, we provide a framework for applications into the translational research of other therapeutic interventions aside from CIT.

PiggyBac transposon-mediated, reversible gene transfer in human embryonic stem cells

Permanent and reversible genetic modifications are important approaches to study gene function in different cell types. They are also important for stem cell researchers to explore and test the therapeutic potential of stem cells. The piggyBac transposon from insects is a rising nonviral system that efficiently mutagenizes and mediates gene transfer into the mammalian genome. It is also characterized by its precise excision, leaving no trace sequence behind so that the genomic integrity of the mutated cell can be restored. Here, we use an optimized piggyBac transposon system to mediate gene transfer and expression of a bifunctional fluorescent reporter in human embryonic stem (ES) cells. We provide molecular evidence for transposase-mediated piggyBac integration events and functional evidence for successful expression of a transferred fluorescent protein genes in human ES cells and their in vitro differentiated derivatives. We also demonstrate that the integrated piggyBac transposon can be removed and an undisrupted insertion site can be restored, which implies potential applications for its use in gene therapy and genetics studies.

Fabrication and magnetic properties of arrays of metallic nanowires

Arrays of ferromagnetic nickel and cobalt nanowires have been fabricated by electrochemical deposition of the metals into templates with nanometer-sized pores prepared by nuclear track etching. These systems display distinctive characteristics because of their one-dimensional microstructure. The preferred magnetization direction is perpendicular to the film plane. Enhanced coercivities as high as 680 oersteds and remnant magnetization up to 90 percent have also been observed.

WITHDRAWN: zVAD-induced autophagic cell death requires c-Src-dependent ERK and JNK activation and reactive oxygen species generation

Ahead of Print article withdrawn by publisher. A previous report showed that the pan-caspase inhibitor zVAD can induce necrosis accompanied by autophagosome formation in L929 fibrosarcoma cells. Such autophagic cell death relies on caspase 8 inhibition and ROS accumulation. Since the connection of these molecules is still poorly understood, we explored the underlying signaling cascades in this event. First, we confirmed zVAD can stimulate LC3 cleavage, beclin 1 gene expression, autophagosome formation, and ROS accumulation in L929 cells. Antioxidants, Beclin 1 or Atg5 silencing, and class III PtdIns3K inhibitors all effectively blocked ROS production and cell death, suggesting ROS accumulation downstream of autophagy contributes to cell necrosis. zVAD also stimulated PARP activation, and the PARP inhibitor DPQ can reduce zVAD-induced cell death, but not affect ROS production, suggesting the increased ROS leads to PARP activation and cell death. Notably, our data also indicated the involvement of Src-dependent JNK and ERK in zVAD-induced autophagic cell death. We found caspase 8 is associated with c-Src at resting state, and upon zVAD treatment this association is decreased and accompanied by c-Src activation. These results provide new insight into the nonenzymatic function of caspase 8. In addition to initiating proteolytic activity for cell apoptosis, inactivated caspase 8 also functions as a signaling molecule for autophagic cell death.