Absence of 3a0 charge density wave order in the infinite-layer nickelate NdNiO2

A hallmark of many unconventional superconductors is the presence of many-body interactions that give rise to broken-symmetry states intertwined with superconductivity. Recent resonant soft X-ray scattering experiments report commensurate 3a0 charge density wave order in infinite-layer nickelates, which has important implications regarding the universal interplay between charge order and superconductivity in both cuprates and nickelates. Here we present X-ray scattering and spectroscopy measurements on a series of NdNiO2+x samples, which reveal that the signatures of charge density wave order are absent in fully reduced, single-phase NdNiO2. The 3a0 superlattice peak instead originates from a partially reduced impurity phase where excess apical oxygens form ordered rows with three-unit-cell periodicity. The absence of any observable charge density wave order in NdNiO2 highlights a crucial difference between the phase diagrams of cuprate and nickelate superconductors.

Phase I Studies of Acebilustat: Pharmacokinetics, Pharmacodynamics, Food Effect, and CYP3A Induction

Acebilustat is a new once-daily oral antiinflammatory drug in development for treatment of cystic fibrosis (CF) and other diseases. It is an inhibitor of leukotriene A4 hydrolase; therefore, production of leukotriene B4 (LTB4) in biological fluids provides a direct measure of the pharmacodynamic (PD) response to acebilustat treatment. Here we compare the pharmacokinetics (PK) and PD between CF patients and healthy volunteers, and investigate the food effect and CYP3A4 induction in healthy volunteers. No significant differences between study populations were observed for peak plasma level (C_max ) or exposure (AUC). In healthy volunteers, a shift in time to C_max (T_max ) was observed after a high-fat meal, but there was no change in AUC. LTB4 production was reduced in the blood of both populations and in sputum from CF patients. Acebilustat did not induce CYP3A4. These results support continued clinical study of once-daily oral acebilustat in CF at doses of 50 and 100 mg.

Intraluminal high-dose-rate brachytherapy for palliation of dysphagia in cancer of the esophagus: initial experience at a single UK center

Esophageal cancer tends to present with advanced disease, and the majority of patients are suitable only for palliative treatment at diagnosis. Dysphagia is the most common presenting symptom and significantly undermines quality of life. High-dose-rate intraluminal brachytherapy (ILBT) has been an option for the palliation of dysphagia for many years and has been used at our center since 2006. Experience was presented in terms of improvement of dysphagia and survival. Patients were identified from the local radiotherapy database. Original treatment sheets and clinical notes were reviewed retrospectively to obtain treatment details, pretreatment and post-treatment dysphagia scores, and survival information. Between January 2006 and January 2010, 21 patients of median age 77 years with a mean pretreatment dysphagia score of 2.5 underwent ILBT for esophageal cancer. All received 12 Gy in a single fraction. Thirteen (62%) had adenocarcinoma and eight (38%) squamous cell carcinoma. Four (19%) tumors were in the mid-esophagus and 17 (81%) in the lower esophagus. Eight had extension of tumor into the gastroesophageal junction. Seven patients (33%) received chemotherapy as first-line treatment prior to brachytherapy. Nineteen patients had clear documentation of dysphagia scores both pretreatment and post-treatment, and the improvement overall was significant (P= 0.04). Ten patients (53%) had an improvement in dysphagia score. Five of these (50%) went on to require further endoscopic intervention due to disease progression. Median duration of response was 4 months. Of the nonresponders, six (67%) went on to require further endoscopic intervention. No patients experienced documented toxicity aside from a short-lived acute esophagitis. Median survival from date of diagnosis was 12 months and from treatment date was 5 months (1-32 months). In our series of elderly patients with significant dysphagia, ILBT was a well-tolerated and effective treatment. It should be considered as a palliative option in esophageal cancer.

TLR-4 signalling accelerates colon cancer cell adhesion via NF-κB mediated transcriptional up-regulation of Nox-1

Surgery induced inflammation is a potent promoter of tumour recurrence and metastasis in colorectal cancer. The recently discovered family of Nox enzymes represent a major source of endogenous reactive oxygen species (ROS) and are now heavily implicated in tumour cell metastasis. Interestingly, Nox enzymes can be ‘purposefully’ activated by inflammatory cytokines and growth factors which are present in abundance in the peri-operative window. As colon cancer cells express Nox enzymes and Toll-like receptor 4 (TLR-4), we hypothesised that LPS may potentiate the ability of colon cancer cells to metastasise via Nox enzyme mediated redox signalling. In support of this hypothesis, this paper demonstrates that LPS induces a significant, transient increase of endogenous ROS in SW480, SW620 and CT-26 colon cancer cells. This increase in LPS-induced ROS activity is completely abrogated by a Nox inhibitor, diphenyleneiodonium (DPI), Nox1 siRNA and an NF-κB inhibitor, Dihydrochloride. A significant increase in Nox1 and Nox2 protein expression occurs following LPS treatment. Inhibition of NF-κB also attenuates the increase of Nox1 and Nox2 protein expression. The sub-cellular location of LPS-induced ROS generation lies mainly in the endoplasmic reticulum. LPS activates the PI3K/Akt pathway via Nox generated ROS and this signal is inhibited by DPI. This LPS activated Nox mechanism facilitates a significant increase in SW480 colon cancer cell adhesion to collagen I, which is inhibited by DPI, Nox1 siRNA and a PI3K inhibitor. Altogether, these data suggest that the LPS-Nox1 redox signalling axis plays a crucial role in facilitation of colon cancer cell adhesion, thus increasing the metastatic potential of colon cancer cells. Nox1 may represent a valuable target in which to prevent colon cancer metastasis.

H2O2 production downstream of FLT3 is mediated by p22phox in the endoplasmic reticulum and is required for STAT5 signalling

The internal tandem duplication (ITD) of the juxtamembrane region of the FLT3 receptor has been associated with increased reactive oxygen species (ROS) generation in acute myeloid leukemia (AML). How this elevated level of ROS contributes to the leukemic phenotype, however, remains poorly understood. In this work we show that ROS in the FLT3-ITD expressing AML cell line MV4-11 is reduced by treatment with PKC412, an inhibitor of FLT3, DPI, a flavoprotein inhibitor, and VAS2870, a Nox specific inhibitor, suggesting that ROS production is both FLT3 and NADPH oxidase dependent. The majority of these ROS co-localize to the endoplasmic reticulum (ER), as determined with the H₂O₂-specific aryl-boronate dye Peroxyorange 1, which also corresponds to co-localization of p22phox. Moreover, knocking down p22phox dramatically reduces H₂O₂ after 24 hours in the ER, without affecting mitochondrial ROS. Significantly, the FLT3 inhibitor PKC412 reduces H₂O₂ in FLT3-ITD expressing cell lines (MV4-11, MOLM-13) through reduction of p22phox over 24 hours. Reduced p22phox is achieved by proteasomal degradation and is prevented upon GSK3-β inhibition. Knockdown of p22phox resulted in reduced STAT5 signalling and reduced Pim-1 levels in the cells after 24 hours. Thus, we have shown that FLT3 driven H₂O₂ production in AML cells is mediated by p22phox and is critical for STAT5 signalling.

Inhibition of protein-tyrosine phosphatase 1B (PTP1B) mediates ubiquitination and degradation of Bcr-Abl protein

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder characterized at the molecular level by the expression of Bcr-Abl, a chimeric protein with deregulated tyrosine kinase activity. The protein-tyrosine phosphatase 1B (PTP1B) is up-regulated in Bcr-Abl-expressing cells, suggesting a regulatory link between the two proteins. To investigate the interplay between these two proteins, we inhibited the activity of PTP1B in Bcr-Abl-expressing TonB.210 cells by either pharmacological or siRNA means and examined the effects of such inhibition on Bcr-Abl expression and function. Herein we describe a novel mechanism by which the phosphatase activity of PTP1B is required for Bcr-Abl protein stability. Inhibition of PTP1B elicits tyrosine phosphorylation of Bcr-Abl that triggers the degradation of Bcr-Abl through ubiquitination via the lysosomal pathway. The degradation of Bcr-Abl consequently inhibits tyrosine phosphorylation of Bcr-Abl substrates and the downstream production of intracellular reactive oxygen species. Furthermore, PTP1B inhibition reduces cell viability and the IC(50) of the Bcr-Abl inhibitor imatinib mesylate. Degradation of Bcr-Abl via PTP1B inhibition is also observed in human CML cell lines K562 and LAMA-84. These results suggest that inhibition of PTP1B may be a useful strategy to explore in the development of novel therapeutic agents for the treatment of CML, particularly because host drugs currently used in CML such as imatinib focus on inhibiting the kinase activity of Bcr-Abl.

N-glycosylation is important for the correct intracellular localization of HFE and its ability to decrease cell surface transferrin binding

HFE is a type 1 transmembrane protein that becomes N-glycosylated during transport to the cell membrane. It influences cellular iron concentrations through multiple mechanisms, including regulation of transferrin binding to transferrin receptors. The importance of glycosylation in HFE localization and function has not yet been studied. Here we employed bioinformatics to identify putative N-glycosylation sites at residues N110, N130 and N234 of the human HFE protein, and used site-directed mutagenesis to create combinations of single, double or triple mutants. Compared with the wild-type protein, which co-localizes with the type 1 transferrin receptor in the endosomal recycling compartment and on distributed punctae, the triple mutant co-localized with BiP in the endoplasmic reticulum. This was similar to the localization pattern described previously for the misfolding HFE-C282Y mutant that causes type 1 hereditary haemachromatosis. We also observed that the triple mutant was functionally deficient in beta2-microglobulin interactions and incapable of regulating transferrin binding, once again, reminiscent of the HFE-C282Y variant. Single and double mutants that undergo limited glycosylation appeared to have a mixed phenotype, with characteristics primarily of the wild-type, but also some from the glycosylation-deficient protein. Therefore, although they displayed an endosomal recycling compartment/punctate localization like the wild-type protein, many cells simultaneously displayed additional reticular localization. Furthermore, although the majority of cells expressing these single and double mutants showed decreased surface binding of transferrin, a number appeared to have lost this ability. We conclude that glycosylation is important for the normal intracellular trafficking and functional activity of HFE.

Rod and cone photoreceptor cells produce ROS in response to stress in a live retinal explant system

PURPOSE

The production of reactive oxygen species (ROS) can lead to oxidative stress, which is a strong contributory factor to many ocular diseases. In this study, the removal of trophic factors is used as a model system to investigate the effects of stress in the retina. The aims were to determine if both rod and cone photoreceptor cells produce ROS when they are deprived of trophic factor support and to demonstrate if the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) enzymes are responsible for this ROS production.

METHODS

Retinas were explanted from mice aged between postnatal days 8-10 and cultured overnight. The following morning, confocal microscopy combined with various fluorescent probes was used to detect the production of ROS. Each time peanut agglutinin (PNA), a cone photoreceptor marker, was used to facilitate orientation of the retina. Dihydroethidium and dihydrorhodamine 123 (DHR123) were used to determine which cells produce ROS. Subsequently, western blots of retinal serial sections were used to detect the presence of Noxs in the different retinal layers. The Nox inhibitor apocynin was then tested to determine if it altered the production of ROS within these cells.

RESULTS

Live retinal explants, viewed at high magnifications using confocal microscopy, displayed an increase in the fluorescent products of dihydroethidium and DHR123 upon serum removal when compared to controls. DHR123 fluorescence, once oxidized, localized to mitochondria and was found in the same focal plane as the PNA staining. This showed that cones and rods produced ROS when stressed. Retinal serial sectioning established that the photoreceptor layer expressed Nox4, dual oxidase (Duox) 1, and Duox2 at varying levels. Finally, the Nox inhibitor apocynin decreased the burst stimulated by the stress of serum removal.

CONCLUSIONS

Confocal microscopy and PNA staining allowed differentiation of cell types within the outermost layers of the retina, demonstrating that both rods and cones generated ROS in response to the stress of serum deprivation. Nox4 was the most abundantly expressed Nox in the photoreceptor layer, but Duox1 and Duox2 were also present at detectable levels, and as apocynin reduced the levels of ROS produced, this implied that these proteins may play some role in this production.

Knockdown of beta2-microglobulin perturbs the subcellular distribution of HFE and hepcidin

Hereditary Haemochromatosis is an iron overload disorder associated with mutations in the HFE gene, and to a lesser degree, the gene encoding its chaperone protein beta-2 microglobulin (beta2M). Here, we report that knockdown of beta2M by RNAi restricts HFE distribution to the endoplasmic reticulum (ER). Additionally, we demonstrate that hepcidin, an iron homeostasis-associated protein, localises predominantly to LBPA-positive late endosomes. Interestingly, we show that knockdown of beta2M by RNAi perturbs hepcidin localisation to late endosomes. In summary, our data suggest that beta2M is essential for the correct subcellular distribution of both HFE and hepcidin, two proteins, which are critical for iron homeostasis.

The Hereditary Hemochromatosis protein HFE and its chaperone β2-microglobulin localise predominantly to the endosomal-recycling compartment

Hereditary Hemochromatosis is an iron overload disease most frequently associated with mutations in the HFE gene. While clinical studies of the disease have received extensive attention by various groups, the localisation, trafficking and function of the HFE protein, and its chaperone beta2-microglobulin (beta2M), require further investigation. In this study, we present data on the cellular localisation of HFE and its clinically relevant mutants in HuTu 80 cells. We find by confocal microscopy that HFE localises to the endosomal-recycling compartment (ERC), with minimal localisation to sorting or late endosomes. Interestingly, we also demonstrate that beta2M localises to the ERC where it co-localises with HFE. We find that exogenous expression of HFE results in enhanced beta2M cellular levels and that beta2M is necessary for cell surface expression of HFE. Finally, we have analysed the functional effects of exogenous expression of HFE and beta2M on transferrin binding to the cell surface. In summary, our study sheds light on the localisation and functional effects of the HFE and its chaperone protein beta2M.

Merging mouse transcriptome analyses with Parkinson's disease linkage studies

The hallmark of Parkinson's disease (PD OMIM #168600) is the degeneration of the nigral dopaminergic system affecting approximately 1% of the human population older than 65. In pursuit of genetic factors contributing to PD, linkage and association studies identified several susceptibility genes. The majority of these genes are expressed by the dopamine-producing neurons in the substantia nigra. We, therefore, propose expression by these neurons as a selection criterion, to narrow down, in a rational manner, the number of candidate genes in orphan PD loci, where no mutation has been associated thus far. We determined the corresponding human chromosome locations of 1435 murine cDNA fragments obtained from murine expression analyses of nigral dopaminergic neurons and combined these data with human linkage studies. These fragments represent 19 genes within orphan OMIM PD loci. We used the same approach for independent association studies and determined the genes in neighborhood to the peaks with the highest LOD score value. Our approach did not make any assumptions about disease mechanisms, but it, nevertheless, revealed α-synuclein, NR4A2 (Nurr1), and the tau genes, which had previously been associated to PD. Furthermore, our transcriptome analysis identified several classes of candidate genes for PD mutations and may also provide insight into the molecular pathways active in nigral dopaminergic neurons.

Identification and developmental analysis of genes expressed by dopaminergic neurons of the substantia nigra pars compacta

The hallmark of Parkinson's Disease is the degenerative loss of mesencephalic dopaminergic (mDA) neurons. Previous studies have shown that the homeobox transcription factors, engrailed-1 and -2, are essential for the survival of these cells. To identify genes downstream of engrailed-1 and -2, we performed a PCR-based differential display, comparing RNA from engrailed-1/2 double mutant and wild type ventral midbrain of different embryonic ages to adult olfactory bulb, a source of unrelated DA neurons. Here, we report the result of this experiment and describe the developmental expression pattern in the ventral midbrain of three of the isolated genes, HNF3alpha, synaptotagmin I, and Ebf3. Though not regulated by engrailed-1 and -2, the expression of all three genes is limited to mDA neurons and a few other brain areas. HNF3alpha appears in the precursors of mDA neurons at E9 and is expressed in the adult brain almost exclusively by this neuronal population. Synaptotagmin I is expressed from E14 into adulthood. Ebf3, in contrast, is transiently expressed during early postmitotic differentiation.

Midbrain dopaminergic neurons: determination of their developmental fate by transcription factors

Midbrain dopaminergic neurons are the main source of dopamine in the mammalian central nervous system and are associated with one of the most prominent human neurological disorders, Parkinson's disease. During development, they are induced in the ventral midbrain by an interaction between two diffusible factors, SHH and FGF8. The local identity of this part of the midbrain is probably determined by the combinatorial expression of three transcription factors, Otx2, Pax2, and Pax5. After the last cell division, the neurons start to express transcription factors that control further differentiation and the manifestation of cellular properties characteristic for adult dopaminergic neurons of the substantia nigra compacta and the ventral tegmentum. The first to appear is the LIM-homeodomain transcription factor, Lmx1b. It is essential for the survival of these neurons, and it regulates the expression of another transcription factor, Pitx3, an activator of tyrosine hydroxylase. Lmx1b is followed by the orphan steroid receptor Nurr1. It is essential for the expression of the dopaminergic phenotype. Several genes involved in dopamine synthesis, transport, release, and reuptake are regulated by Nurr1. This requirement is specific to the midbrain dopaminergic neurons, since other populations of the same neurotransmitter phenotype develop normally in absence of the gene. A day after Nurr1, two homeodomain transcription factors, engrailed-1 and -2, are expressed. In animals deficient in the two genes, the midbrain dopaminergic neurons are generated, but then fail to differentiate and disappear very rapidly. Interestingly, alpha-synuclein, a gene recently linked to familial forms of Parkinson's disease, is regulated by engrailed-1 and -2.

The potential role of serum CA 125 in an ultrasound-based screening program for familial ovarian cancer

We have assessed the potential role of a test based upon the measurement of serum CA 125 in an ultrasound-based screening program for familial ovarian cancer. A sample of peripheral blood was taken from 1502 self-referred, asymptomatic women whose pedigree showed that at least one close relative had developed the disease. All women in the study underwent one screening by transvaginal ultrasonography (consisting of one or more scans) to detect any persistent lesion and a change in ovarian volume. Women with a positive result were referred for surgery. The concentration of serum CA 125 was measured in all samples at the end of the study. Seven ovarian cancers (4 invasive and 3 of borderline malignancy; 5 FIGO stage Ia, 1 stage IIa, 1 stage III) and 55 benign lesions were detected. We calculated the effect that a prescreening test (based on different threshold values for serum CA 125) would have had on the number of women entering the ultrasound-based screening program, and on the detection rate and false-positive rate of the overall procedure. There was a direct relationship between the number of women referred for ultrasound screening and the detection rate. The use of a threshold value for serum CA 125 > or = 20 U/ml would have meant that 380 women (25.3%) were referred for ultrasonography and 5 out of 7 cancers (71%) would have been detected with a false-positive rate of 1.1%. The odds of a woman with a positive screening result having cancer at surgery would have been about 1:3 (which would improve to about 1:1 if observational indices of color Doppler imaging and a morphological score had been used throughout). We concluded that a prescreening immunochemical test based on the measurement of serum CA 125 (with a threshold value of > or = 20 U/ml) would increase the prior odds for familial ovarian cancer by 2.8, but would lower the overall detection rate by 29% at the prevalence screening.