Mutations in the FUS/TLS gene on chromosome 16 cause familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal degenerative motor neuron disorder. Ten percent of cases are inherited; most involve unidentified genes. We report here 13 mutations in the fused in sarcoma/translated in liposarcoma (FUS/TLS) gene on chromosome 16 that were specific for familial ALS. The FUS/TLS protein binds to RNA, functions in diverse processes, and is normally located predominantly in the nucleus. In contrast, the mutant forms of FUS/TLS accumulated in the cytoplasm of neurons, a pathology that is similar to that of the gene TAR DNA-binding protein 43 (TDP43), whose mutations also cause ALS. Neuronal cytoplasmic protein aggregation and defective RNA metabolism thus appear to be common pathogenic mechanisms involved in ALS and possibly in other neurodegenerative disorders.

The gene encoding alsin, a protein with three guanine-nucleotide exchange factor domains, is mutated in a form of recessive amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS) are neurodegenerative conditions that affect large motor neurons of the central nervous system. We have identified a familial juvenile PLS (JPLS) locus overlapping the previously identified ALS2 locus on chromosome 2q33. We report two deletion mutations in a new gene that are found both in individuals with ALS2 and those with JPLS, indicating that these conditions have a common genetic origin. The predicted sequence of the protein (alsin) may indicate a mechanism for motor-neuron degeneration, as it may include several cell-signaling motifs with known functions, including three associated with guanine-nucleotide exchange factors for GTPases (GEFs).

GTP-dependent segregation of H-ras from lipid rafts is required for biological activity

Different sites of plasma membrane attachment may underlie functional differences between isoforms of Ras. Here we show that palmitoylation and farnesylation targets H-ras to lipid rafts and caveolae, but that the interaction of H-ras with these membrane subdomains is dynamic. GTP-loading redistributes H-ras from rafts into bulk plasma membrane by a mechanism that requires the adjacent hypervariable region of H-ras. Release of H-ras-GTP from rafts is necessary for efficient activation of Raf. By contrast, K-ras is located outside rafts irrespective of bound nucleotide. Our studies identify a novel protein determinant that is required for H-ras function, and show that the GTP/GDP state of H-ras determines its lateral segregation on the plasma membrane.

Regulation of protein kinase B/Akt-serine 473 phosphorylation by integrin-linked kinase: critical roles for kinase activity and amino acids arginine 211 and serine 343

Protein kinase B (PKB/Akt) is a regulator of cell survival and apoptosis. To become fully activated, PKB/Akt requires phosphorylation at two sites, threonine 308 and serine 473, in a phosphatidylinositol (PI) 3-kinase-dependent manner. The kinase responsible for phosphorylation of threonine 308 is the PI 3-kinase-dependent kinase-1 (PDK-1), whereas phosphorylation of serine 473 has been suggested to be regulated by PKB/Akt autophosphorylation in a PDK-1-dependent manner. However, the integrin-linked kinase (ILK) has also been shown to regulate phosphorylation of serine 473 in a PI 3-kinase-dependent manner. Whether ILK phosphorylates this site directly or functions as an adapter molecule has been debated. We now show by in-gel kinase assay and matrix-assisted laser desorption-ionization time-of-flight mass spectrometry that biochemically purified ILK can phosphorylate PKB/Akt directly. Co-immunoprecipitation analysis of cell extracts demonstrates that ILK can complex with PKB/Akt as well as PDK-1 and that ILK can disrupt PDK-1/PKB association. The amino acid residue serine 343 of ILK within the activation loop is required for kinase activity as well as for its interaction with PKB/Akt. Mutational analysis of ILK further shows a crucial role for arginine 211 of ILK within the phosphoinositide phospholipid binding domain in the regulation of PKB- serine 473 phosphorylation. A highly selective small molecule inhibitor of ILK activity also inhibits the ability of ILK to phosphorylate PKB/Akt in vitro and in intact cells. These data demonstrate that ILK is an important upstream kinase for the regulation of PKB/Akt.

Ras isoforms vary in their ability to activate Raf-1 and phosphoinositide 3-kinase

Ha-, N-, and Ki-Ras are ubiquitously expressed in mammalian cells and can all interact with the same set of effector proteins. We show here, however, that in vivo there are marked quantitative differences in the ability of Ki- and Ha-Ras to activate Raf-1 and phosphoinositide 3-kinase. Thus, Ki-Ras both recruits Raf-1 to the plasma membrane more efficiently than Ha-Ras and is a more potent activator of membrane-recruited Raf-1 than Ha-Ras. In contrast, Ha-Ras is a more potent activator of phosphoinositide 3-kinase than Ki-Ras. Interestingly, the ability of Ha-Ras to recruit Raf-1 to the plasma membrane is significantly increased when the Ha-Ras hypervariable region is shortened so that the spacing of the Ha-Ras GTPase domains from the inner surface of the plasma membrane mimicks that of Ki-Ras. Importantly, these data show for the first time that the activation of different Ras isoforms can have distinct biochemical consequences for the cell. The mutation of specific Ras isoforms in different human tumors can, therefore, also be rationalized.

Therapeutic intervention with complement and beta-glucan in cancer

Complement (C) has two major effector systems available for host defense. The membrane attack complex (MAC) generated from components C5-C9 can form membrane-penetrating lesions that lead to cell death by causing a rapid loss of cytoplasmic components. The MAC is only effective against pathogens with outer phospholipid membranes, and cannot kill gram-positive bacteria or yeast whose membranes are protected by cell walls. The most important effector mechanism of C is the opsonization of microbial pathogens with the serum protein C3 that leads to their high avidity attachment to the C3-receptors of phagocytic cells. Pathogens that activate complement are first coated with the C3b fragment of C3, which is rapidly proteolyzed into the iC3b fragment by serum factor I. These iC3b fragments serve to promote the high avidity attachment of the 'iC3b-opsonized' pathogens to the iC3b-receptors (CR3, CD11b/CD18) of phagocytic cells and natural killer (NK) cells, stimulating phagocytosis and/or cytotoxic degranulation. Host cells, including neoplastic tumor cells, have been endowed with natural mechanisms for self-protection against both the MAC and the cytotoxic activation of CR3. This review discusses a novel type of immunotherapy for cancer that uses soluble yeast beta-glucan to override the normal resistance of iC3b-opsonized tumor cells to the cytotoxic activation of phagocyte and NK cell CR3, allowing this important effector mechanism of the C system to function against tumor cells in the same way that it normally functions against bacteria and yeast. Moreover, the cytotoxic activation of beta-glucan-primed NK cell CR3 by iC3b-opsonized tumors is shown to be accompanied by a tumor-localized secretion of the cytokines TNFalpha, IFNalpha, IFNgamma, and IL-6.

Characterization of the regional intestinal kinetics of drug efflux in rat and human intestine and in Caco-2 cells

PURPOSE

The aim of the present study was to investigate the transport kinetics of intestinal secretory processes in the jejunum, ileum and colon of rats and humans and in Caco-2 cells, in vitro.

METHODS

Etoposide, vinblastine sulphate and verapamil hydrochloride were chosen as model substrates since they have been reported to undergo efflux in various other tissues. The concentration dependence, inhibition, directionality, temperature dependence, proton/sodium dependence, and ATP dependence of efflux were studied using side-by-side diffusion chambers and brush border membrane vesicles (BBMVs). Intestinal tissue from rats and humans and Caco-2 cells (passage no. 26) were used. Directional steady state effective permeabilities were calculated from drug appearance in the apical (AP) or basolateral (BL) chambers. Kinetic studies were carried out by investigating substrate efflux at concentrations ranging from 0.2 microns to 1000 microns. Since substrate efflux may be a result of more than one transporter, the hybrid efflux Km (Michaelis-constant), Pc (carrier-mediated permeability), and Pm (passive permeability) were determined as a function of intestinal region. Inhibitor studies were performed using quinidine (0.2mM), a mixed inhibitor of P-glycoprotein (Pgp) and Multidrug Resistance-Associated Protein (MRP), and Leukotriene C4 (100 nM), an inhibitor of MRP and the canalicular multispecific organic anion transporter (cMOAT). Temperature dependent efflux was determined by investigating the BL to AP transport at temperatures ranging from 3 degrees C to 37 degrees C. Energies of activation (Ea) were determined from an Arrhenius analysis. Sodium, proton, and ATP dependence were determined using BBMVs. Immunoquantitation of Pgp, MRP and Lung Resistance Protein (LRP) in Caco-2 cells were carried out using Western blot analysis.

RESULTS

Active efflux of all substrates was observed in all regions of rat and human intestine and in Caco-2 cells. Directionality was observed with BL to AP transport exceeding AP to BL transport. The BL to AP/AP to BL permeability ratio, the efflux ratio, ranged from 1.4 to 19.8. Ileal efflux was significantly higher (p < 0.001) than in other regions. Kinetic studies revealed that hybrid efflux Km values ranged from 4 to 350 microns. In some cases, efflux was not saturable due to the solubility limits of the compounds utilized in this study. In presence of inhibitors, efflux ratios approached 1. BL to AP transport was temperature dependent in rat ileum for all substrates. Each of the intestinal efflux was found to be 11.6, 8.3, and 15.8 kcal/mole for etoposide, vinblastine and verapamil, respectively, suggesting an active, energy-dependent efflux mechanism. Substrate efflux was not sodium or proton dependent but was dependent on ATP. Using Western blot analysis the presence of Pgp, MRP, and LRP was demonstrated in Caco-2 cells and the amount of each transport protein varied as a function of passage number.

CONCLUSIONS

Using multiple putative efflux substrates, the current results demonstrate that intestinal efflux was regionally dependent, mediated by multiple efflux transporters, the Km's were in the micro-molar range, and involved an energy dependent mechanism(s).

Corticofugal modulation of frequency processing in bat auditory system

Auditory signals are transmitted from the inner ear through the brainstem to the higher auditory regions of the brain. Neurons throughout the auditory system are tuned to stimulus frequency, and in many auditory regions are arranged in topographical maps with respect to their preferred frequency. These properties are assumed to arise from the interactions of convergent and divergent projections ascending from lower to higher auditory areas; such a view, however, ignores the possible role of descending projections from cortical to subcortical regions. In the bat auditory system, such corticofugal connections modulate neuronal activity to improve the processing of echo-delay information, a specialized feature. Here we show that corticofugal projections are also involved in the most common type of auditory processing, frequency tuning. When cortical neurons tuned to a specific frequency are inactivated, the auditory responses of subcortical neurons tuned to the same frequency are reduced. Moreover, the responses of other subcortical neurons tuned to different frequencies are increased, and their preferred frequencies are shifted towards that of the inactivated cortical neurons. Thus the corticofugal system mediates a positive feedback which, in combination with widespread lateral inhibition, sharpens and adjusts the tuning of neurons at earlier stages in the auditory processing pathway.

Frameshift and novel mutations in FUS in familial amyotrophic lateral sclerosis and ALS/dementia

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a progressive paralytic disorder caused by degeneration of motor neurons. Mutations in the FUS gene were identified in patients with familial ALS (FALS) and patients with sporadic ALS (SALS) from a variety of genetic backgrounds. This work further explores the spectrum of FUS mutations in patients with FALS and patients with FALS with features of frontotemporal dementia (FALS/FTD) or parkinsonism and dementia (FALS/PD/DE).

METHODS

All exons of the FUS gene were sequenced in 476 FALS index cases negative for mutations in SOD1 and TARDBP. A total of 561-726 controls were analyzed for genetic variants observed. Clinical data from patients with FUS mutations were compared to those of patients with known SOD1 and TARDBP mutations.

RESULTS

We identified 17 FUS mutations in 22 FALS families, 2 FALS/FTD families, and 1 FALS/PD/DE family from diverse genetic backgrounds; 11 mutations were novel. There were 4 frameshift, 1 nonsense, and 1 possible alternate splicing mutation. Patients with FUS mutations appeared to have earlier symptom onset, a higher rate of bulbar onset, and shorter duration of symptoms than those with SOD1 mutations.

CONCLUSIONS

FUS gene mutations are not an uncommon cause in patients with FALS from diverse genetic backgrounds, and have a prevalence of 5.6% in non-SOD1 and non-TARDBP FALS, and approximately 4.79% in all FALS. The pathogenicity of some of these novel mutations awaits further studies. Patients with FUS mutations manifest earlier symptom onset, a higher rate of bulbar onset, and shorter duration of symptoms.

Corticofugal modulation of time-domain processing of biosonar information in bats

The Jamaican mustached bat has delay-tuned neurons in the inferior colliculus, medial geniculate body, and auditory cortex. The responses of these neurons to an echo are facilitated by a biosonar pulse emitted by the bat when the echo returns with a particular delay from a target located at a particular distance. Electrical stimulation of cortical delay-tuned neurons increases the delay-tuned responses of collicular neurons tuned to the same echo delay as the cortical neurons and decreases those of collicular neurons tuned to different echo delays. Cortical neurons improve information processing in the inferior colliculus by way of the corticocollicular projection.

Assay of ochratoxin A in wine and beer by high-pressure liquid chromatography photodiode array and gas chromatography mass selective detection

To routinely assay the concentrations of ochratoxin A (OTA) in wines and beers, two new methods were developed and evaluated. The first utilized solid-phase extraction on a C(18) cartridge to achieve a 100-fold sample concentration followed by high-performance liquid chromatography on a C(18) column with gradient elution and quantitation at 333 nm by means of a photodiode array detector. Positive confirmation can be carried out by purity and match-factor analysis as well as peak shift following esterification with BF(3). Total run time is 28 min. The limits of detection (LOD) and quantitation (LOQ) are 0.05 and 0.10 microg/L, respectively. Recovery and imprecision ranged from 83 to 94% and from 4.0 to 8.9%, respectively. With a throughput of 35 assays per working day, this method is ideal for routine OTA analysis. It was used to survey the concentrations of OTA in 942 wines (2 of which gave values between 0.1 and 0.2 microg/L) and 107 beers (2 of which gave values between 0.05 and 0.1 microg/L). OTA was detected more frequently in red than white wines, with the highest incidence in red wines from Spain and Argentina. There was no association between OTA and country of origin or beverage type among the beers analyzed. The second method utilized gas chromatography with mass selective detection monitoring eight specific ions, preceded by extraction in dichloromethane and derivatization with bis[trimethylsilyl]trifluoroacetamide. LOD and LOQ were 0.1 and 2 microg/L, respectively; recovery and imprecision were 69-75 and 9.0-11.1%, respectively. The method is not suitable for routine quantitation but is potentially useful as a confirmatory tool for samples with OTA > or =0.1 microg/L.

Randomised clinical trial: an assessment of acupuncture on specific meridian or specific acupoint vs. sham acupuncture for treating functional dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a common disease without an established optimal treatment.

AIM

To determine (i) the effect of acupuncture in relieving FD symptoms and improving life quality; (ii) the effect difference between acupoint and non-acupoint; and (iii) the effect difference among different acupoints.

METHODS

A total of 712 eligible patients were included and randomly assigned to six groups (Group A: specific acupoints of the stomach meridian; Group B: non-specific acupoints of the stomach meridian; Group C: specific acupoints of alarm and transport points; Group D: specific acupoints of the gallbladder meridian; Group E: sham acupuncture of non-acupoints; and Group F: itopride). A treatment period of 4 weeks (continuous five sessions per week), and a follow-up period of 12 weeks were arranged. The outcomes were the (i) patients' response, (ii) symptoms improvement measured using the Symptom Index of Dyspepsia and (iii) quality-of-life improvement based on Nepean Dyspepsia Index.

RESULTS

All groups had an improvement in dyspepsia symptoms and the QoL at the end of treatment, and the improvement was sustained for 4 weeks and 12 weeks. The overall response rate was significantly higher in acupuncture group A (70.69%), and lower in sham acupuncture group (34.75%), compared with itopride and other acupuncture groups. Similarly, the difference in symptoms and QoL improvement was significant between group A and the other acupuncture groups.

CONCLUSIONS

Acupuncture is effective in the treatment of functional dyspepsia, and is superior to non-acupoint puncture. The benefit of acupuncture relies on acupoint specificity.

Probing excitonic states in suspended two-dimensional semiconductors by photocurrent spectroscopy

The optical response of semiconducting monolayer transition-metal dichalcogenides (TMDCs) is dominated by strongly bound excitons that are stable even at room temperature. However, substrate-related effects such as screening and disorder in currently available specimens mask many anticipated physical phenomena and limit device applications of TMDCs. Here, we demonstrate that that these undesirable effects are strongly suppressed in suspended devices. Extremely robust (photogain > 1,000) and fast (response time < 1 ms) photoresponse allow us to study, for the first time, the formation, binding energies, and dissociation mechanisms of excitons in TMDCs through photocurrent spectroscopy. By analyzing the spectral positions of peaks in the photocurrent and by comparing them with first-principles calculations, we obtain binding energies, band gaps and spin-orbit splitting in monolayer TMDCs. For monolayer MoS2, in particular, we obtain an extremely large binding energy for band-edge excitons, E bind ≥ 570 meV. Along with band-edge excitons, we observe excitons associated with a van Hove singularity of rather unique nature. The analysis of the source-drain voltage dependence of photocurrent spectra reveals exciton dissociation and photoconversion mechanisms in TMDCs.

Molecular dissection of developmental behavior of plant height in rice (Oryza sativa L.)

A doubled haploid population of 123 lines from IR64/Azucena was used to dissect the developmental behavior and genotype by environment interaction for plant height by conditional and unconditional quantitative trait loci (QTL) mapping methods in rice. It was shown that the number of QTL detected was different at various measuring stages. Some QTL could be detected at all stages and some only at one or several stages. More QTL could be found on the basis of time-dependent measures of different stages. By conditional QTL mapping of time-dependent measures, it is possible to reveal dynamic gene expression for quantitative traits. Mapping QTL for genetic main effects and GE interaction effects could help us in understanding the nature of QTL x environment interaction for the development of quantitative traits.

Ultrasensitive assay for three polyphenols (catechin, quercetin and resveratrol) and their conjugates in biological fluids utilizing gas chromatography with mass selective detection

The concentrations of three polyphenols ((+)-catechin, quercetin and trans-resveratrol) in blood serum, plasma and urine, as well as whole blood, have been measured after their oral and intragastric administration, respectively, to humans and rats. The method developed for this purpose utilized ethyl acetate extraction of 100 microl samples and their derivatization with bis(trimethylsilyl)trifluoroacetamide (BSTFA) followed by gas-chromatographic analysis on a DB-5 column followed by mass selective detection employing two target ions and one qualifier ion for each compound. Total run time was 17 min with excellent resolution and linearity. The limits of detection (LOD) and quantitation (LOQ) were an order of magnitude less than for any previously published method, being 0.01 microg/l and 0.1 microg/l, respectively, for all compounds. Recovery at 1 microg/l and 10 microg/l was >80% in all instances but one, and was >90% in 50%. Imprecision was acceptable at 0.25 and 1.0 microg/l, concentrations below the LOQ of previous methods. Aglycones released from conjugates after hydrolysis were easily measurable. Optimal conditions for hydrolysis were established. After oral administration of the three polyphenols to humans, their conjugates vastly exceeded the concentrations of the aglycones in both plasma and urine. Concentrations peaked within 0.5-1.0 h in plasma and within 8 h in urine. During the first 24 h, 5.1% of the (+)-catechin and 24.6% of the trans-resveratrol given were recovered in the urine (free plus conjugated). This method can be proposed as the method of choice to assay these polyphenols and their conjugates in biological fluids.

Hypoxia inducible factor-1 as a target for neurodegenerative diseases

Hypoxia inducible factor-1 (HIF-1) is a transcriptional factor responsible for cellular and tissue adaption to low oxygen tension. HIF-1, a heterodimer consisting of a constitutively expressed β subunit and an oxygen-regulated α subunit, regulates a series of genes that participate in angiogenesis, iron metabolism, glucose metabolism, and cell proliferation/survival. The activity of HIF-1 is controlled by post-translational modifications on different amino acid residues of its subunits, mainly the alpha subunit. Besides in ischemic stroke (see review [1]), emerging evidence has revealed that HIF-1 activity and expression of its down-stream genes, such as vascular endothelial growth factor and erythropoietin, are altered in a range of neurodegenerative diseases. At the same time, experimental and clinical evidence has demonstrated that regulating HIF-1 might ameliorate the cellular and tissue damage in the neurodegenerative diseases. These new findings suggest HIF-1 as a potential medicinal target for the neurodegenerative diseases. This review focuses on HIF-1α protein modifications and HIF-1's potential neuroprotective roles in Alzheimer's (AD), Parkinson's (PD), Huntington's diseases (HD), and amyotrophic lateral sclerosis (ALS).

Ascorbic acid increases the yield of dopaminergic neurons derived from basic fibroblast growth factor expanded mesencephalic precursors

CNS precursors derived from E12 rat mesencephalon proliferate in the presence of basic fibroblast growth factor and differentiate in vitro into functional dopaminergic neurons, which upon transplantation alleviate behavioral symptoms in a rat model of Parkinson's disease. Here we show that the efficiency of dopaminergic differentiation decreases in the mesencephalic precursors that were proliferated or passaged for extended periods in vitro. Ascorbic acid treatment restored dopaminergic differentiation in these precursors and led to a greater than 10-fold increase in dopamine neuron yield compared with untreated cultures. The effect of ascorbic acid was stereospecific and could not be mimicked by any other antioxidants. The expression of sodium-dependent vitamin C transporter, a recently identified stereospecific ascorbic acid transporter, was maintained in mesencephalic precursors for extended in vitro periods. Pre-treatment of in vitro expanded mesencephalic precursors with ascorbic acid might facilitate the large-scale generation of dopaminergic neurons for clinical transplantation.