in-vitro-aggregation-assays-using-hyperphosphorylated-tau-protein

<em>In Vitro</em> Aggregation Assays Using Hyperphosphorylated Tau Protein

Alzheimer's disease is one of a large group of neurodegenerative disorders known as tauopathies that are manifested by the neuronal deposits of ...

Michigan State University

The nuclear protein ETHYLENE INSENSITIVE2 (EIN2) is a central component of the ethylene signal transduction pathway in plants, and plays an important role in mediating cross-links between several hormone response pathways, including abscisic acid (ABA). ABA mediates stress responses in plants, but there is no report on the role of EIN2 on plant response to salt and osmotic stresses. Here, we show that EIN2 gene regulates plant response to osmotic and salt stress through an ABA-dependent pathway in Arabidopsis. The expression of the EIN2 gene is down-regulated by salt and osmotic stress. An Arabidopsis EIN2 null mutant was supersensitive to both salt and osmotic stress conditions. Disruption of EIN2 specifically altered the expression pattern of stress marker gene RD29B in response to the stresses, but not the stress- or ABA-responsive genes RD29A and RD22, suggesting EIN2 modulates plant stress responses through the RD29B branch of the ABA response. Furthermore, disruption of EIN2 caused substantial increase in ABA. Lastly, our data showed that mutations of other key genes in ethylene pathway also had altered sensitivity to abiotic stresses, indicating that the intact ethylene may involve in the stress response. Taken together, the results identified EIN2 as a cross-link node in ethylene, ABA and stress signaling pathways, and EIN2 is necessary to induce developmental arrest during seed germination, and seedling establishment, as well as subsequent vegetative growth, thereby allowing the survival and growth of plants under the adverse environmental conditions.

Arabidopsis EIN2 modulates stress response through abscisic acid response pathway.

Plant root architecture is highly plastic during development and can adapt to many environmental stresses. The proper distribution of roots within the soil under various conditions such as salinity, water deficit, and nutrient deficiency greatly affects plant survival. Salinity profoundly affects the root system architecture of Arabidopsis (Arabidopsis thaliana). However, despite the inhibitory effects of salinity on root length and the number of roots, very little is known concerning influence of salinity on root growth direction and the underlying mechanisms. Here we show that salt modulates root growth direction by reducing the gravity response. Exposure to salt stress causes rapid degradation of amyloplasts in root columella cells of Arabidopsis. The altered root growth direction in response to salt was found to be correlated with PIN-FORMED2 (PIN2) messenger RNA abundance and expression and localization of the protein. Furthermore, responsiveness to gravity of salt overly sensitive (sos) mutants is substantially reduced, indicating that salt-induced altered gravitropism of root growth is mediated by ion disequilibrium. Mutation of SOS genes also leads to reduced amyloplast degradation in root tip columella cells and the defects in PIN2 gene expression in response to salt stress. These results indicate that the SOS pathway may mediate the decrease of PIN2 messenger RNA in salinity-induced modification of gravitropic response in Arabidopsis roots. Our findings provide new insights into the development of a root system necessary for plant adaptation to high salinity and implicate an important role of the SOS signaling pathway in this process.

Salt modulates gravity signaling pathway to regulate growth direction of primary roots in Arabidopsis.

Different statistical methods and path analysis were used to study the relationship between leaf water use efficiency (WUE) and physio-biochemical traits for 19 wheat genotypes, including photosynthesis rate (P(n)), stomatal conductance (g(s)), transpiration rate (T(r)), intercellular concentration of carbon oxide (C(i)), leaf water potential (Psi(w)), leaf temperature, wax content, leaf relative water content (RWC), rate of water loss from excised-leaf (RWL), peroxidase (POD) and superoxide dismutase (SOD) activities. The results showed that photosynthesis rate, stomatal conductance and transpiration rate were the most important leaf WUE variables under rained conditions. Based on the results of five statistical analyses, it is reasonable to assume that high leaf WUE wheat under the rained could be obtained by selecting breeding materials with high photosynthesis rate, low transpiration rate and stomatal conductance.

Investigation on the relationship between leaf water use efficiency and physio-biochemical traits of winter wheat under rained condition.

To investigate the age-related changes in resting functional connectivity of the marginal division (MrD) of the neostriatum in healthy adults detected using resting-state functional magnetic resonance imaging (rs-fMRI).

[Age-related changes in resting functional connectivity of the marginal division of the neostriatum in healthy adults].

To investigate the structural connectivity between visual cortex and auditory cortex in healthy adults.

[Structural connectivity between visual cortex and auditory cortex in healthy adults: a diffusion tensor imaging study].

To elucidate the volume changes of cortical and subcortical reward circuitry in patients with type 2 diabetes mellitus.

[Volume changes of cortical and subcortical reward circuitry in the brain of patients with type 2 diabetes mellitus].

Under the changing climate, asymmetric warming pattern would be more likely during day and night time, instead of symmetric one. Concurrently, the growth responses and water use of plants may be different compared with those estimated based on symmetric warming. In this work, it was compared with the effects of symmetric (ETs) and asymmetric (ETa) elevation of temperature alone, and in interaction with elevated carbon dioxide concentration (EC), on the grain yield (GY) and evapotranspiration in winter wheat (Triticum aestivum L.) based on pot experiment in the North China Plain (NCP). The experiment was carried out in six enclosed-top chambers with following climate treatments: (1) ambient temperature and ambient CO2 (CON), (2) ambient temperature and elevated CO2 (EC), (3) elevated temperature and ambient CO2 (ETs; ETa), and (4) elevated temperature and elevated CO2 (ECETs, ECETa). In symmetric warming, temperature was increased by 3°C and in asymmetric one by 3.5°C during night and 2.5°C during daytime, respectively. As a result, GY was in ETa and ETs 15.6 (P < 0.05) and 10.3% (P < 0.05) lower than that in CON. In ECETs and ECETa treatments, GY was 14.9 (P < 0.05) and 9.1% (P < 0.05) higher than that in CON. Opposite to GY, evapotranspiration was 7.8 (P < 0.05) and 17.9% (P < 0.05) higher in ETa and ETs treatments and 7.2 (P < 0.05) and 2.1% (P > 0.05) lower in ECETs and ECETa treatments compared with CON. Thus, GY of wheat could be expected to increase under the changing climate with concurrent elevation of CO2 and temperature as a result of increased WUE under the elevated CO2. However, the gain would be lower under ETa than that estimated based on ETs due to higher evapotranspiration.

Comparison of the effects of symmetric and asymmetric temperature elevation and CO2 enrichment on yield and evapotranspiration of winter wheat (Triticum aestivum L.).

Chronic exposure to low-levels of organophosphate (OP) compounds, such as chlorpyrifos (CPF), induces oxidative stress and could be related to neurological disorders. Hydrogen has been identified as a novel antioxidant which could selectively scavenge hydroxyl radicals. We explore whether intake of hydrogen-rich water (HRW) can protect Wistar rats from CPF-induced neurotoxicity. Rats were gavaged daily with 6.75mg/kg body weight (1/20 LD50) of CPF and given HRW by oral intake. Nissl staining and electron microscopy results indicated that HRW intake had protective effects on the CPF-induced damage of hippocampal neurons and neuronal mitochondria. Immunostaining results showed that the increased glial fibrillary acidic protein (GFAP) expression in astrocytes induced by CPF exposure can be ameliorated by HRW intake. Moreover, HRW intake also attenuated CPF-induced oxidative stress as evidenced by enhanced level of MDA, accompanied by an increase in GSH level and SOD and CAT activity. Acetylcholinesterase (AChE) activity tests showed significant decrease in brain AChE activity after CPF exposure, and this effect can be ameliorated by HRW intake. An in vitro study demonstrated that AChE activity was more intense in HRW than in normal water with or without chlorpyrifos-oxon (CPO), the metabolically-activated form of CPF. These observations suggest that HRW intake can protect rats from CPF-induced neurotoxicity, and the protective effects of hydrogen may be mediated by regulating the oxidant and antioxidant status of rats. Furthermore, this work defines a novel mechanism of biological activity of hydrogen by directly increasing the AChE activity.

Oral intake of hydrogen-rich water ameliorated chlorpyrifos-induced neurotoxicity in rats.

Protein acetylation and phosphorylation are key modifications that regulate both normal and pathological protein functions. The gel systems currently used for analyzing modified proteins require either expensive reagents or time-consuming second dimension electrophoresis. Here we present a neutral pH gel system that allows the analysis of acetylated and phosphorylated proteins. The neutral pH urea Triton-polyacrylamide gel electrophoresis (NUT-PAGE) system separates proteins based on their charge at pH 7.0 and generates discrete bands from each acetylated and/or phosphorylated species. In addition, the gel is composed of common and inexpensive laboratory reagents and requires only a single dimension of electrophoresis. We demonstrate the effectiveness of this system by analyzing the phosphorylated species of an acidic protein, α-synuclein, and both acetylated and phosphorylated species of a basic protein, histone H3. NUT-PAGE thus provides a cost-effective alternative for resolving acetylated and phosphorylated proteins, and potentially proteins with other post-translational modifications that alter net charge.

Resolving acetylated and phosphorylated proteins by neutral urea Triton-polyacrylamide gel electrophoresis: NUT-PAGE.

To evaluate early occult brain functional damage in patients with type 2 diabetes mellitus using resting-state functional magnetic resonance imaging (MRI).

[Resting-state brain functional magnetic resonance imaging in patients with type 2 diabetes mellitus].

Many biomedically critical proteins are underrepresented in proteomics and biochemical studies due to difficulties of their production in E. coli. These proteins may possess a posttranslational modification vital to their functions, tend to misfold and be partitioned into bacterial inclusion bodies, or act only in a stoichiometric dimeric complex. Successful production of these proteins requires efficient interaction between these proteins and a specific "facilitator", such as a protein-modifying enzyme, a molecular chaperone, or a natural physical partner within the dimeric complex. Here we report the design and applications of a PIMAX system (protein interaction module-assisted function X) that effectively overcomes these hurdles. By fusing two proteins of interest to a pair of well-studied protein-protein interaction modules, we were able to potentiate the association of these two proteins, resulting in successful production of hyperphosphorylated tau protein intimately linked to Alzheimer's disease, and an enzymatically active cyclin-dependent kinase complex. Furthermore, using tau isoforms quantitatively phosphorylated by GSK-3β and CDK5 kinases via PIMAX, we demonstrated the hyperphosphorylation-stimulated tau oligomerization in vitro, paving the way for new Alzheimer's disease drug discoveries. Vectors for PIMAX can be easily modified to meet the needs of different applications. This approach thus provides a convenient and modular suite with broad impacts on proteomics and biomedical research.

Mengyu Liu

Department of Biochemistry and Molecular Biology

Michigan State University

In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

Mengyu Liu

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Biochemistry and Molecular Biology

Michigan State University

In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

Department of Biochemistry and Molecular Biology