Paeonol Derivative, 6'-Methyl Paeonol, Attenuates Aß-Induced Pathophysiology in Cortical Neurons and in an Alzheimer's Disease Mice Model.

Herbs themselves and various herbal medicines are great resources for discovering therapeutic drugs for various diseases, including Alzheimer's disease (AD), one of the common neurodegenerative diseases. Utilizing mouse primary cortical neurons and DiBAC4(3), a voltage-sensitive indicator, we have set up a drug screening system and identified an herbal extraction compound, paeonol, obtained from Paeonia lactiflora; this compound is able to ameliorate the abnormal depolarization induced by Aß42 oligomers. Our aim was to further find effective paeonol derivatives since paeonol has been previously studied. 6'-Methyl paeonol, one of the six paeonol derivatives surveyed, is able to inhibit the abnormal depolarization induced by Aß oligomers. Furthermore, 6'-methyl paeonol is able to alleviate the NMDA- and AMPA-induced depolarization. When a molecular mechanism was investigated, 6'-methyl paeonol was found to reverse the Aß-induced increase in ERK phosphorylation. At the animal level, mice injected with 6'-methyl paeonol showed little change in their basic physical parameters compared to the control mice. 6'-Methyl paeonol was able to ameliorate the impairment of memory and learning behavior in J20 mice, an AD mouse model, as measured by the Morris water maze. Thus, paeonol derivatives could provide a structural foundation for developing and designing an effective compound with promising clinical benefits.

Dynamical characteristics of AC-driven hybrid WSe2 monolayer/AlGaInP quantum wells light-emitting device.

The exploration of functional light-emitting devices and numerous optoelectronic applications can be accomplished on an elegant platform provided by rapidly developing transition metal dichalcogenides (TMDCs). However, TMDCs-based light emitting devices encounter certain serious difficulties, such as high resistance losses from ohmic contacts or the need for complex heterostructures, which restricts the device applications. Despite the fact that AC-driven light emitting devices have developed ways to overcome these challenges, there is still a significant demand for multiple wavelength emission from a single device, which is necessary for full color light emitting devices. Here, we developed a dual-color AC-driven light-emitting device by integrating the WSe2 monolayer and AlGaInP-GaInP multiple quantum well (MQW) structures in the form of capacitor structure using AlOx insulating layer between the two emitters. In order to comprehend the characteristics of the hybrid device under various driving circumstances, we investigate the frequency-dependent EL intensity of the hybrid device using an equivalent RC circuit model. The time-resolved electroluminescence (TREL) characteristics of the hybrid device were analyzed in details to elucidate the underlying physical mechanisms governing its performance under varying applied frequencies. This dual-color hybrid light-emitting device enables the use of 2-D TMDC-based light emitters in a wider range of applications, including broad-band LEDs, quantum display systems, and chip-scale optoelectronic integrated systems.

Early Life Exposure to C16-Ceramide Improves Learning and Short-Term Memory Behavior during Adulthood in Mice.

Ceramides, structural components of the cell, are known to play a range of roles in glucose metabolism and apoptosis. C16-ceramide, an abundant molecular species of endogenous ceramide, has not had its influence on learning and memory explored. We administered C16-ceramide to mice immediately after weaning and examined the learning and memory behavior of these mice during adulthood. Mice given C16-ceramide early in life showed improved adult learning/short-term memory behavior without affecting their glucose metabolism. Looking for a plausible mechanism for this, we found that calcium influx, CaMKII/CREB, and the Erk-relevant signaling transduction are increased after C16-ceramide stimulation in primary neurons in vitro. Possible downstream epigenetic molecular events, such as H3K4 methylation and Egr-1 abundance, were also found to be upregulated. Utilizing J20 mice, an Alzheimer disease mice model in which mice were injected after weaning with C16-ceramide, we found that these mice also show improved learning and short-term memory behavior when assessed by the Morris water maze test. Taken together, giving C16-ceramide early in life would seem to benefit learning and short-term memory behavior during adulthood.

AC-driven multicolor electroluminescence from a hybrid WSe2 monolayer/AlGaInP quantum well light-emitting device.

Light-emitting diodes (LEDs) are used widely, but when operated at a low-voltage direct current (DC), they consume unnecessary power because a converter must be used to convert it to an alternating current (AC). DC flow across devices also causes charge accumulation at a high current density, leading to lowered LED reliability. In contrast, gallium-nitride-based LEDs can be operated without an AC-DC converter being required, potentially leading to greater energy efficiency and reliability. In this study, we developed a multicolor AC-driven light-emitting device by integrating a WSe2 monolayer and AlGaInP-GaInP multiple quantum well (MQW) structures. The CVD-grown WSe2 monolayer was placed on the top of an AlGaInP-based light-emitting diode (LED) wafer to create a two-dimensional/three-dimensional heterostructure. The interfaces of these hybrid devices are characterized and verified through transmission electron microscopy and energy-dispersive X-ray spectroscopy techniques. More than 20% energy conversion from the AlGaInP MQWs to the WSe2 monolayer was observed to boost the WSe2 monolayer emissions. The voltage dependence of the electroluminescence intensity was characterized. Electroluminescence intensity-voltage characteristic curves indicated that thermionic emission was the mechanism underlying carrier injection across the potential barrier at the Ag-WSe2 monolayer interface at low voltage, whereas Fowler-Nordheim emission was the mechanism at voltages higher than approximately 8.0 V. These multi-color hybrid light-emitting devices both expand the wavelength range of 2-D TMDC-based light emitters and support their implementation in applications such as chip-scale optoelectronic integrated systems, broad-band LEDs, and quantum display systems.

Optical Mode Tuning of Monolayer Tungsten Diselenide (WSe2) by Integrating with One-Dimensional Photonic Crystal through Exciton-Photon Coupling.

Two-dimensional materials, such as transition metal dichalogenides (TMDs), are emerging materials for optoelectronic applications due to their exceptional light-matter interaction characteristics. At room temperature, the coupling of excitons in monolayer TMDs with light opens up promising possibilities for realistic electronics. Controlling light-matter interactions could open up new possibilities for a variety of applications, and it could become a primary focus for mainstream nanophotonics. In this paper, we show how coupling can be achieved between excitons in the tungsten diselenide (WSe2) monolayer with band-edge resonance of one-dimensional (1-D) photonic crystal at room temperature. We achieved a Rabi splitting of 25.0 meV for the coupled system, indicating that the excitons in WSe2 and photons in 1-D photonic crystal were coupled successfully. In addition to this, controlling circularly polarized (CP) states of light is also important for the development of various applications in displays, quantum communications, polarization-tunable photon source, etc. TMDs are excellent chiroptical materials for CP photon emitters because of their intrinsic circular polarized light emissions. In this paper, we also demonstrate that integration between the TMDs and photonic crystal could help to manipulate the circular dichroism and hence the CP light emissions by enhancing the light-mater interaction. The degree of polarization of WSe2 was significantly enhanced through the coupling between excitons in WSe2 and the PhC resonant cavity mode. This coupled system could be used as a platform for manipulating polarized light states, which might be useful in optical information technology, chip-scale biosensing and various opto-valleytronic devices based on 2-D materials.

Glutamatergic Neurons Differentiated from Embryonic Stem Cells: An Investigation of Differentiation and Associated Diseases.

Neurons that have been derived from various types of stem cells have recently undergone significant study due to their potential for use in various aspects of biomedicine. In particular, glutamatergic neurons differentiated from embryonic stem cells (ESCs) potentially have many applications in both basic research and regenerative medicine. This review summarized the literatures published thus far and focused on two areas related to these applications. Firstly, these neurons can be used to investigate neuronal signal transduction during differentiation and this means that the genes/proteins/markers involved in this process can be identified. In this way, the dynamic spatial and temporal changes associated with neuronal morphology can be investigated relatively easily. Such an in vitro system can also be used to study how neurons during neurogenesis integrate into normal tissue. At the same time, the integration, regulation and functions of extracellular matrix secretion, various molecular interactions, various ion channels, the neuronal microenvironment, etc., can be easily traced. Secondly, the disease-related aspects of ESC-derived glutamatergic neurons can also be studied and then applied therapeutically. In the future, greater efforts are needed to explore how ESC-differentiated glutamatergic neurons can be used as a neuronal model for the study of Alzheimer's disease (AD) mechanistically, to identify possible therapeutic strategies for treating AD, including tissue replacement, and to screen for drugs that can be used to treat AD patients. With all of the modern technology that is available, translational medicine should begin to benefit patients soon.

Phytochemicals as modulators of ß-cells and immunity for the therapy of type 1 diabetes: Recent discoveries in pharmacological mechanisms and clinical potential.

Type 1 diabetes (T1D) is a lethal autoimmune disease afflicting as many as 10 million people worldwide. Considerable advances have been made in early diagnosis and understanding the cause of T1D development. However, new remedies are still in great demand as TID remains an incurable disease. Natural products, primarily phytochemicals, are an extraordinary source of discovery of drug leads for diabetes. This review covers recent findings regarding plant compounds and extracts for T1D based on a literature search of articles published between 2004-2019 in PubMed, Reaxyx, and America/European patent databases. Over this period more than 90 plant compounds and extracts were reported to have beneficial effects on T1D via multiple mechanisms involving the regulation of immunity and/or ß cells. In this review, we focus on recent progress in the understanding of the chemistry (chemical structure and plant source), anti-diabetic bioactivities, and likely mechanisms of action of plant compounds for T1D. Mechanistic studies are summarized, which indicate that flavonoids, terpenoids, and anthranoids can inhibit starch-digesting enzymes, aldose reductase, MAP kinases, NFκB, and/or IκB kinases implicated in energy metabolism, ß-cells, and immunity. Furthermore, human clinical trials centering on flavonoids, isoflavonoids, terpenoids, stilbenoids, and polyynes are discussed, and an overview of emerging anti-diabetic strategies using plant compounds and extracts for applications in T1D prophylaxis and therapy is also provided.

Ginkgolide A Prevents the Amyloid-ß-Induced Depolarization of Cortical Neurons.

Utilizing the N-methyl-d-aspartate (NMDA) receptor antagonist as a strategy, memantine is the only agent available for clinically treating mild to severe Alzheimer's disease (AD). Our aim was to develop novel similar herb-based drugs. Using a screening platform, ginkgolide A (GA), a pure compound extracted from Ginkgo biloba, was found to attenuate amyloid ß (Aß)-induced abnormal depolarization in mouse primary cortical neurons. Using receptor agonists, it was determined that GA inhibits both NMDA receptors and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. Furthermore, the Aß-induced increase in c-Jun N-terminal kinase phosphorylation in neurons was prevented by GA. Body weight, glutamate oxaloacetate transaminase, glutamic-pyruvic transaminase, liver histology, and kidney histology were similar when the wild-type/AD animal model mice with and without GA treatment were compared. This pure compound improves the memory of wild-type mice. Our findings indicate that GA has great potential clinically for the treatment of AD because it might target NMDA receptors just like memantine.

Association of mSin1 with mTORC2 Ras and Akt reveals a crucial domain on mSin1 involved in Akt phosphorylation.

mSin1 is a unique component within the mammalian target of rapamycin (mTOR) complex 2 (mTORC2), which is responsible for cellular morphology and glucose metabolism. The association between mSin1 and other mTORC2 components, as well as their functions, has been explored previously; nevertheless, the mapping of the various binding domains of the components is lacking. Based on an evolutionary analysis of the gene, we constructed various fragments and truncated-forms of mSin1. We characterized the individual binding sites of mSin1 with its various partners, including mTOR, Rictor, Ras, and Akt. mTOR and Rictor bind to the amino acid (aa) 100-240 region of mSin1, which is different to the Ras binding site, the aa 260-460 region. A reciprocal examination found that mSin1 associated with the aa 2148-2300 region of mTOR, which is within the kinase domain, and with the carboxyl terminus of Rictor. Interestingly, Akt was found to associate with mSin1 in a region that slightly overlapped with the mTOR/Rictor complex binding site, namely aa 220-260. When only the Akt binding site was deleted from mSin1, phosphorylation of Akt S473 was greatly reduced. Furthermore, the association between Akt and mTOR can be regulated by serum, insulin and LY294002, but not by rapamycin or MAPK kinase inhibitors. Taken together, mSin1 would seem to act as a hub that allows mTORC2 to phosphorylate Akt S473. Our findings should facilitate future proteomic and crystallographic studies, help the development of dominant inhibitors and promote the identification of new drug targets.

An Improved Drugs Screening System Reveals that Baicalein Ameliorates the Aß/AMPA/NMDA-Induced Depolarization of Neurons.

The presence of amyloid-ß (Aß) plaque and tau protein hyperphosphorylation in brain tissue is the pathological hallmark of Alzheimer's disease (AD). At least some Aß neurotoxicity is caused by the presence of excess glutamate that has been induced by Aß accumulation. Memantine is currently the only NMDA receptor inhibitor approved for treating moderate-to-severe AD patients. We utilized primary cortical neurons and DiBAC4(3), a slow-response voltage sensitive fluorescence dye, to create a novel system for screening herbal medicines that allows the identification of pure compounds able to ameliorate Aß-induced abnormal depolarization. The intensity of DiBAC4(3) fluorescence was increased when primary neurons were stimulated by Aß; furthermore, pre-treatment with memantine abolished this change. Using this system, we identified six crude extracts made from herbal medicines that effectively alleviated this Aß-induced abnormal depolarization. Among these herbal medicines, one pure compound, baicalein, which was known to be present in Scutellaria baricalensis and is known to improve memory using an AD mouse model, was identified by our assay. However, the compound's molecular mechanism remained unknown. We found that baicalein, in addition to inhibiting Aß-induced depolarization, possibly functions as an antagonist of AMPA and NMDA receptors. Taken together, we have established a system/platform to identify herbal medicines that ameliorate Aß-induced depolarization of neurons. Equally important, baicalein is a candidate drug with great potential for the treatment of AD patients.

Heterogeneous nuclear ribonucleoprotein M associates with mTORC2 and regulates muscle differentiation.

Mammalian target of rapamycin (mTOR) plays a range of crucial roles in cell survival, growth, proliferation, metabolism, and morphology. However, mTOR forms two distinct complexes, mTOR complex 1 and mTOR complex 2 (mTORC1 and mTORC2), via association with a series of different components; this allows the complexes to execute their wide range of functions. This study explores further the composition of the mTORC2 complex. Utilizing Rictor knock-out cells, immunoprecipitation and mass spectrometry, a novel Rictor associated protein, heterogeneous nuclear ribonucleoprotein M (hnRNP M), was identified. The association between hnRNP M and Rictor was verified using recombinant and endogenous protein and the binding site was found to be within aa 1~532 of hnRNP M. The presence of hnRNP M significantly affects phosphorylation of SGK1 S422, but not of Akt S473, PKCα S657 and PKCζ T560. Furthermore, hnRNP M also plays a critical role in muscle differentiation because knock-down of either hnRNP M or Rictor in C2C12 myoblasts reduced differentiation. This decrease is able to be rescued by overexpression SGK S422D in hnRNP M knockdown C2C12 myoblasts. Taken together, we have identified a novel Rictor/mTOR binding molecule, hnRNP M, that allows mTORC2 signaling to phosphorylate SGK1 thus regulating muscle differentiation.

Neural differentiation from embryonic stem cells in vitro: An overview of the signaling pathways.

Neurons derived from embryonic stem cells (ESCs) have gained great merit in both basic research and regenerative medicine. Here we review and summarize the signaling pathways that have been reported to be involved in the neuronal differentiation of ESCs, particularly those associated with in vitro differentiation. The inducers and pathways explored include retinoic acid, Wnt/ß-catenin, transforming growth factor/bone morphogenetic protein, Notch, fibroblast growth factor, cytokine, Hedgehog, c-Jun N-terminal kinase/mitogen-activated protein kinase and others. Some other miscellaneous molecular factors that have been reported in the literature are also summarized and discussed. These include calcium, calcium receptor, calcineurin, estrogen receptor, Hox protein, ceramide, glycosaminioglycan, ginsenoside Rg1, opioids, two pore channel 2, nitric oxide, chemically defined medium, cell-cell interactions, and physical stimuli. The interaction or crosstalk between these signaling pathways and factors will be explored. Elucidating these signals in detail should make a significant contribution to future progress in stem cell biology and allow, for example, better comparisons to be made between differentiation in vivo and in vitro. Of equal importance, a comprehensive understanding of the pathways that are involved in the development of neurons from ESCs in vitro will also accelerate their application as part of translational medicine.

Chemical constituents analysis and antidiabetic activity validation of four fern species from Taiwan.

Pterosins are abundant in ferns, and pterosin A was considered a novel activator of adenosine monophosphate-activated protein kinase, which is crucial for regulating blood glucose homeostasis. However, the distribution of pterosins in different species of ferns from various places in Taiwan is currently unclear. To address this question, the distribution of pterosins, glucose-uptake efficiency, and protective effects of pterosin A on ß-cells were examined. Our results showed that three novel compounds, 13-chloro-spelosin 3-O-ß-d-glucopyranoside (1), (3R)-Pterosin D 3-O-ß-d-(3'-p-coumaroyl)-glucopyranoside (2), and (2R,3R)-Pterosin L 3-O-ß-d-(3'-p-coumaroyl)-glucopyranoside (3), were isolated for the first time from four fern species (Ceratopteris thalictroides, Hypolepis punctata, Nephrolepis multiflora, and Pteridium revolutum) along with 27 known compounds. We also examined the distribution of these pterosin compounds in the mentioned fern species (except N. multiflora). Although all pterosin analogs exhibited the same effects in glucose uptake assays, pterosin A prevented cell death and reduced reactive oxygen species (ROS) production. This paper is the first report to provide new insights into the distribution of pterosins in ferns from Taiwan. The potential anti-diabetic activity of these novel phytocompounds warrants further functional studies.

Ceramide inhibits insulin-stimulated Akt phosphorylation through activation of Rheb/mTORC1/S6K signaling in skeletal muscle.

Ceramide is a negative regulator of insulin activity. At the molecular level, it causes a decrease in insulin-stimulated Akt Ser473 phosphorylation in C2C12 myotubes. Interestingly, we found that the phosphorylation of S6K at Thr389 was increased under the same conditions. Utilizing both rapamycin to inhibit mTORC1 activity and shRNA to knock down Rheb, we demonstrated that the decrease in Akt Ser473 phosphorylation stimulated by insulin after C2-ceramide incubation can be prevented. The mechanism by which C2-ceramide impairs signaling would seem to involve a negative feedback of activated S6K via phosphorylation of insulin receptor substrate-1 at Ser636/639, since S6K inhibitor can block this phenomenon. Finally, rapamycin treatment was found not to affect C2-ceramide-induced PKCζ activation, suggesting that the pathway revealed in this study is parallel to the one involving PKCζ activation. We proposed a novel pathway/mechanism involving Rheb/mTORC1/S6K signaling to explain how C2-ceramide impairs insulin signaling via Akt phosphorylation. The existence of multiple pathways involved in insulin signaling impairment by C2-ceramide treatment implies that different strategies might be needed to ameliorate insulin resistance caused by C2-ceramide.

Differentiation of glutamatergic neurons from mouse embryonic stem cells requires raptor S6K signaling.

Although the mammalian target of rapamycin complex 1 (mTORC1) functions as an important signaling complex in many cellular processes, the role of mTORC1 in neurons derived from embryonic stem cells (ESCs) has been less explored. Here, using a modified protocol to differentiate mouse ESCs (mESCs) into almost uniform glutamatergic neurons, we explored the importance of raptor/mTORC1 in the differentiation of mESCs. Raptor gene-trap mESCs, and raptor-knockdown mESCs formed smaller-sized embryonic bodies than the wild type and failed to undergo neuronal differentiation. Treatment with 1µM rapamycin starting at the point when neuronal precursors began to differentiate from mESCs caused the gradual loss of neurites, shrinkage of soma, and a decreased ratio of neurite length to cell number over 48 to 72h of treatment. This change was accompanied by activation of caspase-3 and S6 kinase (S6K), but not 4E-binding protein 1 (4EBP1). Knockdown of raptor during neuronal differentiation from mESCs also resulted in gradual loss of neurites and shrinkage of cell bodies. Loss of neurite density resulting from rapamycin treatment could be reversed by overexpression of S6K T389E. Taken together, these data demonstrate that raptor/mTORC1/S6K plays a critical role in the differentiation and survival of neurons derived from mESCs.

Herbal therapies for type 2 diabetes mellitus: chemistry, biology, and potential application of selected plants and compounds.

Diabetes mellitus has been recognized since antiquity. It currently affects as many as 285 million people worldwide and results in heavy personal and national economic burdens. Considerable progress has been made in orthodox antidiabetic drugs. However, new remedies are still in great demand because of the limited efficacy and undesirable side effects of current orthodox drugs. Nature is an extraordinary source of antidiabetic medicines. To date, more than 1200 flowering plants have been claimed to have antidiabetic properties. Among them, one-third have been scientifically studied and documented in around 460 publications. In this review, we select and discuss blood glucose-lowering medicinal herbs that have the ability to modulate one or more of the pathways that regulate insulin resistance, ß-cell function, GLP-1 homeostasis, and glucose (re)absorption. Emphasis is placed on phytochemistry, anti-diabetic bioactivities, and likely mechanism(s). Recent progress in the understanding of the biological actions, mechanisms, and therapeutic potential of compounds and extracts of plant origin in type 2 diabetes is summarized. This review provides a source of up-to-date information for further basic and clinical research into herbal therapy for type 2 diabetes. Emerging views on therapeutic strategies for type 2 diabetes are also discussed.

Optimal concentrations of N-decanoyl-N-methylglucamine and sodium dodecyl sulfate allow the extraction and analysis of membrane proteins.

We studied the extraction and analysis of integral membrane proteins possessing hydrophobic and hydrophilic domains and found that a nonionic detergent called MEGA-10, used in lysis buffers, had a superior extraction effect compared to most conventional detergents. A sodium dodecyl sulfate (SDS) concentration of >0.4% (w/v) in the sample buffer was crucial for those proteins to be clearly analyzed by electrophoresis and Western blotting. Furthermore, MEGA-10 had the tendency to maximally extract proteins around its critical micelle concentration (CMC) of 0.24% (w/v). These solutions can greatly assist functional investigations of membrane proteins in the proteomics era.

An approach for differentiating uniform glutamatergic neurons from mouse embryonic stem cells.

Much effort is being marshaled to generate uniform neuronal populations from embryonic stem (ES) cells, but a completely reliable method has yet to be developed. Here we modified and established a method that brings us closer to this goal. By examining many parameters, we found that the optimal timing of applying a freshly made trypsin/EDTA (ethylenediaminetetraacetic acid) solution to dissociate embryoid bodies determines the success of the outcome. Analyses demonstrated that with this approach, more than 87% of cells differentiated into glutamatergic neurons. Hence, these uniform neurons that were differentiated from ES cells provide an ideal cellular model for many aspects of research.

pTOM, a vector for expressing two proteins in mammalian cells.

We developed a pTOM construct that can express two proteins in a cell. Using pTOM ensures that two polypeptide-encoding nucleotide sequences are simultaneously transfected into the same cell. The ability to simultaneously express two separate polypeptide-encoding nucleotide sequences from the same vector in the same cell allows the user to determine the relationship between the two proteins. Another advantage is that one of the proteins can be used as a transfection marker/selector. The vector contains multiple cloning sites for insertions of polypeptide-encoding nucleotide sequences. Positive clones can be easily selected when performing cloning using ampicillin. Overall, this vector provides a convenient way to express dual proteins in a single mammalian cell.

Activation of mTORC1 in two steps: Rheb-GTP activation of catalytic function and increased binding of substrates to raptor.

The signalling function of mTOR complex 1 is activated by Rheb-GTP, which controls the catalytic competence of the mTOR (mammalian target of rapamycin) kinase domain by an incompletely understood mechanism. Rheb can bind directly to the mTOR kinase domain, and association with inactive nucleotide-deficient Rheb mutants traps mTOR in a catalytically inactive state. Nevertheless, Rheb-GTP targets other than mTOR, such as FKBP38 (FK506-binding protein 38) and/or PLD1 (phospholipase D(1)), may also contribute to mTOR activation. Once activated, the mTOR catalytic domain phosphorylates substrates only when they are bound to raptor (regulatory associated protein of mTOR), a separate polypeptide within the complex. The mechanism of insulin/nutrient stimulation of mTOR complex 1 signalling, in addition to Rheb-GTP activation of the mTOR catalytic function, also involves a stable modification of the configuration of mTORC1 (mTOR complex 1) that increases access of substrates to their binding site on the raptor polypeptide. The mechanism underlying this second step in the activation of mTORC1 is unknown.