Signaling mechanisms underlying inhibition of neuroinflammation by resveratrol in neurodegenerative diseases

Neurodegenerative diseases (NDs), including Alzheimer's disease (AD), and Parkinson's disease (PD), are characterized by the progressive loss of the structure and function of neurons and most commonly occur in the elderly population. Microglia are resident macrophages of the central nervous system (CNS). The neuroinflammation caused by excessive microglial activation is closely related to the onset and progression of many NDs. Therefore, inhibiting excessive microglial activation is a potential drug target for controlling neuroinflammation. In recent years, natural products as modulators of microglial polarization have attracted considerable attention in the field of NDs therapy. Furthermore, resveratrol (RES) has been found to have a protective effect in NDs through the inhibition of microglial activation and the regulation of neuroinflammation. In this review, we mainly summarize the therapeutic potential of RES and its various molecular mechanisms in the treatment of NDs through the modulation of microglial activation.     

Cell-based high-throughput proliferation and cytotoxicity assays for screening traditional Chinese herbal medicines

A simple, reliable, high-throughput screening method was developed and used to assess the pharmaceutical effects of extracts of traditional Chinese herbal medicines (TCHMs). This method is based on 3-dimensional (3-D) cultures of mouse embryonic stem (mES) and human colon cancer and breast cancer cells expressing enhanced green fluorescent protein (EGFP) in polyethylene terephthalate (PET) fibrous scaffolds on modified 384-well plates with online monitoring of culture fluorescence for dynamic responses of cells to drugs present in culture media. Cell responses to deoxycholic acid and the extracts of 3 TCHMs (Ganoderma lucidum spores, Ginkgo biloba, and Epimedium brevicornum) at various concentrations were investigated for their effects on proliferation and cytotoxicity. The screening results, i.e., the growth responses of cancer cells to those drugs, were consistent with what have been reported in the literature, confirming the reliability of the new screening approach. Different from previous screening methods for both TCHMs and western medicines that used animal models or 2-D cell-based assays with single cell lines, this 3-D cell-based screening method employs both cancer and normal cells and thereby provides a way for quick, direct evaluation of the anticancer effects of TCHMs. This method also offers assessment on the side effects of TCHMs.     

'Axogenic' and 'somagenic' neurodegenerative diseases: definitions and therapeutic implications.

Neurodegenerative diseases are characterized by a relentless loss of specific groups of neuronal subtypes. Many of these diseases share similar molecular mechanisms and extracellular mediators of neuronal loss. We now suggest that neurodegeneration originating in the neuronal cell bodies (e.g. in Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis) should be distinguished from that originating in the axons (e.g. in glaucoma, certain peripheral neuropathies and spinal stenosis). We propose that the former group of diseases be defined as 'somagenic' and the latter as 'axogenic'. Although axogenic disorders may share common symptoms and mediators of toxicity with somagenic disorders, they have distinct temporal, subcellular and signal-transduction features. We further suggest that, by adopting this classification of disorders based on pathophysiological processes, we will come to recognize additional diseases (in particular, those defined as axogenic) as being neurodegenerative and therefore possibly amenable to neuroprotective therapy.     

Critical cysteines in Akt1 regulate its activity and proteasomal degradation: implications for neurodegenerative diseases

Impaired Akt1 signaling is observed in neurodegenerative diseases, including Parkinson׳s disease (PD). In PD models oxidative modification of Akt1 leads to its dephosphorylation and consequent loss of its kinase activity. To explore the underlying mechanism we exposed Neuro2A cells to cadmium, a pan inhibitor of protein thiol disulfide oxidoreductases, including glutaredoxin 1 (Grx1), or downregulated Grx1, which led to dephosphorylation of Akt1, loss of its kinase activity, and also decreased Akt1 protein levels. Mutation of cysteines to serines at 296 and 310 in Akt1 did not affect its basal kinase activity but abolished cadmium- and Grx1 downregulation-induced reduction in Akt1 kinase activity, indicating their critical role in redox modulation of Akt1 function and turnover. Cadmium-induced decrease in phosphorylated Akt1 correlated with increased association of wild-type (WT) Akt1 with PP2A, which was absent in the C296–310S Akt1 mutant and was also abolished by N-acetylcysteine treatment. Further, increased proteasomal degradation of Akt1 by cadmium was not seen in the C296–310S Akt1 mutant, indicating that oxidation of cysteine residues facilitates degradation of WT Akt1. Moreover, preventing oxidative modification of Akt1 cysteines 296 and 310 by mutating them to serines increased the cell survival effects of Akt1. Thus, in neurodegenerative states such as PD, maintaining the thiol status of cysteines 296 and 310 in Akt1 would be critical for Akt1 kinase activity and for preventing its degradation by proteasomes. Preventing downregulation of Akt signaling not only has long-range consequences for cell survival but could also affect the multiple roles that Akt plays, including in the Akt–mTOR signaling cascade.     

Phospholipase A2 in the central nervous system: implications for neurodegenerative diseases

Phospholipase A2 (PLA2) belongs to a family of enzymes that catalyze the cleavage of fatty acids from the sn-2 position of phospholipids. There are more than 19 different isoforms of PLA2 in the mammalian system, but recent studies have focused on three major groups, namely, the group IV cytosolic PLA2, the group II secretory PLA2 (sPLA2), and the group VI Ca(2+)-independent PLA2. These PLA2s are involved in a complex network of signaling pathways that link receptor agonists, oxidative agents, and proinflammatory cytokines to the release of arachidonic acid (AA) and the synthesis of eicosanoids. PLA2s acting on membrane phospholipids have been implicated in intracellular membrane trafficking, differentiation, proliferation, and apoptotic processes. All major groups of PLA2 are present in the central nervous system (CNS). Therefore, this review is focused on PLA2 and AA release in neural cells, especially in astrocytes and neurons. In addition, because many neurodegenerative diseases are associated with increased oxidative and inflammatory responses, an attempt was made to include studies on PLA2 in cerebral ischemia, Alzheimer's disease, and neuronal injury due to excitotoxic agents. Information from these studies has provided clear evidence for the important role of PLA2 in regulating physiological and pathological functions in the CNS.     

Regulation of RNA granules by FMRP and implications for neurological diseases

RNA granule formation, which can be regulated by RNA‐binding proteins (RBPs) such as fragile X mental retardation protein (FMRP), acts as a mechanism to control both the repression and subcellular localization of translation. Dysregulated assembly of RNA granules has been implicated in multiple neurological disorders, such as amyotrophic lateral sclerosis. Thus, it is crucial to understand the cellular pathways impinging upon granule assembly or disassembly. The goal of this review is to summarize recent advances in our understanding of the role of the RBP, FMRP, in translational repression underlying RNA granule dynamics, mRNA transport and localized. We summarize the known mechanisms of translational regulation by FMRP, the role of FMRP in RNA transport granules, fragile X granules and stress granules. Focusing on the emerging link between FMRP and stress granules, we propose a model for how hyperassembly and hypoassembly of RNA granules may contribute to neurological diseases.     

Coenzyme Q10 administration and its potential for treatment of neurodegenerative diseases.

Coenzyme Q10 (CoQ10) is an essential cofactor of the electron transport chain as well as an important antioxidant. Previous studies have suggested that it may exert therapeutic effects in patients with known mitochondrial disorders. We investigated whether it can exert neuroprotective effects in a variety of animal models. We have demonstrated that CoQ10 can protect against striatal lesions produced by both malonate and 3-nitropropionic acid. It also protects against MPTP toxicity in mice. It extended survival in a transgenic mouse model of amyotrophic lateral sclerosis. We demonstrated that oral administration can increase plasma levels in patients with Parkinson's disease. Oral administration of CoQ10 significantly decreased elevated lactate levels in patients with Huntington's disease. These studies therefore raise the prospect that administration of CoQ10 may be useful for the treatment of neurodegenerative diseases.     

Elemental analysis of herbal preparations for traditional medicines by neutron activation analysis with the k0 standardization method

Medicinal herb preparations prescribed for specific treatment purposes were purchased from markets and were analyzed by instrumental neutron activation analysis withk ₀ standardization. Then, 500–700 mg of each sample was pelletized under a pressure of six tones and irradiated together with monitors for a and neutron flux ratio determinations for about 6 h in a thermal flux of 2.29 x 10¹² n/cm²/s. The accuracy of the method was established by analyzing standard reference materials. Twenty-nine elements, Ag, As, Au, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Mn, Mo, Na, Rb, Sb, Sc, Se, Sm, Sr, Th, U, Yb, and Zn, were measured in all the samples, and Hg was detected in some samples, with good accuracy and reproducibility. The concentration of elements determined was found to vary depending on the composition of the herbs used. Although the trend linking the element of the medicinal plants to its curative abilities could not be clearly determined, this study showed that the toxic elements found in the samples were below the levels prescribed by health regulations. Nevertheless, such data are important to understand the pharmacological action and the exact mechanisms of action and formation of active constituents for each medicinal plant and to decide the dosage of the herbs used in the final formulation.     

The role of the estrogen in neuroprotection: implications for neurodegenerative diseases

In trying to rectify the differences in the risk, onset, and progression of neurodegenerative diseases between men and women, the gonadal hormone estrogen has been the primary focus of investigation for many years. Although this gender difference may encompass disparate and overlapping reasons, estrogen and signaling events mediated by its receptor have been shown to be neuroprotective in a number of neurodegenerative disease models such as Alzheimer's, Parkinson's, and Schizophrenia. Although data from human studies remains highly controversial, a large body of research findings suggests that this hormone plays a pivotal role in retarding and preventing the formation of neurodegenerative diseases through its receptor. By activating common intracellular signaling pathways and initiating "cross talk" with neurotrophins, estrogen plays an influential role in neuronal survival from injuries induced by ischemia or other environmental insults. Gaining a better understanding of these estrogen receptor mediated neuroprotective mechanisms may lead to new therapeutic strategies for the treatment or prevention of neurodegenerative diseases.     

Neuronal expression of constitutive heat shock proteins: implications for neurodegenerative diseases

Neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis have been termed "protein misfolding disorders." These diseases differ widely in frequency and impact different classes of neurons. Heat shock proteins provide a line of defense against misfolded, aggregation-prone proteins and are among the most potent suppressors of neurodegeneration in animal models. Analysis of constitutively expressed heat shock proteins revealed variable levels of Hsc70 and Hsp27 in different classes of neurons in the adult rat brain. The differing levels of these constitutively expressed heat shock proteins in neuronal cell populations correlated with the relative frequencies of the previously mentioned neurodegenerative diseases.     

Application of native mass spectrometry in studying intrinsically disordered proteins: A special focus on neurodegenerative diseases

Intrinsically disordered proteins (IDPs) are integral part of the proteome, regulating vital biological processes. Such proteins gained further visibility due to their key role in neurodegenerative diseases and cancer. IDPs however, escape structural characterization by traditional biophysical tools owing to their extreme flexibility and heterogeneity. In this review, we discuss the advantages of native mass spectrometry (MS) in analysing the atypical conformational dynamics of IDPs and recent advances made in the field. Especially, MS studies unravelling the conformational facets of IDPs involved in neurodegenerative diseases are highlighted. The limitations and the future promises of native MS while studying IDPs have been discussed.     

In silico toxicity studies of traditional Chinese herbal medicine: A mini review

With the availability of public databases that store compound-target/compound-toxicity information, and Traditional Chinese medicine (TCM) databases, in silico approaches are used in toxicity studies of TCM herbal medicine. Here, three in silico approaches for toxicity studies were reviewed, which include machine learning, network toxicology and molecular docking. For each method, its application and implementation e.g., single classifier vs. multiple classifier, single compound vs. multiple compounds, validation vs. screening, were explored. While these methods provide data-driven toxicity prediction that is validated in vitro and/or in vivo, it is still limited to single compound analysis. In addition, these methods are limited to several types of toxicity, with hepatotoxicity being the most dominant. Future studies involving the testing of combination of compounds on the front end i.e., to generate data for in silico modeling, and back end i.e., validate findings from prediction models will advance the in silico toxicity modeling of TCM compounds.     

Copper reduction by copper binding proteins and its relation to neurodegenerative diseases

Increasing evidence supports an important role for metals in neurobiology. In fact, copper binding proteins that form bioinorganic complexes are able to display oxidant or anti-oxidant properties, which would impact on neuronal function or in the triggering of neurodegenerative process. Two proteins related to neurodegenerative diseases have been described as copper binding proteins: the amyloid precursor protein (APP), a protein related to Alzheimer's disease, and the Prion protein (PrP), related to Creutzfeldt-Jakob disease. We used different synthetic peptides from APP and PrP sequences in order to evaluate the ability to reduce copper. We observed that APP_135–156, amyloid--peptide (A_1–40), and PrP_59–91 all have copper reducing ability, with the APP_135–156 peptide being more potent than the other fragments. Moreover, we identify His, Cys and Trp residues as key amino acids involved in the copper reduction of A, APP and PrP, respectively. We postulated, that in a cellular context, the interaction of these proteins with copper could be necessary to reduce copper on plasma membrane, possibly presenting Cu(I) to the copper transporter, driving the delivery of this metal to antioxidant enzymes. Moreover, protein-metal complexes could be the catalytic centers for the formation of reactive oxygen species involved in the oxidative damage present both in Alzheimer's and Prion disease.     

A herbal medicine for Alzheimer's disease and its active constituents promote neural progenitor proliferation

Aberrant neural progenitor cell (NPC) proliferation and self‐renewal have been linked to age‐related neurodegeneration and neurodegenerative disorders including Alzheimer's disease (AD). Rhizoma Acori tatarinowii is a traditional Chinese herbal medicine against cognitive decline. In this study, we found that the extract of Rhizoma Acori tatarinowii (AT) and its active constituents, asarones, promote NPC proliferation. Oral administration of AT enhanced NPC proliferation and neurogenesis in the hippocampi of adult and aged mice as well as that of transgenic AD model mice. AT and its fractions also enhanced the proliferation of NPCs cultured in vitro. Further analysis identified α‐asarone and β‐asarone as the two active constituents of AT in promoting neurogenesis. Our mechanistic study revealed that AT and asarones activated extracellular signal‐regulated kinase (ERK) but not Akt, two critical kinase cascades for neurogenesis. Consistently, the inhibition of ERK activities effectively blocked the enhancement of NPC proliferation by AT or asarones. Our findings suggest that AT and asarones, which can be orally administrated, could serve as preventive and regenerative therapeutic agents to promote neurogenesis against age‐related neurodegeneration and neurodegenerative disorders.     

肠道菌群在中药代谢中的作用

近年来,中药在疾病防治方面所发挥的巨大作用受到了广泛认可。科学合理地解释中药的作用机制将有助于提高其利用价值。越来越多的证据表明肠道菌群在中药治疗中起着至关重要的作用,是打开我国中医药宝库的一把钥匙。肠道菌群在中药成分代谢过程中发挥着复杂的作用：一方面,人类肠道菌群通过编码多种活性酶,促进了中药组分中的非碳水化合物小分子与碳水化合物在肠道中的代谢过程;另一方面,经肠道菌群代谢转化后产生的中药产物具有多种药理作用。因此,在未来中药研究中应更多地考虑肠道微生态因素,这有助于为中药的药理作用机制研究奠定新的科学基础。     

Knowledge discovery and system biology in molecular medicine: an application on neurodegenerative diseases

The possibility to study an organism in terms of system theory has been proposed in the past, but only the advancement of molecular biology techniques allow us to investigate the dynamical properties of a biological system in a more quantitative and rational way than before . These new techniques can gave only the basic level view of an organisms functionality. The comprehension of its dynamical behaviour depends on the possibility to perform a multiple level analysis. Functional genomics has stimulated the interest in the investigation the dynamical behaviour of an organism as a whole. These activities are commonly known as System Biology, and its interests ranges from molecules to organs. One of the more promising applications is the 'disease modeling'. The use of experimental models is a common procedure in pharmacological and clinical researches; today this approach is supported by 'in silico' predictive methods. This investigation can be improved by a combination of experimental and computational tools. The Machine Learning (ML) tools are able to process different heterogeneous data sources, taking into account this peculiarity, they could be fruitfully applied to support a multilevel data processing (molecular, cellular and morphological) that is the prerequisite for the formal model design; these techniques can allow us to extract the knowledge for mathematical model development. The aim of our work is the development and implementation of a system that combines ML and dynamical models simulations. The program is addressed to the virtual analysis of the pathways involved in neurodegenerative diseases. These pathologies are multifactorial diseases and the relevance of the different factors has not yet been well elucidated. This is a very complex task; in order to test the integrative approach our program has been limited to the analysis of the effects of a specific protein, the Cyclin dependent kinase 5 (CDK5) which relies on the induction of neuronal apoptosis. The system has a modular structure centred on a textual knowledge discovery approach. The text mining is the only way to enhance the capability to extract ,from multiple data sources, the information required for the dynamical simulator. The user may access the publically available modules through the following site: http://biocomp.ge.ismac.cnr.it.     

Characterization of flavonoids in the traditional Chinese herbal medicine-Huangqin by liquid chromatography coupled with electrospray ionization mass spectrometry

The root of Scutellaria baicalensis, called Huangqin in Chinese, is one of the most commonly used traditional Chinese medicines for the treatment of hepatitis, tumors, diarrhea, and inflammatory diseases. The major chemical constituents of Huangqin are flavonoids. In the present paper, HPLC-DAD-ESI-MS(n) was used to analyze flavonoids in the roots of S. baicalensis. A total of 26 flavonoids were identified or tentatively characterized, including 5 C-glycosides, 12 O-glycosides, and 9 free aglycones. Two C-glycosides, apigenin-6-C-glucyl-8-C-arabinoside and chrysin-6,8-di-C-glucoside, together with some O-glycosides, are reported from S. baicalensis for the first time. This method is simple, reliable and sensitive, and could be used for the quality control of Huangqin and its related preparations.     

Interference with ubiquitination causes oxidative damage and increased protein nitration: implications for neurodegenerative diseases

Inhibition of the proteasomal pathway for degrading abnormal proteins leads to protein aggregation, increased oxidative damage and increased protein nitration. We now show that interference with polyubiquitination has similar consequences. Expression of a dominant-negative mutant form of ubiquitin (K48R) in NT-2 and SK-N-MC cells caused decreased cell growth rates and increased oxidative damage (protein carbonyls and lipid peroxidation), nitric oxide production and elevated protein nitration. It also rendered cells highly sensitive to 4-hydroxy-2,3-trans-nonenal, a neurotoxic end-product of lipid peroxidation, hydrogen peroxide and deprivation of growth factors. Overexpression of wild-type ubiquitin did not produce these effects. Our data show that interference with the ubiquitin-proteasome pathway at a different point and by a different mechanism can produce many of the common features of human neurodegenerative diseases, such as increased lipid peroxidation, protein oxidation and protein nitration. We suggest that defects in this pathway at multiple points could produce the common features of neurodegenerative diseases, and that more such defects remain to be discovered.