Think locally: control of ubiquitin‐dependent protein degradation in neurons

The nervous system coordinates many aspects of body function such as learning, memory, behaviour and locomotion. Therefore, it must develop and maintain an intricate network of differentiated neuronal cells, which communicate efficiently with each other and with non‐neuronal target cells. Unlike most somatic cells, differentiated neurons are post‐mitotic and characterized by a highly polarized morphology that determines the flow of information. Among other post‐translational modifications, the ubiquitination of specific protein substrates was recently shown to have a crucial role in the regulation of neuronal development and differentiation. Here, we review recent findings that illustrate the mechanisms that mediate the temporal and spatial control of neuronal protein turnover by the ubiquitin–proteasome system (UPS), which is crucial for the development and function of the nervous system.     

Herbal medicine use in the districts of Nakapiripirit, Pallisa, Kanungu, and Mukono in Uganda

ABSTRACT: BACKGROUND: Traditional medicine (TM) occupies a special place in the management of diseases in Uganda. Not with standing the many people relying on TM, indigenous knowledge (IK) related to TM is getting steadily eroded. To slow down this loss it is necessary to document and conserve as much of the knowledge as possible. This study was conducted to document the IK relevant to traditional medicine in the districts of Mukono, Nakapiripirit, Kanungu and Pallisa, in Uganda. METHODS: An ethnobotanical survey was conducted between October 2008 and February 2009 using techniques of key informant interviews and household interviews. RESULTS: The common diseases and conditions in the four districts include malaria, cough, headache, diarrhea, abdominal pain, flu, backache and eye diseases. Respondents stated that when they fall sick they self medicate using plant medicines or consult western-trained medicine practitioners. Self medication using herbal medicines was reported mostly by respondents of Nakapiripirit and Mukono. Respondents have knowledge to treat 78 ailments using herbal medicines. 44 species, mentioned by three or more respondents have been prioritized. The most frequently used part in herbal medicines is the leaf, followed by the stem and root. People sometime use animal parts, soil, salt and water from a grass roof, in traditional medicines. Herbal medicines are stored for short periods of time in bottles. The knowledge to treat ailments is acquired from parents and grandparents. Respondents' age and tribe appears to have a significant influence on knowledge of herbal medicine, while gender does not. CONCLUSION: This survey has indicated that IK associated with TM stills exists and that TM is still important in Uganda because many people use it as a first line of health care when they fall sick. Age and tribe influence the level of IK associated with herbal medicine, but gender does not.     

Aspirin inhibits proliferation and promotes differentiation of neuroblastoma cells via p21Waf1 protein up‐regulation and Rb1 pathway modulation

Several clinical and experimental studies have demonstrated that regular use of aspirin (acetylsalicylic acid, ASA) correlates with a reduced risk of cancer and that the drug exerts direct anti‐tumour effects. We have previously reported that ASA inhibits proliferation of human glioblastoma multiforme‐derived cancer stem cells. In the present study, we analysed the effects of ASA on nervous system‐derived cancer cells, using the SK‐N‐SH (N) human neuroblastoma cell line as an experimental model. ASA treatment of SK‐N‐SH (N) dramatically reduced cell proliferation and motility, and induced neuronal‐like differentiation, indicated by the appearance of the neuronal differentiation marker tyrosine hydroxylase (TH) after 5 days. ASA did not affect cell viability, but caused a time‐dependent accumulation of cells in the G₀/G₁ phase of the cell cycle, with a concomitant decrease in the percentage of cells in the G₂ phase. These effects appear to be mediated by a COX‐independent mechanism involving an increase in p21^Waf1 and underphosphorylated retinoblastoma (hypo‐pRb1) protein levels. These findings may support a potential role of ASA as adjunctive therapeutic agent in the clinical management of neuroblastoma.     

Potential toxicity of flavonoids and other dietary phenolics: significance for their chemopreventive and anticancer properties

Flavonoids, including isoflavones, are natural components in our diet and, with the burgeoning interest in alternative medicine, are increasingly being ingested by the general population. Plant phenolics, which form moieties on flavonoid rings, such as gallic acid, are also widely consumed. Several beneficial properties have been attributed to these dietary compounds, including antioxidant, anti-inflammatory, and anticarcinogenic effects. Flavonoid preparations are marketed as herbal medicines or dietary supplements for a variety of alleged nontoxic therapeutic effects. However, they have yet to pass controlled clinical trials for efficacy, and their potential for toxicity is an understudied field of research. This review summarizes the current knowledge regarding potential dietary flavonoid/phenolic-induced toxicity concerns, including their pro-oxidant activity, mitochondrial toxicity (potential apoptosis-inducing properties), and interactions with drug-metabolizing enzymes. Their chemopreventive activity in animal in vivo experiments may result from their ability to inhibit phase I and induce phase II carcinogen metabolizing enzymes that initiate carcinogenesis. They also inhibit the promotion stage of carcinogenesis by inhibiting oxygen radical-forming enzymes or enzymes that contribute to DNA synthesis or act as ATP mimics and inhibit protein kinases that contribute to proliferative signal transduction. Finally, they may prevent tumor development by inducing tumor cell apoptosis by inhibiting DNA topoisomerase II and p53 downregulation or by causing mitochondrial toxicity, which initiates mitochondrial apoptosis. While most flavonoids/phenolics are considered safe, flavonoid/phenolic therapy or chemopreventive use needs to be assessed as there have been reports of toxic flavonoid-drug interactions, liver failure, contact dermatitis, hemolytic anemia, and estrogenic-related concerns such as male reproductive health and breast cancer associated with dietary flavonoid/phenolic consumption or exposures.     

Prevention of inflammation‐mediated neurotoxicity by butylidenephthalide and its role in microglial activation

Microglial cells are the prime effectors in immune and inflammatory responses of the central nervous system (CNS). During pathological conditions, the activation of these cells helps restore CNS homeostasis. However, chronic microglial activation endangers neuronal survival through the release of various proinflammatory molecules and neurotoxins. Thus, negative regulators of microglial activation have been considered as potential therapeutic candidates to target neurodegeneration, such as that in Alzheimer's and Parkinson's diseases. The rhizome of Ligusticum chuanxiong Hort. (Ligusticum wallichii Franch) has been widely used for the treatment of vascular diseases in traditional oriental medicine. Butylidenephthalide (BP), a major bioactive component from L. chuanxiong, has been reported to have a variety of pharmacological activities, including vasorelaxant, anti‐anginal, anti‐platelet and anti‐cancer effects. The aim of this study was to examine whether BP represses microglial activation. In rat brain microglia, BP significantly inhibited the lipopolysaccharide (LPS)‐induced production of nitric oxide (NO), tumour necrosis factor‐α and interleukin‐1β. In organotypic hippocampal slice cultures, BP clearly blocked the effect of LPS on hippocampal cell death and inhibited LPS‐induced NO production in culture medium. These results newly suggest that BP provide neuroprotection by reducing the release of various proinflammatory molecules from activated microglia. Copyright © 2013 John Wiley & Sons, Ltd.     

Polysaccharides derived from Balanophora polyandra significantly suppressed the proliferation of ovarian cancer cells through P53‐mediated pathway

Ovarian cancer (OC) is ranked the first among the cancers threatening women's health. It attracts tremendous attention of cancer researchers because of its extremely high mortality rate. Recent studies have indicated that traditional herbal medicines (THMs) can play a pivotal role in cancer prevention and treatment. THMs are gaining popularity as a source of anti‐cancer agents. The plant of Balanophora polyandra, which has been used as a traditional herbal medicine, has been known for exhibiting potential haemostatic, analgesic, anti‐inflammatory and anti‐cancer properties. However, few studies on inhibitory effect of B. polyandra on OC have been performed. In the present study, we found that B. polyandra polysaccharides (BPP) induced cell cycle arrest at S phase, triggered apoptosis and inhibited migration and invasion of OC cells. Furthermore, we also found that there was a potential and close relationship between BPP and P53‐mediated pathway. Overall, these findings suggest that BPP can be a potential therapeutic agent for the treatment of OC.     

Regulation of Signaling by Protein-Tyrosine Phosphatases: Potential Roles in the Nervous System

During neuronal development, cells respond to a variety of environmental cues through cell surface receptors that are coupled to a signaling transduction machinery based on protein tyrosine phosphorylation and dephosphorylation. Receptor and non-receptor tyrosine kinases have received a great deal of attention; however, in the last few years, receptor (plasma membrane associated) and non-receptor protein-tyrosine phosphatases (PTPs) have also been shown to play important roles in development of the nervous system. In many cases PTPs have provocative distribution patterns or have been shown to be associated with specific cell adhesion and growth factor receptors. Additionally, altering PTP expression levels or activity impairs neuronal behavior. In this review we outline what is currently known about the role of PTPs in development, differentiation and neuronal physiology.     

Neuropeptide orphanin FQ inhibits dendritic morphogenesis through activation of RhoA

Brain‐derived neurotrophic factor (BDNF) plays a facilitatory role in neuronal development and promotion of differentiation. Mechanisms that oppose BDNF's stimulatory effects create balance and regulate dendritic growth. However, these mechanisms have not been studied. We have focused our studies on the BDNF‐induced neuropeptide OrphaninFQ/ Nociceptin (OFQ); while BDNF is known to enhance synaptic activity, OFQ has opposite effects on activity, learning, and memory. We have now examined whether OFQ provides a balance to the stimulatory effects of BDNF on neuronal differentiation in the hippocampus. Golgi staining in OFQ knockout (KO) mice revealed an increase in primary dendrite length as well as spine density, suggesting that endogenous OFQ inhibits dendritic morphology. We have also used cultured hippocampal neurons to demonstrate that exogenous OFQ has an inhibitory effect on dendritic growth and that the neuropeptide alters the response to BDNF when pre‐administered. To determine if BDNF and OFQ act in a feedback loop, we inhibited the actions of the BDNF and OFQ receptors, TrkB and NOP using ANA‐12 and NOP KO mice respectively but our data suggest that the two factors do not act in a negative feedback loop. We found that the inhibition of dendritic morphology induced by OFQ is via enhanced RhoA activity. Finally, we have evidence that RhoA activation is required for the inhibitory effects of OFQ on dendritic morphology. Our results reveal basic mechanisms by which neurons not only regulate the formation of proper dendritic growth during development but also control plasticity in the mature nervous system. © 2013 Wiley Periodicals, Inc. Develop Neurobiol 73: 769–784, 2013     

Notch3 is necessary for neuronal differentiation and maturation in the adult spinal cord

Notch receptors are key regulators of nervous system development and promoters of neural stem cells renewal and proliferation. Defects in the expression of Notch genes result in severe, often lethal developmental abnormalities. Notch3 is generally thought to have a similar proliferative, anti‐differentiation and gliogenic role to Notch1. However, in some cases, Notch3 has an opposite, pro‐differentiation effect. Here, we show that Notch3 segregates from Notch1 and is transiently expressed in adult rat and mouse spinal cord neuron precursors and immature neurons. This suggests that during the differentiation of adult neural progenitor cells, Notch signalling may follow a modified version of the classical lateral inhibition model, involving the segregation of individual Notch receptors. Notch3 knockout mice, otherwise neurologically normal, are characterized by a reduced number of mature inhibitory interneurons and an increased number of highly excitable immature neurons in spinal cord laminae I–II. As a result, these mice have permanently lower nociceptive thresholds, similar to chronic pain. These results suggest that defective neuronal differentiation, for example as a result of reduced Notch3 expression or activation, may underlie human cases of intractable chronic pain, such as fibromyalgia and neuropathic pain.     

Neuronal cytoskeleton in synaptic plasticity and regeneration

During development, dynamic changes in the axonal growth cone and dendrite are necessary for exploratory movements underlying initial axo‐dendritic contact and ultimately the formation of a functional synapse. In the adult central nervous system, an impressive degree of plasticity is retained through morphological and molecular rearrangements in the pre‐ and post‐synaptic compartments that underlie the strengthening or weakening of synaptic pathways. Plasticity is regulated by the interplay of permissive and inhibitory extracellular cues, which signal through receptors at the synapse to regulate the closure of critical periods of developmental plasticity as well as by acute changes in plasticity in response to experience and activity in the adult. The molecular underpinnings of synaptic plasticity are actively studied and it is clear that the cytoskeleton is a key substrate for many cues that affect plasticity. Many of the cues that restrict synaptic plasticity exhibit residual activity in the injured adult CNS and restrict regenerative growth by targeting the cytoskeleton. Here, we review some of the latest insights into how cytoskeletal remodeling affects neuronal plasticity and discuss how the cytoskeleton is being targeted in an effort to promote plasticity and repair following traumatic injury in the central nervous system.     

Analytical methods for heavy metals in herbal medicines

Introduction – It is estimated that about 70–80% of the world's population relies on non‐conventional medicine, mainly of herbal origin. However, owing to the nature and sources of herbal medicines, they are sometimes contaminated with toxic heavy metals such as lead, arsenic, mercury and cadmium, which impose serious health risks to consumers. It is critical to analyse source materials for heavy metals in order to ensure that their concentrations meet the related standards or regulations limiting their concentrations in herbal medicines. In this review, different analytical methods for analysis of heavy metals in herbal medicines are discussed. Objective – To provide a comprehensive review of the current state of the art in analytical methods used to detect heavy metals in herbal medicines. Methodology – We systematically searched and reviewed the research articles regarding analytical methods for heavy metals in herbal medicine from various databases, such as Medline/PubMed, ScienceDirect, SciFinder, Google Scholar, EBSCO, Gale InfoTrac, Ingenta, Ovid, ProQuest and ISI Web of Knowledge. Results – In this review, we discuss in detail several commonly used and sensitive analytical techniques, including atomic absorption spectrometry, inductively coupled plasma optical emission spectrometry or mass spectrometry, X‐ray fluorescence spectrometry, high‐performance liquid chromatography, differential pulse polarography, neutron activation analysis and anodic stripping voltammetry. We also provide some application examples of these analytical techniques for heavy metals in herbal medicines. Copyright © 2011 John Wiley & Sons, Ltd.     

Coordination of proliferation and neuronal differentiation by the retinoblastoma protein family

Once neurons enter the post‐mitotic G0 phase during central nervous system (CNS) development, they lose their proliferative potential. When neurons re‐enter the cell cycle during pathological situations such as neurodegeneration, they undergo cell death after S phase progression. Thus, the regulatory networks that drive cell proliferation and maintain neuronal differentiation are highly coordinated. In this review, the coordination of cell cycle control and neuronal differentiation during development are discussed, focusing on regulation by the Rb family of tumor suppressors (including p107 and p130), and the Cip/Kip family of cyclin dependent kinase (Cdk) inhibitors. Based on recent findings suggesting roles for these families in regulating neurogenesis and neuronal differentiation, I propose that the Rb family is essential for daughter cells of neuronal progenitors to enter the post‐mitotic G0 phase without affecting the initiation of neuronal differentiation in most cases, while the Cip/Kip family regulates the timing of neuronal progenitor cell cycle exit and the initiation of neuronal differentiation at least in the progenitor cells of the cerebral cortex and the retina. Rb's lack of involvement in regulating the initiation of neuronal differentiation may explain why Rb family‐deficient retinoblastomas characteristically exhibit neuronal features.     

Separation methods for antibacterial and antirheumatism agents in plant medicines

Traditional oriental medicines (TOM), with a very long history and many remarkable features, are very popular in Asian countries, especially in China, Japan and Korea. With the development of advanced analytical techniques, the modernization of traditional medicine has become a hot area in recent years and some herbal medicines have been increasingly accepted in western countries. Separation and determination of active components in various herbal medicines are considered to be critical for the modernization process. Antibacterial and antirheumatism agents are widely distributed in many medical plants and commonly used in clinical treatment. Therefore, the development of effective separation methods for the quality control of herbal medicines is absolutely important. In this article, the separation methods for the analysis of antibacterial and antirheumatism compounds in TOM were reviewed, including thin layer chromatography (TLC), gas chromatography (GC), supercritical fluid chromatography (SFC), high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and related hyphenation techniques. Sample preparation procedures and further development of these methods were also discussed.     

微生物合成黄酮类研究进展

黄酮类化合物是植物特有的多酚类化合物,具有抗氧化、抗炎、抗肿瘤、改善血液循环等生理功能,在保健品、化妆品和医药等方面具有广阔的应用前景。黄酮类化合物主要通过植物提取制备,受时间空间及植物种类等因素限制,且分离纯化步骤复杂,产率较低。随着合成生物学与代谢工程的发展,构建黄酮类物质的生物合成代谢途径线路,并对基因来源、基因序列、基因组合方式、菌株底盘改造等方面进行筛选和优化已取得较大成果。现已能用工程酵母和大肠杆菌等微生物合成二氢黄酮、黄酮、异黄酮、黄酮醇、花色素和黄烷酮等黄酮类化合物,在此基础上还可经甲基化酶或糖基化酶修饰,增加新的生物活性。综述了目前国内外微生物合成各类黄酮类物质的研究进展,并对将来的发展趋势进行了讨论和分析。     

Ellagic acid protects dopamine neurons from rotenone‐induced neurotoxicity via activation of Nrf2 signalling

Parkinson's disease (PD) is the second most prevalent central nervous system (CNS) degenerative disease. Oxidative stress is one of key contributors to PD. Nuclear factor erythroid‐2‐related factor 2 (Nrf2) is considered to be a master regulator of many genes involved in anti‐oxidant stress to attenuate cell death. Therefore, activation of Nrf2 signalling provides an effective avenue to treat PD. Ellagic acid (EA), a natural polyphenolic contained in fruits and nuts, possesses amounts of pharmacological activities, such as anti‐oxidant stress and anti‐inflammation. Recent studies have confirmed EA could be used as a neuroprotective agent in neurodegenerative diseases. Here, mice subcutaneous injection of rotenone (ROT)‐induced DA neuronal damage was performed to investigate EA‐mediated neuroprotection. In addition, adult Nrf2 knockout mice and different cell cultures including MN9D‐enciched, MN9D‐BV‐2 and MN9D‐C6 cell co‐cultures were applied to explore the underlying mechanisms. Results demonstrated EA conferred neuroprotection against ROT‐induced DA neurotoxicity. Activation of Nrf2 signalling was involved in EA‐mediated DA neuroprotection, as evidenced by the following observations. First, EA activated Nrf2 signalling in ROT‐induced DA neuronal damage. Second, EA generated neuroprotection with the presence of astroglia and silence of Nrf2 in astroglia abolished EA‐mediated neuroprotection. Third, EA failed to produce DA neuroprotection in Nrf2 knockout mice. In conclusion, this study identified EA protected against DA neuronal loss via an Nrf2‐dependent manner.     

Trikatu,a herbal compound that suppresses monosodium urate crystal‐induced inflammation in rats,an experimental model for acute gouty arthritis

Gout is an inflammatory joint disorder characterized by hyperuricaemia and precipitation of monosodium urate crystals in the joints. In the present study, we aimed to investigate the anti‐inflammatory effect of trikatu, a herbal compound in monosodium urate crystal‐induced inflammation in rats, an experimental model for acute gouty arthritis. Paw volume and levels/activities of lysosomal enzymes, lipid peroxidation, anti‐oxidant status and histopathological examination of ankle joints were determined in control and monosodium urate crystal‐induced rats. In addition, analgesic (acetic acid‐induced writhing response), anti‐pyretic (yeast‐induced pyrexia) and gastric ulceration effects were tested. The levels of lysosomal enzymes, lipid peroxidation and paw volume were significantly increased, and anti‐oxidant status was found to be reduced in monosodium urate crystal‐induced rats, whereas the biochemical changes were reverted to near normal levels upon trikatu (1000 mg/kg b.wt) administration. The trikatu has also been found to exhibit significant analgesic and anti‐pyretic effects with the absence of gastric damage. In conclusion, the present results clearly indicated that trikatu exert a potent anti‐inflammatory effect against monosodium urate crystal‐induced inflammation in rats in association with analgesic and anti‐pyretic effects in the absence of gastrointestinal damage. Copyright © 2013 John Wiley & Sons, Ltd.     

The MAP1B case: An old MAP that is new again

The functions of microtubule‐associated protein 1B (MAP1B) have historically been linked to the development of the nervous system, based on its very early expression in neurons and glial cells. Moreover, mice in which MAP1B is genetically inactivated have been used extensively to show its role in axonal elongation, neuronal migration, and axonal guidance. In the last few years, it has become apparent that MAP1B has other cellular and molecular functions that are not related to its microtubule‐stabilizing properties in the embryonic and adult brain. In this review, we present a systematic review of the canonical and novel functions of MAP1B and propose that, in addition to regulating the polymerization of microtubule and actin microfilaments, MAP1B also acts as a signaling protein involved in normal physiology and pathological conditions in the nervous system. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 74: 953–971, 2014     

Reproductive and Developmental Toxicity of Orally Administered Botanical Composition,UP446‐Part I: Effects on Embryo‐Fetal Development in New Zealand White Rabbits and Sprague Dawley Rats

The pharmacotoxicology impacts of dietary supplements taken at the time of pregnancy have remained alarming since women are the frequent herbal medicine users in many countries as a complement to the conventional pregnancy management. The use of herbal medicines and diet supplements in expectant mothers linked closely to the health of the childbearing mothers and the fetuses where the lack of developmental safety data imposes a challenge to make the right choices. Here, we describe the potential adverse effects of UP446, a standardized bioflavonoid composition from the roots of Scutellaria baicalensis and the heartwoods of Acacia catechu, on embryo‐fetal development following maternal exposure during the critical period of major organogenesis in rabbits and rats. Pregnant dams were treated orally with UP446 at doses of 250, 500, and 1000 mg/kg/day during gestation. The number of resorptions, implantations, litter size, body weights, and skeletal development was evaluated. Maternal food intake and body, tissue, and placenta weight were also assessed. There were no statistically significant differences in implantation, congenital malformation, embryo‐fetal mortalities, and fetuses sex ratios in all dosing groups of both species. Therefore, the no observed adverse effect level of UP446 was considered to be greater than 1000 mg/kg in both the maternal and fetus in both species     

Retinoic acid and nitric oxide promote cell proliferation and differentially induce neuronal differentiation in vitro in the cnidarian Renilla koellikeri

Retinoic acid (RA) and nitric oxide (NO) are known to promote neuronal development in both vertebrates and invertebrates. Retinoic acid receptors appear to be present in cnidarians and NO plays various physiological roles in several cnidarians, but there is as yet no evidence that these agents have a role in neural development in this basal metazoan phylum. We used primary cultures of cells from the sea pansy Renilla koellikeri to investigate the involvement of these signaling molecules in cnidarian cell differentiation. We found that 9‐cis RA induce cell proliferation in dose‐ and time‐dependent manners in dishes coated with polylysine from the onset of culture. Cells in cultures exposed to RA in dishes devoid of polylysine were observed to differentiate into epithelium‐associated cells, including sensory cells, without net gain in cell density. NO donors also induce cell proliferation in polylysine‐coated dishes, but induce neuronal differentiation and neurite outgrowth in uncoated dishes. No other cell type undergoes differentiation in the presence of NO. These observations suggest that in the sea pansy (1) cell adhesion promotes proliferation without morphogenesis and this proliferation is modulated positively by 9‐cis RA and NO, (2) 9‐cis RA and NO differentially induce neuronal differentiation in nonadherent cells while repressing proliferation, and (3) the involvement of RA and NO in neuronal differentiation appeared early during the evolutionary emergence of nervous systems. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 842–852, 2010