Oleanolic Acid Inhibiting the Differentiation of Neural Stem Cells into Astrocyte by Down-Regulating JAK/STAT Signaling Pathway

Principal Bioactive Properties of Oleanolic Acid, Its Derivatives, and Analogues

Natural products have always played an important role in pharmacotherapy, helping to control pathophysiological processes associated with human disease. Thus, natural products such as oleanolic acid (OA), a pentacyclic triterpene that has demonstrated important activities in several disease models, are in high demand. The relevant properties of this compound have motivated re-searchers to search for new analogues and derivatives using the OA as a scaffold to which new functional groups have been added or modifications have been realized. OA and its derivatives have been shown to be effective in the treatment of inflammatory processes, triggered by chronic diseases or bacterial and viral infections. OA and its derivatives have also been found to be effective in diabetic disorders, a group of common endocrine diseases characterized by hyperglycemia that can affect several organs, including the liver and brain. This group of compounds has been reported to exhibit significant bioactivity against cancer processes in vitro and in vivo. In this review, we summarize the bioactive properties of OA and its derivatives as anti-inflammatory, anti-bacterial, antiviral, anti-diabetic, hepatoprotective, neuroprotective, and anticancer agents.

Regulation of the JAK/STAT signaling pathway: The promising targets for cardiovascular disease

Individuals have known that Janus kinase (JAK) signal transducer and activator of transcription (STAT) signaling pathway was involved in the growth of the cell, cell differentiation courses advancement, immune cellular survival, as well as hematopoietic system advancement. Researches in the animal models have already uncovered a JAK/STAT regulatory function in myocardial ischemia-reperfusion injury (MIRI), acute myocardial infarction (MI), hypertension, myocarditis, heart failure, angiogenesis and fibrosis. Evidences originating in these studies indicate a therapeutic JAK/STAT function in cardiovascular diseases (CVDs). In this retrospection, various JAK/STAT functions in the normal and ill hearts were described. Moreover, the latest figures about JAK/STAT were summarized under the background of CVDs. Finally, we discussed the clinical transformation prospects and technical limitations of JAK/STAT as the potential therapeutic targets for CVDs. This collection of evidences has essential meanings for the clinical application of JAK/STAT as medicinal agents for CVDs. In this retrospection, various JAK/STAT functions in the normal and ill hearts were described. Moreover, the latest figures about JAK/STAT were summarized under the background of CVDs. Finally, we discussed the clinical transformation prospects and toxicity of JAK/STAT inhibitors as potential therapeutic targets for CVDs. This collection of evidences has essential meanings for the clinical application of JAK/STAT as medicinal agents for CVDs.

Epigenetic signature in neural plasticity: the journey so far and journey ahead

Neural plasticity is a remarkable characteristic of the brain which allows neurons to rewire their structure in response to internal and external stimuli. Many external stimuli collectively referred to as 'epigenetic factors' strongly influence structural and functional reorganization of the brain, thereby acting as a potential driver of neural plasticity. DNA methylation and demethylation, histone acetylation, and deacetylation are some of the frontline epigenetic mechanisms behind neural plasticity. Epigenetic signature molecules (mostly proteins) play a pivotal role in epigenetic reprogramming. Though neuro-epigenetics is an incredibly important field of emerging research, the critical role of signature proteins associated with epigenetic alteration and their involvement in neural plasticity needs further attention. This study gives an integrated and systematic overview of the current state of knowledge with a clear idea of types of neural plasticity and the context-dependent role of epigenetic signature molecules and their modulation by some natural bioactive compounds.

The Use of Bioactive Compounds in Hyperglycemia- and Amyloid Fibrils-Induced Toxicity in Type 2 Diabetes and Alzheimer’s Disease

It has become increasingly apparent that defective insulin signaling may increase the risk for developing Alzheimer’s disease (AD), influence neurodegeneration through promotion of amyloid formation or by increasing inflammatory responses to intraneuronal β-amyloid. Recent work has demonstrated that hyperglycemia is linked to cognitive decline, with elevated levels of glucose causing oxidative stress in vulnerable tissues such as the brain. The ability of β-amyloid peptide to form β-sheet-rich aggregates and induce apoptosis has made amyloid fibrils a leading target for the development of novel pharmacotherapies used in managing and treatment of neuropathological conditions such as AD-related cognitive decline. Additionally, deposits of β-sheets folded amylin, a glucose homeostasis regulator, are also present in diabetic patients. Thus, therapeutic compounds capable of reducing intracellular protein aggregation in models of neurodegenerative disorders may prove useful in ameliorating type 2 diabetes mellitus symptoms. Furthermore, both diabetes and neurodegenerative conditions, such as AD, are characterized by chronic inflammatory responses accompanied by the presence of dysregulated inflammatory biomarkers. This review presents current evidence describing the role of various small bioactive molecules known to ameliorate amyloidosis and subsequent effects in prevention and development of diabetes and AD. It also highlights the potential efficacy of peptide–drug conjugates capable of targeting intracellular targets.

The JAK/STAT signaling pathway: from bench to clinic

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway was discovered more than a quarter-century ago. As a fulcrum of many vital cellular processes, the JAK/STAT pathway constitutes a rapid membrane-to-nucleus signaling module and induces the expression of various critical mediators of cancer and inflammation. Growing evidence suggests that dysregulation of the JAK/STAT pathway is associated with various cancers and autoimmune diseases. In this review, we discuss the current knowledge about the composition, activation, and regulation of the JAK/STAT pathway. Moreover, we highlight the role of the JAK/STAT pathway and its inhibitors in various diseases.

Regulation of Neurogenesis and Neuronal Differentiation by Natural Compounds

Neuronal damage or degeneration is the main feature of neurological diseases. Regulation of neurogenesis and neuronal differentiation is important in developing therapies to promote neuronal regeneration or synaptic network reconstruction. Neurogenesis is a multistage process in which neurons are generated and integrated into existing neuronal circuits. Neuronal differentiation is extremely complex because it can occur in different cell types and can be caused by a variety of inducers. Recently, natural compounds that induce neurogenesis and neuronal differentiation have attracted extensive attention. In this paper, the potential neural induction effects of medicinal plant-derived natural compounds on neural stem/progenitor cells (NS/PCs), the cultured neuronal cells, and mesenchymal stem cells (MSCs) are reviewed. The natural compounds that are efficacious in inducing neurogenesis and neuronal differentiation include phenolic acids, polyphenols, flavonoids, glucosides, alkaloids, terpenoids, quinones, coumarins, and others. They exert neural induction effects by regulating signal factors and cell-specific genes involved in the process of neurogenesis and neuronal differentiation, including specific proteins (β-tubulin III, MAP-2, tau, nestin, neurofilaments, GFAP, GAP-43, NSE), related genes and proteins (STAT3, Hes1, Mash1, NeuroD1, notch, cyclin D1, SIRT1, reggie-1), transcription factors (CREB, Nkx-2.5, Ngn1), neurotrophins (BDNF, NGF, NT-3) and signaling pathways (JAK/STAT, Wnt/β-catenin, MAPK, PI3K/Akt, GSK-3β/β-catenin, Ca2+/CaMKII/ATF1, Nrf2/HO-1, BMP). The natural compounds with neural induction effects are of great value for neuronal regenerative medicine and provide promising prevention and treatment strategies for neurological diseases.

The Act of Controlling Adult Stem Cell Dynamics: Insights from Animal Models

Adult stem cells (ASCs) are the undifferentiated cells that possess self-renewal and differentiation abilities. They are present in all major organ systems of the body and are uniquely reserved there during development for tissue maintenance during homeostasis, injury, and infection. They do so by promptly modulating the dynamics of proliferation, differentiation, survival, and migration. Any imbalance in these processes may result in regeneration failure or developing cancer. Hence, the dynamics of these various behaviors of ASCs need to always be precisely controlled. Several genetic and epigenetic factors have been demonstrated to be involved in tightly regulating the proliferation, differentiation, and self-renewal of ASCs. Understanding these mechanisms is of great importance, given the role of stem cells in regenerative medicine. Investigations on various animal models have played a significant part in enriching our knowledge and giving In Vivo in-sight into such ASCs regulatory mechanisms. In this review, we have discussed the recent In Vivo studies demonstrating the role of various genetic factors in regulating dynamics of different ASCs viz. intestinal stem cells (ISCs), neural stem cells (NSCs), hematopoietic stem cells (HSCs), and epidermal stem cells (Ep-SCs).

Prophylactic and therapeutic roles of oleanolic acid and its derivatives in several diseases

Oleanolic acid (OA) and its derivatives are widely found in diverse plants and are naturally effective pentacyclic triterpenoid compounds with broad prophylactic and therapeutic roles in various diseases such as ulcerative colitis, multiple sclerosis, metabolic disorders, diabetes, hepatitis and different cancers. This review assembles and presents the latest in vivo reports on the impacts of OA and OA derivatives from various plant sources and the biological mechanisms of OA activities. Thus, this review presents sufficient data proposing that OA and its derivatives are potential alternative and complementary therapies for the treatment and management of several diseases.

Traceability of Geographical Origin in Gentiana straminea by UPLC-Q Exactive Mass and Multivariate Analyses

The root of Gentiana straminea Maxim. (Gentianaceae), is officially listed as "Qin-Jiao" in the Chinese Pharmacopoeia for the treatment of rheumatic arthritis, icteric hepatitis, constipation, pain, and hypertension. To establish the geographical origin traceability in G. straminea, its chemical profiles were determined by a UPLC-Q exactive mass spectrometer, from which 43 compounds were identified by comparing retention times and mass spectrometry. Meanwhile, a pair of isomers (loganin and secologanol) was identified by mass spectrometry based on their fragmentation pathway. A total of 42 samples from difference habitats were determined by an UPLC-Q exactive mass spectrometer and the data were assayed with multivariate statistical analysis. Eight characteristic compounds were identified to determine the geographical origin of the herb. To estimate the key characteristic markers associated with pharmacological function, the inhibiting activities of nitric oxide (NO) production in lipopolysaccharide (LPS)-induced macrophages were examined. This finding is crucial in realizing the determination of botanical origin and evaluating the quality of G. straminea.

Downregulation of STAT1 induces the differentiation of neural stem cells through JNK pathway

Neural stem cells (NSCs) generated neurons and glial cells. Thus, it is a preferable candidate to the cell replacement-based therapy against neural disorders. The signaling pathways that regulate differentiation of NSCs are widely studied. In the current study, we used in vitro culture system to elucidate the role of signal transducer and activator of transcription 1 (STAT1) in NSCs' differentiation. Downregulation of STAT1 inhibited the proliferation of NSCs. Meanwhile, we also found STAT1 regulation could control the differentiation of NSCs. More neurons and glia cells were generated from NSCs with STAT1 silencing. This process was mediated by the JNK/STAT1 signaling. STAT1 inhibitor promoted differentiation of NSCs. After transplantation, we observed more neurons generated from NSCs with shRNA-STAT1 treatment. Collectively, this work showed an efficient way to regulate neuronal differentiation of NSCs through regulating the STAT1 expression. This is likely to provide source and theoretical support to cell replacement based theory.

Neurochemical regulation of the expression and function of glial fibrillary acidic protein in astrocytes

Glial fibrillary acidic protein (GFAP), a type III intermediate filament, is a marker of mature astrocytes. The expression of GFAP gene is regulated by many transcription factors (TFs), mainly Janus kinase-2/signal transducer and activator of transcription 3 cascade and nuclear factor κ-light-chain-enhancer of activated B cell signaling. GFAP expression is also modulated by protein kinase and other signaling molecules that are elicited by neuronal activity and hormones. Abnormal expression of GFAP proteins occurs in neuroinflammation, neurodegeneration, brain edema-eliciting diseases, traumatic brain injury, psychiatric disorders and others. GFAP, mainly in α-isoform, is the major component of cytoskeleton and the scaffold of astrocytes, which is essential for the maintenance of astrocytic structure and shape. GFAP also has highly morphological plasticity because of its quick changes in assembling and polymerizing states in response to environmental challenges. This plasticity and its corresponding cellular morphological changes endow astrocytes the functions of physical barrier between adjacent neurons and stabilizer of extracellular environment. Moreover, GFAP colocalizes and even molecularly associates with many functional molecules. This feature allows GFAP to function as a platform for direct interactions between different molecules. Last, GFAP involves transportation and localization of other functional proteins and thus serves as a protein transport guide in astrocytes. This guiding role of GFAP involves an elastic retraction and extension cytoskeletal network that couples with GFAP reassembling, transporting, and membrane protein recycling machinery. This paper reviews our current understanding of the expression and functions of GFAP as well as their regulation.

An overview of fungal glycan-based therapeutics

Edible medicinal mushrooms have been traditionally used for health promotion and longevity in China and other East Asian countries for centuries. Structural and pharmacological studies revealed that fungal glycans show multiple physiological and healthy promoting effects including immunomodulation, anti-tumor, anti-aging, anti-oxidation, hypoglycemic, hypolipidemic, anti-radiation, and other effects. Fungal glycans isolated from different kinds of medicinal mushrooms are partially purified and clinically tested. Without serious safety concerns of mostly glycans from edible mushrooms and/or the cultured mycelium, eight of them are approved by Chinese Food and Drug Administration (SFDA) and used clinically in China since 1980s. In this chapter, 185 independent studies involving in biochemical, pharmacological and clinical studies of fungal glycans during the past four decades (1977-2019) from PubMed, CNKI (China National Knowledge Infrastructure) and Wanfang databases are summarized. In future, understanding the fungal glycan-based drugs at molecular biological level would be needed to comprehend the clinical efficacy of glycan-based drugs.

Botany, traditional use, phytochemistry, pharmacology, quality control, and authentication of Radix Gentianae Macrophyllae-A traditional medicine: A review

BACKGROUND

Radix Gentianae Macrophyllae, commonly known as Qinjiao (in Chinese), is dried roots of medicinal plants that belong to Gentianaceae family and Gentiana genus. It has medically been used for the treatment of various diseases such as arthritis, stroke, facial paralysis, and scapulohumeral periarthritis in China since ancient times.

PURPOSE

The aim of this paper is to provide a comprehensive and constructive overview of Qinjiao mainly containing Gentiana macrophylla Pall., Gentiana straminea Maxim., Gentiana crasicaulis Duthie ex Burk., and Gentiana daurica Fisch. in botany, traditional use, phytochemicals, pharmacology (biological activities and pharmacokinetics), quality control, and authentication according to the up-to-date data of available scientific literatures.

MATERIALS AND METHODS

All information regarding these four plants was collected from various academic search engines for example Google, Google Scholar, Web of Science, SciFinder, Pubmed, CNKI, and Wanfang. Additional information was obtained from botanical books, Chinese classic texts, and medical monographs.

RESULTS

So far 166 compounds have been isolated and identified from Qinjiao plants together with Gentiana tibetica King ex Hook. f., Gentiana siphonantha Maxim., Gentiana officinalis H. Smith, and Gentiana waltonii Burk. Their constituents are mainly classified into iridoid glycosides, triterpenes, flavones, sterols, benzene derivatives, etc. The pharmacological studies demonstrate that Qinjiao plants display a wide range of bioactivities e.g. anti-inflammatory, anti-oxidant, hepato-protective, cardio- and neuro-protective, insecticidal, and anti-influenza effects. The conventional quality control is performed by determination of the concentration of some compounds, e.g., gentiopicroside, or establishment of the fingerprint. In addition to seed propagation, tissue culture technology has been used to address the limited supplies and guarantee the sustainable development of Qinjiao in the experimental scale.

CONCLUSIONS

Although the identification of compounds from Qinjiao and demonstration of medicinal uses in vitro and in vivo have been carried out, various other studies on these plants should deserve our more attention. More efforts should be concentrated on the underlying mechanisms of their beneficial bioactivities. The proper toxic evaluation is indispensable to guarantee the safety, efficacy, and eligibility for medical use. To sum up, the summarized achievements could highlight the importance of Qinjiao and provide a solid foundation for scientists not only to further exploit the therapeutic potentials, but also possibly develop novel drugs in the subsequent research.

miR-17-92 facilitates neuronal differentiation of transplanted neural stem/precursor cells under neuroinflammatory conditions

Background

Neural stem/precursor cells (NSCs) are of particular interest because of their potential application in cell therapy for brain damage. However, most brain injury cases are followed with neuroinflammatory stress, which affects the lineage selection of grafted NSCs by promoting astrocytogenesis, thus hampering the potential for neural replacement. The present study investigated the role of miR-17-92 in protecting against detrimental effects of neuroinflammation on NSC differentiation in cell therapy.

Methods

NSCs were treated with conditioned medium from lesioned astrocytes with/without neutralizing antibodies of leukemia inhibitory factor (LIF) or/and ciliary neurotrophic factor (CNTF), respectively. Afterward, the levels of p-STAT3 and p-JAK2 were determined by western blotting while expression of glial fibrillary acidic protein (GFAP) and β-tubulin III was assessed by immunostaining. The activation of JAK-STAT pathway and cell differentiation were also evaluated after we overexpressed miR-17-92 in NSCs under different neuroinflammatory conditions. After the transplantation of miR-17-92-overexpressing NSCs into injured mouse cortex, PH3, nestin, GFAP, and NeuN were analyzed by immunostaining. In addition, motor coordination of mice was evaluated by rotarod test.

Results

Conditioned medium from lesioned astrocytes activated JAK-STAT pathway and facilitated astrocytic differentiation in NSCs while neutralizing antibodies of LIF and CNTF remarkably attenuated such effects. miR-17-92 cluster repressed the expression of multiple proteins including GP130, CNTFR, JAK2, and STAT3 in JAK-STAT pathway. Overexpression of miR-17-92 in NSCs systematically blocked the activation of JAK-STAT pathway mediated by LIF and CNTF, which facilitated neuronal differentiation in vitro. Furthermore, miR-17-92 increased neuronal generation of grafted NSCs and reduced astrogliosis, which resulted in the improvement of motor coordination of brain-injured mice.

Conclusions

Our results suggest that miR-17-92 promotes neuronal differentiation of grafted NSCs under neuroinflammatory condition via inhibition of multiple proteins in JAK-STAT pathway.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0685-5) contains supplementary material, which is available to authorized users.