Oxyimperatorin attenuates LPS-induced microglial activation in vitro and in vivo via suppressing NF-κB p65 signaling.

BACKGROUND: Microglia-mediated neuroinflammation is an important pathological feature in many neurological diseases; thus, suppressing microglial activation is considered a possible therapeutic strategy for reducing neuronal damage. Oxyimperatorin (OIMP) is a member of furanocoumarin, isolated from the medicinal herb Glehnia littoralis. However, it is unknown whether OIMP can suppress the neuroinflammation. PURPOSE: To investigate the neuroprotective activity of oxyimperatorin (OIMP) in LPS-induced neuroinflammation in vitro and in vivo models. METHODS: In vitro inflammation-related assays were performed with OIMP in LPS-induced BV-2 microglia. In addition, intraperitoneal injection of LPS-induced microglial activation in the mouse brain was used to validate the anti-neuroinflammatory activity of OIMP. RESULTS: OIMP was found to suppress LPS-induced neuroinflammation in vitro and in vivo. OIMP significantly attenuated LPS-induced the production of free radicals, inducible nitric oxide synthase, cyclooxygenase-2, and pro-inflammatory cytokines in BV-2 microglia without causing cytotoxicity. In addition, OIMP could reduce the M1 pro-inflammatory transition in LPS-stimulated BV-2 microglia. The mechanistic study revealed that OIMP inhibited LPS-induced NF-κB p65 phosphorylation and nuclear translocation. However, OIMP did not affect LPS-induced IκB phosphorylation and degradation. In addition, OIMP also was able to reduce LPS-induced microglial activation in mice brain. CONCLUSION: Our findings suggest that OIMP suppresses microglia activation and attenuates the production of pro-inflammatory mediators and cytokines via inhibition of NF-κB p65 signaling.

Strategies targeting endoplasmic reticulum stress to improve Parkinson's disease.

Parkinson's disease (PD) is a common neurodegenerative disorder with motor symptoms, which is caused by the progressive death of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). Accumulating evidence shows that endoplasmic reticulum (ER) stress occurring in the SNpc DA neurons is an early event in the development of PD. ER stress triggers the activation of unfolded protein response (UPR) to reduce stress and restore ER function. However, excessive and continuous ER stress and UPR exacerbate the risk of DA neuron death through crosstalk with other PD events. Thus, ER stress is considered a promising therapeutic target for the treatment of PD. Various strategies targeting ER stress through the modulation of UPR signaling, the increase of ER's protein folding ability, and the enhancement of protein degradation are developed to alleviate neuronal death in PD models. In this review, we summarize the pathological role of ER stress in PD and update the strategies targeting ER stress to improve ER protein homeostasis and PD-related events.

Azoramide prevents MPP+-induced dopaminergic neuronal death via upregulating ER chaperone BiP expression.

Progressive death of dopaminergic (DA) neurons is the main cause of Parkinson's disease (PD). The discovery of drug candidates to prevent DA neuronal death is required to address the pathological aspects and alter the process of PD. Azoramide is a new small molecule compound targeting ER stress, which was originally developed for the treatment of diabetes. In this study, pre-treatment with Azoramide was found to suppress mitochondria-targeting neurotoxin MPP+-induced DA neuronal death and locomotor defects in zebrafish larvae. Further study showed that pre-treatment with Azoramide significantly attenuated MPP+-induced SH-SY5Y cell death by reducing aberrant changes in nuclear morphology, mitochondrial membrane potential, intracellular reactive oxygen species, and apoptotic biomarkers. The mechanistic study revealed that Azoramide was able to up-regulate the expression of ER chaperone BiP and thereby prevented MPP+-induced BiP decrease. Furthermore, pre-treatment with Azoramide failed to suppress MPP+-induced cytotoxicity in the presence of the BiP inhibitor HA15. Taken together, these results suggested that Azoramide is a potential neuroprotectant with pro-survival effects against MPP+-induced cell death through up-regulating BiP expression.

Neuronal Senescence in the Aged Brain.

Cellular senescence is a highly complicated cellular state that occurs throughout the lifespan of an organism. It has been well-defined in mitotic cells by various senescent features. Neurons are long-lived post-mitotic cells with special structures and functions. With age, neurons display morphological and functional changes, accompanying alterations in proteostasis, redox balance, and Ca2+ dynamics; however, it is ambiguous whether these neuronal changes belong to the features of neuronal senescence. In this review, we strive to identify and classify changes that are relatively specific to neurons in the aging brain and define them as features of neuronal senescence through comparisons with common senescent features. We also associate them with the functional decline of multiple cellular homeostasis systems, proposing the possibility that these systems are the main drivers of neuronal senescence. We hope this summary will serve as a steppingstone for further inputs on a comprehensive but relatively specific list of phenotypes for neuronal senescence and in particular their underlying molecular events during aging. This will in turn shine light on the association between neuronal senescence and neurodegeneration and lead to the development of strategies to perturb the processes.

The effects of bioactive components from the rhizome of gastrodia elata blume (Tianma) on the characteristics of Parkinson's disease.

Parkinson's disease (PD) is an age-related chronic neurodegenerative disease caused by the death and degeneration of dopaminergic neurons in the substantia nigra of the midbrain. The decrease of the neurotransmitter dopamine in the patient's brain leads to various motor symptoms. PD drugs mainly enhance dopamine levels but cannot prevent or slow down the loss of dopaminergic neurons. In addition, they exhibit significant side effects and addiction issues during long-term use. Therefore, it is particularly urgent to develop novel drugs that have fewer side effects, can improve PD symptoms, and prevent the death of dopaminergic neurons. The rhizome of Gastrodia elata Blume (Tianma) is a well-known medicinal herb and has long been used as a treatment of nervous system-related diseases in China. Several clinical studies showed that formula comprising Tianma could be used as an add-on therapy for PD patients. Pharmacological studies indicated that Tianma and its bioactive components can reduce the death of dopaminergic neurons, α-synuclein accumulation, and neuroinflammation in various PD models. In this review, we briefly summarize studies regarding the effects of Tianma and its bioactive components' effects on major PD features and explore the potential use of Tianma components for the treatment of PD.

Presenilin-1 F105C mutation leads to tau accumulation in human neurons via the Akt/mTORC1 signaling pathway.

BACKGROUND: The mammalian target of rapamycin (mTOR) plays a critical role in controlling cellular homeostasis, and its dysregulation has been implicated in Alzheimer's disease (AD). Presenilin-1 (PS1) mutations account for the most common causes of familial Alzheimer's disease (FAD); however, whether PS1 mutation causes mTOR dysregulation in human neurons remains a key unresolved issue. METHODS: We generated heterozygotes and homozygotes of PS1 F105C knock-in mutation in human induced pluripotent stem cells (iPSCs) via CRISPR/Cas9/piggyback-based gene editing and differentiated them into human neurons. Secreted Aß and tau accumulation were determined by ELISA assay, immunofluorescence staining, and western blotting analysis. mTOR signaling was evaluated by western blotting analysis, immunofluorescence staining, and co-immunoprecipitation. Autophagy/lysosome activities were determined by LC3-based assay, LysoTracker Red staining, and DQ-Red BSA staining. RESULTS: Through comparison among these isogenic neurons, PS1 F105C mutant neurons exhibited elevated Aß and tau accumulation. In addition, we found that the response of mTORC1 to starvation decreases in PS1 F105C mutant neurons. The Akt/mTORC1/p70S6K signaling pathway remained active upon EBSS starvation, leading to the co-localization of the vast majority of mTOR with lysosomes. Consistently, PS1 F105C neurons displayed a significant decline in starvation-induced autophagy. Notably, Torin1, a mTOR inhibitor, could efficiently reduce prominent tau pathology that occurred in PS1 F105C neurons. CONCLUSION: We demonstrate that Chinese PS1 F105C mutation causes dysregulation of mTORC1 signaling, contributing to tau accumulation in human neurons. This study on inherited FAD PS1 mutation provides unprecedented insights into our understanding of the molecular mechanisms of AD. It supports that pharmaceutical blocking of mTOR is a promising therapeutic strategy for the treatment of AD.

Neuroendocrine-Immune Regulatory Network of Eucommia ulmoides Oliver.

Eucommia ulmoides Oliver (E. ulmoides) is a popular medicinal herb and health supplement in China, Japan, and Korea, and has a variety of pharmaceutical properties. The neuroendocrine-immune (NEI) network is crucial in maintaining homeostasis and physical or psychological functions at a holistic level, consistent with the regulatory theory of natural medicine. This review aims to systematically summarize the chemical compositions, biological roles, and pharmacological properties of E. ulmoides to build a bridge between it and NEI-associated diseases and to provide a perspective for the development of its new clinical applications. After a review of the literature, we found that E. ulmoides has effects on NEI-related diseases including cancer, neurodegenerative disease, hyperlipidemia, osteoporosis, insomnia, hypertension, diabetes mellitus, and obesity. However, clinical studies on E. ulmoides were scarce. In addition, E. ulmoides derivatives are diverse in China, and they are mainly used to enhance immunity, improve hepatic damage, strengthen bones, and lower blood pressure. Through network pharmacological analysis, we uncovered the possibility that E. ulmoides is involved in functional interactions with cancer development, insulin resistance, NAFLD, and various inflammatory pathways associated with NEI diseases. Overall, this review suggests that E. ulmoides has a wide range of applications for NEI-related diseases and provides a direction for its future research and development.

Comprehensive Perspectives on Experimental Models for Parkinson's Disease.

Parkinson's disease (PD) ranks second among the most common neurodegenerative diseases, characterized by progressive and selective loss of dopaminergic neurons. Various cross-species preclinical models, including cellular models and animal models, have been established through the decades to study the etiology and mechanism of the disease from cell lines to nonhuman primates. These models are aimed at developing effective therapeutic strategies for the disease. None of the current models can replicate all major pathological and clinical phenotypes of PD. Selection of the model for PD largely relies on our interest of study. In this review, we systemically summarized experimental PD models, including cellular and animal models used in preclinical studies, to understand the pathogenesis of PD. This review is intended to provide current knowledge about the application of these different PD models, with focus on their strengths and limitations with respect to their contributions to the assessment of the molecular pathobiology of PD and identification of the therapeutic strategies for the disease.

The Potentials of Uncariae Ramulus Cum Uncis for the Treatment of Migraine: Targeting CGRP in the Trigeminovascular System.

Migraine is a common chronic neurovascular disease characterized by headaches. Calcitonin gene-related peptide (CGRP) signaling in the trigeminovascular system plays a critical role in the development of migraine. The monoclonal antibodies against CGRP and its receptor have been used clinically for the prevention of migraine; however, they may not be a cost-effective option for patients with low-frequency episodic migraine. Thus, it is quite valuable to search for an alternative strategy to downregulate CGRP signaling. Uncariae Ramulus Cum Uncis (UR) has a longterm history for the treatment of cardiovascular and central nervous systems disorders in China and Eastern Asia. Several clinical studies showed that famous herbal formulas comprising UR were able to improve headaches in migraineurs. In addition, increasing in vivo studies further indicated that migraine-related changes, such as CGRP increase, inflammation, nitric oxide increase, and spontaneous behavior problems could be reduced by UR extraction and its active constituents. In this review, we summarize the pathophysiological factors affecting abnormal CGRP release in the trigeminovascular system during a migraine, and for the first time, analyze the effects of UR on these factors and evaluate the potentials of UR for the treatment of migraine.

Azoramide protects iPSC-derived dopaminergic neurons with PLA2G6 D331Y mutation through restoring ER function and CREB signaling.

The endoplasmic reticulum (ER)-stress-induced cascade events are implicated in Parkinson's disease (PD). The discovery of drug candidates to protect dopaminergic (DA) neurons from ER-stress-induced oxidative damage is important to resolve the pathological aspects of PD and modify its progress. In this study, we found that a recently identified unfolded protein response (UPR) modulator, azoramide, showed protective effects on patient induced pluripotent stem cells-derived midbrain DA neurons with the homozygous phospholipase A2 group 6 (PLA2G6) D331Y mutant. A series of PD-related cascade events such as ER stress, abnormal calcium homeostasis, mitochondrial dysfunction, increase of reactive oxygen species, and apoptosis were observed in PLA2G6 D331Y mutant DA neurons, whereas azoramide significantly protected PLA2G6 D331Y mutant DA neurons against these events. The beneficial effects of azoramide were abolished by treatment with a cAMP-response element binding protein (CREB) inhibitor. Our results suggest that azoramide is a potential neuroprotectant against DA neuron damage via restoring ER function and the CREB signaling.

Using induced pluripotent stem cells for modeling Parkinson's disease.

Parkinson's disease (PD) is an age-related neurodegenerative disease caused by the progressive loss of dopaminergic (DA) neurons in the substantia nigra. As DA neurons degenerate, PD patients gradually lose their ability of movement. To date no effective therapies are available for the treatment of PD and its pathogenesis remains unknown. Experimental models that appropriately mimic the development of PD are certainly needed for gaining mechanistic insights into PD pathogenesis and identifying new therapeutic targets. Human induced pluripotent stem cells (iPSCs) could provide a promising model for fundamental research and drug screening. In this review, we summarize various iPSCs-based PD models either derived from PD patients through reprogramming technology or established by gene-editing technology, and the promising application of iPSC-based PD models for mechanistic studies and drug testing.

Hydroxyurea Facilitates Manifestation of Disease Relevant Phenotypes in Patients-Derived IPSCs-Based Modeling of Late-Onset Parkinson's Disease.

Induced pluripotent stem cells (iPSCs)-derived dopaminergic neurons might be reset back to the fetal state due to reprogramming. Thus, it is a compelling challenge to reliably and efficiently induce disease phenotypes of iPSCs-derived dopaminergic neurons to model late-onset Parkinson's disease (PD). Here, we applied a small molecule, hydroxyurea (HU), to promote the manifestation of disease relevant phenotypes in iPSCs-based modeling of PD. We established two iPS cell lines derived from two sporadic PD patients. Both patients-iPSCs-derived dopaminergic neurons did not display PD relevant phenotypes after 6 weeks culture. HU treatment remarkably induced ER stress on patients-iPSCs-derived dopaminergic neurons. Moreover, HU treatment significantly reduced neurite outgrowth, decreased the expression of p-AKT and its downstream targets (p-4EBP1 and p-ULK1), and increased the expression level of cleaved-Caspase 3 in patients-iPSCs-derived dopaminergic neurons. The findings of the present study suggest that HU administration could be a convenient and reliable approach to induce disease relevant phenotypes in PD-iPSCs-based models, facilitating to study disease mechanisms and test drug effects.

The effects of bioactive components from the rhizome of Salvia miltiorrhiza (Danshen) on the characteristics of Alzheimer's disease.

Alzheimer's disease (AD) is a common human neurodegenerative disease, which is characterized by the progressive loss of memory and the cognitive impairment. Since the etiology of AD is still unknown, it is extremely difficult to develop the effective drugs for preventing or slowing the AD process. The major characteristics of AD such as amyloid ß plaques, neurofibrillary tangles, mitochondrial dysfunction, and autophagy dysfunction are commonly used as the important indicators for evaluating the effects of potential candidate drugs. The rhizome of Salvia miltiorrhiza (known as 'Danshen' in Chinese), a famous traditional Chinese medicine, which is widely used for the treatment of hyperlipidemia, stroke, cardiovascular and cerebrovascular diseases. Increasing evidences suggest that the bioactive components of Danshen can improve cognitive deficits in mice, protect neuronal cells, reduce tau hyperphosylation, prevent amyloid-ß fiber formation and disaggregation. Here we briefly summarize the studies regarding the effects of bioactive component from Danshen on those major characteristics of AD in preclinical studies, as well as explore the potential of these Danshen component in the treatment of AD.

Ponatinib exerts anti-angiogenic effects in the zebrafish and human umbilical vein endothelial cells via blocking VEGFR signaling pathway.

Angiogenesis is a hallmark for cancer development because it is essential for cancer growth and provides the route for cancer cell migration (metastasis). Understanding the mechanism of angiogenesis and developing drugs that target the process has therefore been a major focus for research on cancer therapy. In this study, we screened 114 FDA-approved anti-cancer drugs for their effects on angiogenesis in the zebrafish. Among those with positive effects, we chose to focus on Ponatinib (AP24534; Iclusig®) for further investigation. Ponatinib is an inhibitor of the tyrosine kinase BCR-ABL in chronic myeloid leukemia (CML), and its clinical trial has been approved by FDA for the treatment of the disease. In recent clinical trials, however, some side effects have been reported for Ponatinib, mostly on blood vessel disorders, raising the possibility that this drug may influence angiogenesis. In this study, we demonstrated that Ponatinib was able to suppress the formation of intersegmental vessels (ISV) and subintestinal vessels (SIV) in the zebrafish larvae. The anti-angiogenic effect of Ponatinib was further validated by other bioassays in human umbilical vein endothelial cells (HUVECs), including cell proliferation and migration, tube formation, and wound healing. Further experiments showed that Ponatinib inhibited VEGF-induced VEGFR2 phosphorylation and its downstream signaling pathways including Akt/eNOS/NO pathway and MAPK pathways (ERK and p38MAPK). Taken together, these results suggest that inhibition of VEGF signaling at its receptor level and downstream pathways may likely be responsible for the antiangiogenic activity of Ponatinib.

Presenilin 1 deficiency suppresses autophagy in human neural stem cells through reducing γ-secretase-independent ERK/CREB signaling.

Autophagy impairment is commonly implicated in the pathological characteristic of Alzheimer's disease (AD). Presenilin 1 (PS1) expression in human brain gradually decreases with age and its mutations account for the most common cases of early-onset familial Alzheimer's disease (FAD). The dominant autophagy phenotypes occur in PS1-knockout and PS1 mutant neurons; it is still unknown whether PS1 deficiency causes serious autophagy impairment in neural stem cells (NSCs). Herein, we generated the heterozygote and homozygote of PS1 knockout in human induced pluripotent stem cells (iPSCs) via CRISPR/Cas9-based gene editing and differentiated them into human NSCs. In these human PS1-deficient NSCs, reduced autophagosome formation and downregulated expression of autophagy-lysosome pathway (ALP)-related mRNAs, as well as proteins were observed. Mechanistically, ERK/CREB inhibition and GSK3ß activation had key roles in reducing TFEB expression in PS1-knockout NSCs. Pharmacological inhibition of GSK3ß upregulated the expression of TFEB and ALP-related proteins in PS1-knockout NSCs, whereas this effect could be blocked by CREB inhibition. These findings demonstrate that PS1 deficiency causes autophagy suppression in human NSCs via downregulating ERK/CREB signaling.

Berberine Protects Human Retinal Pigment Epithelial Cells from Hydrogen Peroxide-Induced Oxidative Damage through Activation of AMPK.

Age-related macular degeneration (AMD) is the leading cause of central vision loss in the elderly with less effective treatment, especially for dry AMD (90% of AMD). Although the etiology of this disease is not well elucidated, increasing evidences indicate that excessive reactive oxygen species (ROS) impairing the physiological functions of retinal pigment epithelium (RPE) cells may be one of the main causes. Therefore, it could be a great strategy to find some drugs that can effectively protect RPE cells from oxidative damage which is desired to treat and slow the process of AMD. In the present study, a well-known traditional Chinese medicine berberine (BBR) was found to suppress hydrogen peroxide (H2O2)-induced oxidative damage in D407 cells, a human RPE cell line. Pre-treatment of D407 cells with BBR significantly suppressed H2O2-induced cell apoptosis by restoring abnormal changes in nuclear morphology, preventing the decline of mitochondrial membrane potential, reducing lactate dehydrogenase release and inhibiting caspase 3/7 activities induced by H2O2. Western blot analysis showed that BBR was able to stimulate the phosphorylation/activation of AMPK in a time- and dose-dependent manner in D407 cells, while treatment of cells with AMPK pathway inhibitor Compound C, or knockdown of the AMPK by specific siRNA blocked the effect of BBR. Similar results were obtained in primary cultured human RPE cells. Taken together, these results demonstrated that BBR was able to protect RPE cells against oxidative stress via the activation of AMPK pathway. Our findings also indicate the potential application of BBR in AMD treatment.

Roles of Nitric Oxide Synthase Isoforms in Neurogenesis.

Nitric oxide (NO), a free radical gas, acts as a neurotransmitter or neuromodulator in the central nervous system (CNS). It has been widely explored as a mediator of neuroinflammation, neuronal damages, and neurodegeneration at its pathological levels. Recently, increasing evidence suggests that NO plays key roles in mediating adult neurogenesis, the process of neural stem cells (NSCs) to generate newborn neurons for replacing damaged neurons or maintaining the function of the brain. NO synthase (NOS) is a major enzyme catalyzing the generation of NO in the brain. Recent studies indicate that three homologous NOS isoforms are involved in the proliferation of NSCs and neurogenesis. Therefore, the impact of NOS isoforms on NSC functions needs to be elucidated. Here, we summarize the studies on the role of NO and NOS with different isoforms in NSC proliferation and neurogenesis with the focus on introducing action mechanisms involved in the regulation of NSC function. This growing research area provides the new insight into controlling NSC function via regulating NO microenvironment in the brain. It also provides the evidence on targeting NOS for the treatment of brain diseases.