Cyclin Y regulates spatial learning and memory flexibility through distinct control of the actin pathway.

Spatial learning and memory flexibility are known to require long-term potentiation (LTP) and long-term depression (LTD), respectively, on a cellular basis. We previously showed that cyclin Y (CCNY), a synapse-remodeling cyclin, is a novel actin-binding protein and an inhibitory regulator of functional and structural LTP in vitro. In this study, we report that Ccny knockout (KO) mice exhibit enhanced LTP and weak LTD at Schaffer collateral-CA1 synapses in the hippocampus. In accordance with enhanced LTP, Ccny KO mice showed improved spatial learning and memory. However, although previous studies reported that normal LTD is necessary for memory flexibility, Ccny KO mice intriguingly showed improved memory flexibility, suggesting that weak LTD could exert memory flexibility when combined with enhanced LTP. At the molecular level, CCNY modulated spatial learning and memory flexibility by distinctively affecting the cofilin-actin signaling pathway in the hippocampus. Specifically, CCNY inhibited cofilin activation by original learning, but reversed such inhibition by reversal learning. Furthermore, viral-mediated overexpression of a phosphomimetic cofilin-S3E in hippocampal CA1 regions enhanced LTP, weakened LTD, and improved spatial learning and memory flexibility, thus mirroring the phenotype of Ccny KO mice. In contrast, the overexpression of a non-phosphorylatable cofilin-S3A in hippocampal CA1 regions of Ccny KO mice reversed the synaptic plasticity, spatial learning, and memory flexibility phenotypes observed in Ccny KO mice. Altogether, our findings demonstrate that LTP and LTD cooperatively regulate memory flexibility. Moreover, CCNY suppresses LTP while facilitating LTD in the hippocampus and negatively regulates spatial learning and memory flexibility through the control of cofilin-actin signaling, proposing CCNY as a learning regulator modulating both memorizing and forgetting processes.

Prospects of Marine Sterols against Pathobiology of Alzheimer's Disease: Pharmacological Insights and Technological Advances.

Alzheimer's disease (AD) is a degenerative brain disorder characterized by a progressive decline in memory and cognition, mostly affecting the elderly. Numerous functional bioactives have been reported in marine organisms, and anti-Alzheimer's agents derived from marine resources have gained attention as a promising approach to treat AD pathogenesis. Marine sterols have been investigated for several health benefits, including anti-cancer, anti-obesity, anti-diabetes, anti-aging, and anti-Alzheimer's activities, owing to their anti-inflammatory and antioxidant properties. Marine sterols interact with various proteins and enzymes participating via diverse cellular systems such as apoptosis, the antioxidant defense system, immune response, and cholesterol homeostasis. Here, we briefly overview the potential of marine sterols against the pathology of AD and provide an insight into their pharmacological mechanisms. We also highlight technological advances that may lead to the potential application of marine sterols in the prevention and therapy of AD.

Effect of the Gintonin-Enriched Fraction on Glucagon-Like-Protein-1 Release.

Ginseng-derived gintonin reportedly contains functional lysophosphatidic acids (LPAs) as LPA receptor ligands. The effect of the gintonin-enriched fraction (GEF) on in vitro and in vivo glucagon-like protein-1 (GLP-1) secretion, which is known to stimulate insulin secretion, via LPA receptor(s) remains unclear. Accordingly, we examined the effects of GEF on GLP-1 secretion using human enteroendocrine NCI-H716 cells. The expression of several of LPA receptor subtypes in NCI-H716 cells using qPCR and Western blotting was examined. LPA receptor subtype expression was in the following order: LPA6 > LPA2 > LPA4 > LPA5 > LPA1 (qPCR), and LPA6 > LPA4 > LPA2 > LPA1 > LPA3 > LPA5 (Western blotting). GEF-stimulated GLP-1 secretion occurred in a dose- and time-dependent manner, which was suppressed by cAMP-Rp, a cAMP antagonist, but not by U73122, a phospholipase C inhibitor. Furthermore, silencing the human LPA6 receptor attenuated GEF-mediated GLP-1 secretion. In mice, low-dose GEF (50 mg/kg, peroral) increased serum GLP-1 levels; this effect was not blocked by Ki16425 co-treatment. Our findings indicate that GEF-induced GLP-1 secretion could be achieved via LPA6 receptor activation through the cAMP pathway. Hence, GEF-induced GLP secretion via LPA6 receptor regulation might be responsible for its beneficial effects on human endocrine physiology.

Protective Effects of Gintonin on Reactive Oxygen Species-Induced HT22 Cell Damages: Involvement of LPA1 Receptor-BDNF-AKT Signaling Pathway.

Gintonin is a kind of ginseng-derived glycolipoprotein that acts as an exogenous LPA receptor ligand. Gintonin has in vitro and in vivo neuroprotective effects; however, little is known about the cellular mechanisms underlying the neuroprotection. In the present study, we aimed to clarify how gintonin attenuates iodoacetic acid (IAA)-induced oxidative stress. The mouse hippocampal cell line HT22 was used. Gintonin treatment significantly attenuated IAA-induced reactive oxygen species (ROS) overproduction, ATP depletion, and cell death. However, treatment with Ki16425, an LPA1/3 receptor antagonist, suppressed the neuroprotective effects of gintonin. Gintonin elicited [Ca2⁺]i transients in HT22 cells. Gintonin-mediated [Ca2⁺]i transients through the LPA1 receptor-PLC-IP3 signaling pathway were coupled to increase both the expression and release of BDNF. The released BDNF activated the TrkB receptor. Induction of TrkB phosphorylation was further linked to Akt activation. Phosphorylated Akt reduced IAA-induced oxidative stress and increased cell survival. Our results indicate that gintonin attenuated IAA-induced oxidative stress in neuronal cells by activating the LPA1 receptor-BDNF-TrkB-Akt signaling pathway. One of the gintonin-mediated neuroprotective effects may be achieved via anti-oxidative stress in nervous systems.

Ginseng Gintonin Contains Ligands for GPR40 and GPR55.

Gintonin, a novel ginseng-derived glycolipoprotein complex, has an exogenous ligand for lysophosphatidic acid (LPA) receptors. However, recent lipid analysis of gintonin has shown that gintonin also contains other bioactive lipids besides LPAs, including linoleic acid and lysophosphatidylinositol (LPI). Linoleic acid, a free fatty acid, and LPI are known as ligands for the G-protein coupled receptors (GPCR), GPR40, and GPR55, respectively. We, herein, investigated whether gintonin could serve as a ligand for GPR40 and GPR55, using the insulin-secreting beta cell-derived cell line INS-1 and the human prostate cancer cell line PC-3, respectively. Gintonin dose-dependently enhanced insulin secretion from INS-1 cells. Gintonin-stimulated insulin secretion was partially inhibited by a GPR40 receptor antagonist but not an LPA1/3 receptor antagonist and was down-regulated by small interfering RNA (siRNA) against GPR40. Gintonin dose-dependently induced [Ca2+]i transients and Ca2+-dependent cell migration in PC-3 cells. Gintonin actions in PC-3 cells were attenuated by pretreatment with a GPR55 antagonist and an LPA1/3 receptor antagonist or by down-regulating GPR55 with siRNA. Taken together, these results demonstrated that gintonin-mediated insulin secretion by INS-1 cells and PC-3 cell migration were regulated by the respective activation of GPR40 and GPR55 receptors. These findings indicated that gintonin could function as a ligand for both receptors. Finally, we demonstrated that gintonin contained two more GPCR ligands, in addition to that for LPA receptors. Gintonin, with its multiple GPCR ligands, might provide the molecular basis for the multiple pharmacological actions of ginseng.

Ginseng Gintonin Enhances Hyaluronic Acid and Collagen Release from Human Dermal Fibroblasts Through Lysophosphatidic Acid Receptor Interaction.

Gintonin is a newly discovered component of ginseng and acts as a ligand for G protein-coupled lysophosphatidic acid (LPA) receptors. It is currently unclear whether gintonin has skin-related effects. Here, we examined the effects of a gintonin-enriched fraction (GEF) on [Ca2+]i transient induction in human dermal fibroblasts (HDFs). We found that GEF treatment transiently induced [Ca2+]i in a dose-dependent manner. GEF also increased cell viability and proliferation, which could be blocked by Ki16425, an LPA1/3 receptor antagonist, or 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM), a calcium chelator. We further found that GEF stimulated hyaluronic acid (HA) release from HDFs in a dose- and time-dependent manner, which could be attenuated by Ki16425, U73122, a phospholipase C inhibitor, 2-Aminoethoxydiphenyl borate (2-APB), an IP3 receptor antagonist, and BAPTA-AM. Moreover, we found that GEF increased HA synthase 1 (HAS1) expression in a time-dependent manner. We also found that GEF stimulates collagen release and the expression of collagen 1, 3, and 7 synthases in a time-dependent manner. GEF-mediated collagen synthesis could be blocked by Ki16425, U73122, 2-APB, and BAPTA-AM. GEF treatment also increased the mRNA levels of LPA1-6 receptor subtypes at 8 h and increased the protein levels of LPA1-6 receptor subtypes at 8 h. Overall, these results indicate that the GEF-mediated transient induction of [Ca2+]i is coupled to HA and collagen release from HDFs via LPA receptor regulations. We can, thus, conclude that GEF might exert a beneficial effect on human skin physiology via LPA receptors.

Functional significance of O-GlcNAc modification in regulating neuronal properties.

Post-translational modifications (PTMs) covalently modify proteins and diversify protein functions. Along with protein phosphorylation, another common PTM is the addition of O-linked ß-N-acetylglucosamine (O-GlcNAc) to serine and/or threonine residues. O-GlcNAc modification is similar to phosphorylation in that it occurs to serine and threonine residues and cycles on and off with a similar time scale. However, a striking difference is that the addition and removal of the O-GlcNAc moiety on all substrates are mediated by the two enzymes regardless of proteins, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), respectively. O-GlcNAcylation can interact or potentially compete with phosphorylation on serine and threonine residues, and thus serves as an important molecular mechanism to modulate protein functions and activation. However, it has been challenging to address the role of O-GlcNAc modification in regulating protein functions at the molecular level due to the lack of convenient tools to determine the sites and degrees of O-GlcNAcylation. Studies in this field have only begun to expand significantly thanks to the recent advances in detection and manipulation methods such as quantitative proteomics and highly selective small-molecule inhibitors for OGT and OGA. Interestingly, multiple brain regions, especially hippocampus, express high levels of both OGT and OGA, and a number of neuron-specific proteins have been reported to undergo O-GlcNAcylation. This review aims to discuss the recent updates concerning the impacts of O-GlcNAc modification on neuronal functions at multiple levels ranging from intrinsic neuronal properties to synaptic plasticity and animal behaviors.

Gintonin Attenuates D-Galactose-Induced Hippocampal Senescence by Improving Long-Term Hippocampal Potentiation, Neurogenesis, and Cognitive Functions.

BACKGROUND: Ginseng has been used to improve brain function and increase longevity. However, little is known about the ingredients of ginseng and molecular mechanisms of its anti-brain aging effects. Gintonin is a novel exogenous ginseng-derived lysophosphatidic acid (LPA) receptor ligand; LPA and LPA1 receptors are involved in adult hippocampal neurogenesis. D-galactose (D-gal) is used to induce brain -aging in animal models because long-term treatment with D-gal facilitates hippocampal aging in experimental adult animals by decreasing hippocampal neurogenesis and inducing learning and memory dysfunction. OBJECTIVE: To investigate the protective effects of gintonin on D-gal-induced hippocampal senescence, impairment of long-term potentiation (LTP), and memory dysfunction. METHODS: Brain hippocampal aging was induced by D-gal administration (150 mg/kg/day, s.c.; 10 weeks). From the 7th week, gintonin (50 or 100 mg/kg/day, per os) was co-administered with D-gal for 4 weeks. We performed histological analyses, LTP measurements, and object location test. RESULTS: Co-administration of gintonin ameliorated D-gal-induced reductions in hippocampal Ki67-immunoreactive proliferating cells, doublecortin-immunoreactive neuroblasts, 5-bromo-2'-deoxyuridine-incorporating NeuN-immunoreactive mature neurons, and LPA1 receptor expression. Co-administration of gintonin in D-gal-treated mice increased the expression of phosphorylated cyclic adenosine monophosphate response element binding protein in the hippocampal dentate gyrus. In addition, co-administration of gintonin in D-gal-treated mice enhanced LTP and restored the cognitive functions compared with those in mice treated with D-gal only. CONCLUSION: These results show that gintonin administration restores D-gal-induced memory deficits by enhancing hippocampal LPA1 receptor expression, LTP, and neurogenesis. Finally, the present study shows that gintonin exerts anti-brain aging effects that are responsible for alleviating brain aging-related dysfunction.

Effects of Gintonin-Enriched Fraction in an Atopic Dermatitis Animal Model: Involvement of Autotaxin Regulation.

Ginseng extract has been used for prevention of atopic dermatitis (AD) in experimental animal models. However, little is known about its active ingredients and the molecular mechanisms underlying its anti-AD effects. Recently, we isolated a unique lysophosphatidic acid (LPA) receptor ligand, gintonin, from ginseng. Gintonin, the glycolipoprotein fraction of ginseng, contains LPAs, mainly LPA C18 : 2 with other minor lysophospholipid components. A line of evidence showed that serum autotaxin (ATX) activity and level are significantly elevated in human AD patients compared to those in normal controls, which indicates that ATX may be involved in human AD. In a previous study, we demonstrated that gintonin exerted anti-inflammatory effects via inhibition of microglial activation and proinflammatory cytokine production by immune cells and that it strongly inhibited ATX activity. In this study, we investigated whether oral administration of the gintonin-enriched fraction (GEF) could ameliorate the symptoms of 2,4-dinitrofluorobenzene (DNFB)-induced AD in NC/Nga mice. We found that oral administration of GEF to DNFB-induced AD mice for 2 weeks reduced ear swelling and AD skin index. In addition, oral administration of GEF reduced the serum levels of immunoglobulin E, histamine, interleukin-4, and interferon-γ. Histological examination showed that oral administration of GEF attenuated skin inflammation and significantly reduced eosinophil and mast cell infiltration into the skin. Moreover, oral administration of GEF not only decreased serum ATX level but also reduced serum ATX activity. The present study shows that the anti-AD effects of ginseng might be attributed to GEF-induced anti-inflammatory activity and ATX regulation.

Structure of ginseng major latex-like protein 151 and its proposed lysophosphatidic acid-binding mechanism.

Lysophosphatidic acid (LPA) is a phospholipid growth factor with myriad effects on biological systems. LPA is usually present bound to animal plasma proteins such as albumin or gelsolin. When LPA complexes with plasma proteins, it binds to its cognate receptors with higher affinity than when it is free. Recently, gintonin from ginseng was found to bind to LPA and to activate mammalian LPA receptors. Gintonin contains two components: ginseng major latex-like protein 151 (GLP) and ginseng ribonuclease-like storage protein. Here, the crystal structure of GLP is reported, which belongs to the plant Bet v 1 superfamily, and a model is proposed for how GLP binds LPA. Amino-acid residues of GLP recognizing LPA were identified using site-directed mutagenesis and isothermal titration calorimetry. The resulting GLP mutants were used to study the activation of LPA receptor-dependent signalling pathways. In contrast to wild-type GLP, the H147A mutant did not bind LPA, elicit intracellular Ca(2+) transients in neuronal cells or activate Ca(2+)-dependent Cl(-) channels in Xenopus oocytes. Based on these results, a mechanism by which GLP recognizes LPA and its requirement to activate G protein-coupled LPA receptors to elicit diverse biological responses were proposed.

Synthesis and biological evaluation of isoxazoline derivatives as potent M1 muscarinic acetylcholine receptor agonists.

A series of azacyclic compounds substituted with isoxazole and 5-substituted isoxazolines were synthesized as acyclic modifications of the oxime class M1 mACh receptor agonist. Among them, 3-(tetrahydropyrin-3-yl)-5-(2-pyrrolodin-1-yl)isoxazoline compound 4f displayed potent and selective M1 mACh receptor agonist activity in the functional calcium mobilization assay (EC50=31 nM). Introduction of 2-pyrrolidinone and 3-tetrahydropyridine groups are pivotal to the high potency. Moreover, 4f was found to facilitate non-amyloidogenic amyloid precursor protein (APP) processing by significantly increasing ERK1/2 phosphorylation and sAPPα secretion, known disease-modifying effects related to M1 mAChR agonists in Alzheimer's disease (AD).

Synthesis and biological evaluation of 4-nitroindole derivatives as 5-HT2A receptor antagonists.

A novel series of 4-nitroindole sulfonamides containing a methyleneamino-N,N-dimethylformamidine were prepared. The binding of these compounds to 5-HT2A and 5-HT2C was evaluated, and most of the compounds showed IC50 values of less than 1µM, and exhibited high selectivity for the 5-HT2C receptor. However, little selectivity was observed in the functional assay for 5-HT6 receptors. The computational modeling studies further validated the biological results and also demonstrated a reasonable correlation between the activity of compounds and the mode of superimposition with specified pharmacophoric features.

3-Benzamides and 3,4,5-trimethoxyphenyl amines as calcium channel blockers.

T- and N-type calcium channels have known for relating to therapy of neuropathic pain which is chronic, debilitating pain state. Neuropathic pain is caused by damage of the somatosensory system. It may be associated with abnormal sensations and pain produced by normally non-painful stimuli (allodynia). Neuropathic pain is very difficult to treat, and only some 40-60% of patients achieve partial relief. For a neuropathic pain therapy, anticonvulsant like Lamotrigine, Carbamazepine and a topical anesthetic such as Lidocaine are used. We synthesized 15 novel amine derivatives and evaluated their activities against T-type and N-type calcium channels by whole-cell patch clamp recording on HEK293 cells. Among the tested compounds, compound 10 showed good inhibitory activity for both T-type and N-type calcium channels with the IC50 value of 1.9 µM and 4.3 µM, respectively. Compound 10 also showed good analgesic activity on rat spinal cord injury model.

Monitoring of Intracellular Tau Aggregation Regulated by OGA/OGT Inhibitors.

Abnormal phosphorylation of tau has been considered as a key pathogenic mechanism inducing tau aggregation in multiple neurodegenerative disorders, collectively called tauopathies. Recent evidence showed that tau phosphorylation sites are protected with O-linked ß-N-acetylglucosamine (O-GlcNAc) in normal brain. In pathological condition, tau is de-glycosylated and becomes a substrate for kinases. Despite the importance of O-GlcNAcylation in tau pathology, O-GlcNAc transferase (OGT), and an enzyme catalyzing O-GlcNAc to tau, has not been carefully investigated in the context of tau aggregation. Here, we investigated intracellular tau aggregation regulated by BZX2, an inhibitor of OGT. Upon the inhibition of OGT, tau phosphorylation increased 2.0-fold at Ser199 and 1.5-fold at Ser396, resulting in increased tau aggregation. Moreover, the BZX2 induced tau aggregation was efficiently reduced by the treatment of Thiamet G, an inhibitor of O-GlcNAcase (OGA). Our results demonstrated the protective role of OGT in tau aggregation and also suggest the counter-regulatory mechanism of OGA and OGT in tau pathology.

Novel N-biphenyl-2-ylmethyl 2-methoxyphenylpiperazinylalkanamides as 5-HT7R antagonists for the treatment of depression.

5-HT7 receptor (5-HT7R) is a promising target for the treatment of depression and neuropathic pain. 5-HT7R antagonists exhibited antidepressant effects, while the agonists produced strong anti-hyperalgesic effects. In our efforts to discover selective 5-HT7R antagonists or agonists, N-biphenylylmethyl 2-methoxyphenylpiperazinylalkanamides 1 were designed, synthesized, and biologically evaluated against 5-HT7R. Among the synthesized compounds, N-2'-chlorobiphenylylmethyl 2-methoxyphenylpiperazinylpentanamide 1-8 showed the best binding affinity with a Ki value of 8.69nM and it was verified as a novel antagonist according to functional assays. The compound 1-8 was very selective over 5-HT1DR, 5-HT2AR, 5-HT3R, 5-HT5AR and 5-HT6R and moderately selective over 5-HT1AR, 5-HT1BR and 5-HT2CR. The novel 5-HT7R antagonist 1-8 exhibited an antidepressant effect at a dose of 25mg/kg in the forced swimming test in mice and showed a U-shaped dose-response curve which typically appears in 5-HT7R antagonists such as SB-269970 and lurasidone.

Resveratrol inhibits glycine receptor-mediated ion currents.

Resveratrol is found in grapes, red wine, and berries. Resveratrol has been known to have many beneficial health effects, such as anti-cancer, neuroprotective, anti-nociceptive, and life-prolonging effects. However, the single cellular mechanisms by which resveratrol acts are relatively unknown, especially in terms of possible regulation of receptors involved in synaptic transmission. The glycine receptor is an inhibitory ligand-gated ion channel involved in fast synaptic transmission in spinal cord. In the present study, we investigated the effect of resveratrol on human glycine receptor channel activity. Glycine α1 receptors were expressed in Xenopus oocytes and glycine receptor channel activity was measured using a two-electrode voltage clamp technique. Treatment with resveratrol alone had no effect on oocytes injected with H2O or on oocytes injected with glycine α1 receptor cRNA. In the oocytes injected with glycine α1 receptor cRNA, co- or pre-treatment of resveratrol with glycine inhibited the glycine-induced inward peak current (IGly) in a reversible manner. The inhibitory effect of resveratrol on IGly was also concentration dependent, voltage independent, and non-competitive. These results indicate that resveratrol regulates glycine receptor channel activity and that resveratrol-mediated regulation of glycine receptor channel activity is one of several cellular action mechanisms of resveratrol for pain regulation.

Atypical formations of gintonin lysophosphatidic acids as new materials and their beneficial effects on degenerative diseases.

Fresh ginseng is prone to spoilage due to its high moisture content. For long-term storage, most fresh ginsengs are dried to white ginseng (WG) or steamed for hours at high temperature/pressure and dried to form Korean Red ginseng (KRG). They are further processed for ginseng products when subjected to hot water extraction/concentration under pressure. These WG or KRG preparation processes affect ginsenoside compositions and also other ginseng components, probably during treatments like steaming and drying, to form diverse bioactive phospholipids. It is known that ginseng contains high amounts of gintonin lysophosphatidic acids (LPAs). LPAs are simple lipid-derived growth factors in animals and humans and act as exogenous ligands of six GTP-binding-protein coupled LPA receptor subtypes. LPAs play diverse roles ranging from brain development to hair growth in animals and humans. LPA-mediated signaling pathways involve various GTP-binding proteins to regulate downstream pathways like [Ca2+]i transient induction. Recent studies have shown that gintonin exhibits anti-Alzheimer's disease and anti-arthritis effects in vitro and in vivo mediated by gintonin LPAs, the active ingredients of gintonin, a ginseng-derived neurotrophin. However, little is known about how gintonin LPAs are formed in high amounts in ginseng compared to other herbs. This review introduces atypical or non-enzymatic pathways under the conversion of ginseng phospholipids into gintonin LPAs during steaming and extraction/concentration processes, which exert beneficial effects against degenerative diseases, including Alzheimer's disease and arthritis in animals and humans via LPA receptors.

Loss of MEF2C function by enhancer mutation leads to neuronal mitochondria dysfunction and motor deficits in mice.

Genetic changes and epigenetic modifications are associated with neuronal dysfunction in the pathogenesis of neurodegenerative disorders. However, the mechanism behind genetic mutations in the non-coding region of genes that affect epigenetic modifications remains unclear. Here, we identified an ALS-associated SNP located in the intronic region of MEF2C (rs304152), residing in a putative enhancer element, using convolutional neural network. The enhancer mutation of MEF2C reduces own gene expression and consequently impairs mitochondrial function in motor neurons. MEF2C localizes and binds to the mitochondria DNA, and directly modulates mitochondria-encoded gene expression. CRISPR/Cas-9-induced mutation of the MEF2C enhancer decreases expression of mitochondria-encoded genes. Moreover, MEF2C mutant cells show reduction of mitochondrial membrane potential, ATP level but elevation of oxidative stress. MEF2C deficiency in the upper and lower motor neurons of mice impairs mitochondria-encoded genes, and leads to mitochondrial metabolic disruption and progressive motor behavioral deficits. Together, MEF2C dysregulation by the enhancer mutation leads to mitochondrial dysfunction and oxidative stress, which are prevalent features in motor neuronal damage and ALS pathogenesis. This genetic and epigenetic crosstalk mechanism provides insights for advancing our understanding of motor neuron disease and developing effective treatments.

An increase in voltage-gated sodium channel current elicits microglial activation followed inflammatory responses in vitro and in vivo after spinal cord injury.

Inflammation induced by microglial activation plays a pivotal role in progressive degeneration after traumatic spinal cord injury (SCI). Voltage-gated sodium channels (VGSCs) are also implicated in microglial activation following injury. However, direct evidence that VGSCs are involved in microglial activation after injury has not been demonstrated yet. Here, we show that the increase in VGSC inward current elicited microglial activation followed inflammatory responses, leading to cell death after injury in vitro and in vivo. Isoforms of sodium channel, Nav 1.1, Nav 1.2, and Nav 1.6 were expressed in primary microglia, and the inward current of VGSC was increased by LPS treatment, which was blocked by a sodium channel blocker, tetrodotoxin (TTX). TTX inhibited LPS-induced NF-κB activation, expression of TNF-α, IL-1ß and inducible nitric oxide synthase, and NO production. LPS-induced p38MAPK activation followed pro-nerve growth factor (proNGF) production was inhibited by TTX, whereas LPS-induced JNK activation was not. TTX also inhibited caspase-3 activation and cell death of primary cortical neurons in neuron/microglia co-cultures by inhibiting LPS-induced microglia activation. Furthermore, TTX attenuated caspase-3 activation and oligodendrocyte cell death at 5 d after SCI by inhibiting microglia activation and p38MAPK activation followed proNGF production, which is known to mediate oligodendrocyte cell death. Our study thus suggests that the increase in inward current of VGSC appears to be an early event required for microglia activation after injury.

In vitro cytotoxicity on human ovarian cancer cells by T-type calcium channel blockers.

The growth inhibition of human cancer cells via T-type Ca(2+) channel blockade has been well known. Herein, a series of new 3,4-dihydroquinazoline derivatives were synthesized via a brief SAR study on KYS05090 template and evaluated for both T-type Ca(2+) channel (Cav3.1) blockade and cytotoxicity on three human ovarian cancer cells (SK-OV-3, A2780 and A2780-T). Most of compounds except 6i generally exhibited more potent cytotoxicity on SK-OV-3 than mibefradil as a positive control regardless of the degree of T-type channel blockade. In particular, eight compounds (KYS05090, 6a and 6c-6h) showing strong channel blockade exhibited almost equal and more potent cytotoxicity on A2780 when compared to mibefradil. On A2780-T paclitaxel-resistant human ovarian carcinoma, two compounds (KYS05090 and 6d) were 20-fold more active than mibefradil. With respect to cell cycle arrest effect on A2780 and A2780-T cells, KYS05090 induced large proportion of sub-G1 phase in the cell cycle progression of A2780 and A2780-T, meaning the induction of cancer cell death instead of cell cycle arrest via blocking T-type Ca(2+) channel. Among new analogues, compounds 6g and 6h induced cell cycle arrest at G1 phase of A2780 and A2780-T cells in dose-dependent manner and exhibited strong anti-proliferation effects of ovarian cancer cells by blocking T-type Ca(2+) channel. Furthermore, 6g and 6h possessing strong cytotoxic effects could induce apoptosis of A2780 cells, which was detected by confocal micrographs using DAPI staining.