Inhibition of intracellular Ca2+ release by a Rho-kinase inhibitor for the treatment of ischemic damage in primary cultured rat hippocampal neurons

Early chronic fasudil treatment rescues hippocampal alterations in the Ts65Dn model for down syndrome

Down syndrome (DS) is the most common genetic disorder associated with intellectual disability. To study this syndrome, several mouse models have been developed. Among the most common is the Ts65Dn model, which mimics most of the alterations observed in DS. Ts65Dn mice, as humans with DS, show defects in the structure, density, and distribution of dendritic spines in the cerebral cortex and hippocampus. Fasudil is a potent inhibitor of the RhoA kinase pathway, which is involved in the formation and stabilization of dendritic spines. Our study analysed the effect of early chronic fasudil treatment on the alterations observed in the hippocampus of the Ts65Dn model. We observed that treating Ts65Dn mice with fasudil induced an increase in neural plasticity in the hippocampus: there was an increment in the expression of PSA-NCAM and BDNF, in the dendritic branching and spine density of granule neurons, as well as in cell proliferation and neurogenesis in the subgranular zone. Finally, the treatment reduced the unbalance between excitation and inhibition present in this model. Overall, early chronic treatment with fasudil increases cell plasticity and eliminates differences with euploid animals.

Toxic mechanism on phenanthrene-triggered cell apoptosis, genotoxicity, immunotoxicity and activity changes of immunity protein in Eisenia fetida: Combined analysis at cellular and molecular levels

Phenanthrene (PHE) is a harmful organic contaminant and exists extensively in the soil environment. The accumulation of PHE would potentially threaten soil invertebrates, including earthworms, and the toxicity is also high. Currently, the possible mechanisms underlying apoptotic pathways induced by PHE and its immunotoxicity and genotoxicity in earthworms remain unclear. Thus, Eisenia fetida coelomocytes and immunity protein lysozyme (LYZ) were chosen as targeted receptors to reveal the apoptotic pathways, genotoxicity, and immunotoxicity triggered by PHE and its binding mechanism with LYZ, using cellular, biochemical, and molecular methods. Results indicated that PHE exposure can cause cell membrane damage, increase cell membrane permeability, and ultimately trigger mitochondria-mediated apoptosis. Increased 8-hydroxy-2-deoxyguanosine (8-OHdG) levels indicated PHE had triggered DNA oxidative damage in cells after PHE exposure. Occurrence of detrimental effects on the immune system in E. fetida coelomocytes due to decreased phagocytic efficacy and destroyed the lysosomal membrane. The LYZ activity in coelomocytes after PHE exposure was consistent with the molecular results, in which the LYZ activity was inhibited. After PHE binding, the protein structure (secondary structure and protein skeleton) and protein environment (the micro-environment of aromatic amino acids) of LYZ were destroyed, forming a larger particle size of the PHE-LYZ complex, and causing a significant sensitization effect on LYZ fluorescence. Molecular simulation indicated the key residues Glu 35, Asp 52, and Trp 62 for protein function located in the binding pocket, suggesting PHE preferentially binds to the active center of LYZ. Additionally, the primary driving forces for the binding interaction between PHE and LYZ molecule are hydrophobicity forces and hydrogen bonds. Taken together, PHE exposure can induce apoptosis by mitochondria-mediated pathway, destroy the normal immune system, and trigger DNA oxidative damage in earthworms. Besides, this study provides a comprehensive evaluation of phenanthrene toxicity to earthworms on molecular and cellular level.

TMEM16A/ANO1: Current Strategies and Novel Drug Approaches for Cystic Fibrosis

Cystic fibrosis (CF) is the most common of rare hereditary diseases in Caucasians, and it is estimated to affect 75,000 patients globally. CF is a complex disease due to the multiplicity of mutations found in the CF transmembrane conductance regulator (CFTR) gene causing the CFTR protein to become dysfunctional. Correctors and potentiators have demonstrated good clinical outcomes for patients with specific gene mutations; however, there are still patients for whom those treatments are not suitable and require alternative CFTR-independent strategies. Although CFTR is the main chloride channel in the lungs, others could, e.g., anoctamin-1 (ANO1 or TMEM16A), compensate for the deficiency of CFTR. This review summarizes the current knowledge on calcium-activated chloride channel (CaCC) ANO1 and presents ANO1 as an exciting target in CF.

Effects of bone marrow mesenchymal stem cells transplantation on the recovery of neurological functions and the expression of Nogo-A, NgR, Rhoa, and ROCK in rats with experimentally-induced convalescent cerebral ischemia

Background

To investigate the effects of intravenous transplantation of bone marrow mesenchymal stem cells (BMSCs) on neurological function in rats with experimentally-induced convalescent cerebral ischemia and the expression of Nogo-A, NgR, Rhoa, and ROCK expression.

Methods

BMSCs were isolated and cultured in vitro using the whole bone marrow adherent method. Eighty-one adult male Sprague-Dawley rats were divided at random into three groups: the sham-operated group, the cerebral ischemia group, and the BMSC treatment group (n=27 rats per group). In the latter two groups, the middle cerebral artery occlusion (MCAO) model was performed by the modified Zea Longa method. After MCAO, rats in the sham-operated and cerebral ischemic groups were injected with 1 mL of phosphate buffered saline (PBS) via the tail vein. In the BMSC-treatment group, 1 mL of the BMSC suspension (containing 3×10⁶ BMSCs) was injected through the rats’ femoral vein. At 12, 24, and 72 h after BMSC transplantation, modified neurological deficit scores (mNSS) were used to assess neurological function. TTC (2,3,5-triphenyl tetrazolium chloride) staining was used to measure the ischemic lesion volume, and the distribution of Nogo-A protein was observed by immunohistochemistry. The expressions of Nogo-A, NgR, Rhoa, and ROCK were detected by Western blot.

Results

At 72 h after BMSC transplantation, the mNSS scores were significantly lower in the BMSC treatment group than those in the cerebral ischemia group (7.50±0.55 vs. 8.67±0.52, P<0.01), and the ischemic lesions volume was significantly reduced. The expressions of Nogo-A, NgR, RhoA, and ROCK were significantly decreased compared with the controls (P<0.05).

Conclusions

The transplantation of BMSCs can improve neurological function in rats after convalescent cerebral ischemia, and their therapeutic effect may be related to the downregulation of Nogo-A, NgR, RhoA, and ROCK expression.

Inhibition of Rho-associated protein kinase improves the survival of human induced pluripotent stem cell-derived cardiomyocytes after dissociation

Heart disease remains the leading cause of morbidity and mortality worldwide. Induced pluripotent stem cells (iPSCs) have the ability to differentiate into cardiomyocytes (CMs), rendering this cell type to be a promising pre-cursor of cardiomyocytes for cell-based cardiac regeneration. Obtaining CMs with a high yield and purity coupled with improved subsequent survival could prove to be invaluable for the future cell replacement therapeutic strategies. Rho-associated protein kinase (ROCK) is involved in a wide range of fundamental cellular functions and serves significant roles in cardiac physiology. In the present study, human (h)iPSC-CMs were generated from iPSCs by including glycogen synthase kinase 3β and Wnt inhibitors in the basal culture media. The possible effect of Y27632, a ROCK inhibitor, on hiPSC-CMs was then investigated. hiPSC-CMs of high purity were harvested with >96% of cells expressing cardiac troponin T. Additionally, treatment with 10 µM Y27632 significantly improved the viability of dissociated hiPSC-CMs. The effects of ROCK inhibitors Y27632 and fasudil, on the proliferation and apoptosis of hiPSC-CMs were also examined. Treatment with ROCK inhibitors markedly enhanced hiPSC-CM proliferation, by up to 2.5-fold, whilst Y27632 treatment reduced apoptosis in hiPSC-derived CMs under serum starvation and suspension by suppressing the expression of caspase-3. Taken together, data from the present study indicated that ROCK kinase inhibitors effectively improved the cultural system of hiPSC-derived CMs.

Dexmedetomidine Protects Against Chemical Hypoxia-Induced Neurotoxicity in Differentiated PC12 Cells Via Inhibition of NADPH Oxidase 2-Mediated Oxidative Stress

Dexmedetomidine (Dex) is a widely used sedative in anesthesia and critical care units, and it exhibits neuroprotective activity. However, the precise mechanism of Dex-exerted neuroprotection is not clear. Increased neuronal NADPH oxidase 2 (NOX2) contributes to oxidative stress and neuronal damage in various hypoxia-related neurodegenerative disorders. The present study investigated whether Dex regulated neuronal NOX2 to exert its protective effects under hypoxic conditions. Well-differentiated PC12 cells were exposed to cobalt chloride (CoCl₂) to mimic a neuronal model of chemical hypoxia-mediated neurotoxicity. The data showed that Dex pretreatment of PC12 cells significantly suppressed CoCl₂-induced neurotoxicity, as evidenced by the enhanced cell viability, restoration of cellular morphology, and reduction in apoptotic cells. Dex improved mitochondrial function and inhibited CoCl₂-induced mitochondrial apoptotic pathways. We further demonstrated that Dex attenuated oxidative stress, downregulated NOX2 protein expression and activity, and inhibited intracellular calcium ([Ca²⁺]i) overload in CoCl₂-treated PC12 cells. Moreover, knockdown of the NOX2 gene markedly improved mitochondrial function and attenuated apoptosis under hypoxic conditions. These results demonstrated that the protective effects of Dex against hypoxia-induced neurotoxicity in neural cells were mediated, at least partially, via inhibition of NOX2-mediated oxidative stress.

ZD7288, a selective hyperpolarization-activated cyclic nucleotide-gated channel blocker, inhibits hippocampal synaptic plasticity

The selective hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyrimidinium chloride (ZD7288) blocks the induction of long-term potentiation in the perforant path–CA3 region in rat hippocampus in vivo. To explore the mechanisms underlying the action of ZD7288, we recorded excitatory postsynaptic potentials in perforant path–CA3 synapses in male Sprague-Dawley rats. We measured glutamate content in the hippocampus and in cultured hippocampal neurons using high performance liquid chromatography, and determined intracellular Ca²⁺ concentration [Ca²⁺]_i) using Fura-2. ZD7288 inhibited the induction and maintenance of long-term potentiation, and these effects were mirrored by the nonspecific HCN channel blocker cesium. ZD7288 also decreased glutamate release in hippocampal tissue and in cultured hippocampal neurons. Furthermore, ZD7288 attenuated glutamate-induced rises in [Ca²⁺]_i in a concentration-dependent manner and reversed 8-Br-cAMP-mediated facilitation of these glutamate-induced [Ca²⁺]_i rises. Our results suggest that ZD7288 inhibits hippocampal synaptic plasticity both glutamate release and resultant [Ca²⁺]_i increases in rat hippocampal neurons.

Intravitreal Injection of a Rho-Kinase Inhibitor (Fasudil) for Recent-Onset Nonarteritic Anterior Ischemic Optic Neuropathy

This study evaluated the effects of intravitreal injection of fasudil (IVF), a Rho-kinase inhibitor, in cases of recent-onset nonarteritic anterior ischemic optic neuropathy (NAION). In this interventional case series, 13 eyes of 13 patients diagnosed with NAION within 14 days of onset were included. The affected eyes received a 0.025 mg/0.05 mL IVF. Functional and structural outcomes were assessed 1 and 3 months following treatment. Best corrected visual acuity (BCVA) was the main outcome measured, with mean deviation (MD) index of the VF test and peripapillary retinal nerve fiber layer thickness as secondary measures. There was a statistically significant improvement in the patients' BCVA 1 and 3 months following IVF; BCVA improved from 1.69 ± 0.55 logMAR at baseline to 0.98 ± 0.47 and 0.93 ± 0.51 logMAR at 1 and 3 months, respectively (P = .004). The change in BCVA was not significant between month 1 and month 3 (P = .22). Peripapillary retinal nerve fiber layer thickness decreased from 173.5 ± 29.28 µm in the baseline evaluation to 85.8 ± 8.8 µm at 1 month, and 62.9 ± 5.97 µm at 3 months (P = .003). MD values changed from 24.60 ± 3.80 to 21.0 ± 6.10 and 20.5 ± 6.50 at 1 and 3 months, respectively (P = .007 and .005, respectively). This pilot study suggests that IVF may be an effective treatment for patients with recent-onset NAION. Larger studies are required to establish the therapeutic role of fasudil for NAION.

The role of Rho/Rho-kinase pathway and the neuroprotective effects of fasudil in chronic cerebral ischemia

The Rho/Rho-kinase signaling pathway plays an important role in cerebral ischemia/reperfusion injury. However, very few studies have examined in detail the changes in the Rho/Rho-kinase signaling pathway in chronic cerebral ischemia. In this study, rat models of chronic cerebral ischemia were established by permanent bilateral common carotid artery occlusion and intragastrically administered 9 mg/kg fasudil, a powerful ROCK inhibitor, for 9 weeks. Morris water maze results showed that cognitive impairment progressively worsened as the cerebral ischemia proceeded. Immunohistochemistry, semi-quantitative RT-PCR and western blot analysis showed that the expression levels of Rho-kinase, its substrate myosin-binding subunit, and its related protein alpha smooth muscle actin, significantly increased after chronic cerebral ischemia. TUNEL staining showed that chronic cerebral ischemia could lead to an increase in neuronal apoptosis, as well as the expression level of caspase-3 in the frontal cortex of rats subjected to chronic cerebral ischemia. Fasudil treatment alleviated the cognitive impairment in rats with chronic cerebral ischemia, and decreased the expression level of Rho-kinase, myosin-binding subunit and alpha smooth muscle actin. Furthermore, fasudil could regulate cerebral injury by reducing cell apoptosis and decreasing caspase-3 expression in the frontal cortex. These findings demonstrate that fasudil can protect against cognitive impairment induced by chronic cerebral ischemia via the Rho/Rho-kinase signaling pathway and anti-apoptosis mechanism.

Hypoxia-inducible factor-1α regulates the expression of L-type voltage-dependent Ca(2+) channels in PC12 cells under hypoxia

Hypoxia is an important factor in regulation of cell behavior both under physiological and pathological conditions. The mechanisms of hypoxia-induced cell death have not been completely elucidated yet. It is well known that Ca(2+) is critically related to cell survival. Hypoxia-inducible factor-1α (HIF-1α) is a core regulatory factor during hypoxia, and L-type voltage-dependent Ca(2+) channels (L-VDCCs) have been reported to play a critical role in cell survival. This study was conducted to explore the relationship between L-VDCC expression and HIF-1α regulation in PC12 cells under hypoxia. PC12 cells were treated at 20 or 3 % O2 to observe its proliferation and the intracellular calcium concentration. Then, we detected the protein expression of HIF-1α and L-VDCCs subtypes, Cav1.2 and Cav1.3. At last, to verify the relationship between HIF-1α and Cav1.2 and Cav1.3, we got the expression of Cav1.2 and Cav1.3 with Western blot and luciferase report gene assays after PC12 cells were treated by echinomycin, which is an HIF-1α inhibitor. Compared with 20 % O2 (normoxia), 3 % O2 (hypoxia) inhibited cell proliferation, increased the intracellular calcium concentration, and induced protein expression of HIF-1α. The protein expression of two L-VDCCs subtypes expressed in the nervous system, Cav1.2 and Cav1.3, was upregulated by hypoxia and reduced dose dependently by treatment with echinomycin, a HIF-1α inhibitor. Luciferase report gene assays showed that the expression of Cav1.2 and Cav1.3 genes was augmented under 3 % O2. However, echinomycin only slightly and dose dependently decreased expression of the Cav1.2 gene, but not that of the Cav1.3 gene. These data indicated that Cav1.2 might be regulated by HIF-1α as one of its downstream target genes and involved in regulation of PC12 cells death under hypoxia.

Effect of Rho-kinase pathway on neurite outgrowth of rat hippocampal neurons under atomic force microscopy

Hippocampal neurons of neonatal rats were cultured in serum-free culture medium for 5 days in vitro, and treated with the Rho-kinase inducer lysophosphatidic acid. Atomic force microscopy revealed that the numbers of level-1, -2 and -3 neurites protruding from rat hippocampal neurons was significantly reduced. After treatment with the Rho kinase inhibitor Y27632, a significant increase in the numbers of these neurites was observed. Our experimental findings indicate that the Rho-kinase pathway is closely associated with the neurites of hippocampal neurons.

Neuroprotective effects of the allosteric agonist of metabotropic glutamate receptor 7 AMN082 on oxygen-glucose deprivation- and kainate-induced neuronal cell death

Although numerous studies demonstrated a neuroprotective potency of unspecific group III mGluR agonists in in vitro and in vivo models of excitotoxicity, little is known about the protective role of group III mGlu receptor activation against neuronal cell injury evoked by ischemic conditions. The aim of the present study was to assess neuroprotective potential of the allosteric agonist of mGlu7 receptor, N,N'-Bis(diphenylmethyl)-1,2-ethanediamine dihydrochloride (AMN082) against oxygen-glucose deprivation (OGD)- and kainate (KA)-evoked neuronal cell damage in primary neuronal cultures, with special focus on its efficacy after delayed application. We demonstrated that in cortical neuronal cultures exposed to a 180 min OGD, AMN082 (0.01-1 µM) in a concentration- and time-dependent way attenuated the OGD-induced changes in the LDH release and MTT reduction assays. AMN082 (0.5 and 1 µM) produced also neuroprotective effects against KA-evoked neurotoxicity both in cortical and hippocampal cultures. Of particular importance was the finding that AMN082 attenuated excitotoxic neuronal injury after delayed application (30 min after OGD, or 30 min-1 h after KA). In both models of neurotoxicity, namely OGD- and KA-induced injury, the neuroprotective effects of AMN082 (1 µM) were reversed by the selective mGlu7 antagonist, 6-(4-Methoxyphenyl)-5-methyl-3-(4-pyridinyl)-isoxazolo[4,5-c]pyridin-4(5H)-one hydrochloride (MMPIP, 1 µM), suggesting the mGlu7-dependent mechanism of neuroprotective effects of AMN082. Next, we showed that AMN082 (0.5 and 1 µM) attenuated the OGD-induced increase in the number of necrotic nuclei as well inhibited the OGD-evoked calpain activation, suggesting the participation of these processes in the mechanism of AMN082-mediated protection. Additionally, we showed that protection evoked by AMN082 (1 µM) in KA model was connected with the inhibition of toxin-induced caspase-3 activity, and this effect was abolished by the mGlu7 receptor antagonist. The obtained results indicated that the activation of mGlu7 receptors may be a promising target for neuroprotection against ischemic and excitotoxic insults.

Decreased calcium-activated potassium channels by hypoxia causes abnormal firing in the spontaneous firing medial vestibular nuclei neurons

Vertebrobasilar insufficiency (VBI) presents complex varied clinical symptoms, including vertigo and hearing loss. Little is known, however, about how Ca(2+)-activated K(+) channel attributes to the medial vestibular nucleus (MVN) neural activity in VBI. To address this issue, we performed whole-cell patch clamp and quantitative polymerase chain reaction (qPCR) to examine the effects of hypoxia on neural activity and the changes of the large conductance Ca(2+) activated K(+) channels (BKCa channels) in the MVN neurons in brain slices of male C57BL/6 mice. Brief hypoxic stimuli of the brain slices containing MVN were administrated by switching the normoxic artificial cerebrospinal fluid (ACSF) equilibrated with 21% O2/5% CO2 to hypoxic ACSF equilibrated with 5% O2/5% CO2 (balance N2). 3-min hypoxia caused a depolarization in the resting membrane potential (RM) in 8/11 non-spontaneous firing MVN neurons. 60/72 spontaneous firing MVN neurons showed a dramatic increase in firing frequency and a depolarization in the RM following brief hypoxia. The amplitude of the afterhyperpolarization (AHPA) was significantly decreased in both type A and type B spontaneous firing MVN neurons. Hypoxia-induced firing response was alleviated by pretreatment with NS1619, a selective BKCa activator. Furthermore, brief hypoxia caused a decrease in the amplitude of iberiotoxin-sensitive outward currents and mRNA level of BKCa in MVN neurons. These results suggest that BKCa channels protect against abnormal MVN neuronal activity induced by hypoxia, and might be a key target for treatment of vertigo and hearing loss in VBI.

Piracetam ameliorated oxygen and glucose deprivation-induced injury in rat cortical neurons via inhibition of oxidative stress, excitatory amino acids release and P53/Bax

Our previous work has demonstrated that piracetam inhibited the decrease in amino acid content induced by chronic hypoperfusion, ameliorated the dysfunction of learning and memory in a hypoperfusion rat model, down-regulated P53, and BAX protein, facilitated the synaptic plasticity, and may be helpful in the treatment of vascular dementia. To explore the precise mechanism, the present study further evaluated effects of piracetam on Oxygen and glucose deprivation (OGD)-induced neuronal damage in rat primary cortical cells. The addition of piracetam to the cultured cells 12 h before OGD for 4 h significantly reduced neuronal damage as determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and lactate dehydrogenase release experiments. Piracetam also lowered the levels of malondialdehyde, nitrogen monoxidum, and xanthine oxidase which was increased in the OGD cells, and enhanced the activities of superoxide dismutase and glutathione peroxidase, which were decreased in the OGD cells. We also demonstrated that piracetam could decrease glutamate and aspartate release when cortical cells were subjected to OGD. Furthermore, Western blot study demonstrated that piracetam attenuated the increased expression of P53 and BAX protein in OGD cells. These observations demonstrated that piracetam reduced OGD-induced neuronal damage by inhibiting the oxidative stress and decreasing excitatory amino acids release and lowering P53/Bax protein expression in OGD cells.

Leptin counteracts the hypoxia-induced inhibition of spontaneously firing hippocampal neurons: a microelectrode array study

Besides regulating energy balance and reducing body-weight, the adipokine leptin has been recently shown to be neuroprotective and antiapoptotic by promoting neuronal survival after excitotoxic and oxidative insults. Here, we investigated the firing properties of mouse hippocampal neurons and the effects of leptin pretreatment on hypoxic damage (2 hours, 3% O(2)). Experiments were carried out by means of the microelectrode array (MEA) technology, monitoring hippocampal neurons activity from 11 to 18 days in vitro (DIV). Under normoxic conditions, hippocampal neurons were spontaneously firing, either with prevailing isolated and randomly distributed spikes (11 DIV), or with patterns characterized by synchronized bursts (18 DIV). Exposure to hypoxia severely impaired the spontaneous activity of hippocampal neurons, reducing their firing frequency by 54% and 69%, at 11 and 18 DIV respectively, and synchronized their firing activity. Pretreatment with 50 nM leptin reduced the firing frequency of normoxic neurons and contrasted the hypoxia-induced depressive action, either by limiting the firing frequency reduction (at both ages) or by increasing it to 126% (in younger neurons). In order to find out whether leptin exerts its effect by activating large conductance Ca(2+)-activated K(+) channels (BK), as shown on rat hippocampal neurons, we applied the BK channel blocker paxilline (1 µM). Our data show that paxilline reversed the effects of leptin, both on normoxic and hypoxic neurons, suggesting that the adipokine counteracts hypoxia through BK channels activation in mouse hippocampal neurons.

EGCG ameliorates the suppression of long-term potentiation induced by ischemia at the Schaffer collateral-CA1 synapse in the rat

The function of Epigallocatechin gallate (EGCG), a main component of green tea, has been widely investigated, amelioration of synaptic transmission and neuroprotective effects against ischemia-induced brain damage among others. However, the mechanism underlying is still unveiled. We investigated the effects of EGCG on high frequency stimulation-induced long-term potentiation (LTP) in the Schaffer collateral-CA1 synapse with or without cerebral ischemia injury induced by middle cerebral artery occlusion (MCAO) in vivo to examine the possible relations between EGCG and synaptic transmission. Application of EGCG modulated synaptic transmission and produced a dose-dependent improvement of the induction of LTP. However, relative high-dose EGCG can block the induction of LTP at the Schaffer collateral-CA1 synapse in normal rat in vivo. In addition, the effects of EGCG were observed on the infarct volume and neurological deficit in rats subjected to MCAO; furthermore, the cell viability of primary cultured rat hippocampal and cortical neurons suffered from oxygen-glucose deprivation were evaluated with MTT and LDH assay, which showed significant neuroprotective properties in vitro. Surprisingly, the contents of the glutamate (Glu), glycine (Gly), and gamma-aminobutyric acid amino acids were totally disequilibrated before and after cerebral ischemia injury and could be rebalanced to original level by application of EGCG. Our results suggest that EGCG is able to improve the efficiency of synaptic transmission in cerebral ischemia injury with attenuated effect related to the neuroprotection of EGCG through regulating excitatory and inhibitory amino acid balance.

MicroRNA-9 up-regulates E-cadherin through inhibition of NF-κB1-Snail1 pathway in melanoma

MicroRNAs (miRNAs) are short non-coding RNAs that post-transcriptionally regulate gene expression. Hsa-miR-9 has been shown to have opposite functions in different tumour types; however, the underlying mechanism is unclear. Here we show that hsa-miR-9 is down-regulated in metastatic melanomas compared to primary melanomas. Overexpression of miR-9 in melanoma cells resulted in significantly decreased cell proliferation and migratory capacity with decreased F-actin polymerization and down-regulation of multiple GTPases involved in cytoskeleton remodelling. miR-9 overexpression induced significant down-regulation of Snail1 with a concomitant increase in E-cadherin expression. In contrast, knockdown of miR-9 increased Snail1 expression as well as melanoma cell proliferation and migration capacity. Mechanistically, miR-9 expression down-regulated NF-κB1 in melanoma and the effect was abolished by mutations in the putative miR-9 binding sites within the 3'-untranslated region (UTR) of NF-κB1. Anti-miR-9 miRNA inhibitor also increased the expression of NF-κB1. The effects of miR-9 on Snail1 expression and melanoma cell proliferation and migration were rescued by overexpression of NF-κB1 in these cells. Furthermore, miR-9 overexpression resulted in significantly decreased melanoma growth and metastasis in vivo. In summary, miR-9 inhibits melanoma proliferation and metastasis through down-regulation of the NF-κB1-Snail1 pathway. This study finds a new mechanism that miR-9 utilizes to decrease E-cadherin expression and inhibit melanoma progression. The results suggest that function of microRNAs is context and tumour type-specific.

Anti-endothelial and anti-neuronal effects from auto-antibodies in subsets of adult diabetes having a cluster of microvascular complications

AIMS

To test autoantibodies from subsets of diabetes with painful neuropathy, maculopathy and nephropathy for effects in neurons.

METHODS

Protein-A eluates from plasma of 27 diabetic and 19 age-matched controls were tested for effects on endothelial cell survival, and neurite outgrowth in rat pheochromocytoma PC12 cells. Painful diabetic neuropathy or control autoantibodies were compared for binding to PC12-derived heparan sulfate proteoglycans. The mechanism of the effects from pathologic autoantibodies was investigated by changes in intracellular calcium in endothelial cells, whole cell current in neurons, or using the Rho kinase inhibitor Y27632.

RESULTS

Autoantibodies from diabetic patients with maculopathy, nephropathy, and painful neuropathy (n=5) caused significantly greater mean inhibition of neurite outgrowth (p<0.005) than diabetic or control patients with fewer or no complications (n=30). Painful diabetic autoantibodies (3 μg/mL) bound neuronal heparan sulfate proteoglycan (HSPG) more than autoantibodies from diabetic or control subjects without painful neuropathy (p<.0001). Inhibition of PC12 neurite outgrowth by the painful neuropathy antibodies was completely prevented by 1 μM concentrations of Y27632.

CONCLUSION

These results suggest anti-endothelial and anti-neuronal effects from auto-antibodies in a subset of diabetic patients with a cluster of microvascular complications.

Fasudil mesylate protects PC12 cells from oxidative stress injury via the Bax-mediated pathway

We previously reported that fasudil mesylate (FM) improves neurological deficit and neuronal damage in rats with ischemia following middle cerebral artery occlusion and reperfusion in vivo. In this study, the properties of FM on hydrogen peroxide (H(2)O(2))-induced oxidative stress insult in cultured PC12 cells as well as the underlying mechanisms were investigated in vitro. Pretreatment with FM (5, 10 μM) prior to H(2)O(2) exposure significantly elevated cell viability, reduced cell apoptosis by MTT assay, LDH assay, Hoechst 33258 dye staining, and FM also decreased the accumulation of reactive oxygen species (ROS) by DCFH-DA staining and NBT test. Furthermore, FM also reversed the upregulation of Bax/Bcl-2 ratio, the downstream cascade following ROS. FM protected PC12 cells from oxidative stress insult via downregulating the Bax/Bcl-2 ratio. These findings indicate that a direct effect of fasudil mesylate on PC12 cells may be partly responsible for its protective effect against oxidative stress injury.

Hypoxia-induced cell damage is reduced by mild hypothermia and postconditioning with catalase in-vitro: application of an enzyme based oxygen deficiency system

Mild hypothermia and pharmacological postconditioning are widespread therapeutical treatment options that positively influence the clinical outcome after tissue hypoxia. In the study presented, a two-enzyme based in-vitro oxygen deficiency model in combination with cultured HT-1080 fibrosarcoma cells was employed to mimic the in-vivo situation of hypoxia and to evaluate the influence of mild hypothermia and postconditioning with catalase on hypoxia-mediated cell damage. Using the in-vitro oxygen deficiency model, partial pressure of oxygen was rapidly reduced to levels below 5mmHg in the culture media and cells responded with an increased expression of hypoxia inducible factor-1 on protein level. Hypoxia resulted in significant cell rounding and retraction of cytoplasmic cell extensions. Evaluation of cytotoxicity revealed a 3.5-fold increase in lactate dehydrogenase levels which was accompanied by 40-fold elevated levels of hydrogen peroxide. The hypoxia-induced increase of lactate dehydrogenase was 2.5-fold reduced in the hypothermia group, although morphological correlates of cytotoxicity were still visible. Hypothermia did not significantly influence hydrogen peroxide concentrations in the culture media. Pharmacological postconditioning with catalase however dose-dependently decreased hypoxia-induced lactate dehydrogenase release. This cytoprotective effect was accompanied by a dose-dependent, up to 50-fold reduction of hydrogen peroxide concentrations and retention of normal cell morphology. We suggest that the described in-vitro oxygen deficiency model is a convenient and simple culture system for the investigation of cellular and subcellular events associated with oxygen deficiency. Moreover, our in-vitro results imply that catalase postconditioning may be a promising approach to attenuate hypoxia-induced and hydrogen peroxide-mediated cell and tissue damage.