Cell adhesion molecule immobilized gold surfaces for enhanced neuron-electrode interfaces

To provide a long-term solution for increasing the biocompatibility of neuroprosthetics, approaches to reduce the side effects of invasive neuro-implantable devices are still in need of improvement. Physical, chemical, and bioactive design aspects of the biomaterials are proven to be important for providing proper cell-to-cell, cell-to-material interactions. Particularly, modification of implant surfaces with bioactive cues, especially cell adhesion molecules (CAMs) that capitalize on native neural adhesion mechanisms, are promising candidates in favor of providing efficient interfaces. Within this concept, this study utilized specific CAMs, namely N-Cadherin (Neural cadherin, N-Cad) and neural cell adhesion molecule (NCAM), to enhance neuron-electrode contact by mimicking the cell-to-ECM interactions for improving the survival of cells and promoting neurite outgrowth. For this purpose, representative gold electrode surfaces were modified with N-Cadherin, NCAM, and the mixture (1:1) of these molecules. Modifications were characterized, and the effect of surface modification on both differentiated and undifferentiated neuroblastoma SH-SY5Y cell lines were compared. The findings demonstrated the successful modification of these molecules which subsequently exhibited biocompatible properties as evidenced by the cell viability results. In cell culture experiments, the CAMs displayed promising results in promoting neurite outgrowth compared to conventional poly-l-lysine coated surfaces, especially NCAM and N-Cad/NCAM modified surfaces clearly showed significant improvement. Overall, this optimized approach is expected to provide an insight into the action mechanisms of cells against the local environment and advance processes for the fabrication of alternative neural interfaces.

Functional Interaction between Adenosine A2A and mGlu5 Receptors Mediates STEP Phosphatase Activation and Promotes STEP/mGlu5R Binding in Mouse Hippocampus and Neuroblastoma Cell Line

(1) Background: Recently, we found that adenosine A2A receptor (A2AR) stimulation results in an increase in STEP phosphatase activity. In order to delve into the mechanism through which A2AR stimulation induced STEP activation, we investigated the involvement of mGlu5R since it is well documented that A2AR and mGlu5R physically and functionally interact in several brain areas. (2) Methods: In a neuroblastoma cell line (SH-SY5Y) and in mouse hippocampal slices, we evaluated the enzymatic activity of STEP by using a para-nitrophenyl phosphate colorimetric assay. A co-immunoprecipitation assay and a Western blot analysis were used to evaluate STEP/mGlu5R binding. (3) Results: We found that the A2AR-dependent activation of STEP was mediated by the mGlu5R. Indeed, the A2AR agonist CGS 21680 significantly increased STEP activity, and this effect was prevented not only by the A2AR antagonist ZM 241385, as expected, but also by the mGlu5R antagonist MPEP. In addition, we found that mGlu5R agonist DHPG-induced STEP activation was reversed not only by the mGlu5R antagonist MPEP but also by ZM 241385. Finally, via co-immunoprecipitation experiments, we found that mGlu5R and STEP physically interact when both receptors are activated (4) Conclusions: These results demonstrated a close functional interaction between mGlu5 and A2A receptors in the modulation of STEP activity.

Vibrational spectroscopies for biochemical investigation of X-ray exposure effects on SH-SY5Y human neuroblastoma cells

Neuroblastoma is the most recurring cancer in childhood and adolescence. The SH-SY5Y neuroblastoma cell line is generally adopted for elaborating new therapeutical approaches and/or elaborating strategies for the prevention of central nervous system disturbances. In fact, it represents a valid model system for investigating in vitro the effects on the brain of X-ray exposure using vibrational spectroscopies that can detect early radiation-induced molecular alterations of potential clinical usefulness. In recent years, we dedicated significant efforts in the use of Fourier-transform and Raman microspectroscopy techniques for characterizing such radiation-induced effects on SH-SY5Y cells by examining the contributions from different cell components (DNA, proteins, lipids, and carbohydrates) to the vibrational spectra. In this review, we aim at revising and comparing the main results of our studies to provide a wide outlook of the latest outcomes and a framework for future radiobiology research using vibrational spectroscopies. A short description of our experimental approaches and data analysis procedures is also reported.

Unravelling the neuroprotective mechanisms of carotenes in differentiated human neural cells: Biochemical and proteomic approaches

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Total mixed carotenes (TMC) protect differentiated human neural cells against 6-hydroxydopamine-induced toxicity.

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TMC elevated the antioxidant enzymes activities and suppressed generation of reactive oxygen species.

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TMC augmented the dopamine and tyrosine hydroxylase levels.

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TMC exerted differential protein expression in human neural cells.

Carotenoids, fat-soluble pigments found ubiquitously in plants and fruits, have been reported to exert significant neuroprotective effects against free radicals. However, the neuroprotective effects of total mixed carotenes complex (TMC) derived from virgin crude palm oil have not been studied extensively. Therefore, the present study was designed to establish the neuroprotective role of TMC on differentiated human neural cells against 6-hydroxydopamine (6-OHDA)-induced cytotoxicity. The human neural cells were differentiated using retinoic acid for six days. Then, the differentiated neural cells were pre-treated for 24 hr with TMC before exposure to 6-OHDA. TMC pre-treated neurons showed significant alleviation of 6-OHDA-induced cytotoxicity as evidenced by enhanced activity of the superoxide dismutase (SOD) and catalase (CAT) enzymes. Furthermore, TMC elevated the levels of intra-neuronal dopamine and tyrosine hydroxylase (TH) in differentiated neural cells. The 6-OHDA induced overexpression of α-synuclein was significantly hindered in neural cells pre-treated with TMC. In proteomic analysis, TMC altered the expression of ribosomal proteins, α/β isotypes of tubulins, protein disulphide isomerases (PDI) and heat shock proteins (HSP) in differentiated human neural cells. The natural palm phytonutrient TMC is a potent antioxidant with significant neuroprotective effects against free radical-induced oxidative stress.

Overexpression of Neuroglobin Promotes Energy Metabolism and Autophagy Induction in Human Neuroblastoma SH-SY5Y Cells

Neuroglobin (NGB) is an O₂-binding globin mainly expressed in the central and peripheral nervous systems and cerebrospinal fluid. Previously, it was demonstrated that NGB overexpression protects cells from hypoxia-induced death. To investigate processes promoted by NGB overexpression, we used a cellular model of neuroblastoma stably overexpressing an NGB-FLAG construct. We used a proteomic approach to identify the specific profile following NGB overexpression. To evaluate the role of NGB overexpression in increasing energetic metabolism, we measured oxygen consumption rate (OCR) and the extracellular acidification rate through Seahorse XF technology. The effect on autophagy induction was evaluated by analyzing SQSTM1/p62 and LC3-II expression. Proteomic analysis revealed several differentially regulated proteins, involved in oxidative phosphorylation and integral mitochondrial proteins linked to energy metabolism. The analysis of mitochondrial metabolism demonstrated that NGB overexpression increases mitochondrial ATP production. Indeed, NGB overexpression enhances bioenergetic metabolism, increasing OCR and oxygen consumption. Analysis of autophagy induction revealed an increase of LC3-II together with a significant decrease of SQSTM1/p62, and NGB-LC3-II association during autophagosome formation. These results highlight the active participation of NGB in several cellular processes that can be upregulated in response to NGB overexpression, playing a role in the adaptive response to stress in neuroblastoma cells.

Nucleoredoxin Knockdown in SH-SY5Y Cells Promotes Cell Renewal

Nucleoredoxin (NXN) is a redox regulator of Disheveled and thereby of WNT signaling. Deficiency in mice leads to cranial dysmorphisms and defects of heart, brain, and bone, suggesting defects of cell fate determination. We used shRNA-mediated knockdown of NXN in SH-SY5Y neuroblastoma cells to study its impact on neuronal cells. We expected that shNXN cells would easily succumb to redox stress, but there were no differences in viability on stimulation with hydrogen peroxide. Instead, the proliferation of naïve shNXN cells was increased with a higher rate of mitotic cells in cell cycle analyses. In addition, basal respiratory rates were higher, whereas the relative change in oxygen consumption upon mitochondrial stressors was similar to control cells. shNXN cells had an increased expression of redox-sensitive heat shock proteins, Hsc70/HSPA8 and HSP90, and autophagy markers suggested an increase in autophagosome formation upon stimulation with bafilomycin and higher flux under low dose rapamycin. A high rate of self-renewal, autophagy, and upregulation of redox-sensitive chaperones appears to be an attractive anti-aging combination if it were to occur in neurons in vivo for which SH-SY5Y cells are a model.

An optically active isochroman-2H-chromene conjugate potently suppresses neuronal oxidative injuries associated with the PI3K/Akt and MAPK signaling pathways

Increasing evidence suggests that the use of potent neuroprotective agents featured with novel pharmacological mechanism would offer a promising strategy to delay or prevent the progression of neurodegeneration. Here, we provide the first demonstration that the chiral nonracemic isochroman-2H-chromene conjugate JE-133, a novel synthetic 1,3-disubstituted isochroman derivative, possesses superior neuroprotective effect against oxidative injuries. Pretreatment with JE-133 (1-10 μM) concentration-dependently prevented H2O2-induced cell death in SH-SY5Y neuroblastoma cells and rat primary cortical neurons. Pretreatment with JE-133 significantly alleviated H2O2-induced apoptotic changes. These protective effects could not be simply attributed to the direct free radical scavenging as JE-133 had moderate activity in reducing DPPH free radical. Further study revealed that pretreatment with JE-133 (10 μM) significantly decreased the phosphorylation of MAPK pathway proteins, especially ERK and P38, in the neuronal cells. In addition, blocking PI3K/Akt pathway using LY294002 partially counteracted the cell viability-enhancing effect of JE-133. We conclude that JE-133 exerts neuroprotection associated with dual regulative mechanisms and consequently activating cell survival and inhibiting apoptotic changes, which may provide important clues for the development of effective neuroprotective drug lead/candidate.

Design and Microwave-Assisted Synthesis of Aza-Resveratrol Analogs with Potent Cholinesterase Inhibition

BACKGROUND

Currently approved Alzheimer's disease medications mainly comprise acetylcholinesterase inhibitors. Many of these inhibitors are either natural compounds or synthetic molecules inspired in natural compounds. Hybrid molecules that can interact with different target sites of the enzyme could lead to the discovery of effective multitarget drugs.

OBJECTIVE

To design, synthesize, and evaluate a series of new aza-resveratrol analogs as in vitro acetyl- and butyrylcholinesterase inhibitors.

METHODS

The synthesis is achieved by a simple and efficient microwave-assisted method, from commercially available starting materials. Compounds are designed as hybrids of an aza-stilbene nucleus (Schiff base) connected to a tertiary amine by a hydrocarbon chain of variable length, designed to interact both with the peripheric anionic site and the catalytic site of the enzyme.

RESULTS

All the derivatives inhibit both enzymes in a concentration-dependent manner, acting as moderate to potent cholinesterase inhibitors. The most potent inhibitors are compounds 12b (IC₅₀ = 0.43 μM) and 12a (IC₅₀ = 0.31 μM) for acetyl- and butyrylcholinesterase, respectively. Compounds 12a and 12b also exhibit significant acetylcholinesterase inhibition in SH-SY5Y human neuroblastoma cells without cytotoxic properties. Enzyme kinetic studies and molecular modeling reveal that inhibitor 12b targets both the catalytic active site and the peripheral anionic site of acetylcholinesterase what makes it able to modulate the self-induced β-amyloid aggregation. Furthermore, the molecular modeling analysis helps to assess the impact of the linker length in the inhibitory activity of this family of new cholinesterase inhibitors.

CONCLUSION

These compounds have the potential to serve as a dual binding site inhibitor and might provide a useful template for the development of new anti-Alzheimer's disease agents.

Impact of rapeseed pomace extract on markers of oxidative stress and DNA damage in human SH-SY5Y cells

With increased longevity and subsequent rise in people with age-related neurodegenerative diseases, protection of neurons from oxidative stress damage has become an important field of study. For the first time, we highlight the neuroprotective properties of rapeseed pomace (RSP) extract in SH-SY5Y human neuroblastoma cells. We used resazurin to determine cell metabolism, 2,7'-dichlorofluorescin diacetate (H₂ DCFDA) to assess the potential of RSP extracts to shield cells from reactive oxygen species (ROS) induced by H₂ O₂ using flow cytometry, HPLC to analyze for malondialdehyde (MDA) as a lipid peroxidation marker and the COMET assay to assess DNA strand breakage. Protein stress arrays were used to investigate the cellular pathways affected by RSP extract. No effect on cell metabolism in SH-SY5Y cells was observed after RSP extract treatment (up to 1.5 mg/ml). Pretreatment (24 hr) with RSP extract (1 mg/ml), before H₂ O₂ -induced stress, alleviated ROS production and DNA strand breakage by 68%, and 38%, respectively. At protein level, the RSP extract increased the levels of FABP-1, HIF-1α, SOD2, and Cytochrome c proteins. Under H₂ O₂ -induced stress, however, it helped to downregulate p38α levels, a protein kinase which is receptive to stress impulse (mitogen-activated). RSP extract shows very promising cell protective properties in relation to oxidative stress. PRACTICAL APPLICATIONS: Oxidative stress has been associated with numerous diseases for example cancer, diabetes, and many neurological disorders including Parkinson's and Alzheimer's diseases. Hence, there is acceptance among the scientific community of antioxidant therapy and the quest for effective, low cost and readily available sources of natural antioxidants is paramount. Rapeseed plantations are abundant around the world due to the use of rapeseed oil in cooking and as a biofuel. The resulting rapeseed pomace (by-product), specifically its extract, contains high levels of phytochemicals that protect cells against oxidative stress. Therefore, RSP extract can potentially be used/developed as functional food and nutraceuticals in the prevention of many complex neurodegenerative diseases.

Influence of serum concentration in retinoic acid and phorbol ester induced differentiation of SH-SY5Y human neuroblastoma cell line

Numerous protocols to establish dopaminergic phenotype in SH-SY5Y cells have been reported. In most of these protocols there are variations in concentration of serum used. In this paper, we compared the effects of high (10%), low (3%) and descending (2.5%/1%) serum concentration in differentiation medium containing different proportion of retinoic acid (RA) and 12-O-Tetradecanoylphorbol-13-acetate (TPA) or RA-only on the undifferentiated SH-SY5Y cells with regards to cell morphology, biochemical and gene expression alterations. Cells differentiated in culture medium containing low and descending serum concentrations showed increased number of neurite projections and reduced proliferation rates when compared to undifferentiated cells. The SH-SY5Y cells differentiated in culture medium containing 3% RA and low serum or descending (2.5%/1% RA/TPA) were found to be more susceptible to 6-hydroxydopamine (6-OHDA) induced cytotoxicity. Cells differentiated with RA/TPA or RA differentiated showed increased production of the α-synuclein (SNCA) neuroprotein and dopamine neurotransmitter compared to undifferentiated cells, regardless serum concentrations used. There was no significant difference in the expression of tyrosine hydroxylase (TH) gene between undifferentiated and differentiated SH-SY5Y cells. However, the expression of dopamine receptor D2 (DRD2) gene was markedly increased (p<0.05) in differentiated cells with 3% serum and RA only when compared to undifferentiated cells. In conclusion, to terminally differentiate SH-SY5Y cells to be used as a cell-based model to study Parkinson's disease (PD) to investigate molecular mechanisms and drug discovery, the optimal differentiation medium should contain 3% serum in RA-only.

Thyroid hormones reduce nicotinic receptor mediated currents in SH-SY5Y neuroblastoma cells

BACKGROUND

Thyroid hormones (THs) are crucial for maturation and functioning of mammalian CNS. THs "classical" signaling involves nuclear receptors binding but also their non genomic actions, as rapid modulators of cell activity, are widely recognized. Since THs imbalance affects cognition and the cholinergic system is deeply involved in learning and memory processes we have studied THs effects at the level of the nicotinic acetylcholine receptors (nAchR).

METHODS

We used the patch-clamp technique to analyze T3 and T4 modulation of nicotine (NIC)-mediated current in SH-SY5Y neuroblastoma cells.

RESULTS

Both hormones decreased NIC-evoked current in a dose dependent fashion. The antagonism was reversible, not competitive and not blocked by Tetrac, an integrin αVβ3 receptor antagonist. A similar effect was detected with the endogenous agonist Acetylcholine. THs potencies were higher at 100 μM NIC (IC₅₀ = 4.6 ± 2 μM for T3 and 4.8 ± 2 μM for T4) compared to those measured at 10 μM NIC (IC₅₀ = 10 ± 4 μM for T3 and 8 ± 4 μM for T4). Furthermore, the efficacy of THs reached almost 90% at 100 μM NIC while was about 30 % at 10 μM NIC. THs inhibited nAchR-mediated currents by enhancing receptor desensitization and this effect was more pronounced at high agonist concentrations.

CONCLUSIONS

Our results make light on a new non genomic activity of THs at the level of nAchR. This mechanism of action  of THs  can provide  a new explanation for the cognitive deficits associated with tyroid dysfunction.

Effect of AmyTrap, an amyloid-β binding drug, on Aβ induced mitochondrial dysfunction and tau phosphorylation in cultured neuroblastoma cells

Alzheimer's Disease (AD) is the most common cause of dementia, affecting 25 million people worldwide. Accumulation of Amyloid-β (Aβ) in the mitochondria has been shown to adversely affect key enzymes including pyruvate dehydrogenase (PDH), succinate dehydrogenase (SDH), oxoglutarate dehydrogenase (OGDH). Accumulation of Aβ is also believed to increase Tau expression and pathology. Tau, in its toxic state, results in synaptic damage causing memory and cognitive dysfunction. We are developing a drug to treat AD namely AmyTrap. The active pharmacological ingredient is a retro inverso, Aβ-binding peptide which sequesters Aβ. We wanted to examine the effect of AmyTrap peptide on Aβ-induced mitochondrial dysfunction and Tau phosphorylation. Therefore, we treated SH-SY5Y neuroblastoma cells with wild-type Aβ, a mutant AβY10A, AmyTrap peptide (RI-peptide), or Aβ and RI-peptide for 72 h. The mutant AβY10A is known to impact the self-aggregating property of Aβ as this Tyr10 is essential for self-aggregation. As expected, AβY10A reversed PDH, OGDH and SDH dysfunction to near normal levels. Further, AβY10A successfully reversed Tau phosphorylation, suggesting that Tyr10 is also associated with Aβ-induced cytotoxicity. RI-peptide was able to significantly reverse SDH dysfunction with limited effect on PDH and Tau phosphorylation. The findings are suggestive that the Tyr10 on Aβ plays a critical role in the self-aggregation. Further studies are warranted to expand these findings.

CD81 Promotes a Migratory Phenotype in Neuronal-Like Cells

Tetraspanins, such as CD81, can form lateral associations with each other and with other transmembrane proteins. These interactions may underlie CD81 functions in multiple cellular processes, such as adhesion, morphology, migration, and differentiation. Since CD81's role in neuronal cells' migration has not been established, we here evaluated effects of CD81 on the migratory phenotype of SH-SY5Y neuroblastoma cells. CD81 was found enriched at SH-SY5Y cell's membrane, co-localizing with its interactor filamentous-actin (F-actin) in migratory relevant structures of the leading edge (filopodia, stress fibers, and adhesion sites). CD81 overexpression increased the number of cells with a migratory phenotype, in a potentially phosphatidylinositol 3 kinase (PI3K)-Ak strain transforming (AKT) mediated manner. Indeed, CD81 also co-localized with AKT, a CD81-interactor and actin remodeling agent, at the inner leaflet of the plasma membrane. Pharmacologic inhibition of PI3K, the canonical AKT activator, led both to a decrease in the acquisition of a migratory phenotype and to a redistribution of intracellular CD81 and F-actin into cytoplasmic agglomerates. These findings suggest that in neuronal-like cells CD81 bridges active AKT and actin, promoting the actin remodeling that leads to a motile cell morphology. Further studies on this CD81-mediated mechanism will improve our knowledge on important physiological and pathological processes such as cell migration and differentiation, and tumor metastasis.

Characterization of SH-SY5Y human neuroblastoma cell growth over glass and SU-8 substrates

The physical properties of substrates can have profound effects on the structure and function of cultured cells. In this study, we aimed to examine the viability, adherence, and morphological and functional variations between SH-SY5Y human neuroblastoma cells cultured on SU-8 surfaces compared with control surfaces composed of borosilicate glass, which are routinely used for cell culture. The SU-8 polymer has been extensively studied for its biocompatibility, but there has been little investigation into the characteristic differences between cells cultured on SU-8 when compared with glass. SH-SY5Y cells were cultured within polydimethylsiloxane wells on both SU-8 and glass substrates for up to 72 h after which flow cytometry and enzyme-linked immunosorbent assay analysis was performed to examine cell viability and neurotoxicity. Immunocytochemistry was also performed to analyze the morphological and functional characteristics of the cells. Atomic force microscopy was performed to measure surface roughness and to map cell-substrate interactions. Nanoindentation testing was used to characterize the mechanical properties of polymer surface. Results showed that SH-SY5Y cells grown on SU-8 have significantly improved viability and increased morphological and functional characteristics of neurodevelopment. The results from this study suggest that the mechanical properties of the polymer are optimal for the study of cultured cell lines, which could account for the increased viability, adherence, and morphological and functional characteristics of neurodevelopment. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2129-2138, 2017.

Berry Extract Treatment in the Human SH-SY5Y Neuroblastoma Cells

Plant phenolics have shown to activate apoptotic cell death in different tumourigenic cell lines. In this study, we evaluated the effects of juniper berry extract (Juniperus communis L.) on p53 protein, gene expression and DNA fragmentation in human neuroblastoma SH-SY5Y cells. In addition, we analyzed the phenolic composition of the extract. We found that juniper berry extract activated cellular relocalization of p53 and DNA fragmentation-dependent cell death. Differentially expressed genes between treated and non-treated cells were evaluated with the cDNA-RDA (representational difference analysis) method at the early time point of apoptotic process when p53 started to be activated and no caspase activity was detected. Twenty one overexpressed genes related to cellular stress, protein synthesis, cell survival and death were detected. Interestingly, they included endoplasmic reticulum (ER) stress inducer and sensor HSPA5 and other ER stress-related genes CALM2 and YKT6 indicating that ER stress response was involved in juniper berry extract mediated cell death. In composition analysis, we identified and quantified low concentrations of fifteen phenolic compounds. The main groups of them were flavones, flavonols, phenolic acids, flavanol and biflavonoid including glycosides of quercetin, apigenin, isoscutellarein and hypolaetin. It is suggested that juniper berry extract induced the p53-associated apoptosis through the potentiation and synergism by several phenolic compounds.

Rapamycin Loaded Solid Lipid Nanoparticles as a New Tool to Deliver mTOR Inhibitors: Formulation and in Vitro Characterization

Recently, the use of mammalian target of rapamycin (mTOR) inhibitors, in particular rapamycin (Rp), has been suggested to improve the treatment of neurodegenerative diseases. However, as Rp is a strong immunosuppressant, specific delivery to the brain has been postulated to avoid systemic exposure. In this work, we fabricated new Rp loaded solid lipid nanoparticles (Rp-SLN) stabilized with polysorbate 80 (PS80), comparing two different methods and lipids. The formulations were characterized by differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), wide angle X-ray scattering (WAXS), cryo-transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS) and particle tracking. In vitro release and short-term stability were assessed. Biological behavior of Rp-SLN was tested in SH-SY5Y neuroblastoma cells. The inhibition of mTOR complex 1 (mTORC1) was evaluated over time by a pulse-chase study compared to free Rp and Rp nanocrystals. Compritol Rp-SLN resulted more stable and possessing proper size and surface properties with respect to cetyl palmitate Rp-SLN. Rapamycin was entrapped in an amorphous form in the solid lipid matrix that showed partial crystallinity with stable Lβ, sub-Lα and Lβ′ arrangements. PS80 was stably anchored on particle surface. No drug release was observed over 24 h and Rp-SLN had a higher cell uptake and a more sustained effect over a week. The mTORC1 inhibition was higher with Rp-SLN. Overall, compritol Rp-SLN show suitable characteristics and stability to be considered for further investigation as Rp brain delivery system.

The large conductance Ca(2+) -activated K(+) (BKCa) channel regulates cell proliferation in SH-SY5Y neuroblastoma cells by activating the staurosporine-sensitive protein kinases

Here we investigated on the role of the calcium activated K(+)-channels(BKCa) on the regulation of the neuronal viability. Recordings of the K(+)-channel current were performed using patch-clamp technique in human neuroblastoma cells (SH-SY5Y) in parallel with measurements of the cell viability in the absence or presence of the BKCa channel blockers iberiotoxin(IbTX) and tetraethylammonium (TEA) and the BKCa channel opener NS1619. Protein kinase C/A (PKC, PKA) activities in the cell lysate were investigated in the presence/absence of drugs. The whole-cell K(+)-current showed a slope conductance calculated at negative membrane potentials of 126.3 pS and 1.717 nS(n = 46) following depolarization. The intercept of the I/V curve was -33 mV. IbTX(10(-8) - 4 × 10(-7) M) reduced the K(+)-current at +30 mV with an IC50 of 1.85 × 10(-7) M and an Imax of -46% (slope = 2.198) (n = 21). NS1619(10-100 × 10(-6) M) enhanced the K(+)-current of +141% (n = 6), at -10 mV(Vm). TEA(10(-5)-10(-3) M) reduced the K(+)-current with an IC50 of 3.54 × 10(-5) M and an Imax of -90% (slope = 0.95) (n = 5). A concentration-dependent increase of cell proliferation was observed with TEA showing a maximal proliferative effect(MPE) of +38% (10(-4) M). IbTX showed an MPE of +42% at 10(-8) M concentration, reducing it at higher concentrations. The MPE of the NS1619(100 × 10(-6) M) was +42%. The PKC inhibitor staurosporine (0.2-2 × 10(-6) M) antagonized the proliferative actions of IbTX and TEA. IbTX (10 × 10(-9) M), TEA (100 × 10(-6) M), and the NS1619 significantly enhanced the PKC and PKA activities in the cell lysate with respect to the controls. These results suggest that BKCa channel regulates proliferation of the SH-SY5Y cells through PKC and PKA protein kinases.

Synthesis and cholinesterase inhibition of cativic acid derivatives

Alzheimer's disease (AD) is a neurodegenerative disorder associated with memory impairment and cognitive deficit. Most of the drugs currently available for the treatment of AD are acetylcholinesterase (AChE) inhibitors. In a preliminary study, significant AChE inhibition was observed for the ethanolic extract of Grindelia ventanensis (IC₅₀=0.79 mg/mL). This result prompted us to isolate the active constituent, a normal labdane diterpenoid identified as 17-hydroxycativic acid (1), through a bioassay guided fractionation. Taking into account that 1 showed moderate inhibition of AChE (IC₅₀=21.1 μM), selectivity over butyrylcholinesterase (BChE) (IC₅₀=171.1 μM) and that it was easily obtained from the plant extract in a very good yield (0.15% w/w), we decided to prepare semisynthetic derivatives of this natural diterpenoid through simple structural modifications. A set of twenty new cativic acid derivatives (3-6) was prepared from 1 through transformations on the carboxylic group at C-15, introducing a C2-C6 linker and a tertiary amine group. They were tested for their inhibitory activity against AChE and BChE and some structure-activity relationships were outlined. The most active derivative was compound 3c, with an IC₅₀ value of 3.2 μM for AChE. Enzyme kinetic studies and docking modeling revealed that this inhibitor targeted both the catalytic active site and the peripheral anionic site of this enzyme. Furthermore, 3c showed significant inhibition of AChE activity in SH-SY5Y human neuroblastoma cells, and was non-cytotoxic.