Functional expression, targeting and Ca2+ signaling of a mouse melanopsin-eYFP fusion protein in a retinal pigment epithelium cell line

Melanopsin, first discovered in Xenopus melanophores, is now established as a functional sensory photopigment of the intrinsically photosensitive retinal ganglion cells. These ganglion cells drive circadian rhythm and pupillary adjustments through projection to the brain. Melanopsin shares structural similarities with all known opsins. Comprehensive characterization of melanopsin with respect to its spectral properties, photochemical cascade and signaling partners requires a suitable recombinant system and high expression levels. This combination has not yet been described. To address this issue, we have expressed recombinant mouse melanopsin in several cell lines. Using enhanced yellow fluorescent protein (eYFP) as a visualization tag, expression was observed in all cell lines. Confocal microscopy revealed that melanopsin was properly routed to the plasma membrane only in retinal pigment epithelium (RPE)-derived D407 cells and in human embryonic kidney (HEK) cells. Further, we performed intracellular calcium measurements in order to probe the melanopsin signaling activity of this fusion protein. Transfected cells were loaded with the calcium indicator Fura2-AM. Upon illumination, an immediate but transient calcium response was observed in HEK as well as in D407 cells, while mock-transfected cells showed no calcium response under identical conditions. Supplementation with 11-cis retinal or all-trans retinal enhanced the response. After prolonged illumination the cells became desensitized. Thus, RPE-derived cells expressing recombinant melanopsin may constitute a suitable system for the study of the structural and functional characteristics of melanopsin.     

Gq-coupled rhodopsin subfamily composed of invertebrate visual pigment and melanopsin

Rhodopsins (rhodopsins and their related photopigments) are phylogenetically classified into at least seven subfamilies, which are also roughly discriminated by molecular function. The Gq-coupled rhodopsin subfamily, members of which activate the Gq type G protein upon light absorption, contains pigments which underlie both visual and nonvisual physiologic functions. Gq-coupled visual pigments have been found in the rhabdomeric photoreceptor cells of varied protostomes, and those of molluskans and arthropods have been extensively investigated. Recently, a novel photopigment, melanopsin, and its homologs have been identified in varied vertebrates. In mammals, melanopsin is localized in retinal ganglion cells and is involved in nonvisual systems, including circadian entrainment and pupillary light responses. More recently, we discovered a melanopsin homolog in amphioxus, the closest living invertebrate to vertebrates. Amphioxus melanopsin is localized in putative nonvisual photoreceptor cells with rhabdomeric morphology and exhibits molecular properties almost identical to those of invertebrate Gq-coupled visual pigments. The localization and properties of amphioxus melanopsin bridged the functional and evolutionary gap between invertebrate Gq-coupled visual pigments and vertebrate circadian photopigment melanopsins. Research into the Gq-coupled rhodopsin subfamily, especially invertebrate melanopsins, will provide an opportunity to investigate the evolution of various physiologic functions, based on orthologous genes, during animal evolution.     

Light-Activated Carbon Monoxide Prodrugs Based on Bipyridyl Dicarbonyl Ruthenium(II) Complexes

Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide-functionalised bipyridine scaffold (4-position) equipped with an alkyne functionality or a green-fluorescent BODIPY (boron-dipyrromethene) dye have been prepared and used to investigate their light-induced decarbonylation. UV/Vis, FTIR and ¹³C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least-squares analysis (MCR-ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order to characterise the anti-proliferative and anti-apoptotic activities. The BODIPY-labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria.     

The absolute stereochemistry and cytotoxicity of the ascidian-derived metabolite, longithorone J

The absolute stereochemistry of longithorone J (1) from the ascidian Aplidium longithorax has been determined using the advanced Mosher method. Based on biosynthetic reasoning and chiroptical data comparison the absolute stereochemistry for longithorone K (2) was also assigned. Longithorone J was tested for cytotoxicity against the cell lines SHSY5Y, HEK293T and A549. Compound 1 showed minimal cytotoxicity towards the SHSY5Y and HEK293T cell lines.     

Characterization and cytotoxicity and antihuman renal cell carcinoma potentials of starch capped-copper oxide nanoparticles synthesized by ultrasonic irradiation: Introducing a novel chemotherapeutic drug

In this research article we have demonstrated the sustainable green synthesis of a novel starch templated CuO NP following a clean and non-hazardous pathway. Ultrasonic irradiation was used to promote the reaction in alkaline medium. The numerous hydroxyl groups present in starch was exploited in the green reduction of immobilized copper ions in situ. They also helped to stabilize the as synthesized Cu NPs by encapsulation or capping. The morphology and physicochemical characteristics were ascertained over an array of analytical techniques like Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Elemental Mapping, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Biologically, the nanocomposite exhibited excellent cytotoxicity against human renal cell carcinoma (RCC-GH, CaKi-2 and HEK293) cell lines without affecting the normal (HUVEC) cell line. IC₅₀ values of the nanocomposite were found at 139, 208and 125 against RCC-GH, CaKi-2 and HEK293 cell lines respectively and accordingly, HEK293 afforded the best adenocarcinoma activity.     

T4-Lysozyme Fusion for the Production of Human Formyl Peptide Receptors for Structural Determination

T4-lysozyme (T4L) fusion was introduced in the intracellular loop of a G protein-coupled receptor (GPCR) of human formyl peptide receptor 3 (FPR3), and the ability of T4L fusion to be used in the production of human FPR3 for structural determination was evaluated in this work. The T4L variant of human FPR3 termed FPR3-T4L was expressed in stable tetracycline-inducible HEK293 cells. A systematic detergent screening showed that fos-choline-14 was the optimal detergent to solubilize and subsequently purify FPR3-T4L from HEK293 cells. Immunoaffinity purification in combination with gel filtration was employed to purify the T4L-fused receptor to high homogeneity. The final yield of the human FPR3-T4L monomer from 2 g of cells was 0.2 mg. Circular dichroism spectroscopy indicated that the receptor adopted a correct secondary structure after purification, while ligand binding measurement indicated that the receptor was functional. Thus, the presence of T4L fusion did not evidently disturb the expression in HEK293 cells, proper folding, and functionality of human FPR3. Our study of evaluating T4L fusion for the recombinant production of human formyl peptide receptor would facilitate ongoing efforts in the structural characterization of GPCRs.     

The first oxalamide‐bridged ferrocene: Facile synthesis,preliminary conformational analysis and biological evaluation

tert ‐Butyl‐1′‐methoxycarbonyl‐1‐ferrocenecarbamate ( 1 ) was Boc‐deprotected to give free amine which underwent oxalyl chloride‐mediated dimerization. The structure of the so‐obtained oxalamide‐bridged ferrocene 2 was elucidated using infrared and NMR (¹H, ¹³C, COSY, NOESY, HSQC, HMBC) spectroscopies, crystal structure analysis, and electrospray ionization and high‐resolution mass spectrometry. The preliminary conformational analysis in solution suggested the intramolecular engagement of oxalamide protons, while single‐crystal analysis revealed an intermolecular hydrogen‐bonding pattern. Also, the effect of oxalamide‐bridged ferrocene 2 on cell viability of three human cell lines (HEK293T, HeLa and HepG2) was tested. In vitro screening revealed proliferative as well as cytotoxic effects of the tested compound in the applied concentration range (1–350 μM) on HEK293T and HepG2 cells. Stimulatory effect on cell growth was the most pronounced for normal HEK293T cells, while the highest cytotoxic effect was observed towards HeLa tumour cells and it was dose‐dependent. The observed dual biological activity of 2 implies its potential application in drug development.     

The Light‐Induced FOS Response in Melanopsin Expressing HEK‐293 Cells is Correlated with Melanopsin Quantity and Dependent on Light Duration and Irradiance

We established a cell line (HEK‐hMel) expressing melanopsin in a tetracycline dependent manner to elucidate new aspects of melanopsin's light response. Different light stimuli were evaluated using FOS expression as response parameter. Immunoblotting was used to evaluate expression of melanopsin and FOS and qPCR to quantify FOS mRNA responses. The magnitude of the FOS response was found to correlate with the amount of melanopsin expressed by the cells, and a transient FOS mRNA induction followed by FOS protein still elevated after 24 h of illumination was revealed. Exposing the cells to darkness after light resulted in reduction of the response compared to exposure to light solely showing dependency on continuous light. Increasing irradiances of blue light (480 nm) up to 10¹¹ quanta cm^?2 s^?1 elicited steep increases in FOS mRNA, while increases between 10¹² and 5 × 10¹³ quanta  cm^?2 s^?1 resulted in equally high FOS expression. The HEK‐hMel cells were used to characterize facets of melanopsin's light‐induced FOS response not approachable in vivo. Novel information such as dependency of the FOS response on both melanopsin amount and light intensity in addition to a detailed time‐course of both FOS mRNA and protein were revealed.     

Using unnatural protein fusions to engineer resveratrol biosynthesis in yeast and Mammalian cells

Resveratrol is a naturally occurring defense compound produced by a limited number of plants in response to stresses. Besides cardiovascular benefits, this health-promoting compound has been reported to extend life spans in yeasts, flies, worms, and fish. To biosynthesize resveratrol de novo, tyrosine ammonia lyase (TAL), 4-coumarate CoA-ligase (4CL), and stilbene synthase (STS) were isolated from Rhodobacter sphaeroides, Arabidopsis thaliana, and Vitis vinifera, respectively. Yeast cells expressing 4CL and STS produce resveratrol when fed with 4-coumaric acid, the substrate of 4CL. When a translational fusion protein joining 4CL and STS was used, yeast cells produced 15-fold more resveratrol than the cotransformed cells, suggesting that physical localization of 4CL and STS facilitate resveratrol production. When the resveratrol pathway was introduced into human HEK293 cells, de novo biosynthesis was detected, leading to intracellular accumulation of resveratrol. We successfully engineered an entire plant natural product pathway into a mammalian host.     

用高表达EGFR细胞膜色谱-HPLC/MS联用快速筛选独活中抗EGFR活性成分

报道了用高表达表皮生长因子受体细胞膜色谱与高效液相色谱/质谱在线联用方法(EGFR/CMC-online-HPLC/MS)快速筛选发现中药独活中的活性成分.实验中,采用高表达EGFR的细胞膜制备色谱固定相,建立EGFR/细胞膜色谱(EGFR/CMC)模型,利用柱切换和固相萃取技术,将EGFR/CMC模型与高效液相色谱/质谱(HPLC/MS)在线联用,构成一种新的可同时"识别-鉴定"目标成分的二维色谱系统,并应用于快速筛选独活中具有抗EGFR活性的目标成分.结果发现独活中的蛇床子素具有与对照药物达沙替尼类似的色谱保留特性,能够作用于EGFR;同时MTT及Elisa分析实验证实蛇床子素对HEK293EGFR细胞增殖及EGFR表达均有抑制作用.本文建立的EGFR/CMC-online-HPLC/MS二维色谱方法,可以选择性地从中药复杂体系中快速"识别-鉴定"目标组分,且筛选结果与特定生物效应显著相关.     

Towards an integrated device that utilizes adherent cells in a micro-free-flow electrophoresis chip to achieve separation and biosensing

We immobilized adherent human embryonic kidney (HEK) cells—which are able to trace adenosine triphosphate (ATP) —inside a microfluidic free-flow electrophoresis (μFFE) chip in order to develop an integrated device combining separation and biosensing capabilities. HEK 293 cells loaded with fluorescent calcium indicators were used as a model system to enable the spatially and temporally resolved detection of ATP. The local position of a 20 μM ATP stream was successfully visualized by these cells during free-flow electrophoresis, demonstrating the on-line detection capability of this technique towards native, unlabeled compounds.     

Characterization of intracellular calcium oscillations induced by extracellular nucleotides in HEp-2 cells

The effect of extracellular nucleotides on the cytosolic calcium concentration of fluo-3-loaded HEp-2 cells was examined using confocal microscopy. Extracellular ATP and UTP at micromolar concentration induced cytosolic calcium oscillations in 42-66% of the cells. Oscillations were usually sinusoid and their frequency depended only slightly on agonist concentration. Oscillations developed in calcium-free medium but were diminished by depletion of intracellular calcium stores with thapsigargin, indicating periodic calcium release from internal stores. Inhibition of phospholipase C with U73122 prevented the development of oscillations, while ryanodine did not abolish the response to extracellular nucleotides. Activation of protein kinase C with 4beta-phorbol 12-myristate 13-acetate also prevented the development of oscillations. These results indicate that extracellular nucleotides induce periodic calcium release from inositol 1,4,5-trisphosphate-sensitive pools in HEp-2 cells and that the inhibitory effect of protein kinase C on the phosphatidylinositol signaling pathway can contribute to the development of intracellular calcium oscillations.     

An Optochemical Oxygen Scavenger Enabling Spatiotemporal Control of Hypoxia

We present an optochemical O₂ scavenging system that enables precise spatiotemporal control of the level of hypoxia in living cells simply by adjusting the light intensity in the illuminated region. The system employs rhodamine containing a selenium or tellurium atom as an optochemical oxygen scavenger that rapidly consumes O₂ by photochemical reaction with glutathione as a coreductant upon visible light irradiation (560–590 nm) and has a rapid response time, within a few minutes. The glutathione-consuming quantum yields of the system were calculated as about 5 %. The spatiotemporal O₂ consuming in cultured cells was visualized with a hypoxia-responsive fluorescence probe, MAR. Phosphorescence lifetime imaging was applied to confirmed that different light intensities could generate different levels of hypoxia. To illustrate the potential utility of this system for hypoxia research, we show that it can spatiotemporally control calcium ion (Ca²⁺) influx into HEK293T cells expressing the hypoxia-responsive Ca²⁺ channel TRPA1.     

Comparison of alpha1-adrenergic receptor cell-membrane stationary phases prepared from expressed cell line and from rabbit hepatocytes

A G-protein-coupled receptor-cell-membrane stationary phase (CMSP) has been prepared by immobilizing cell membranes on the surface of silica, as carrier. The resulting HEK293 α _1A adrenoceptor cell-membrane stationary phase can be used for rapid on-line chromatographic determination of potential subtype-selective α ₁ -adrenoceptor ligand-binding affinities for α ₁ -adrenoceptor subtypes. The objective of the research was to study whether cell lines stably overexpressing subtype receptors could improve the sensitivity and specificity of cell-membrane chromatography (CMC) compared with use of homogenized tissue and cells in primary culture. Effects of mobile-phase ionic strength, sample concentration, and the presence of competitive agents on ligand-receptor interaction in CMSP were also evaluated. We found that cell lines stably overexpressing subtype receptors led to improved sensitivity and specificity in CMC. The technique leads to useful procedures-cell-membrane stationary phases may, for example, facilitate exploration of ligand-receptor interaction and determination of ligand-receptor binding affinity in initial screening and separation of lead compounds or active components in Chinese traditional natural medicine and herbs. This might eventually be an important contribution and an addition to our collection of techniques.     

GlcNAcstatin: a picomolar, selective O-GlcNAcase inhibitor that modulates intracellular O-glcNAcylation levels

Many phosphorylation signal transduction pathways in the eukaryotic cell are modulated by posttranslational modification of specific serines/threonines with N-acetylglucosamine (O-GlcNAc). Levels of O-GlcNAc on key proteins regulate biological processes as diverse as the cell cycle, insulin signaling, and protein degradation. The two enzymes involved in this dynamic and abundant modification are the O-GlcNAc transferase and O-GlcNAcase. Structural data have recently revealed that the O-GlcNAcase possesses an active site with significant structural similarity to that of the human lysosomal hexosaminidases HexA/HexB. PUGNAc, an O-GlcNAcase inhibitor widely used to raise levels of O-GlcNAc in human cell lines, also inhibits these hexosaminidases. Here, we have exploited recent structural information of an O-GlcNAcase-PUGNAc complex to design and synthesize a glucoimidazole-based inhibitor, GlcNAcstatin, which is a 5 pM competitive inhibitor of enzymes of the O-GlcNAcase family, shows 100000-fold selectivity over HexA/B, and binds to the O-GlcNAcase active site by mimicking the transition state as revealed by X-ray crystallography. This compound is able to raise O-GlcNAc levels in human HEK 293 and SH-SY5Y neuroblastoma cell lines and thus provides a novel, potent tool for the study of the role of O-GlcNAc in intracellular signal transduction pathways.     

Glycyrrhizin (Glycyrrhizic Acid) HMGB1 (high mobility group box 1) inhibitor upregulate mitochondrial function in adipocyte,cell viability and in-silico study

BackgroundMitochondrial plays a vital role in regulating obesity and related comorbidity. Targeting mitochondrial function could be a potent therapeutic approach to inhibit metabolic-related diseases like obesity, liver disease. Prolonged use of existing drug moieties demonstrated severe adverse effects.MethodsWe apply Ucp1-A-GFP immortalized reporter cell lines and HEK293T cell lines to evaluate cell viability, mitochondrial ATP production, and the in-silico model.ResultsWe found Glycyrrhizin, an HMGB1 (high mobility group box 1) inhibitor, plays a significant role in modulating mitochondrial function against obesity. At the cellular level, the adipocytes treated with Glycyrrhizin have increased mitochondrial function. Further analysis shows that compared with the control group, the cells in the treatment group contain more mitochondria. Glycyrrhizin demonstrated a nontoxic effect on the HEK293T cell line, upregulating mitochondrial DNA and reducing mitochondrial ATP production levels. In-silico study exhibited drug-protein interaction and binding side with UCP1.ConclusionGlycyrrhizin improves mitochondrial function that would be an effective drug candidate to treat metabolic diseases and obesity-related diseases. Further investigation will require both the human and animal models to reveal new insight into the mechanism against obesity, metabolic diseases or mitochondrial dysfunction-related diseases.     

Development and validation of a fluorescence-based HTS assay for the identification of P/Q-type calcium channel blockers

Dysfunction of P/Q-type calcium channels is thought to underlie a variety of neurological diseases. There is evidence that migraine, Alzheimer's disease, and epilepsy involve a gain-of-function of the channel, leading to abnormal presynaptic vesicle release. P/Q-channel blockers may normalize current flow and consequently lead to an alleviation of disease symptoms. Although the medical need is high, there are no such compounds on the market. Here we describe a high throughput screen (HTS) for P/Q-type calcium channel blockers and the confirmation of hits by automated electrophysiology. We generated a HEK293 cell line stably expressing the α1A subunit of the P/Q-type calcium channel under control of a tetracycline (Tet) promoter. The accessory β1.1 and α2δ1 subunits were co-expressed constitutively. The cell line was pharmacologically characterized by ion channel specific modulators, and revealed functional P/Q-type calcium currents. Using a fluorescence imaging plate reader (FLIPR), an assay for P/Q-type calcium channels was established based on a calcium sensitive dye. HTS of a 150,000 compound-containing sub-library led to the identification of 3262 hits that inhibited the fluorescence signal with potencies below 10 μM. Hit-to-lead (HTL) efforts identified 12,400 analogues. Compounds were clustered into 37 series, and 8 series of interest were prioritized. An electrophysiological secondary screen, providing a more direct measure of channel function, was implemented into the HTL process. 27 selected exemplars of different chemotypes were validated by automated whole-cell patch clamp analysis at inactivated channel state. The discovery of P/Q-channel blockers may foster the development of new therapeutics for a variety of neurological diseases.     

High transfection efficiency of cationic lipids with asymmetric acyl-cholesteryl hydrophobic tails

The ability of a nonviral gene delivery system to overcome extra- and intracellular barriers is a critical issue for the future clinical applications of gene therapy. In recent years much effort has been focused on the development of a variety of DNA carriers, and cationic liposomes have become the most common nonviral gene delivery system. One hundred and eighty novel cationic lipids with asymmetric acyl-cholesteryl hydrophobic tails were synthesized by parallel solid-phase chemistry. The liposomes were prepared and gel retardation assays were used to study the binding efficiency between the prepared liposome and the DNA. Transfection efficiencies of the lipids were evaluated against various mammalian cells, such as human embryonic kidney (HEK293), human cervical adenocarcinoma (HeLa), canine osteosarcoma (D17), colorectal adenocarcinoma (COLO 205), and human prostate adenocarcinoma (PC3) cells. The lipids with an acyl portion at the terminal part of the polyamine backbone exhibited higher transfection efficiency than those with the acyl portion as an internal part of the backbone. These compounds also showed higher transfection efficiency and lower cytotoxicity than the commercially available agents, Effectene, DOTAP, and DC-Chol.     

Effect of Cold Atmospheric Plasma Jet and Gamma Radiation Treatments on Gingivobuccal Squamous Cell Carcinoma and Breast Adenocarcinoma Cells

Surgery, chemotherapy and radiotherapy, the conventional treatment modalities of cancer though successful are limited by presence of residual tumor cells, toxic side-effects and treatment resistance, thus raising the need for investigating other novel approaches. Here, we have used a cold atmospheric plasma (CAP) jet and assessed the in vitro efficacy in gingivobuccal squamous cell carcinoma (GB-SCC) – ITOC-03, breast adenocarcinoma—MCF7 and HEK293 cells. Cells lines were subjected to varying doses of ionizing radiation (0, 2, 4, 6, 8 Gy) and CAP jet treatment (0, 60, 180, 240, 300 s). CAP jet treatment showed time dependent increase in H₂O₂ and NO₂^? concentration. Cell viability assay showed potent effect of CAP jet on all three cell lines in comparison to radiation treatment, while helium gas treatment showed minimal inhibitory effect. Irradiated, CAP jet and helium gas treated cells showed loss of nucleic acid features, 788 cm^?1 and 1340 cm^?1 in Raman spectra, indicating DNA damage. Principal Component Analysis (PCA) showed distinct classification of CAP-treated and control cells, while Principal Component – Linear Discriminant Analysis (PC-LDA) based classification of Raman spectra showed ITOC-03 and HEK293 cells to be sensitive to CAP jet and radiation treatment in comparison to MCF7 cells. Collectively, cell viability assay and Raman spectroscopy have shown potent effect of CAP jet in GB-SCC and breast adenocarcinoma cells.