Luciferin-luciferase Reaction Research Articles

Non-Invasive In Vivo Bioimaging in Pigs

Imaging technologies are used to observe the morphology and function of various organs in the body and have become indispensable in a multitude of fields, ranging from basic research to clinical medicine. The luminescence technology based on the luciferin–luciferase reaction has been used in many research fields as an imaging technique, enabling quantitative analysis and detection at high sensitivity. Specifically in gene therapy and cell therapy, it has been developed as an in vivo bioimaging technique mainly for small animal models because of its non-invasive and time-sequential analysis. Currently, translational research using this luminescence imaging technology in pigs for clinical applications is ongoing. In this review, we discuss the progress of these technologies and issues for their clinical application, focusing on pigs, by comparing conventional imaging techniques, including fluorescent probes, with luminescence imaging techniques.

Hyperglycemia adversely affects critical physiological events related to rat sperm capacitation

Hyperglycemia, the hallmark of diabetes mellitus (DM), is the main cause of DM-related systemic complications, including reproductive issues. Furthermore, the incidence of DM in males of reproductive ages is becoming an increasing concern, as the complexity of sperm capacitation (an essential process for fertilizing the egg) extends beyond conventional sperm parameters such as count, viability, and motility. Capacitation defects cause male infertility, and DM-related hyperglycemia may affect this process. We explore the effects of uncontrolled hyperglycemia on sperm using alloxan-induced hyperglycemic Wistar rats. In addition to assessing conventional sperm parameters, we also evaluated functional indicators, including hyperactivation (HA) with a pharmacological approach and assessed its effects with a computer-assisted sperm analysis (CASA); fluorescence indicators to monitor membrane potential (EmR, DiSC3(5)) and mitochondrial membrane potential (Ψ, JC-1); CatSper activity, using its ability to permeate Na+ ions, and ATP levels with the luciferin-luciferase reaction. We confirmed previous findings with our hyperglycemic model, which replicated the typical reduction on conventional sperm parameters. In sperm from hyperglycemic rats, we observed increased motility and HA levels after pharmacological treatment. Additionally, CatSper activity was unaffected by hyperglycemia, while EmR was hyperpolarized under non-capacitating condition. Finally, we noted a low percentage of hyperpolarized Ψ and reduced ATP content. This study highlights the significance of impact of hyperglycemia on sperm physiology and capacitation. We proposed that low ATP levels perturb energy state, signaling pathways, ion channels activity, motility, and HA. Our findings offer insight into DM-associated infertility and potential treatment strategies.

In Vivo Luciferin-Luciferase Reaction in Micro-Mini Pigs Using Xenogeneic Rat Bone Marrow Transplantation.

Luminescent technology based on the luciferin-luciferase reaction has been extensively employed across various disciplines as a quantitative imaging modality. Owing to its non-invasive imaging capacity, it has evolved as a valuable in vivo bioimaging tool, particularly in small animal models in fields such as gene and cell therapies. We have previously successfully generated rats with a systemic expression of the luciferase gene at the Rosa26 locus. In this study, we transplanted bone marrow from these rats into micro-mini pigs and used in vivo imaging to non-invasively analyze the dynamics of the transplanted cells. In addition, we established that the rat-to-pig transplantation system is a discordant system, similar to the pig-to-human transplantation system. Thus, rat-to-pig transplantation may provide a clinically appropriate large animal model for pig-to-human xenotransplantation.

A Comprehensive Exploration of Bioluminescence Systems, Mechanisms, and Advanced Assays for Versatile Applications.

Bioluminescence has been a fascinating natural phenomenon of light emission from living creatures. It happens when the enzyme luciferase facilitates the oxidation of luciferin, resulting in the creation of an excited-state species that emits light. Although there are many bioluminescent systems, few have been identified. D-luciferin-dependent systems, coelenterazine-dependent systems, Cypridina luciferin-based systems, tetrapyrrole-based luciferins, bacterial bioluminescent systems, and fungal bioluminescent systems are natural bioluminescent systems. Since different bioluminescence systems, such as various combinations of luciferin-luciferase pair reactions, have different light emission wavelengths, they benefit industrial applications such as drug discovery, protein-protein interactions, in vivo imaging in small animals, and controlling neurons. Due to the expression of luciferase and easy permeation of luciferin into most cells and tissues, bioluminescence assays are applied nowadays with modern technologies in most cell and tissue types. It is a versatile technique in a variety of biomedical research. Furthermore, there are some investigated blue-sky research projects, such as bioluminescent plants and lamps. This review article is mainly based on the theory of diverse bioluminescence systems and their past, present, and future applications.

Dynamic recycling of extracellular ATP in human epithelial intestinal cells.

Intestinal epithelial cells play important roles in the absorption of nutrients, secretion of electrolytes and food digestion. The function of these cells is strongly influenced by purinergic signalling activated by extracellular ATP (eATP) and other nucleotides. The activity of several ecto-enzymes determines the dynamic regulation of eATP. In pathological contexts, eATP may act as a danger signal controlling a variety of purinergic responses aimed at defending the organism from pathogens present in the intestinal lumen. In this study, we characterized the dynamics of eATP on polarized and non-polarized Caco-2 cells. eATP was quantified by luminometry using the luciferin-luciferase reaction. Results show that non-polarized Caco-2 cells triggered a strong but transient release of intracellular ATP after hypotonic stimuli, leading to low micromolar eATP accumulation. Subsequent eATP hydrolysis mainly determined eATP decay, though this effect could be counterbalanced by eATP synthesis by ecto-kinases kinetically characterized in this study. In polarized Caco-2 cells, eATP showed a faster turnover at the apical vs the basolateral side. To quantify the extent to which different processes contribute to eATP regulation, we created a data-driven mathematical model of the metabolism of extracellular nucleotides. Model simulations showed that eATP recycling by ecto-AK is more efficient a low micromolar eADP concentrations and is favored by the low eADPase activity of Caco-2 cells. Simulations also indicated that a transient eATP increase could be observed upon the addition of non-adenine nucleotides due the high ecto-NDPK activity in these cells. Model parameters showed that ecto-kinases are asymmetrically distributed upon polarization, with the apical side having activity levels generally greater in comparison with the basolateral side or the non-polarized cells. Finally, experiments using human intestinal epithelial cells confirmed the presence of functional ecto-kinases promoting eATP synthesis. The adaptive value of eATP regulation and purinergic signalling in the intestine is discussed.

Alteration of enzyme-substrate interactions by ultra-high dilutions of the substrate

The effects of different ultra-high dilutions of luciferin ranged from 1010 to 10102 on luciferin-luciferase reaction of fireflies were investigated. Luciferin substrate concentration varied from 0.0025 nM to 2.5 nM and ATP concentration remained unchanged. This study evaluated the bioluminescence intensity after addition of ultra-high dilutions of luciferin or ultra-high dilutions of water to the bioluminescent system and some multidirectional and significant differences were found. The number of ultra-high dilutions from studied starting materials, for which significant differences were found, increased sharply with decreasing substrate concentration to 0.0025 nM. No differences were found when the effects of ultra-high dilutions of a non-specific control imidazole and ultra-high dilutions of water on the signal intensity were compared. Our results suggest that ultra-high dilutions of luciferin can specifically inhibit the luciferin-luciferase reaction.

Coelenterazine-Type Bioluminescence-Induced Optical Probes for Sensing and Controlling Biological Processes.

Bioluminescence-based probes have long been used to quantify and visualize biological processes in vitro and in vivo. Over the past years, we have witnessed the trend of bioluminescence-driven optogenetic systems. Typically, bioluminescence emitted from coelenterazine-type luciferin-luciferase reactions activate light-sensitive proteins, which induce downstream events. The development of coelenterazine-type bioluminescence-induced photosensory domain-based probes has been applied in the imaging, sensing, and control of cellular activities, signaling pathways, and synthetic genetic circuits in vitro and in vivo. This strategy can not only shed light on the mechanisms of diseases, but also promote interrelated therapy development. Here, this review provides an overview of these optical probes for sensing and controlling biological processes, highlights their applications and optimizations, and discusses the possible future directions.

Quantitative Analysis of Bioluminescence Optical Signal.

Bioluminescence is light emission based on the luciferin-luciferase enzymatic reaction in living organisms. Optical signals from bioluminescence (BL) reactions are available for bioanalysis and bioreporters for gene expression, in vitro, in vivo, and ex vivo bioimaging, immunoassay, and other applications. Although there are numerous bioanalysis methods based on BL signal measurements, the BL signal is measured as a relative value, and not as an absolute value. Recently, some approaches have been established to completely quantify the BL signal, resulting in, for instance, the redetermination of the quantum yield of the BL reaction and counting the photon number of the BL signal at the single-cell level. Reliable and reproducible understanding of biological events in the bioanalysis and bioreporter fields can be achieved by means of standardized absolute optical signal measurements, which is described in an International Organization for Standardization (ISO) document.

Assessment of metabolic activity and energy supply of peripheral blood lymphocytes

BACKGROUND: T-cells have the capability to change their metabolism in response to activation signals. Resting T-cells primarily use the oxidation of higher fatty acids and oxidative phosphorylation in mitochondria for their energy needs, whereas activated T-cells switch to aerobic glycolysis and glutaminolysis, using glucose, and glutamine as substrates, respectively.
 AIM: To determine the metabolic activity and energy supply of peripheral blood lymphocytes in predominantly healthy northerners by measuring the intracellular content of HIF-1 (hypoxia-induced factor 1), SIRT3 (sirtuin 3), and ATP (adenosine triphosphate).
 MATERIALS AND METHODS: 39 volunteers, residents of the Arkhangelsk region (23 women and 16 men, 2362 years old), were selected, and examined for this experiment. We established the total number of peripheral blood lymphocytes with CD-typing of lymphocytes (CD3+, CD4+, CD8+, CD71+) by indirect immunoperoxidase reactions, the content of HIF-1 and SIRT3 in the lymphocyte lysate employing enzyme immunoassay, the concentration of ATP by luminescent analysis through luciferin-luciferase reaction. Statistical analysis was conducted in "Statistica 10.0", cluster analysis was applied using the k-means method. Mean values (M) and standard deviations (SD) were calculated, the normal distribution was tested by the KolmogorovSmirnov and Lilliefors criterion. Student's t-test was calculated, and the differences were considered statistically significant at p 0.05.
 RESULTS: The study revealed that the metabolic activity of lymphocytes associated with HIF-1 regulation differs significantly in the examined volunteers,, while in the group with a lower total number of lymphocytes and their subpopulations (CD3+, CD4+, CD8+, CD71+) there is a predominant glycolytic orientation of metabolism with proliferated cells energy supply.
 CONCLUSION: Metabolic activity which can be determined by the HIF-1/SIRT3 ratio, and the energy supply of lymphocytes have a substantial impact on their differentiation, proliferation, and functioning.

Bioluminescent Dinoflagellates as a Bioassay for Toxicity Assessment.

Dinoflagellates bioluminescence mechanism depends upon a luciferin-luciferase reaction that promotes blue light emission (480 nm) in specialized luminogenic organelles called scintillons. The scintillons contain luciferin, luciferase and, in some cases, a luciferin-binding protein (LBP), which prevents luciferin from non-enzymatic oxidation in vivo. Even though dinoflagellate bioluminescence has been studied since the 1950s, there is still a lack of mechanistic understanding on whether the light emission process involves a peroxidic intermediate or not. Still, bioassays employing luminous dinoflagellates, usually from Gonyaulax or Pyrocystis genus, can be used to assess the toxicity of metals or organic compounds. In these dinoflagellates, the response to toxicity is observed as a change in luminescence, which is linked to cellular respiration. As a result, these changes can be used to calculate a percentage of light inhibition that correlates directly with toxicity. This current approach, which lies in between fast bacterial assays and more complex toxicity tests involving vertebrates and invertebrates, can provide a valuable tool for detecting certain pollutants, e.g., metals, in marine sediment and seawater. Thus, the present review focuses on how the dinoflagellates bioluminescence can be applied to evaluate the risks caused by contaminants in the marine environment.

Multiplex quadruple bioluminescent assay system

Bioluminescence (BL) is unique cold body radiation of light, generated by luciferin–luciferase reactions and commonly used in various bioassays and molecular imaging. However, most of the peak emissions of BL populate the blue-yellow region and have broad spectral bandwidths and thus superimpose each other, causing optical cross-leakages in multiplex assays. This study synthesized a new series of coelenterazine (CTZ) analogues, named K-series, that selectively illuminates marine luciferases with unique, blue-shifted spectral properties. The optical property and specificity of the K-series CTZ analogues were characterized by marine luciferases, with K2 and K5 found to specifically luminesce with ALuc- and RLuc-series marine luciferases, respectively. The results confirmed that the luciferase specificity and color variation of the CTZ analogues minimize the cross-leakages of BL signals and enable high-throughput screening of specific ligands in the mixture. The specificity and color variation of the substrates were further tailored to marine luciferases (or single-chain bioluminescent probes) to create a multiplex quadruple assay system with four integrated, single-chain bioluminescent probes, with each probe designed to selectively luminesce only with its specific ligand (first authentication) and a specific CTZ analogue (second authentication). This unique multiplex quadruple bioluminescent assay system is an efficient optical platform for specific and high-throughput imaging of multiple optical markers in bioassays without optical cross-leakages.

Bioluminescent test systems based on firefly luciferase for studying stress effects on living cells.

The bioluminescent luciferin-luciferase reaction is based on the oxidation of D-luciferin by oxygen in the presence of ATP and magnesium ions, catalyzed by firefly luciferase. The possibilities of using this reaction to study the influence of external effectors of a physical and chemical nature (temperature exposure, additions of drugs, membrane-active compounds, etc.) on living cells (prokaryotes and eukaryotes) are considered. Examples of the use of test systems based on living cells producing thermostable firefly luciferase for monitoring cellular homeostasis are given. The study of the kinetics of changes in the concentration of ATP and luciferase inside and outside cells made it possible to determine in dynamics the metabolic activity, cytotoxicity, and survival of cells under conditions of cellular stress, to study the processes of ATP synthesis/hydrolysis, and to evaluate the effectiveness of lytic agents in changing the permeability of the cell membrane.

Gene Cloning and Functional Analysis of the Luciferase from Luminous Syllids of the Genus Odontosyllis.

The marine fireworm Odontosyllis spp. produce the bluish-green bioluminescence (BL). Despite years of research, molecular mechanisms of this unique luciferin-luciferase reaction have not been elucidated. Recently, the genes encoding luciferases of O. undecimdonta and O. enopla have been identified. Here, we describe gene cloning techniques for the luciferase of Odontosyllis spp. from a small number of specimens using highly sensitive mass spectrometry analysis in combination with RNA-sequencing. The luciferase activities of the cloned cDNAs are confirmed by BL assay in vitro using recombinant protein expressed in mammalian cells.

Enzymatic Bioluminescence Modulation with an ATP Synthase Integrated Biotransducer

AbstractIon carriers play an important role in biology in terms of control of a biological system, whereas electron carriers are key to engineered systems. Therefore, a biodevice requires an electron–ion coupling mechanism that can transmit an ion signal from a device to a biological system via an external voltage. In this study, a protonic biodevice is demonstrated that translates the proton signals from the device into an enzyme cascade by means of an ATP synthase and bioluminescent luciferase. The proton signals can be modulated through the applied potential to a sulfonated polyaniline biotransducer, with such protonic modulation controlling ATP synthesis at the ATP synthase membrane, followed by bioluminescence in the luciferin–luciferase reaction. The present electron–proton‐transportation platform provides a new means of controlling biological cascade reactions, with proton signals mediated by an external voltage.

Etmopterus lantern sharks use coelenterazine as the substrate for their luciferin-luciferase bioluminescence system

The lantern shark genus Etmopterus contains approximately 40 species of deep-sea bioluminescent cartilaginous fishes. They emit blue light mainly from the ventral body surface. The biological functions of this bioluminescence have been discussed based on the luminescence patterns, but the bioluminescence mechanism remains uncertain. In this study, we detected both coelenterazine and coelenterazine-dependent luciferase activity in the ventral photophore tissue of Etmopterus molleri. The results suggested that bioluminescence in lantern sharks is produced using coelenterazine as the substrate for the luciferin-luciferase reaction, as some luminous bony fishes.

Experimental Protocol for Detecting Mitochondrial Function in Hepatocytes Exposed to Organochlorine Pesticides

This paper presents detailed methods on detecting hepatic mitochondrial function for a better understanding the cause of metabolic disorders caused by environmental organochlorine pesticides (OCPs) in hepatocytes. HepG2 cells were exposed to β-hexachlorocyclohexane (β-HCH) for 24 h at an equivalent dose of internal exposure in general population. Ultrastructure in hepatocytes was examined by transmission electron microscopy (TEM) to show the damage of mitochondria. Mitochondrial function was further evaluated by mitochondrial fluorescence intensity, adenosine 5'-triphosphate (ATP) levels, oxygen consumption rate (OCR) and mitochondrial membrane potential (MMP) in HepG2 cells incubated with β-HCH. The mitochondria fluorescence intensity after stained by mitochondrial green fluorescent probe was observed with a fluorescence microscopy. The luciferin-luciferase reaction was used to determine ATP levels. The MMP was detected by the cationic dye JC-1 and analyzed under flow cytometry. OCR was measured with an extracellular flux analyzer. In summary, these protocols were used in detecting mitochondrial function in hepatocytes with to investigate mitochondria damages.

Experimental Protocol for Detecting Mitochondrial Function in Hepatocytes Exposed to Organochlorine Pesticides.

This paper presents detailed methods on detecting hepatic mitochondrial function for a better understanding the cause of metabolic disorders caused by environmental organochlorine pesticides (OCPs) in hepatocytes. HepG2 cells were exposed to β-hexachlorocyclohexane (β-HCH) for 24 h at an equivalent dose of internal exposure in general population. Ultrastructure in hepatocytes was examined by transmission electron microscopy (TEM) to show the damage of mitochondria. Mitochondrial function was further evaluated by mitochondrial fluorescence intensity, adenosine 5'-triphosphate (ATP) levels, oxygen consumption rate (OCR) and mitochondrial membrane potential (MMP) in HepG2 cells incubated with β-HCH. The mitochondria fluorescence intensity after stained by mitochondrial green fluorescent probe was observed with a fluorescence microscopy. The luciferin-luciferase reaction was used to determine ATP levels. The MMP was detected by the cationic dye JC-1 and analyzed under flow cytometry. OCR was measured with an extracellular flux analyzer. In summary, these protocols were used in detecting mitochondrial function in hepatocytes with to investigate mitochondria damages.

Advanced Bioluminescence System for In Vivo Imaging with Brighter and Red-Shifted Light Emission.

In vivo bioluminescence imaging (BLI), which is based on luminescence emitted by the luciferase–luciferin reaction, has enabled continuous monitoring of various biochemical processes in living animals. Bright luminescence with a high signal-to-background ratio, ideally red or near-infrared light as the emission maximum, is necessary for in vivo animal experiments. Various attempts have been undertaken to achieve this goal, including genetic engineering of luciferase, chemical modulation of luciferin, and utilization of bioluminescence resonance energy transfer (BRET). In this review, we overview a recent advance in the development of a bioluminescence system for in vivo BLI. We also specifically examine the improvement in bioluminescence intensity by mutagenic or chemical modulation on several beetle and marine luciferase bioluminescence systems. We further describe that intramolecular BRET enhances luminescence emission, with recent attempts for the development of red-shifted bioluminescence system, showing great potency in in vivo BLI. Perspectives for future improvement of bioluminescence systems are discussed.

P0968THE INFLUENCE OF ALPHA KLOTHO ON NPP1 ACTIVITY IN CULTURED RAT PODOCYTES

Abstract Background and Aims Kidney is the principal contributor to circulating αKlotho (αKL), and simultaneously, constitutes the major organ where circulating αKlotho is taken up from the circulation. Klotho is mainly expressed in proximal renal tubule and in distal tubular epithelium. In the kidney soluble αKlotho acts from the urinary luminal side as an autocrine or paracrine enzyme to regulate transporters and ion channels. Recently, it has been demonstrated that the glomerulus is another source of αKlotho production. NPP1 is the best characterized nucleotide pyrophosphatases/phosphodiesterases (NPP) family member, encoded by the ENPP1 gene, and is a type II transmembrane glycoprotein that forms disulfide-bonded homodimers in the plasma membrane and in the mineral-depositing matrix vesicles. The major function of NPP1 is generation of PPi from adenosine triphosphate (ATP). Recently, we demonstrated that extracellular nucleotides stimulate an increase in glomerular albumin permeability, in part due to glomerular NO production and actin reorganization in podocytes . Furthermore, both αKlotho and NPP1 regulate insulin-dependent signaling. Thus, a key aim of this study is to fully examine the role of αKlotho on NPP1 function and its role in the protection of glomerular filtration barrier and podocyte function in diabetes. Method We measured glomerular permeability to albumin (Palb) in a single isolated rat glomerulus based on the video-microscopy method and permeability to albumin across the podocyte monolayer. Expression of αKlotho and NPP1 was confirmed in podocytes using Western blotting and immunofluorescence. Ecto-nucleotide pyrophosphatase/phosphodiesterase activity in podocytes was assessed using p-nitrophenyl-5′-thymidine monophosphate (p-Nph-5′-TMP) as a substrate. The ATP concentration was measured using luciferin-luciferase reaction. Results Since NPP1 and Klotho regulate insulin-dependent signaling we investigated the role of Klotho on NPP1 dimerization and NPPs activity. Podocyte treatment withαKlotho (0.5 nM, 30 min) in non-reducing conditions (maleimide, 100 mM) increased the disulfide bond formation of NPP1 (Fig. 1A). The percentage of dimerized (260 kDa) NPP1 increased approximately by 45%. This effect was abolished in the presence of ATP (100 µM, 30 min). As a positive control, we used hydrogen peroxide (100 μM, 5 min) which induces oxidative disulfide bond formation (Fig. 1A). We also demonstrated time-dependent decrease of NPPs activity in the presence of αKL (Fig. 1B). Klotho also induces an increase of extracellular ATP concentration by 76% (from 3.19±0.01 to 5.62±0.43, n=6, P<0.05). Moreover, we confirmed the role of soluble αKlotho in ATP-evoked increases of glomerular and podocyte albumin permeability. Conclusion Summarizing, we have clearly demonstrated an interaction between αKL and NPP1 in podocytes. Moreover, we observed the protective role of αKlotho in podocyte permeability to albumin.

Recombinant expression of ecto-nucleotide pyrophosphatase/phosphodiesterase 4 (NPP4) and development of a luminescence-based assay to identify inhibitors.

Nucleotide pyrophosphatase/phosphodiesterase 4 (NPP4) is a membrane-bound enzyme that hydrolyzes extracellular diadenosine polyphosphates such as diadenosine triphosphate (Ap3A) and diadenosine tetraphosphate (Ap4A) yielding mononucleotides. NPP4 on the surface of endothelial cells was reported to promote platelet aggregation by hydrolyzing Ap3A to ADP, which activates pro-thrombotic G protein-coupled P2Y1 and P2Y12 receptors. Thus, NPP4 inhibitors have potential as novel antithrombotic drugs. In the present study we expressed soluble human NPP4 in Sf9 insect cells and established an enzyme assay using diadenosine tetraphosphate (Ap4A) as a substrate. The reaction product ATP was quantified by luciferin-luciferase reaction in a 96-well plate format. The sensitive method displayed a limit of detection (LOD) of 14.6nM, and a Z'-factor of 0.68 indicating its suitability for high-throughput screening. The new assay was applied for studying enzyme kinetics and led to the identification of the first NPP4 inhibitors.