1001 lights: luciferins, luciferases, their mechanisms of action and applications in chemical analysis, biology and medicine

A method for particulate matter 2.5 (PM2.5) biotoxicity assay using luminescent bacterium

The ability to analyze biotoxicity of atmospheric pollution plays an important role in public health. It provides the potential to directly analyze the health information of at-risk individuals. Although air quality standards have received significant attention in many countries, the potential for better biotoxicity assessment has remained largely unexplored. Here we propose a method using one kind of luminescent bacterium Photobacterium phosphereum to detect the biotoxicity of atmospheric particulate matter ≤ 2.5 µm (PM_2.5). Combined with the results of air pollution data of the year 2013-2014, this method has been proven to have good biotoxicity detection performance, and can evaluate the severity of at least 85% of PM_2.5 related biotoxicity in Shanghai during this time period. Based on an established algorithm of this detection system, the biotoxicity of twelve PM_2.5 real samples (collected over a month) were tested and divided into different biotoxicity levels. It allows an effective evaluation of biotoxicity of PM_2.5 due to the quick and sensitive response of bioluminescence to the concentration of toxic components, which provides a valuable reference to evaluate the biotoxicity of PM_2.5. This established method can be easily applied to the analysis and evaluation of any other PM_2.5 samples assay by following the steps.

Firefly-Inspired Approach to Develop New Chemiluminescence Materials

Bioluminescence, wherein marine and terrestrial organisms chemically produce light for communication, is a burgeoning area of research. Herein, we demonstrate a new series of artificial chemiluminescent compounds inspired by the enol-degradation reaction of natural bioluminescent molecules, luciferins. Based on systematic optical experiments, isotope labeling, and theoretical calculations, the chemiluminescent mechanism of these new materials and the relationship of enol-degradation reaction and chemiluminescence are fully discussed. The color and efficiency of the artificial chemiluminescent materials can be easily adjusted, and blue (486 nm), yellow (565 nm), and near-infrared (756 nm) luminescence can thus be obtained. The findings and in-depth understanding herein may accelerate the development of bio/chemiluminescent materials for analytical applications and non-invasive bioluminescence imaging.

Visualization of mercury(ii) accumulation in vivo using bioluminescence imaging with a highly selective probe

Mercury is a highly toxic environmental pollutant that negatively affects human health. Thus, an in vivo method for noninvasive imaging of mercury(ii) and visualization of its accumulation within living systems would be advantageous. Herein, we describe a reaction-based bioluminescent probe for detection of mercury(ii) in vitro and accumulation in vivo. The application of this probe would help to shed light on the intricate contributions of mercury(ii) to various physiological and pathological processes.

A brief review of bioluminescent systems (2019)

Despite being widely used in reporter technologies, bioluminescent systems are largely understudied. Of at least forty different bioluminescent systems thought to exist in nature, molecular components of only seven light-emitting reactions are known, and the full biochemical pathway leading to light emission is only understood for two of them. Here, we provide a succinct overview of currently known bioluminescent systems highlighting available tools for research and discussing future applications.

Shining Light on the Secreted Luciferases of Marine Copepods: Current Knowledge and Applications

Copepod luciferases-a family of small secretory proteins of 18.4-24.3 kDa, including a signal peptide-are responsible for bright secreted bioluminescence of some marine copepods. The copepod luciferases use coelenterazine as a substrate to produce blue light in a simple oxidation reaction without any additional cofactors. They do not share sequence or structural similarity with other identified bioluminescent proteins including coelenterazine-dependent Renilla and Oplophorus luciferases. The small size, strong luminescence activity and high stability, including thermostability, make secreted copepod luciferases very attractive candidates as reporter proteins which are particularly useful for nondisruptive reporter assays and for high-throughput format. The most known and extensively investigated representatives of this family are the first cloned GpLuc and MLuc luciferases from copepods Gaussia princeps and Metridia longa, respectively. Immediately after cloning, these homologous luciferases were successfully applied as bioluminescent reporters in vivo and in vitro, and since then, the scope of their applications continues to grow. This review is an attempt to systemize and critically evaluate the data scattered through numerous articles regarding the main structural features of copepod luciferases, their luminescent and physicochemical properties. We also review the main trends of their application as bioluminescent reporters in cell and molecular biology.

In-Taken Labeling and in Vivo Tracing Foodborne Probiotics via DNA-Encapsulated Persistent Luminescence Nanoprobe Assisted Autofluorescence-Free Bioimaging

An in vivo probing strategy that can real-time and in situ trace target probiotics inside the living body is herein proposed by employing plasmid-like DNA as in-taken assistance, persistent luminescence nanophosphors (PLNPs) as optical labeling, and background-free fluorescence bioimaging as signal readout. PLNPs with superlong afterglow and excellent biocompatibility and stability were surface-modified by DNA molecules with a specific sequence, which greatly promoted the nanoparticle penetration into the bacteria and facilitated the in vivo bioimaging with high sensitivity and signal-to-noise ratio. Compared with the previous surface-labeling strategy by antibody recognition, the in-taken optical labeling demonstrated improved stability, and reached ideal results of real-time and in situ monitoring the in vivo behaviors of target probiotics, supporting the further development of in vivo investigation methodology for foodborne probiotics. Moreover, such a strategy offers a promising platform that leverage nanoscience to food nutrition as well as food-safety research, aiming to collect more accurate and fresh information from the living body.

Gram-scale synthesis of luciferins derived from coelenterazine and original insights into their bioluminescence properties

An original three component synthetic access to coelenterazine and analogues can lead to grams of marine luciferins which are extensively used in bioluminescence-based assays.

Transcriptional Activity of FOXO Transcription Factors Measured by Luciferase Assays

The Forkhead box O (FOXO) family of transcription factors translates environmental cues into gene expression. FOXO factors are crucial for the maintenance of cell homeostasis, with important roles in cell fate decisions and differentiation. Identification of FOXO target genes requires strict validation by several methods. Luciferase-based reporters are a valuable starting point for determining the transcription-promoting capacity of potential FOXO-binding sites in candidate genes. Luciferase, an enzyme found in bioluminescent organisms catalyzes oxidation of luciferin to produce oxyluciferin together with light, which can be easily detected and measured with a luminometer. Due to their many advantages, transcriptional assays based on luciferase activity are widely used; they are easy, highly reproducible, and very sensitive. Continued improvements in luciferase-based vectors and measurement reagents confer considerable versatility. Luciferase-based reporters are also a reliable approach in the search for unknown components in the signaling pathways that control FOXO factor activity.We previously reported that FOXO transcription factors control expression of the enzyme diacylglycerol kinase α (DGKα) in T cells. DGKα consumes diacylglycerol, a lipid that activates several mitogenic pathways. Here, we describe the use of a luciferase-based promoter bearing the FOXO-binding sites of the DGKα gene to explore the relationship between the expression of this enzyme and stress conditions in NIH3T3 mouse fibroblasts. Our data support a role for FOXO factors in promoting high DGKα levels in conditions of growth factor deprivation. DGKα regulation by FOXO factors correlates with the reported alterations in DGKα expression during cell transformation and cancer progression.

Bioluminescent imaging: new opportunities

Modern biomedical research technologies actively use bioimaging for studying cells, tissues and whole organisms. Multicolor bioimaging is applied when simultaneous observation of different events at the molecular and cellular level is needed. Bioluminescent imaging methods are the most sensitive, however, their use for multicolor labeling is complicated due to the insufficient number of available uciferin-luciferase pairs. Having a number of advantages compared to previously studied bioluminescent systems, the new bioluminescence systems of higher fungi and marine polychaete Odontosyllis could become a useful expansion of the bioimaging toolbox.

Comparative study of the chemiluminescence of coelenterazine, coelenterazine-e and Cypridina luciferin with an experimental and theoretical approach

Imidazopyrazinone is a typical scaffold present in marine bioluminescence, in which thermal energy is converted into excitation energy in an enzyme-catalyzed reaction. In fact, the imidazopyrazinone scaffold is a common link among organisms of eight phyla. The characterization of the light emission mechanism is essential for the development of future applications in bioimaging, bioanalysis and biomedicine. Herein, we have studied the chemiluminescent reaction of three commercially-available imidazopyrazinones (Cypridina luciferin, Coelenterazine and Coelenterazine-e) in several aprotic solvents at different pH. We have found that at acidic pH only DMF and DMSO consistently present high light emission, while chemiluminescence in other solvents is negligible. We have attributed this to the inability of most solvents to allow for the deprotonation of the imidazopyrazinone core, thereby preventing the oxygenation step. We have also observed that increasing the pH of the solution leads to the inhibition of chemiluminescence, which we attributed to the deprotonation of the dioxetanone intermediate, as the neutral species is the one associated with efficient chemiexcitation. We have also observed that the pK_a of dioxetanone increases with the dielectric constant of the medium. Finally, our work indicated that the chemiexcitation yield increases with increasing polarity of the medium, due to a reduced transition dipole moment associated with S₀ → S₁ transition.

Inhibition and stimulation of the human breast cancer resistance protein as in vitro predictor of drug-drug interactions of drugs of abuse

Transporter-mediated drug-drug interactions (DDI) may induce adverse clinical events. As drugs of abuse (DOA) are marketed without preclinical safety studies, only very limited information about interplay with membrane transporters are available. Therefore, 13 DOA of various classes were tested for their in vitro affinity to the human breast cancer resistance protein (hBCRP), an important efflux transporter. As adenosine 5'-triphosphate (ATP) hydrolysis is crucial for hBCRP activity, adenosine 5'-diphosphate (ADP) formation was measured and used as in vitro marker for hBCRP ATPase activity. ADP quantification was performed by hydrophilic interaction liquid chromatography coupled to high-resolution tandem mass spectrometry and its amount in test compound incubations was compared to that in reference incubations using the hBCRP substrate sulfasalazine or the hBCRP inhibitor orthovanadate. If DOA caused stimulation or inhibition, further investigations such as Michaelis-Menten kinetic modeling or IC₅₀ value determination were conducted. Among the tested DOA, seven compounds showed statistically significant hBCRP ATPase stimulation. The entactogen 3,4-BDB and the plant alkaloid mitragynine were identified as strongest stimulators. Their affinity to the hBCRP ATPase was lower than that of sulfasalazine but comparable to that of rosuvastatin, another hBCRP model substrate. Five DOA showed statistically significant hBCRP ATPase inhibition. Determination of IC₅₀ values identified the synthetic cannabinoid receptor agonists JWH-200 and WIN 55,212-2 as the strongest inhibitors comparable to orthovanadate. The present study clearly demonstrated that tested DOA show in part high affinities to the hBCRP within the range of model substrates or inhibitors. Thus, there is a risk of hBCRP-mediated DDI, which needs to be considered in clinical settings.

Advances in bioluminescence imaging: new probes from old recipes

Bioluminescent probes are powerful tools for visualizing biology in live tissues and whole animals. Recent years have seen a surge in the number of new luciferases, luciferins, and related tools available for bioluminescence imaging. Many were crafted using classic methods of optical probe design and engineering. Here we highlight recent advances in bioluminescent tool discovery and development, along with applications of the probes in cells, tissues, and organisms. Collectively, these tools are improving in vivo imaging capabilities and bolstering new research directions.

Novel photoactivatable substrates for Renilla luciferase imaging in vitro and in vivo

To develop a photoactivatable bioluminescence imaging technique, a set of high and efficient photoactivatable substrates for Renilla luciferase has been well designed and synthesized. Surprisingly, all of them could release the free luciferin that presented robust bioluminescent signals ex vivo and in living animals after UV irradiation at 365 nm.

Theoretical Development of Near-Infrared Bioluminescent Systems

The luciferin/luciferase system of the firefly has been used in bioluminescent imaging to monitor biological processes. In order to enhance the efficiency and expand the application range, some efforts have been made to tune the light emission, especially the effort to obtain NIR light. However, those case-by-case studies have not together revealed the nature and mechanism of the color tuning. In this paper, we theoretically investigated the fluorescence of all kinds of typical oxyluciferin analogues. The present systematical modifications of both oxyluciferin and luciferase indicate that the essential factor affecting the emission color is the charge distribution (or the electric dipole moment) on the oxyluciferin, which impacts on the charge transfer to form the light emitter and, subsequently, influence the strength and wavelength of the emission light. More negative charge distributed on the "thiazolone moiety" of the oxyluciferin or its analogues leads to a redshift. Based on this conclusion, we theoretically designed optimal pairs of luciferin analogue and luciferase for emitting NIR light, which could inspire new synthetic procedures and practical applications.

QM/MM Study of the Formation of the Dioxetanone Ring in Fireflies through a Superoxide Ion

The bioluminescence emission from fireflies is an astounding tool to mark and view cells. However, the bioluminescent mechanism is not completely deciphered, limiting the comprehension of key processes. We use a theoretical approach to study for the first time the arrival of a dioxygen molecule inside the fireflies protein and one path of the formation of the dioxetanone ring, the high-energy intermediate precursor of the bioluminescence. To describe this reaction step, a joint approach combining classical molecular dynamics (MD) simulations and hybrid quantum mechanics/molecular mechanics (QM/MM) calculations is used. The formation of the dioxetanone ring has been studied for both singlet and triplet states with the help of MS-CASPT2 calculations. We also emphasize the role played by the proteinic environment in the formation of the dioxetanone ring. The results obtained shed some light on an important reaction step and give new insights concerning the bioluminescence in fireflies.

Optimized application of the secreted Nano-luciferase reporter system using an affinity purification strategy

Secreted Nano-luciferase (secNluc) is a newly engineered secreted luciferase that possesses advantages of high structural stability, long half-life, and glow-type kinetics together with high light emission intensity, and thus would become one of the most valuable tools for bioluminescence assays. However, like other secreted luciferases, secNluc has to mix with the components in the conditioned medium surrounding test cells, or in the biological samples such as blood or urine after being secreted. These components may interfere with secNluc-catalyzed bioluminescence reactions and thus limit the application of the secNluc reporter system. In this study, we first examined the effects of three factors, pH, serum and residual reagents, on secNluc-catalyzed bioluminescence reactions, finding that these factors could interfere with bioluminescence reactions and result in background signal. To resolve these problems, we applied a simple affinity purification strategy in which secNluc was fused with a FLAG-tag, and anti-FLAG magnetic beads were used to catch and transfer the fusion protein to PBST, an optimal buffer for secNluc-catalyzed bioluminescence reactions that was identified in this study. The results indicated that this strategy could not only negate the interferences from serum or residual reagents and enhance the stability of light emission but also greatly increase signal intensity through enzyme enrichment. This strategy may contribute to biomedical studies that utilize secNluc and other secreted luciferases, especially those requiring superior sensitivity, low background noise and high reproducibility.

Coelenterazine analogues emit red-shifted bioluminescence with NanoLuc

We report the synthesis and characterization of novel coelenterazine analogues that demonstrate a red-shift in their bioluminescent emission with NanoLuc luciferase. These coelenterazines can be tuned to shift the bioluminescent emission from blue light in the native system. In particular, direct attachment of an aryl moiety to the imidazopyrazinone core of furimazine at the C8 position provides a significant red-shift while maintaining reasonable light output. In addition, modification of the C6 aryl moiety provided additive red-shifts, and by combining the most promising modifications we report a coelenterazine with a maximum emission near 600 nm with NanoLuc. Finally, we show that this new bioluminescent system is capable of efficient BRET to far-red fluorophores. We anticipate these new principles of NanoLuc substrate design will impact applications that depend on shifting the colour of emission to the red, most notably in vivo bioluminescent imaging.

Synthesis of N-peptide-6-amino-D-luciferin Conjugates

A general strategy for the synthesis of N-peptide-6-amino-D-luciferin conjugates has been developed. The applicability of the strategy was demonstrated with the preparation of a known substrate, N-Z-Asp-Glu-Val-Asp-6-amino-D-luciferin (N-Z-DEVD-aLuc). N-Z-DEVD-aLuc was obtained via a hybrid liquid/solid phase synthesis method, in which the appropriately protected C-terminal amino acid was coupled to 6-amino-2-cyanobenzothiazole and the resulting conjugate was reacted with D-cysteine in order to get the protected amino acid-6-amino-D-luciferin conjugate, which was then attached to resin. The resulting loaded resin was used for the solid-phase synthesis of the desired N-peptide-6-amino-D-luciferin conjugate without difficulties, which was then attested with NMR spectroscopy and LC-MS, and successfully tested in a bioluminescent system.

Firefly Luciferase Mutant with Enhanced Activity and Thermostability

The luciferase isolated from the firefly Photinus pyralis (Ppy) catalyzes a two-step reaction that results in the oxidation of d-luciferin accompanied by emission of yellow-green light with a peak at 560 nm. Among many applications, Ppy luciferase has been used extensively as a reporter gene in living cells and organisms. However, some biological applications are limited by the low stability of the luciferase and limited intracellular luciferin concentration. To address these challenges, efforts to protein engineer Ppy luciferase have resulted in a number of mutants with improved properties such as thermostability, pH tolerance, and catalytic turn over. In this work, we combined amino acid mutations that were shown to enhance the enzyme's thermostability (Mutant E) with those reported to enhance catalytic activity (LGR). The resulting mutant (YY5) contained eight amino acid changes from the wild-type luciferase and exhibited both improved thermostability and brighter luminescence at low luciferin concentrations. Therefore, YY5 may be useful for reporter gene applications.

A bioluminescent system of fungi: prospects for application in medical research

Bioluminescence is chemical oxidation of a small luciferin molecule by air catalyzed by luciferase and accompanied by the emission of photons in the visible spectrum. This reaction is used in bioluminescent bioimaging, the method for the visualization of organism’s interior. Bioimaging is a popular tool used in medical research. However, it has an unfortunate drawback: it requires introduction of external luciferin to the system before every experiment. In this work we discuss a possibility of developing an autonomous luminescent system in eukaryotes based on the bioluminescent system of higher fungi.

Pyridone Luciferins and Mutant Luciferases for Bioluminescence Imaging

New applications for bioluminescence imaging require an expanded set of luciferase enzymes and luciferin substrates. Here, we report two novel luciferins for use in vitro and in cells. These molecules comprise regioisomeric pyridone cores that can be accessed from a common synthetic route. The analogues exhibited unique emission spectra with firefly luciferase, although photon intensities remained weak. Enhanced light outputs were achieved by using mutant luciferase enzymes. One of the luciferin-luciferase pairs produced light on par with native probes in live cells. The pyridone analogues and complementary luciferases add to a growing set of designer probes for bioluminescence imaging.

Chemi- and Bioluminescence of Cyclic Peroxides

Bioluminescence is a phenomenon that has fascinated mankind for centuries. Today the phenomenon and its sibling, chemiluminescence, have impacted society with a number of useful applications in fields like analytical chemistry and medicine, just to mention two. In this review, a molecular-orbital perspective is adopted to explain the chemistry behind chemiexcitation in both chemi- and bioluminescence. First, the uncatalyzed thermal dissociation of 1,2-dioxetane is presented and analyzed to explain, for example, the preference for triplet excited product states and increased yield with larger nonreactive substituents. The catalyzed fragmentation reaction and related details are then exemplified with substituted 1,2-dioxetanone species. In particular, the preference for singlet excited product states in that case is explained. The review also examines the diversity of specific solutions both in Nature and in artificial systems and the difficulties in identifying the emitting species and unraveling the color modulation process. The related subject of excited-state chemistry without light absorption is finally discussed. The content of this review should be an inspiration to human design of new molecular systems expressing unique light-emitting properties. An appendix describing the state-of-the-art experimental and theoretical methods used to study the phenomena serves as a complement.

Methods and approaches to disease mechanisms using systems kinomics

All cellular functions, ranging from regular cell maintenance and homeostasis, specialized functions specific to cellular types, or generating responses due to external stimulus, are mediated by proteins within the cell. Regulation of these proteins allows the cell to alter its behavior under different circumstances. A major mechanism of protein regulation is utilizing protein kinases and phosphatases; enzymes that catalyze the transfer of phosphates between substrates [1]. Proteins involved in phosphate signaling are well studied and include kinases and phosphatases that catalyze opposing reactions regulating both structure and function of the cell. Kinomics is the study of kinases, phosphatases and their targets, and has been used to study the functional changes in numerous diseases and infectious diseases with aims to delineate the cellular functions affected. Identifying the phosphate signaling pathways changed by certain diseases or infections can lead to novel therapeutic targets. However, a daunting 518 putative protein kinase genes have been identified [2], indicating that this protein family is very large and complex. Identifying which enzymes are specific to a particular disease can be a laborious task. In this review, we will provide information on large-scale systems biology methodologies that allow global screening of the kinome to more efficiently identify which kinase pathways are pertinent for further study.

New Zealand glowworm (Arachnocampa luminosa) bioluminescence is produced by a firefly-like luciferase but an entirely new luciferin

The New Zealand glowworm, Arachnocampa luminosa, is well-known for displays of blue-green bioluminescence, but details of its bioluminescent chemistry have been elusive. The glowworm is evolutionarily distant from other bioluminescent creatures studied in detail, including the firefly. We have isolated and characterised the molecular components of the glowworm luciferase-luciferin system using chromatography, mass spectrometry and 1H NMR spectroscopy. The purified luciferase enzyme is in the same protein family as firefly luciferase (31% sequence identity). However, the luciferin substrate of this enzyme is produced from xanthurenic acid and tyrosine, and is entirely different to that of the firefly and known luciferins of other glowing creatures. A candidate luciferin structure is proposed, which needs to be confirmed by chemical synthesis and bioluminescence assays. These findings show that luciferases can evolve independently from the same family of enzymes to produce light using structurally different luciferins.

Novel caged luciferin derivatives can prolong bioluminescence imaging in vitro and in vivo

Based on N-cyclobutylaminoluciferin (cybLuc), a set of high and efficient caged bioluminescent derivatives (Clucs) as firefly luciferase pro-substrates has been developed herein. After careful examination, these molecules exhibited low cytotoxicity and prolonged bioluminescence imaging up to 6 h in vitro and in vivo. Importantly, these caged luciferin derivatives have the potential to serve as long-term tracking tools to explore some biological process by using bioluminescent imaging.

A set of high and efficient caged luciferin derivatives exhibited low cytotoxicity and prolonged bioluminescence in vitro and in vivo.

Secreted dual reporter assay with Gaussia luciferase and the red fluorescent protein mCherry

The availability of a wide range of reporter proteins, which can easily be quantitated, has had a major impact on many fields of biomedical research. In some experiments with tissue culture cells, it is necessary to control for differences in transfection efficiency and in other expression parameters. This requirement has been very conveniently met with the popular dual luciferase assay. Its disadvantages are the requirement for cell lysis, the inability to analyze the same cells repeatedly, and the cost, at least in its most commonly used commercial format. Here we describe a novel dual reporter assay with the naturally secreted luciferase from Gaussia princeps as the main reporter protein and a secreted version of the red fluorescent protein mCherry as internal standard. After first measuring mCherry fluorescence in the medium, an enzyme buffer with coelenterazine as substrate is added to the same sample to trigger a glow-type luminescence of the luciferase. The simple and cheap assay can easily be adapted to a variety of experimental situations. As a case in point, we have developed a panel of Gaussia luciferase reporter genes for transcriptional activation assays with estrogen and glucocorticoid response elements, and with response elements for fusion proteins with the Gal4 DNA binding domain for use in mammalian cells. Our secreted dual reporter assay should be an attractive alternative to the currently available commercial kits.

An easy and fast adenosine 5'-diphosphate quantification procedure based on hydrophilic interaction liquid chromatography-high resolution tandem mass spectrometry for determination of the in vitro adenosine 5'-triphosphatase activity of the human breast cancer resistance protein ABCG2

Interactions with the human breast cancer resistance protein (hBCRP) significantly influence the pharmacokinetic properties of a drug and can even lead to drug-drug interactions. As efflux pump from the ABC superfamily, hBCRP utilized energy gained by adenosine 5'-triphosphate (ATP) hydrolysis for the transmembrane movement of its substrates, while adenosine 5'-diphosphate (ADP) and inorganic phosphate were released. The ADP liberation can be used to detect interactions with the hBCRP ATPase. An ADP quantification method based on hydrophilic interaction liquid chromatography (HILIC) coupled to high resolution tandem mass spectrometry (HR-MS/MS) was developed and successfully validated in accordance to the criteria of the guideline on bioanalytical method validation by the European Medicines Agency. ATP and adenosine 5'-monophosphate were qualitatively included to prevent interferences. Furthermore, a setup consisting of six sample sets was evolved that allowed detection of hBCRP substrate or inhibitor properties of the test compound. The hBCRP substrate sulfasalazine and the hBCRP inhibitor orthovanadate were used as controls. To prove the applicability of the procedure, the effect of amprenavir, indinavir, nelfinavir, ritonavir, and saquinavir on the hBCRP ATPase activity was tested. Nelfinavir, ritonavir, and saquinavir were identified as hBCRP ATPase inhibitors and none of the five HIV protease inhibitors turned out to be an hBCRP substrate. These findings were in line with a pervious publication.

High-Throughput Screening for Identification of Novel Innate Immune Activators

Modern drug discovery has embraced in vitro platforms that enable investigation of large numbers of compounds within tractable timeframes and for feasible costs. These endeavors have been greatly aided in recent years by advances in molecular and cell-based methods such as gene delivery and editing technology, advanced imaging, robotics, and quantitative analysis. As such, the examination of phenotypic impacts of novel molecules may only be limited by the size of the compound collection. Innate immune signaling processes in mammalian cells are especially amenable to high-throughput screening platforms since the cellular responses elicited by their activation often result in high level transcription that can be harnessed in the form of bioluminescent or fluorescent signal. In addition, targeted activation of innate immune pathways represents a valuable therapeutic strategy applicable to multiple chronic and acute human diseases. Herein, we describe the optimization and utilization of a high-throughput screening method using human reporter cells reactive to stimulation of the type I interferon response. Importantly, the principles and methods described can be applied to adherent reporter cells of diverse derivation and innate signaling pathway readouts.