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Illuminating Cell Signaling Pathways: The Power of Luciferase-Based Reporter Assays

Scientist on July 18, 2023

Tech Snapshot® captures today’s cutting-edge tools and technologies that will help drive tomorrow’s drug discoveries. This installment was written by BPS Bioscience, a biotechnology development and manufacturing company focused on innovating proteins, antibodies, cell lines, lentiviruses and assay kits for biopharmaceutical and academic research.

BPS Bioscience strives to advance new scientific discoveries that lead to therapies by creating innovative start-to-finish solutions for research. We drive advancements in immunotherapy, epigenetics, coronavirus, cell signaling and other research areas, providing 4500+ high quality recombinant cell lines, virus-based tools, proteins and biochemical and cell-based assay kits focused on drug discovery. One of our core expertise areas is the engineering of cell lines for drug discovery, providing cell systems that enable high throughput compound screening using cellular readouts.

Cell-based assays are an essential part of drug development as they allow researchers to evaluate the biological activity of potential drug candidates on living cells and gain a better understanding of their mechanism of action. They are necessary to evaluate membrane permeability issues and interferences within a complex system, which are not seen in biochemical assays. Overall, they provide a more accurate representation of the complex interactions between compounds and living cells, as compared to biochemical assays.

Genetically engineered cells serve as model systems in a variety of research applications, including overexpression of a target protein or knockout cell lines that can be used to validate candidate therapeutic targets, evaluate new compounds and therapeutic approaches and more. To identify and characterize effectors of cell signaling pathways in the context of intact functioning cells, inducible reporter assays are an ideal option. Luciferase reporters downstream of a pathway-specific promoter response element allow simple, robust and quantitative measurement of signaling activity. They are perfect for co-culture assays because the presence of effector cells will not interfere with the measurements.

Conditional reporter systems can be applied across a wide variety of cell types and signaling pathways and allow for high throughput screening of large libraries of compounds for inhibitory or activating function, support research that span immunotherapy, CAR and TCR functional evaluation, ADCC assays, cell signaling studies, co-culture experiments, RNA editing and much more.

Applications:

  • Measure activation or inhibition of a cell signaling pathway converging on a specific transcription factor:
    • Identify new agonists or antagonists of a signaling pathway.
    • Screen compound libraries for molecules that selectively alter a target of interest or disease pathway.
    • Decipher the mechanism of action for a candidate compound.
    • Study the parameters affecting a pathway of interest (analysis of function).
  • Perform co-culture cytotoxicity assays such as used in immunotherapy development to test the efficacy of a new effector immune cell.

BPS Bioscience has developed a collection of pathway-specific cell lines, including IL-2, IL-15 and IL-6-responsive reporter cells; GLP-1-responsive cells to assist the development of diabetes/obesity drugs; TL1A-responsive Jurkat cells overexpressing TL1-A receptor DDR; primary CAR-T cells designed to support research on BCMA, CD20 or CD19; and a new line of antigen-specific TCR cells to monitor responses to antigen presentation.

TL1A-Responsive Luciferase Reporter Jurkat Cell Line

TNF-like ligand 1A (TL1A, also known as Vascular endothelial growth inhibitor) is an anti-angiogenic cytokine mediator of inflammation, which participates in innate and adaptive immune homeostasis through binding to its receptor DR3 and activating downstream signaling. Recent clinical studies have shown the promise of anti-TL1A antibody treatment to treat inflammatory disorders.

TL1A-responsive DR3/NF-kB luciferase reporter Jurkat cells express firefly luciferase under the control of NF-kB response elements, as well as human DR3 (death receptor 3; or TNFRSF25). Activation of the NF-kB signaling pathway by TL1A can be monitored by measuring luciferase activity.

Figure 1: Schematic representation of the TL1A response in TLA-1 Responsive Luciferase Reporter Jurkat Cell Line (BPS Bioscience #78811). Top right: Cells were treated with increasing concentrations of TL1A for 5 hours prior to performing a ONE-Step™ Luciferase assay (BPS Bioscience 60690). Jurkat cells that do not express DR3 (NF-kB Luciferase Reporter Jurkat cell line, BPS Bioscience #60651) do not show stimulation by TL1A. Bottom right: neutralizing anti-TL1A antibody (BPS Bioscience #101729) was preincubated with 1 µg/ml human TL1A for 1 hour before being added to the cells for 5 hours. Luciferase activity was assessed using ONE-Step™ Luciferase Detection Reagent.

MART-1-Specific TCR (DMF4) CD8+ NFAT-Luciferase Reporter Jurkat Cell Line

MART-1 (Melanoma-associated antigen recognized by T cells-1, also known as Melan-A) is a differentiation antigen expressed on the surface of melanocytes. A peptide fragment of the protein is found in MHC complexes that are recognized by CD8+ cytotoxic T cells. MART-1 is present in most skin cancers, including melanomas, and is used as a biomarker for diagnostic purposes. Since the expression of the protein is restricted to melanocyte containing tissues (skin and retina), MART-1 is an attractive target for cancer vaccines and adoptive cell therapy. The MART-1 peptide 26-35 is a fragment commonly associated with MHC and recognized by T cell receptors.

This cell line expresses firefly luciferase under the control of NF-kB response elements. Knockout of the TCR (T Cell Receptor) was performed using CRISPR/Cas9 genome editing. Thus, the TRAC (T-Cell Receptor Alpha Constant) and TRBC1 (T-Cell Receptor Beta Constant 1) domains of the TCRα/β chains were genetically removed and the cells do not respond to CD3 agonists. Cells were further modified to overexpress human CD8 and MART-1-specific TCR (clone DMF4). The human TCR clone DMF4 specifically recognizes tumor antigen MART-1.

The cells are stimulated by the presence of a MART-1 peptide on MHC-I presented by cancer cells or by antigen-presenting cells. They are useful to design and optimize co-culture bioassays used in TCR-cell development projects and can be used as a positive control in experiments evaluating MART-1-specific TCR expressing cells.

Figure 2; top: Illustration of the functional co-culture assay using the MART-1 TCR (DMF4) CD8+ NFATα Luciferase Reporter Jurkat cell line (BPS Bioscience #78772). Bottom left: MART-1 TCR (DMF4) CD8+ NFAT Luciferase Reporter Jurkat cells were stained with APC-conjugated MHC-I Dextramer and analyzed by flow cytometry (blue). Parental CD8+ TCR knockout NFAT Luciferase Reporter Jurkat cells were used as negative control (red). Bottom right: MART-1 TCR (DMF4) CD8+ NFAT Luciferase Reporter Jurkat cells were co-cultured for 6 hours with T2 cells loaded with various concentration of MART-1 peptides (BPS Bioscience #78759, #78760 and #78761) prior to performing a ONE-Step™ Luciferase Assay. MART-1 peptide variants have different affinities for MART-1, with MART-1 (26-35, Leu 27) showing the highest affinity and MART-1 (27-35) peptide the lowest.

Luciferase reporter cells offer elegant solutions for the rapid, quantitative bioluminescent detection of virtually any cellular response of interest, allowing the screening and characterization of compounds regulating signaling pathways, the study of biological functions or the identification of key players within a pathway. Our portfolio spans various research areas including cancer, neurological disease, diabetes and metabolic disorders, as well as cardiovascular disease. In addition, reporter cells are available to support the development of adoptive cell therapies and for the optimization of antibody-based biologics. A suite of support products, including optimized cell culture media and the ultra- simple ONE-Step™ Luciferase Assay System, was designed to streamline your projects.

Learn more about BPS Bioscience cell line purchasing options and licensing terms on our Cell Lines page.