Cell Biology

NAD: A Renaissance Molecule and its Role in Cell Health

Posted on by Kari Kenefick

NAD is a pyridine nucleotide. It provides the oxidation and reduction power for generation of ATP by mitochondria. For many years it was believed that the primary function of NAD/NADH in cells was to harness and transfer energy  from glucose, fatty and amino acids through pathways like glycolysis, beta-oxidation and the citric acid cycle.

Promega NAD/NADH-Glo system and how to prepare samples for identification of NAD or NADH.
Promega NAD/NADH-Glo system and how to prepare samples for identification of NAD or NADH.

However NAD also is recognized as an important cell signaling molecule and substrate. The many regulatory pathways now known to use NAD+ in signaling include multiple aspects of cellular homeostasis, energy metabolism, lifespan regulation, apoptosis, DNA repair and telomere maintenance.

This resurrection of NAD importance is due in no small part to the discovery of NAD-using enzymes, especially the sirtuins.

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Measuring Changing Metabolism in Cancer Cells

Posted on by Isobel Maciver

Because of the central role of energy metabolism in health and disease, and its effect on other cellular processes, assays to monitor changes in cellular metabolic state have wide application in both basic research and drug discovery. In the webinar “Tools for Cell Metabolism: Bioluminescent NAD(P)/NAD(P)H-Glo™ Assays” Jolanta Vidurigiene, a Senior Research Scientist at Promega, introduces three metabolism assays for measuring oxidized and reduced forms of NAD and NADP.

In this webinar, Jolanta provides background information on why it is important to be able to accurately measure metabolites such as NAD/NADH and NADP/NADPH. She outlines the roles of each, and highlights some of the challenges involved in developing assays that can accurately measure these metabolites. She discusses key considerations for successful NAD(P)/NAD(P)H assays and provides examples of how to use these assays to measure either total (both oxidized and reduced) forms of NAD and NADP, or to measure oxidized and reduced forms individually in a single assay plate.

NAD(P)H-Glo™ Assay Mechanism
NAD(P)H-Glo™ Assay Mechanism

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HPK1 Identified as Emerging Immuno-oncology Drug Target

Posted on by Michele Arduengo

Antibody-based immune checkpoint inhibitors remain a major focus of immuno-oncology drug research and development efforts because of their recent success in providing long-term anti-tumor responses. However, the range of response of different tumor types to these drugs is hugely varied. Small molecule kinase inhibitors that block signaling pathways involved in regulation of tumor immunity at multiple points in the “cancer immunity cycle” may provide alternate, effective therapeutics. One kinase that may be a target for such small molecule inhibitors is Hematopoietic Progenitor Kinase 1 or HPK1; the potential of this kinase as a therapeutic target was reviewed by Sawasdikosol and Burakoff (1). HPK1, also known as MAP4K1, is a member of the MAP kinase protein kinase family that negatively regulates signal transduction in T-cells, B-cells and dendritic cells of the immune system.

Artist rendering of what target engagement might look like for kinases like HPK1.
NanoBRET™ Target Engagement Assay (artist rendering)
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Ten Things to Know about Inducible T Cell Co-stimulators (ICOS)

Posted on by Kari Kenefick

The term ICOS —inducible T cell co-stimulators— has been prominent in my work as a science writer at Promega, recently. Here is a brief look at ICOS, how it works, and how it can be used in therapeutics research and development.

T cells do amazing things, like driving or blocking production of B cells and their related antibodies and antibody maturation, and they are the primary drivers of innate immunity. T cells have a variety of surface molecules, the primary and omnipresent T cell receptor (TCR), as well as CD3.

Schematic diagram of a T cell receptor TCR. The TCR interacts with ICOS in the immune response.

In the past 15 years or so, researchers have identified other, inducible receptors on T cells. These receptors appear when T cells are stimulated, enabling interactions with other cell types. The following information is summarized from a Frontiers in Immunology review by Wikenheiser et al.

What is ICOS (inducible T cell co-stimulators)?

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Bioluminescence and Biotechnology: Shining Nature’s Cool Light on Biology

Posted on by Amy Prevost

Imagine you’re taking a refreshing night swim in the warm blue waters of Vieques in Puerto Rico. You splash into the surf and head out to some of the deeper waters of the bay, when what to your wondering eyes should appear, but blue streaks of light in water that once was clear. Do you need to get your eyes checked? Are you hallucinating? No! You’ve just happened upon a cluster of dinoflagellates, harmless bioluminescent microorganisms called plankton, that emit their glow when disturbed by movement. These dinoflagellates are known to inhabit waters throughout the world but are generally not present in large enough numbers to be noticed. There are only five ecosystems in the world where these special bioluminescent bays can be seen, and three of them are in Puerto Rico. 

Bioluminescent plankton exhibit a blue glow when disturbed.
Bioluminescent plankton in the ocean

But you don’t have to travel to Puerto Rico or swim with plankton to see bioluminescence. There are bioluminescent organisms all over the world in many unexpected places. There are bioluminescent mushrooms, bioluminescent sea creatures—both large and small (squid, jellyfish, and shrimp, in addition to the dinoflagellates)—and bioluminescent insects, to name a few. Bioluminescence is simply the ability of living things to produce light.

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Just What Is an RLU (Relative Light Unit)?

Posted on by Promega

This post was contributed by guest blogger, Scott Messenger, Technical Support Scientist 2 at Promega Corporation.

It’s always an exciting time in the lab when you find a new assay to answer an important research question. Once you get your hands on the assay, it is always good to confirm it will work for your experimental setup. Repeating the control experiment shown in the technical manual is a great way to test the assay in your hands.

After running that first experiment of your assay, it looks pretty good. The trends of control and treatment are consistent. Time to get on with the experiments…but wait—the RLUs (Relative Light Units) are two orders of magnitude lower than the example data! I can’t show this data to my colleagues; it doesn’t match. What did I do wrong?

Relative Light Units, Measuring, Luminescence

This is a concern that we in Technical Services hear frequently. The concern is real, and I had this same thought when doing some of my first experiments using luminescence. When a question like this comes in, a Technical Service Scientist will make sure the experiment was performed as we described, and in most cases it is. We then start talking about RLUs (Relative Light Units).

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A Closer Look at C. difficile Biology with Luminescent Tagging

Posted on by Jordan Villanueva

Clostridium difficile is a bacterium that infects around half a million people per year in the United States. The infection causes symptoms ranging from diarrhea to severe colitis, and it’s one of the most common infections contracted while staying in the hospital. As the global incidence of C. diff infection has risen over the past decade, so has the pressure to develop novel therapeutic strategies. This requires a thorough exploration of all aspects of C. difficile biology.

Two recent papers published by researchers at the University of Leiden have shed light on C. difficile physiology using HiBiT protein tagging. The HiBiT system allows detection of proteins in live cells using an 11 amino acid tag. The HiBiT tag binds to the complementary LgBiT polypeptide to reconstitute the luminescent NanoBiT® enzyme. The resulting luminescence is proportional to the amount of HiBiT-tagged protein that is present.

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Maximize Your Time in the Lab: Improve Experimental Reproducibility with Thaw-and-Use Cells

Posted on by Michele Arduengo

Many cell biology researchers can name their department’s  or institutions’s “cell culture wizard”—the technician with 20+ years of experience whose cell cultures are always free from contamination, exhibit reliable doubling rates and show no phenotype or genotype weirdness. Cell culture takes skill and experience. Primary cell culture can be even more difficult still, and many research and pharmaceutical applications require primary cells.

Yet, among the many causes of failure to replicate study results, variability in cell culture stands out (1). Add to the normal challenges of cell culture a pandemic that shut down cell culture facilities and still limits when and how often researchers can monitor their cell culture lines, and the problem of cell culture variability is magnified further.

Treating Cells as Reagents

A good way to reduce variability in cell-based studies is to use the thaw-and-use frozen stock approach. This involves freezing a large batch of “stock” cells, then performing quality control tests to ensure they respond appropriately to treatment. Then whenever you need to perform an assay, just thaw another vial of cells from that batch and begin your assay—just like an assay reagent! This approach eliminates the need to grow your cells to a specific stage, which could take days and introduce more variability.

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How A Change in Immune Cell Metabolism Contributes to Severe COVID-19

Posted on by Johanna Lee
Illustration of energy metablism in cell.

There is still a lot we don’t know about COVID-19 and the virus, SARS-CoV-2, that caused the pandemic and changed the way we live. But there are two things we do know about the disease: 1) Patients with diabetes and high blood glucose levels are more likely to develop severe COVID-19 symptoms with higher mortality.  2) Patients that experience an uncontrolled inflammatory response, called the cytokine storm, also develop more severe COVID-19 symptoms. The fact that both high glucose levels and an exaggerated immune response drive severe disease suggests that the two may be linked. But how? The answer may lie in the metabolism of immune cells in the lungs of COVID-19 patients, according to a recent study published in Cell Metabolism.

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Antibodies, Immunity and Vaccines: A Short Primer on the Adaptive Immune Response

Posted on by Michele Arduengo
MERS-CoV credit: NIAID

Our skin, respiratory system and gastrointestinal tract are continually bombarded by environmental challenges from potential pathogens like SARS-CoV-2. Yet, these exposures do not often cause illness because our immune system protects us. The human immune system is complex. It has both rapid, non-specific responses to injury and disease as well as long-term, pathogen-specific responses. Understanding how the immune response works helps us understand how some pathogens get past it and how to stop that from happening. It also provides key information to help us develop safe and effective vaccines.

The immune response involves two complementary pathways: Innate Immunity and Adaptive Immunity. Innate immunity is non-specific, rapid and occurs quickly after an injury or infection. As a result of the innate immune response, cytokines (small signaling molecules) are secreted to recruit immune cells to an injury or infection site.  Innate immunity does not develop “memory” of an antigen or confer long-term immunity.

The immune response involves to complementary pathways: Innate Immunity and Adaptive Immunity.

Unlike innate immunity, adaptive immunity is both antigen-dependent and antigen-specific, meaning that adaptive immune response requires the presence of a triggering antigen—something like a spike protein on the surface of a virus. The adaptive immune response is also specific to the antigen that triggers the response. The adaptive immune response takes longer to develop, but it has the capacity for memory in the form of memory B and T cells. This memory is what enables a fast, specific immune response (immunity) upon subsequent exposure to the antigen.

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