Drug Repurposing Screens: Redeploying Old Dogs for New Tricks

This blog was written by guest author, Amy Landreman, PhD.

Drug repurposing, identifying new uses for approved or investigational drugs, is an attractive strategy when looking for new disease treatments. Because the compounds have already gone through some level of pre-clinical optimization and safety testing, this approach can reduce risk, reduce cost, and speed up the timeline for further drug development. An additional benefit of this approach is that it can result in new biological insights or a better understanding of disease mechanisms since these compounds usually already have some level of mechanistic characterization. Indeed, there are now a number of compound collections openly available specifically for the purpose of facilitating drug repurposing efforts. For example, the ReFRAME (Repurposing, Focused Rescue, and Accelerated Medchem) library is a collection of 12,000 compounds developed by Scripps Research Center and has been screened to identify novel candidate therapeutics for Cryptosporidium infection (1). The Broad Institute also offers a drug repurposing hub that contains an annotated collection of over 7,000 compounds.

Drug repurposing libraries, although often smaller than novel compound small molecule libraries, are designed for implementation into high-throughput screening workflows in order to efficiently triage compounds for the desired result. Effective compound screens require assays that can be scaled to 384 or 1536-well microplate formats and implemented in batch or continuous processing workflows. The firefly luciferase reaction has been leveraged to create many assays that are well-suited to these types of high-throughput screening approaches. In particular, the generation of “Glow” assays that have stable luminescent signals and homogenous assay design is a good fit. The signal stability allows for multi-plate processing and because the reagent is added directly to cells in culture, pre-processing steps are eliminated allowing for automated workflows. Assay reagents such as the CellTiter-Glo® Cell Viability Assay and the ADP-Glo™ Kinase Assay are commonly used in screening efforts including those done with repurposing libraries.  In addition, there are several firefly luciferase reporter assay reagents such as Steady-Glo® and Bright-Glo™ Luciferase Assays that have been optimized for high-throughput detection of firefly luciferase activity making them well-suited to repurposing screens.

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Awakening From Despair to Awe: 2021 International Forum on Consciousness

Banner for the International Forum on Consciousness 2021

Each year, the International Forum on Consciousness draws thought leaders from around the world to explore important, and often challenging, topics related to the exploration of consciousness. The theme for this year, Consciousness of Connection: Awakening from Despair to Awe, is an invitation to broaden curiosity about connection and take a closer look at the variety of connections that we forge in our lives.

Participants will examine the kinds of connections that transcend our individual selves and reach our inner desire to be part of an interconnected world, perhaps to transform our current sense of the individual, community, and society, from independent to interdependent. More specifically, the Forum will examine connection across the primary aspects of our lives with:

  • Self, and the many selves in our amazing neural networks
  • Others, and the multiple communities we intersect
  • Nature, and the breadth of life forms that surround us
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Herd Immunity: What the Flock Are You Talking About?

When it comes to blocking the spread of viral pathogens that cause human disease, epidemiologists—people who study disease outbreaks—like to talk about herd immunity. But what do they mean when discussing the herd and their immunity? Today, I will tackle this subject but with a side jaunt: I am going to co-opt the word “herd” and replace it with “flock” thus making chickens the center of attention rather than cattle for this analogy about immunity in a population. (Disclaimer: I am utterly biased toward chickens and enjoy talking about my flock of 24 hens and pullets).

Who is the Herd Flock They Keep Talking About?

By using a collective term for a number of individuals such as “herd” or “flock”, epidemiologists and public health experts are referring to a population or community. Doing some investigation, I learned herd immunity was a term first used in 1917 and referred to…cows. That makes sense, right? When we talk about groups of cattle, the term used is “herd”. Turns out there was an infection that caused spontaneous miscarriages in cattle and became epidemic in American herds. Farmers managed this threat by destroying or selling the infected cows. However, a livestock veterinarian had a different view, describing this pathogen as “…a fire, which, if new fuel is not constantly added, soon dies down. Herd immunity is developed, therefore, by retaining the immune cows, raising the calves, and avoiding the introduction of foreign cattle” (1). Essentially, this veterinarian was noting that keeping the infected cows who had immunity against the contagion meant the herd were less likely to be reinfected and, thus, put an end to the epidemic.

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NAD: A Renaissance Molecule and its Role in Cell Health

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.

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.

Today, however, NAD 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. Continue reading “NAD: A Renaissance Molecule and its Role in Cell Health”

Bartonella sp. and Your Cat (or Dog, Horse, Rat): An Emerging Infectious Disease

If we’ve learned nothing else since February or March of 2020, we’ve learned that emerging infectious diseases are a real threat to human health globally. In a bad news/good news kind of way, Bartonellosis is an emerging infectious disease; however, it’s not spread by airborne droplets or respiration.

But if any of your family pets bring a flea or tick into the house, or if you live in proximity to mice, rats, ground squirrels, rabbits, sheep, horses or cattle–you could be at risk.

Bartonella sp. is a Gram negative, rod-shaped bacteria that has been around since ancient times. It’s the bacteria responsible for cat scratch disease (1) and for Trench fever (2), which affected soldiers during WWs I and II, and affects people living in over-crowded, unsanitary conditions around the world today.

Bartonella henselae bacteria, the causative agent of cat-scratch disease or bartonellosis,. 3D illustration
Bartonella henselae bacteria, the causative agent of cat-scratch disease or bartonellosis

Bartonella sp. are known to be spread by vectors such as fleas, which are part of the transmission cycle for cat scratch disease and the human body louse, the vector for transmission of Trench fever (3).

This animal-to-human transmission of Bartonella sp. classifies it as a zoonosis.

Infection due to Bartonella sp. often appear to be self-limiting, such as swelling in regional lymph nodes due to a cat scratch disease. In such cases, symptoms can subside without intervention. But Bartonella sp. have a nasty habit of hiding in red blood cells and in cells lining blood vessels, where they can remain undetected for a substantial period of time. This hiding place affects a host’s ability to mount an immune response, as well as affecting the ability of antibiotics to attack the bacteria.

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Measuring Changing Metabolism in Cancer Cells

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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Directed Targeted Protein Degradation with Pre-Built HiBiT Cell Lines

Recently, selectively targeting proteins for degradation using the cell’s natural ubiquitin proteasome pathway (UPS) has surfaced as an effective strategy to bypass difficult-to-drug proteins related to diseases like cancer. Using sensitive bioluminescence technology, CRISPR-edited cell lines can facilitate studying popular protein degradation targets.

Woman at lab bench and artist 3D rendering of directed targeted protein degradation in a HiBiT cell line

NanoLuc® Luciferase (NLuc) has made biology more accessible than ever (1). Further experimentation with NLuc led to creation of a protein complementation system (2) and the discovery of the HiBiT bioluminescent peptide. HiBiT combines spontaneously with the engineered complementary subunit LgBiT to yield an active luciferase called NanoBiT® Luciferase.

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The Power of Vulnerability

Today’s blog is written by Malynn Utzinger, Director of Integrative Practices, and Tim Weitzel, ESI Architect.

If we want to reignite innovation and passion, we must rehumanize work.

-Silicon Valley CEO of Several Start-ups

If we want to rehumanize work, we need to be more human in the workplace.

-Promega’s ESI Bootcamp

Vulnerability is the birthplace of intimacy, trust connection, creativity, innovation. For leaders, it is the birthplace of trusted influence. But it is not permission to overshare.

-Brené Brown

Myths of Vulnerability

It’s important that we start off by making a few things about vulnerability crystal clear:  being vulnerable is not about over-sharing, being emotional—or worse, gushy. It is not about sacrificing necessary boundaries or letting go of all discernment when speaking. Vulnerability, as we intend it, is about being real with others. It is about being clear and honest enough within yourself that you can use courage and clarity to state a need or a perspective. Quite the opposite of requiring tears or grand displays of emotion, vulnerability can be expressed with utter command of one’s emotions, so that the clarity and authenticity of the message is what remains.

Vulnerability is also knowing that you cannot know everything or do your work perfectly or even to your full satisfaction sometimes, and it is having this same understanding and acceptance for others. It is being able to speak to that honestly so that we can build sustainable bridges between ourselves and others. We call this speaking our truths–with discernment.

Finally, vulnerability is knowing that while we must give our best efforts where and whenever we can, we must also know what we can’t control.  In most cases, what we cannot control is outcomes.  Therefore, vulnerability is embracing the uncertainty in how things will go in our relationships and in our work if we risk emotional exposure.  We cannot always know how others will hear what we share, but we can learn to take that risk and speak in service to a common goal.  For example, we might decide to share that the reason we are being so obsessive or insistent on a process is because of a past failure (perceived or real) that we still carry with us.  Even though we cannot control what others will think of our story, we trust that the sharing may help them share a need of their own or to hear our own need differently, so that we can all work together.  This is true in every relationship of our lives, where we learn to share something true for the sake of allowing another human being to know us as we are. 

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There’s a Vaccine for That—Could mRNA Vaccines be Used to Prevent Cancer Recurrence?

mRNA vaccines came roaring onto the public stage in 2020. In the United States and Europe, two of the vaccines that are being used against the SARS-CoV-2 virus are mRNA vaccines. The scientific community has been talking about the potential of this technology against infectious diseases as well as cancer for several years, but no one thought that the first mRNA vaccines would make such a huge, and public, debut.

One big benefit of mRNA vaccines is the speed at which they can be developed. mRNA vaccines use messenger RNA particles to teach our cells to make a bit of protein, which then triggers our body’s immune response, and it is relatively easy to synthesize large amounts of mRNA in a laboratory. As promising as this sounds for infectious diseases, the application of mRNA vaccines for oncology might be even more exciting.

Could mRNA vaccines be used for personalized cancer vaccines?
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Monochromator vs Filter-Based Plate Reader: Which is Better?

When it comes to purchasing a microplate reader for fluorescence detection, the most common question is whether to choose a monochromator-based reader or filter-based reader. In this blog, we’ll discuss how both types of plate readers work and factors to consider when determining the best plate reader for your need.

How do monochromator-based plate readers work?

Monochromators work by taking a light source and splitting the light to focus a particular wavelength on the sample. During excitation, the light passes through a narrow slit, directed by a series of mirrors and diffraction grating and then passes through a second narrow slit prior to reaching the sample. This ensures the desired wavelength is selected to excite the fluorophore. Once the fluorophore is excited, it emits light at a different, longer wavelength. This emission light is captured by another series of mirrors, grating and slits to limit the emission to a desired wavelength, which then enters a detector for signal readout.

Continue reading “Monochromator vs Filter-Based Plate Reader: Which is Better?”