Cell-Based Target Engagement and Functional Assays for NLRP3 Inhibitor Profiling Help Identify Successes and Failures

Identifying Inflammasome Inhibitors: What’s Missing
The NLRP3 inflammasome is implicated in a wide range of diseases. The ability to inhibit this protein complex could provide more precise, targeted relief to inflammatory disease sufferers than current broad-spectrum anti-inflammatory compounds, potentially without side effects.

Studies of NLRP3 inflammasome inhibitors have relied on cell-free assays using purified NLRP3. But cell-free assays cannot assess physical engagement of the inhibitor and target in the cellular micro-environment. Cell-free assays cannot show if an NLRP3 inhibitor enters the cell, binds the target and how long the inhibitor binding lasts.

Cell-based assays that interrogate the physical interaction of the NLRP3 target and inhibitor inside cells are needed.

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Cellular Senescence and Cancer Therapy: Overcoming Immortality?

At the time of writing this post, no scientist had yet discovered the secret to immortality. In our world, we’ve come to accept that living things are born, grow old and die—the circle of life.

And yet, for many years, life scientists believed that the circle of life did not apply to our constituent cells when cultured in a laboratory. That is, cultured normal human cells were immortal, and they would continue to grow and proliferate forever, as long as they were provided with the necessary nutrients.

The animal cell cycle. Image by Kelvinsong; made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication

Pioneering work published in 1961 by Leonard Hayflick and Paul Moorhead challenged that theory (reviewed in 1). Their research showed that normal cells in culture have a finite capacity to replicate. After they reach a certain number of replicative cycles, cells stop dividing. Hayflick and Moorhead made the important distinction between normal human cells and cultured cancer cells, which are truly immortal. In later years, the limit to the number of replicative cycles normal human cells can undergo became known as the Hayflick limit. Although some scientists still express skepticism about these findings, the Hayflick limit is widely recognized as a fundamental principle of cell biology.

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Infographic: Assays for Measuring Insulin Activity

We rely on insulin supplied by our pancreas at the right dose and at the right time to control our blood glucose levels and energy storage. Insulin works by regulating the energy usage of various cell types in the body. When this process goes awry, it can cause diabetes.

There are two types of diabetes, defined by how insulin is dysregulated. In Type 1 Diabetes (T1D), the pancreas produces too little insulin. Patients need to give themselves insulin in order to respond to glucose in the diet. In Type 2 Diabetes (T2D), patients do not respond well to the insulin produced in their body. Therefore, they need to give themselves more to avoid hyperglycemia (high blood glucose).

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Deubiquitinases: A Backdoor into Undruggable Targets?

Molecular model of the yeast proteasome.
Molecular model of the yeast proteasome.

Ubiquitin modification of a protein directs events such as targeting for proteasomal degradation. Targeting a protein for degradation through ubiquitin modification is one way to regulate the amount of time a signaling protein, such as a kinase or other enzyme, is available to participate in cell signaling events. Deubiquitinases (DUBs) are enzymes that cleave the ubiquitin tags from proteins, and they have been implicated in several diseases, including cancer.

With their roles in the stabilization of proteins involved in cell cycle progression and other critical processes, DUBs are promising targets for small molecule inhibitors, particularly since they may provide a “back door” for targeting otherwise intractable, undruggable proteins by modulating their half lives. However, finding small molecule inhibitors of the ubiquitin proteases to date has not been trivial. Here we highlight two papers describing the identification and characterization of small molecule inhibitors against the DUB USP7. Continue reading “Deubiquitinases: A Backdoor into Undruggable Targets?”

Shining a Bright Light on Deep Questions in Biology with Bioluminescence

artists view inside a cellA quick search of the PubMed database for “dual luciferase” quickly returns over 1,000 papers. The Dual-Luciferase® Reporter Assay is a powerful tool that allows researchers to ask a multitude of questions about gene control and expression in a system that itself could be normalized and internally controlled. For more than 15 years, firefly and Renilla luciferases  have formed the basis of a range of powerful assays and research tools for scientists who are asking questions about the deep and complex genetic and cellular story associated with cancer. Here we talk a bit of about bioluminescent chemistries, some of the newest bioluminescent tools available, and how some of these tools can be used to probe the deeper questions of cell biology, including cancer biology. Continue reading “Shining a Bright Light on Deep Questions in Biology with Bioluminescence”

Considerations for Successful Cell-Based Assays 3: Treatment Parameters

Welcome to the third installment of our series on cell-based assays. Designed for the newbie to the world of cell-based assays, we have covered the topics of choosing your cell type and basic cell culture tips in the previous posts. In this post, we will discuss how decisions about test compound treatment: how much and how long can affect assay results and interpretation. Continue reading “Considerations for Successful Cell-Based Assays 3: Treatment Parameters”

Considerations for Successful Cell Based Assays II: Cell Culture Conditions

This is the second in a series of blog posts covering topics to consider when designing and performing cell-based assays. In the first installment, we discussed the importance of choosing the right cell type for your assay. Here we will discuss how cell culture conditions can influence assay results. Continue reading “Considerations for Successful Cell Based Assays II: Cell Culture Conditions”

Considerations for Successful Cell-Based Assays I: Choosing Your Cells

For those of us entering the world of cell-based assays from a classical or molecular genetics background, the world of cell culture can be daunting. Yet to truly understand how the genetic mutation behind a particular phenotype works, we need to look at the biochemistry and cell biology where it all occurs: the cell.

This series of blogs will cover several topics to consider when designing your cell-based assays. In this first installment, we discuss the basics of choosing the cell type for your assay. Continue reading “Considerations for Successful Cell-Based Assays I: Choosing Your Cells”