In the Literature

Blogs about published peer-reviewed scientific studies.

NanoBiT Assay Applied to Study Role of SOD1 in ALS

Posted on by Isobel Maciver

NanoBiT Protein ComplementationBack in 2015 the Ice Bucket Challenge brought Amyotrophic Lateral Sclerosis (ALS) to public attention, initiating worldwide pleas for more funding of research toward a cure for this fatal disease, which is characterized by progressive degeneration of motor neurons. In spite of many efforts over the last few decades, the precise cause of ALS is still unknown.

The complexity of the problem of ALS pathogenesis is highlighted in the review “Decoding ALS: from genes to mechanism”  published in Nature in November 2016. The review highlights a long list of genetic factors implicated in ALS, grouping them into genes affecting protein quality control, RNA stability/function, and the cytoskeletal structure of neuronal cells.

Mutations in the antioxidant enzyme superoxide dismutase (SOD1) were the first to be associated with ALS. According to the review, more than 170 SOD1 mutations causing ALS have since been identified. Many of these mutations are thought to result in misfolding of SOD1, contributing to toxicity when the misfolded protein accumulates within the cell.

A paper by Oh-hashi et al., published in Cell Biochemistry and Function in October 2016 used the NanoBiT protein complementation assay to investigate the effect of two common ALS-associated SOD1 mutations on dimerization of the SOD1 protein. Continue reading “NanoBiT Assay Applied to Study Role of SOD1 in ALS”

Cell Free Expression Application: In vitro degradation assay

Posted on by Gary Kobs
A protein chain being produced from a ribosome.
A protein chain being produced from a ribosome.

Researchers and clinicians are fairly certain that all cervical cancers are caused by Human Papillomavirus (HPV) infections, and that HPV16 and HPV18 are responsible for about 70% of all cases. HPV16 and HPV18 have also been shown to cause almost half the vaginal, vulvar, and penile cancers, while about 85% of anal cancers are also caused by HPV16.

E6 is a potent oncogene of HR-HPVs, and its role in progression to malignancy continues to be explored. The E6 oncoprotein of HPV can promote viral DNA replication through several pathways. It forms a complex with human E3-ubiquitin ligase E6-associated protein (E6AP), which can in turn target the p53 tumor-suppressor protein, leading to its ubiquitin-mediated degradation. In particular, E6 from HR-HPVs can block apoptosis, activate telomerase, disrupt cell adhesion, polarity and epithelial differentiation, alter transcription and G-protein signaling, and reduce immune recognition of HPV-infected cells.

In a recent publication a new procedure generated a stable, unmutated HPV16 E6 protein (1). Continue reading “Cell Free Expression Application: In vitro degradation assay”

Weaving Tangled Webs with Cell-Free DNA

Posted on by Michele Arduengo

The ability to isolate and assay circulating cell-free DNA from plasma holds promise for improved diagnostics and treatment in the clinic. The use of blood-based non-invasive prenatal testing (NIPT) has been well described. Such testing is based on circulating cell-free fetal DNA in blood of a pregnant woman for diagnosis and screening  of chromosomal anueploidy (e.g. Trisomy 21, Down Syndrome), sex-linked diseases, and genetic diseases that are known to result from a specific mutation in a single gene (1). Additionally, most cancers carry somatic mutations that are unique to the tumors, and dying tumor cells release small pieces of their DNA into the blood stream (2). This circulating cell-free tumor DNA can be used as a biomarker to “follow” cancer progression or regression during treatment, and diagnostic methods also are being developed to detect even early stage cancers from circulating tumor DNA (3). Further, increases in circulating cell-free DNA have been well documented after intense exercise, trauma, sepsis and even associated with autoimmune diseases such as system lupus erythematosus (SLE; 1,4). In these latter examples increases in extracellular DNA are associated with evolutionarily conserved innate immune responses involving the production of neutrophil extracellular traps (NETs). Monitoring the circulating cell-free DNA of NETs has implications for treatment and diagnosis of autoimmune diseases, cardiovascular events and traumatic injuries (4–7).

How Neutrophils Weave a Defensive Web

Blood smear showing two prominent neutrophils in the field of view
Blood smear showing two prominent neutrophils in the field of view

Neutrophils are the most abundant type of white blood cell and are part of the innate immune response, participating in non-specific immune responses to injury or pathogens. They are one of three types of granuolcytes, and can be recognized by their multi-lobed nucleus and the prominent granules that fill their cytoplasm. Generally they are first to the scene of injury or infection. Early in my scientific career, I was taught that neutrophils fought disease via phagocytosis and occasionally by firing a barrage of toxic enzymes and molecules at invaders. Mostly though they released cytokines that recruited the “important” cells of the specific immune system to the area.

For these reasons, I never really thought much about neutrophils. That is until recently, when I learned about Neutrophil Extracellular Traps (NETs). It turns out that neutrophils are pretty awesome, sacrificing themselves in a cloud-like explosion of DNA, chromatin, and granule proteins

Continue reading “Weaving Tangled Webs with Cell-Free DNA”

Top Science Books of 2016

Posted on by Nicole Sandler

While I planned to write about New Year’s resolutions for the first Promega Connections blog of 2017, I was sidetracked by some “best of 2016” lists—in particular, best science books. I realized though that these seemingly unrelated ideas overlapped at some level because every year I resolve to find time to read more books. What was once an easy and natural escape for me, like for so many others, reading for fun now requires a bit of effort and prioritization. With the continual distractions of Netflix, social media and online news stories, it’s a challenge to find time to read books the way I once did.

So, in honor of a new year’s resolution do more of what I like and less of what I don’t like, here is a list of what has been deemed the best science books of 2016. I culled through the lists of several of the most reputable science blogs and publications and looked for overlap among them. Between the Science Friday blog, New York Magazine’s blog, The Science of Us, Smithsonian Magazine, NPR, and the New York Times’ best of 2016 lists there are loads of suggestions to keep you reading until the start of the next decade. Below are eight recommendations that appeared on several “best of” lists. Continue reading “Top Science Books of 2016”

Plumage Revealed: A 99 Million Year Old Feathered Coelurosaur Tail Trapped in Amber

Posted on by Kelly Grooms

Touching a Dinosaur—Almost

Imagine holding a 99 million year old feathered dinosaur tail in the palm of your hand. The only thing keeping you from actually touching its feathers? A few centimeters of petrified resin. This was reality for the group of scientists who published their findings about this discovery in the December issue of Current Biology (1).

It all began roughly ninety-nine million years ago when a young coelurosaur met an untimely death. Continue reading “Plumage Revealed: A 99 Million Year Old Feathered Coelurosaur Tail Trapped in Amber”

The Role of the NanoLuc® Reporter in Investigating Ligand-Receptor Interactions

Posted on by Nicole Sandler

Luminescent reporter assays are powerful research tools for a variety of applications. Last March we presented a webinar on this topic, Understanding Luminescent Reporter Assay Design, which proved to enlighten many who registered. The webinar addressed the importance of careful experimental design when using a luminescent reporter such as Promega’s Firefly or NanoLuc® Luciferase.

Reporters provide a highly sensitive, quantifiable metric for cellular events such as gene expression, protein function and signal transduction. Luminescent reporters have become even more valuable for live, real-time measurement of various processes in living cells. This is backed by the fact that a growing number of scientific publications reference the use of the NanoLuc® Luciferase reporter and demonstrate its effectiveness as a reporter assay. Continue reading “The Role of the NanoLuc® Reporter in Investigating Ligand-Receptor Interactions”

Bioassay for Cannabinoid Receptor Agonists Designed with NanoBiT™ Techology

Posted on by Kyle Hooper

Cannabinoids. What are they? Sometimes, Wikipedia can give a nice definition:

Tetrahydrocannabinol (THC), a partial agonist of the CB1 and CB2 cannabinoid receptors. Wikipedia Commons
Tetrahydrocannabinol (THC), a partial agonist of the CB1 and CB2 cannabinoid receptors. Wikipedia Commons

A cannabinoid is one of a class of diverse chemical compounds that acts on cannabinoid receptors in cells that alter neurotransmitter release in the brain. Ligands for these receptor proteins include the endocannabinoids (produced naturally in the body by animals), the phytocannabinoids (found in Cannabis and some other plants), and synthetic cannabinoids (manufactured artificially).

Synthetic cannabinoids (SCs) were originally created for the scientific investigation of two cannabinoid receptors, CB1 and CB2, but have made their way to the streets as “safe” and “legal” alternatives to marijuana.

The problem is that these SCs engage the cannabinoid receptors more completely and with higher affinity than anything derived from marijuana. As a result, SCs can produce serious side effects that often require medical attention. In fact, you are 30 times more likely to seek emergency medical attention following the use of an SC than with natural cannabinoid sources like marijuana.

Continue reading “Bioassay for Cannabinoid Receptor Agonists Designed with NanoBiT™ Techology”

To Seq, or Not to Seq

Posted on by Nicole Sandler

Seq—shorthand for “sequence”— has become a more recognizable term thanks to a novel and provocative genomics initiative called the BabySeq Project. The project, officially launched in May 2015, was designed to explore the impact of whole-exome sequencing (WES) on newborn infants and their families. A randomized, controlled trial to sequence healthy and sick infants and then provide sequencing information, it is the first of its kind. Those infants randomized to receive WES undergo genetic sequencing of all protein-coding genes and analysis of about 1,700 genes implicated in childhood health, along with 18 years of follow up genetic counseling.29813751-nov-2-blog-post-nicole-600x470-web

The project is directed by Robert C. Green, geneticist and physician at Brigham and Women’s Hospital, Harvard Medical School and the Broad Institute, and Alan H. Beggs of Boston Children’s Hospital and Harvard Medical School. Funding, totaling $25 million, comes from the National Institute of Child Health and Development and the National Human Genome Research Institute. Continue reading “To Seq, or Not to Seq”

Making It Easier to Investigate PGTs

Posted on by Sara Klink

Introduction

Studying cellular molecules can be challenging. Some processes are troublesome to study due to the lack of an assay or a complicated assay exists but lacks sensitivity. Membrane proteins in particular are difficult to isolate and characterize. Phosphoglycosyltransferases (PGTs) are transmembrane proteins that transfer phosphosugars onto phospholipids, initiating the synthesis of oligosaccharides in bacterial cell walls. This transfer creates a diphosphate link between a lipid and a sugar and generates UMP as a byproduct. Once this lipid–P–P–sugar linkage occurs, more sugars can be added by glycosyltransferases, generating membrane-based polysaccharides (e.g., peptidoglycan) used for signaling, recognition and defense.

While PGTs have been studied biochemically and an X-ray structure of one member exists, much is still unknown about these enzymes. Overexpressing and purifying membrane proteins remains a challenge, and the conventional PGT assay requires isotope labeled-UDP-sugar donors and is based on the solubility difference between substrate and product to determine enzyme turnover using extraction-based or chromatographic methods. While there are other assays that use fluorescent modified substrates or multienzyme analysis, none of the methods can be applied to all of the diverse PGT enzymes.

All PGTs generate UMP as a byproduct of the transfer of a phosphosugar to a phospholipid. Based on the principle of the luminescent UDP-Glo™ Glycosyltransferase Assay where UDP released during the glycosyltransferase reaction was quantitated, a new luminescent assay called UMP-Glo™ Assay is able to measure the activity of PGT enzymes by adding a single reagent to detect UMP. Das et al. validated this assay by testing PglC, a PGT from Campylobacter jejuni, as well as PglC from Helicobacter pullorum and WecA from Thermatoga maritime and published the results in Scientific Reports. Continue reading “Making It Easier to Investigate PGTs”

Of Elephant Research and Wildlife Crime – Molecular Tools that Matter

Posted on by Nicole Sandler

Here at Promega we receive some interesting requests…

Take the case of Virginia Riddle Pearson, elephant scientist. Three years ago we received an email from Pearson requesting a donation of GoTaq G2 Taq polymerase to take with her to Africa for her field work on elephant herpesvirus. Working out of her portable field lab (a tent) in South Africa and Botswana, she needed a polymerase she could count on to perform reliably after being transported for several days (on her lap) at room temperature. Through the joint effort of her regional sales representative in New Jersey/Pennsylvania (Pearson’s lab was based out of Princeton University at the time) and our Genomics product marketing team, she received the G2 Taq she needed to take to Africa. There she was able to conduct her experiments, leading to productive results and the opportunity to continue pursuing her work.

Continue reading “Of Elephant Research and Wildlife Crime – Molecular Tools that Matter”