Shantel Gushue is a University of Manitoba M.Sc. candidate studying Prion disease through the department of medical microbiology and infectious diseases.
Prion diseases, otherwise known as transmissible spongiform encephalopathies, consist of a variety of neurological disorders in humans and animals, like Mad Cow Disease. The misfolding of certain cellular proteins—prions—effectively disables the central nervous system’s (CNS) inflammatory response system.
“[Prion diseases] are invariably fatal neurodegenerative diseases, characterized by the conversion of a normal protein found in the brain into an infectious isoform,” stated Gushue in an interview with the Gradzette.
The “infectious isoforms” or misfolded CNS proteins trigger gliosis—the proliferation of supportive glial cells—inevitably leads to progressive neuronal loss.
“Gliosis is the activation of the brain’s imunnofactor cells, known as microglial cells.”
Typically, the activation of these cells results in an inflammatory response, remarked Gushue, explaining that the microglial cell-induced inflammatory response is one of the proposed mechanisms involved in Prion disease that she focused on for her master’s research.
Then and now
Gushue graduated in the spring of 2008 with a four-year Bachelor of Science from the University of Winnipeg (U of W).
During those formative undergrad years, Gushue gained experience as a laboratory demonstrator for introductory level biology courses at the U of W, and spent a summer working as a research assistant for the U of M’s department of animal science – swine nutrition.
“I spent half of my time in the barn with pigs and piglets and the other half in the lab.”
Although it wasn’t exactly medical microbiology, Gushue appreciated the opportunity and learned some valuable lessons that later helped her with her master’s.
“It made me realize that research always takes longer than you originally anticipate. I believe that in our day and age, especially in the science world, it is very important to gain as much experience in as many [fields] as possible.”
In the fall of 2009, she enrolled in her current master’s program under the supervision of Dr. Stephanie A. Booth.
Already well into the writing phase of her master’s, Gushue spent much of her time over the past few years conducting research in the National Microbiology Laboratory (NML) located in the Canadian Science Centre for Human and Animal Health.
Situated at 1015 Arlington Street, just blocks away from the Health Sciences Centre and the U of M’s Bannatyne Campus, the NML is considered Canada’s preeminent infectious disease research facility and is recognized the world over for its high containment level laboratories and state-of-the-art equipment.
Gushue’s research specifically focuses on “a microRNA that’s been shown to be [over-expressed] during Prion disease, and investigating its role within the innate immune response that is elicited during this disease process.”
That particular microRNA [miRNA] is known as miR-146a. According to Gushue, the increase in miR-146a in the brains of Prion infected subjects suggested to the research community that it played a role in the progression of the disease.
Gushue was named first author of a 2012 paper published in the peer-reviewed academic journal, PLOS ONE, entitled “MicroRNA 146a (miR-146a) Is Over-Expressed during Prion Disease and Modulates the Innate Immune Response and the Microglial Activation State.”
“Interestingly, our lab had found a specific miRNA to be upregulated or increased in the brains of infected mice.”
Gushue developed her own in vitro model to test and mimic Prion disease in an attempt to figure out potential targets of miR-146a.
“Because miRNAs target messenger RNAs and effect their degradation or translational repression, which results in less protein being produced,” Gushue described, it was her job within the context of Prion disease “to look at what miR-146a [ . . . ] is potentially targeting that may play a role in disease outcome.”
Using a proteomic approach, Gushue set up a variety of experimental conditions – including one such condition where miR-146a was over-expressed.
According to Gushue, the prediction was that “upon over-expression of miR-146a, potential targets would be exposed, indicated by a reduction in that particular protein when compared against controls.”
The group of potential targets generated from the proteomic data was then compared against both existing genomic data within the lab and “bioinformatically predicted targets” that are readily accessible on the Internet.
“Essentially you’d extract the proteins and then label each different experimental condition with a different tandem mass tag,” said Gushue.
Once labeled, researchers like Gushue mix all of the conditions together, and the “mass spectrometry machine [is] able to look at differentially expressed proteins and compare [ . . . ] each experimental condition. So, you can see the changes in certain proteins from whichever condition.”
The thought was that maybe taking a closer look at miRNA-146a would “expose another molecule that could potentially be therapeutic with regards to Prion disease.”
Gushue ended up finding “one true target known as nitric oxide synthase (iNOS),” explaining that iNOS is responsible for the production of nitric oxide (NO).
Gushue went on to say that NO has a known antiviral function and is often “produced during an anti-inflammatory response and results in the killing of neurons.”
Thus, as a result of iNOS activity, which is triggered during the prion-induced inflammatory response and shown to be harmful to neurons, miR-146a appears to be targeting, dampening and attempting to compensate for the resulting detrimental effects.
“Right now, the hypothesis is that miR-146a is working to dampen the innate immune response,” confirmed Gushue.
That is to say that miR-146a is “trying to restore homeostasis within the brain by bringing down the inflammatory response, which is harmful and detrimental to neurons.”
In identifying the targets of miR-146a, Gushue hopes to gain a better understanding of the disease process in general and potentially identify proteins or pathways that may have therapeutic value.
Gushue is slated to finish her program in the spring.