In vitro diagnostics for frontotemporal dementia

Frontotemporal dementia (FTD) is a group of devastating brain diseases associated with progressive decline in behavior, language, and movement. FTD is the second most common form of dementia in those under 65 years of age. In the early stages of diseases when symptoms are very mild, FTD can be difficult to identify as its symptoms are similar to other neurological disorders like Alzheimer’s disease. Therefore, a reliable biofluid test is needed to help with early and accurate diagnosis of FTD. In this project, I will use state-of-the-art analytical techniques to develop a diagnostic test that can identify individuals with FTD. I will examine how the test performs in individuals with FTD compared to other diseases that have similar symptoms to FTD. This project will result in the creation of new diagnostic tests for the early detection of FTD. Early and accurate diagnosis of dementia is critical to ensure efficient access to medical care and social programs and will help researchers in developing new treatments for FTD.

Developing sensors for rapid detection of biomarker proteins for Alzheimer’s disease

Dementia is a growing health challenge that affects over 500,000 Canadians today, which is estimated to grow to 900,000 by 2030. Alzheimer’s disease, the most common form of dementia, is characterized by protein misfolding in the brain. This process can start over a decade before the occurrence of significant cognitive decline making it possible to diagnose at an early stage when treatment strategies are most effective. Biomarkers are measurable indicators that help determine if a person may have or be at risk of developing a disease. Researchers have identified phosphorylated tau (p-tau) proteins and small proteins called cytokines to be promising biomarkers for Alzheimer’s disease. To detect these biomarkers in blood samples, very sensitive detection methods are needed but existing methods have drawbacks such as being expensive and time consuming, and need to be performed in a laboratory, limiting their availability to Canadians. We have developed a new sensor that can detect proteins at ultra-low concentrations using a simple and rapid test. Our goal is to make a rapid and easy-to-use tool that can be used by clinicians to help diagnose Alzheimer’s disease and patients for personalized health monitoring.

Resisting Vascular Cognitive Impairment: The Effects of Resistance Training on Myelin and Blood-based Biomarkers of Neuroplasticity in Older Adults

We are studying if strength training exercises can reduce myelin loss and preserve cognitive abilities in adults with cognitive impairment due to vascular risk factors (e.g., high blood pressure), also known as vascular cognitive impairment (VCI).

Worldwide, VCI is the second most common cause of dementia and it is associated with myelin loss. Myelin is a component of neurons critical for transmission of brain signals. Thus, myelin is important for the maintenance of cognitive (i.e., thinking) abilities. Animal studies suggest myelin loss may be minimized with physical exercise. The objective is to determine whether strength training (e.g., lifting weights) is an effective strategy for slowing down myelin loss in persons with VCI.

We will conduct a 12-month study with 88 adults with VCI; half will receive strength training and half will receive balance and stretching exercises. At the end of study, the two groups will be compared on myelin content and cognitive function. Reducing myelin loss could preserve cognitive abilities in adults with VCI and reduce their risk of dementia. Our proposal is also timely as the prevalence and burden of VCI will only increase with the world’s aging population.

Building bespoke artificial cells and tissues on a chip for drug discovery

Human cells are fascinating and complex: they reproduce, break down food to create energy and communicate with each other. The ‘skin’ of the cell, the cell membrane, plays a crucial role in choreographing interactions between a cell and the outside environment, for example by allowing or prohibiting the access of drugs from the cell exterior to the cell interior.

I design and build lab-on-a-chip devices, which are plastic chips the size of a postage stamp inside of which I can manipulate tiny amounts of liquids. I use these lab-on-a-chip devices to create artificial cells to be able to study how the cell membrane regulates access to the cell interior. Human cell membranes have lots of different components that are used to transport drugs into and out of the cell.

Since the cell membrane is complex, we do not always know exactly which component is interacting with the drug molecule, and what effect it has. The cost of developing a new drug is around 2.6 billion USD and a significant proportion of drug candidates fail because we cannot predict how they interact with cells.

My research will help design drugs that can interact with cells more efficiently, so that they can get inside the cell in order to work properly.

Elucidating the effect of O-GlcNAc modification on protein stability

The glycosylation of proteins with O-GlcNAc is a ubiquitous post-translational modification found throughout the metazoans. Deregulation of O-GlcNAcylation is implicated in several human diseases including type II diabetes, Alzheimer’s disease, and cancer.

 

However, the basic biochemical roles of O-GlcNAcylation remain largely unanswered. Several recent studies have demonstrated a clear link between O-GlcNAc and cellular thermotolerance.

 

It is likely that a basic function of the O-GlcNAc modification prevents the unfolding or aggregation of target proteins. Dr. King will investigate its role in protein stability through series of biochemical and biophysical experiments to probe the effect of O-GlcNAc on protein unfolding, folding, and aggregation. The results of this research will provide important insights into the basic molecular mechanisms governing O-GlcNAc deregulation in human disease.

 


End of Award Update: July 2022

 

Most exciting outputs

The modification of proteins by O-linked N-acetylglucosamine (O-GlcNAc) is a widespread post-translational modification (PTM) that is dysregulated in several human diseases including type II diabetes, Alzheimer’s disease and cancer. However, research progress in this area is hampered by the fact that it is challenging to detect O-GlcNAc on proteins. Further, the basic biochemical roles of O-GlcNAcylation remain largely unanswered.

 

Therefore, we developed a mass spectrometry based method to precisely map sites of O-GlcNAc on proteins. This method employs a UV laser to produce a diversity of O-GlcNAc retained fragment ions, enabling mapping protein modification sites with unprecedented precision.

 

We then explored the role of O-GlcNAc as a biochemical regulator of protein stability. We developed a new high-throughput approach to profile the effect of O-GlcNAc on the thermostability of the proteome. Using this method, we identify several proteins that are regulated by O-GlcNAc. Interestingly, the majority of these proteins display an O-GlcNAc dependent decrease in stability, challenging the prevailing view of O-GlcNAc as being a predominantly stabilizing modification. Thus, we show that O-GlcNAc is a bi-directional regulator of protein stability. We deliver a powerful approach that provides a blueprint for determining the impact of, in principle, any PTM on the thermostability of thousands of proteins in parallel.

 

Impacts so far
This work delivers powerful tools for exploring the role of O-GlcNAc and other labile PTMs as regulators of protein biochemistry.

 

Potential future influence
Decreased levels of protein O-GlcNAcylation is associated with Alzheimer’s disease. However, the basic biochemical mechanisms underlying this association remain unknown. Here we show that O-GlcNAc regulates the stability of several proteins within human cells, a phenomenon that may impact cellular protein levels in Alzheimer’s disease. This fundamental research is important for understanding the impact O-GlcNAc has on protein structure and stability, particularly in the context of its dysregulation in neurodegenerative disorders.

 

Next steps
We plan to continue exploring the influence O-GlcNAc has on protein structure and function. In doing so, we hope to improve our understanding of the fundamental mechanisms underlying neurodegeneration. This research may ultimately provide knowledge that contributes toward the development of new therapeutic strategies.

 

Useful links

Chemical suppression of nonsense mutations for the treatment of frontotemporal dementia

Michael Smith Foundation for Health Research/Pacific Alzheimer Research Foundation Scholar Award

Frontotemporal dementia is a progressive neurodegenerative syndrome, and the second most common cause of young-onset dementia after Alzheimer’s disease. Members of our team recently reported that loss-of-function mutations in the gene for a protein called progranulin cause 25 percent of frontotemporal dementia cases. Of these mutations, 30-40 percent are “nonsense mutations” that act as stop signs to prematurely end a process required to produce normal progranulin. When progranulin production ends too early, it leads to a shortened protein that cannot carry out the normal brain functions, eventually leading to dementia in the sixth decade.

The goal of this project is to investigate small molecule combinations that can bypass the abnormal “stop sign” in the progranulin gene, increasing the normal production of this important protein. The small molecule combinations will be refined and optimized to find the most effective combination. This approach, also referred to as “suppression of nonsense mutations”, offers the possibility of developing a new drug for patients with frontotemporal dementia cause by a progranulin mutation. The team also plans to develop a mouse model of frontotemporal dementia to test the small molecule combinations in a living organism.

The long-term goal of the project is to bring new drugs for frontotemporal dementia into clinical trials. An effective therapy would alleviate the devastating impact of dementia in many patients and their families, in BC and beyond.