Regulatory DNA sequences determine the leveI, location and timing of gene expression. These sequences are important in nearly all biological processes and many disease conditions. In some cases, the onset of cancer is related to changes in these sequences, such as when gene translocation results in the production of a protein that prevents normal cell death. Expanding on his previous MSFHR-funded work, Obi Griffith will make use of public gene expression data and novel computational approaches to identify genes believed to have undergone a change in regulation leading to cancer. Once these genes have been identified, further analysis will investigate the mechanism responsible for the change in regulatory control. Then, Obi will obtain specific tumour samples and validate the predicted changes in the laboratory. Obi hopes to increase understanding of how genes are controlled under normal conditions and how the loss of this control leads to cancer. Such identified genes could make suitable targets for therapeutic intervention as well as having prognostic and diagnostic value.
Research Pillar: Biomedical
Protein isoforms generated by alternative splicing: prevalence and relevance to models of cancer progression
Continuing the study that he began in his MSFHR-funded Master’s work, Malachi Griffith is examining the changes in the forms of certain genes due to alternative splicing that may be important in the progression of cancer. Alternative splicing is a phenomenon in which one gene is assembled from its component pieces in many different ways, a process which produces immense diversity and enables genes to fulfill many functions. This diversity in gene structure may also account for the differences in the severity of cancers and response to treatment observed among individuals. Malachi is studying colon and prostate cancer cells – some that are responsive to treatment, and others that are resistant. By studying differences in the structure of expressed genes between these contrasting states, he hopes to gain insight into why treatment initially appears to work well in some patients, yet becomes less effective over time. Such knowledge may lead to improved or novel treatment strategies, resulting in better outcomes for cancer patients.
Cytochrome p450 2C Inhibition in Peri-transplant Ischemic Injury and Transplant Vascular Disease
Transplant vascular disease (TVD), characterized by a thickening of the arteries (arteriosclerosis), is the primary cause of chronic heart transplant rejection. TVD can be detected in up to 75 per cent of transplant recipients within only one year of transplantation. One factor that causes TVD is oxidative stress which occurs during the process of transplantation when blood flow is stopped in the donor heart prior to transplantation (ischemia), and then re-established in the recipient (reperfusion). This stress not only damages the heart but also makes it more susceptible to attack by the recipient’s immune system leading to chronic rejection. Previous research has suggested that an enzyme (CYP2C) is involved in triggering oxidative stress and heart damage during reperfusion. Arwen Hunter is investigating the process and mechanisms by which CYP2C causes cardiovascular damage. She will also investigate whether inhibition of CYP2C can suppress the amount of damage that occurs during transplantation and whether suppression of this damage can reduce chronic rejection later on. Results from these studies may lead to novel therapeutic strategies to alleviate chronic heart transplant rejection.
Melanoma gene therapy by conditional replicative adenovirus targeting PUMA and p-Akt
Melanoma is a deadly form of skin cancer arising from the abnormal growth of pigment-producing cells in the skin. Melanoma is an aggressive tumour that spreads quickly to other parts of the body and is very difficult to treat because it does not respond to radiation or chemotherapy. In recent years, researchers have turned to gene therapy as a new approach to fight cancer. This approach is based on the idea that cancer is caused by defective genes. The goal is to eliminate the cancer by inserting therapeutic genes into cancer cells using a vector (a vehicle for delivering genetic material to a cell). Within melanoma cells, the expression (activation) of the cell death gene PUMA is often reduced and expression of the cell growth and survival gene Akt3 is often inappropriately increased. Using viral vectors known as CRAds, Alison Karst is focusing on reversing this pattern of gene expression in order to induce melanoma cell death. CRAD-based gene therapy holds promise for eliminating cancer cells and more effectively treating melanoma.
Regulation of innate epithelial response against A/E bacterial pathogens by TLR5 and single Ig IL-1R-related (SIGIRR) molecule
Bacterial infections in the intestine cause diarrheal disease worldwide, affecting people of all ages. These bacteria also trigger inflammatory conditions of the digestive tract such as in Crohn’s disease and ulcerative colitis which can lead to chronic illness and hospitalization. Growing evidence suggests that the innate immune system is critical in regulating the body’s response to early infection, and recent research suggests that dysfunction of this innate response may contribute to Crohn’s disease. A strain of Escherichia coli (E. coli) that attaches to cells on the inner lining of the intestine is a major cause of diarrhea in children, but little is known about the mechanisms by which the immune system recognizes and responds to this type of bacterial infection. Mohammed Khan is investigating how the innate immune system detects E. coli infection and the mechanisms that regulate subsequent inflammatory events in the intestine. Using laboratory-grown human intestinal cells and mouse models, Mohammed hopes to reveal novel mechanisms of regulation of inflammation in host defense. This research may lead to new treatments for infectious and inflammatory diseases of the human intestine.
Neuroprotective mechanism of connexin43
Stroke is one of the leading causes of death in North America affecting about 16,000 Canadians each year. This disease causes a sudden loss of blood to an area of the brain typically due to blocked or ruptured blood vessels. Michael Kozoriz is studying how to reduce brain damage caused by stroke. The brain has two classes of cells – nerve cells (neurons) and glial cells. Neurons conduct electrical impulses, while glia surround, support and protect neurons. Glia are the most abundant cells in the central nervous system and are connected by a junction made of a protein called connexin43. Because these cells are physically attached they have the ability to share various molecules and nutrients. Studies have shown that stroke damage is less severe in the presence of connexin43, and damage is greater if the protein is absent. Michael is examining how connexin43 protects cells from death. He suspects the junctions remain open during a stroke, allowing neighbouring cells to share nutrients, much like neighbours helping a friend in need. His findings could explain how to protect the brain during stroke, and ultimately, lead to better treatments for this disease.
The function of putative streptococcal family 41 carbohydrate binding modules in carbohydrate recognition during bacterial pathogenesis
Some carbohydrates act as a “fingerprint” or marker for each cell. These markers allow cells to recognize and talk to each other, which is critical for all aspects of cell development and cell-to-cell interaction. Importantly, carbohydrate markers allow the body to discriminate between substances that belong to the body from those that are foreign in order to determine the appropriate immune response required. Further protection against foreign material is provided by protective layers of mucus at entry points to the body such as the nose, throat and lungs. These layers are derived from carbohydrates. Many disease-causing bacteria are able to attach to, and infect cells, by binding to these carbohydrates. Alicia Lammerts van Bueren is studying how enzymes called glycoside hydrolases enable bacteria to infect human cells and hide from the body’s immune system. Her specific focus is on a glycoside hydrolase found on the surface of both Streptococcus pneumonie, which is the leading cause of pneumonia and bacterial meningitis, and Streptococcus pyogenes, which causes strep throat, necrotizing fasciitis and toxic shock. All these diseases can be fatal if left untreated. Alicia’s research into the carbohydrate binding function of these enzymes may explain how these bacteria cause disease in humans, and potentially lead to new drugs or vaccines to treat bacterial infections, which is particularly important given the rise of antibiotic resistance to streptococcal infections.
Characterization and Thrombogenic Contribution of Platelet Microparticles to Pathogenesis of Transient Cerebral Ischemic Attacks and Unstable Angina
Platelets are cells that augment blood coagulation to form blood clots which in some cases can restrict or halt oxygenated blood flow to the heart and the brain, causing a heart attack or stroke. Although drugs like aspirin have an anticoagulant effect that can decrease the chance and severity of a stroke or heart attack, these drugs do not entirely eliminate the risk. Platelets release mini-versions of themselves, called platelet microparticles (PMPs), into circulation, which are not affected by anti-coagulant drugs. The presence of PMPs in blood is a predictor of future blockages in the brain or heart, but their precise role is not clear. Hon Leong is investigating whether PMPs have the same clotting abilities as platelets to determine whether they cause the blood clots that lead to a stroke or heart attack. Hon is examining the structure of platelet microparticles and their ability to bind to other cells and clots. The results potentially may be used to develop more accurate blood tests to predict and detect strokes and heart attacks and, ultimately, new therapies that prevent platelets and PMPs from producing harmful clots.
Involvement of myosin V in glutamate receptor trafficking in neurons
The molecules that are essential for normal brain functions are transported throughout neurons, travelling from the site of their formation to the specific location where they are activated. Defects in the transport and exchange of these molecules may affect brain activity and lead to neurological impairments such as epilepsy and mental retardation. Marie-France Lise is studying Myosin V, a family of proteins that may be important regulators of how molecules travel across neurons and reach their destinations. By characterizing how the Myosin V family regulates transport, she hopes to create a better understanding of how these processes contribute to essential brain development, learning and memory formation.
Elucidating the role of Fa2p in cilliary and cell cycle regulation
The majority of cells in the body contain a microscopic, hair-like organelle projecting from the cell surface called a cilium. Cilia play roles in motility and sensory signalling. In many cells, the disassembly of cilia by the cell is a precursor to mitosis (cell division) and cilia are reassembled by the cell following mitosis. Dysfunction of this structure and process leads to a variety of conditions, including blindness, infertility and polycystic kidney disease. MSFHR funded Moe Mahjoub in 2003 to complete his PhD study of cilia. His previous work showed that the kinase Fa2p is implicated in the regulation of ciliary shedding and assembly, as well as in cell division. He has determined that Fa2p is dynamic, moving to different locations in the cell at different points in the ciliary and cell life cycle. Moe is now working to discover exactly how Fa2p exerts its effects. He hopes his research will provide key insights into the mechanism of various human diseases.