Human embryonic stem cells were successfully cultured in a lab for the first time in 1998. Scientists believe that transplanting these cells holds great promise for treating injury and disease because they have the unique ability to replicate themselves indefinitely and develop into a wide variety of other types of cells. But a number of challenges have to be tackled before stem cells can be safely used in the treatment of patients. These include understanding and being able to control how stem cells are transformed into other types of cells, overcoming immune rejection in patients receiving transplanted cells, and understanding any links between stem cells and the origin of cancer. Jaswinder Khattra is tackling a related challenge: defining the activity of novel genes and proteins in stem cells. Although thousands of human genes are known, many remain uncharacterized. Khattra is investigating the properties of novel genes discovered in stem cells to define how they act within the cells, and whether they play a role in controlling how stem cells differentiate into other cells. This research also examines the proteins produced by these genes and how they interact in regulating cell growth and function. Improved understanding of the molecular structure and function of these genes and proteins could contribute to improvements in cell-based therapies and drug screening for a range of diseases.
Research Pillar: Biomedical
Characterizing the role of palmitoylation in the trafficking of multispanning membrane proteins to the cell surface
Molecules are transported to various parts inside the cell to maintain vital functions, such as cell growth and communication. For example, many proteins regulate the intake of nutrients or detect external signals — it’s crucial to cell survival that these proteins are transported to the cell surface so the cells can recognize and respond appropriately to the different stimuli they encounter. However, there is much to be learned about the way these proteins are transported. This is the focus of Karen Lam’s research, in particular, understanding the mechanisms by which the saturated fatty acid palmitate attaches to proteins (I do not work with brain cells, but with yeast cells, which serve as a model) and affects their transport to the cell surface. For example, palmitate attaches to various proteins found in brain cells. Many of these proteins help chemicals called neurotransmitters send signals in the brain, a process that’s essential for learning and memory. Defects in this communication can result in neurological diseases like Alzheimer, Huntington and Parkinson’s. Lam wants to determine what causes defective function and transport in these proteins by modeling the processes in yeast cells. Understanding the fundamental mechanisms of palmitate attachment may lead to the development of molecular-based therapies to treat a variety of neurological disorders.
Assessing reward-entrainment as a means to activating and identifying the food-entrainable pacemaker
Optimal functioning requires organisms to anticipate and adapt to daily environmental changes driven by the cycle of the sun. Entrainment is the process by which daily rhythms of behaviour and physiology are synchronized to the environment. Shift-workers and air travelers are often out of sync with their environment due to a mismatch between their internal clock and the external environment. This dyssynchrony leads to general discomfort and reduced performance known as shift-work malaise or jet-lag. This has a detrimental effect on health, performance, levels of productivity and quality of life. Glenn Landry aims to achieve a better understanding of the mechanisms of entrainment. In mammals, an area of the brain called the suprachiasmatic nucleus acts as a master pacemaker. In animal models that have access to food and water without restriction, damage to this area of the brain eliminates all daily rhythms. However, if food is restricted to one to two meals at a fixed time each day, these animal models are still capable of anticipating the feeding time. This shows that a separate pacemaker exists for anticipating food. But identifying this food-entrainable pacemaker has been a challenge since many brain structures are activated during food restriction, making it difficult to isolate the pacemaker from background activity. Landry is testing a recently developed strategy to filter out this background activity. By using a number of different stimuli capable of activating the food-entrainable pacemaker, he aims to isolate this pacemaker by identifying brain areas activated in common across these stimuli. Landry hopes identifying the food-entrainable pacemaker could ultimately lead to new approaches to re-setting the clocks of shift-workers and air travelers, improving health and productivity.
Investigating the Role of the O-GlcNAc Post-Translational Modification in the Development of Type II Diabetes and Alzheimer's Disease
There is a growing prevalence of type 2 diabetes. It has been estimated that more than 20 million people have the disease in the United States alone. Type 2 diabetes is a disease characterized by resistance of our bodies to insulin, a hormone needed for normal metabolism of carbohydrates, fats, and proteins. This resistance leads to prolonged elevation of blood sugar levels, eventually giving rise to the diseased state. Understanding what events lead to insulin resistance is an intense topic of research. Nevertheless, the precise molecular mechanisms by which insulin resistance arises still require delineation in order to fully understand the disease Building on his MSFHR-funded Master’s research, Matthew Macauley is investigating what the role of proteins modified by a sugar known as GIcNAc have in causing insulin resistance. One hypothesis is that high levels of glucose over a long time period may increase GlcNAc modification and that this in turn results in insulin resistance. Macauley is using an enzyme inhibitor of O-GlcNAcase to artificially create elevated levels of GlcNAc in animal models to determine if insulin resistance and type 2 diabetes ensue. Using this same enzyme inhibitor, Macauley is also conducting a separate study to increase GIcNAc attached to tau, a key protein involved in the development of Alzheimer’s disease. The goal of this study is to determine if the inhibitor can prevent or delay the onset of Alzheimer’s in an animal model.
The characterization of KiSS1 and GPR54 in breast cancer and other hormonally responsive cancers
Cancers whose growth is influenced by sex hormones, such as estrogen and testosterone, form the largest group of cancers that affect Canadian men and women. Breast cancer remains the second most common cause of cancer death among women in North America, and prostate cancer rates third for men. While there have been advances in treatment, many of these patients will succumb to their disease when tumors metastasize (spread to other organs or tissues in the body). The KiSS1 and GPR54 genes have demonstrated the ability to prevent metastases from developing. While the importance of KiSS1 and GPR54 are being studied in other cancers, little has been done to investigate the involvement of these two genes in clinical breast and ovarian cancers, and no studies have been conducted in prostate cancer. Building on her MSFHR-funded Master’s research, Leah Prentice is investigating whether KiSS1 and GPR54 have dual roles as both tumor promoters, via their involvement in hormonal processes, and also as suppressors of metastasis. By understanding the anti-metastatic mechanism of these two genes, Prentice hopes to contribute to the development of more targeted therapies and diagnostic tests that would allow for earlier detection of these potentially life-threatening cancers.
Targeting Lung Cancer Genomics: A Whole Genome Approach to Predicting Drug Response
Lung cancer is the leading cause of cancer death worldwide, with five-year survival rates among the lowest for commonly diagnosed cancers. The high mortality rate is partially due to the lack of effective treatment options since surgery and chemotherapy are common options, yet non-curative. The epidermal growth factor receptor (EGFR) gene is overexpressed in a majority of lung cancers. Researchers recently discovered a new drug designed to target the product of this gene. Although the drug didn’t benefit the majority of patients, a positive response was often seen in non-smoking women of Asian descent. At the BC Cancer Research Centre, Trevor Pugh is researching why this drug works for this subgroup and not for other patients. Using tumour samples and patient outcomes data, he is searching across the entire genome to pinpoint specific genetic features shared by drug-responsive tumours in patients with lung cancer. Ultimately, his work could result in improved diagnostic tests for predicting who will benefit from specific therapies, and new candidates for gene-targeted cancer drugs.
Characterization of retrograde transport machinery and its relationship to amyotrophic lateral sclerosis (ALS) using the yeast model system
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a rapidly progressive motor neuron disease that causes paralysis and is ultimately fatal. In ALS, motor neurons (nerve cells) are impaired and eventually die. This process breaks the connection between voluntary muscles, which individuals control, and the brain. Other types of brain cells are unaffected, which means patients become paralyzed but their cognitive abilities remain intact. Specialized transport proteins carry survival signals from one end of the neuron to the other. In a mouse model of ALS, the cause of motor neuron disease was found to be due to a mutation in the Vps54 transport protein. In all types of cells, material is transported in a specialized container called a vesicle. In her research, Nicole Quenneville has found that a particular region of the Vps54 transport protein is involved in recognizing the surface of vesicles. It’s this region that is mutated in the mouse model of ALS, suggesting that faulty recognition and transport of these vesicles may lead to motor neuron disease. Using a yeast model, Quenneville is further investigating whether the Vps54 mutation causes transport defects, and whether the mutation changes the interactions that the Vps54 protein has with other proteins. As well, she aims to identify genes and proteins that work with Vps54 to transport molecules within the cell. Quenneville hopes her research will help identify candidate genes for novel therapies, diagnosis, and assessment of susceptibility to ALS.
Development of Fluorinated Carbohydrates for use as Positron Emission Tomography Imaging Agents and Pharmacological Chaperones in the Treatment of Lysosomal storage diseases
Lysosomal Storage Diseases (LSD) are a rare group of more than 40 disorders, including conditions such as Gauchers and Tay Sachs disease, in which a genetic abnormality leads to the buildup of naturally occurring compounds throughout the body. This process may lead to a variety of symptoms including skeletal defects, heart problems, mental retardation, and death. The diseases can be treated by enzyme replacement therapy, in which a missing enzyme is injected into the bloodstream so it can move into cells to alleviate the buildup of these compounds. However, the therapy is extremely expensive and cannot be used to alleviate neurological symptoms. Brian Rempel is developing imaging agents for Positron Emission Tomography (PET), a highly specialized technology that produces powerful images of the body’s biological function. Using PET with enzyme replacement therapy would enable imaging of an injected enzyme and tailoring of the dose to the individual patient, which could reduce the costs of the therapy. As well, PET imaging would allow for a better understanding of how the enzyme is distributed throughout the body. Rempel is also investigating the development of pharmacological chaperones, molecules that bind to the mutant enzyme that is deficient in LSD patients. The molecules help the enzyme migrate to the correct cellular compartment where it can function normally, with the aim of enhancing the patient’s own naturally occurring enzyme levels. Pharmacological chaperones would be a fraction of the cost of enzyme replacement therapy.
Regulatory mechanisms of the anti-apoptotic NAIP gene during cellular stress and malignancy
Apoptosis, or programmed cell death, is a critical physiological process that is turned on and off as appropriate to eliminate abnormal cells. When this switching process goes awry, it can lead to a variety of diseases including cancer. The genetic mechanisms that inhibit activation of the apoptosis protein (IAP) family include molecules that sequester key enzymes necessary for turning on and sustaining the process of programmed cell death. Neuronal apoptosis inhibitory protein (NAIP) is particularly interesting because expression of NAIP is reported to be highly elevated in various leukemias. In addition, NAIP is commonly deleted in the most severe cases of spinal muscular atrophy (SMA) and studies also have shown that a specific copy of this gene is required to suppress replication of the bacterial pathogen that causes Legionnaire’s disease. Researchers have also proposed that expression of NAIP in neurons of patients with Alzheimer’s disease can limit the high levels of cell death. Mark Romanish is studying the expression and regulation of NAIP to better understand its role and function in health and disease. Apoptosis is a highly regulated process receiving many activating and inhibiting signals, but the final outcome relies on which signals tip the scale. Therefore, the question of gene regulation becomes particularly important since those genes capable of rapid activation are more likely to influence the ultimate fate of a cell.
Adaptive resistance to aminoglycosides in Pseudomonas aeruginosa
Cystic fibrosis (CF) is the most common genetic disorder among young children in Canada. CF affects the lungs and digestive system of almost 70,000 children and adults worldwide. A defective gene causes the body to produce thick, sticky mucus that clogs the lungs leading to frequent lung infections and obstructs the pancreas stopping enzymes from helping the body break down and absorb food. Pseudomonas aeruginosa is a bacteria commonly associated with both hospital-acquired infections and chronic lung infections in people with CF. Although these lung infections can be temporarily suppressed, they are never completely cured and are eventually fatal. Kristen Schurek is investigating how P. aeruginosa develops resistance to the class of inhaled antibiotics called aminoglycosides that are used to treat lung infections in CF patients. Schurek believes these antibiotics trigger the organism to adapt its genetic physiology causing small, incremental increases in resistance over time. As a result, the bacteria gradually develop the ability to persist in the presence of the antibiotics. She will determine how these antibiotics cause the bacteria to adapt, and which genes in P. aeruginosa contribute to antibiotic resistance. This knowledge could lead to better methods of administering antibiotics to prevent drug resistance in people with cystic fibrosis.