Pre-mRNA splicing is a critical step in the process by which genes direct the production of proteins. While there are many aspects of this process we do not yet understand, it is clear that splicing must be incredibly accurate. Errors can result in a number of devastating diseases, including myotonic dystrophy, spinal muscular atrophy and retinitis pigmentosa, which results in blindness. Splicing errors have also been linked to the growth of malignant tumours and the development of cystic fibrosis and Alzheimer’s disease. Amy Hayduk’s research at the Rader Lab at the University of Northern British Columbia is directed at understanding the mechanisms that make up the process. Specifically, she is using molecular beacons to study the roles of the four RNA recognition motifs of the protein Prp24. This work builds upon original research conducted by Hayduk involving a novel application of molecular beacon technology to RNA detection. By analyzing the degree of impairment in the activity of Prp24 resulting from specific gene mutations, her work will help explain the molecular interactions through which pre-mRNA splicing is accomplished. By contributing to a more precise understanding of the intricate sequence of molecular interactions that constitutes pre-mRNA splicing, this research will assist with the development of strategies for treating diseases that arise from defects in splicing.
Year: 2007
Functional Analysis of Cilia's Role in Obesity
Cilia are hair-like structures that extend from nearly every cell in mammals. Non-motile cilia are involved in the sensations of the external environment, including light, smell and touch. Improper function of cilia is linked to a growing list of human disorders, including kidney disease, blindness, loss of the sense of smell, loss of left-right body asymmetry, male and female infertility, diabetes and obesity. Bardet-Biedl syndrome is an inherited disorder characterized by mental retardation as well as many of the symptoms linked with improper function of cilia. The known link between Bardet-Biedl syndrome and obesity demonstrates that dysfunction of cilia can predispose an organism to accumulate fat. How this occurs is unknown. However, people with this disorder are known to have an increased appetite and raised levels of certain types of proteins produced by fat cells that are involved in the regulation of appetite. Using a worm, Caenorhabditis elegans, which has sensory cilia remarkably similar to those of human cells, Michael Healey is aiming to clarify the role of ciliated nerve cells in regulating lipid levels. Healey is investigating whether all ciliary proteins or only a specific subset are involved in fat regulation, which ciliated nerve cells are important for fat regulation, and how cilia can control body weight. Ultimately, he aims to understand how Bardet-Biedl syndrome patients become obese, which will provide new insight into body weight control and the development of treatments for obesity.
Leptin Regulation of Hepatic Glucose and Lipid Metabolism
More than 60,000 Canadians are diagnosed with type 2 diabetes each year, making it one of the fastest growing diseases in Canada. About 80 per cent of people with type 2 diabetes are also obese, a deadly combination that results in many long-term complications and makes diabetes the seventh leading cause of death in Canada. It is essential, therefore, to improve our understanding of the links between diabetes and obesity. The fat cell-derived hormone leptin may be a key factor linking the two. Leptin is well known to influence body weight through its ability to depress appetite and increase energy expenditure. However, leptin also has profound direct effects on metabolism. For example, mice completely deficient in leptin or the leptin receptor are obese and also develop increased fat in the blood, increased build-up of fat in tissues, and type 2 diabetes. While it is clear that leptin can act on the brain to regulate body weight, it is less clear how leptin influences glucose and fat metabolism. This is the focus of Frank Huynh’s research; in particular, the role leptin signalling in the liver may have on glucose and fat metabolism and if dysregulation of these pathways can contribute to type 2 diabetes. A better understanding of the mechanisms of leptin action would help clarify its role in the development of diabetes and obesity, potentially pointing the way to better treatment strategies.
Autonomic dysreflexia and axonal plasticity in sympathetic ganglia following spinal cord injury
Each year, 35 people per million in Canada sustain a spinal cord injury. Apart from the well known motor and sensory dysfunctions, there are a number of autonomic nervous system changes that can occur after spinal cord injury, including bladder, bowel, thermoregulatory, sexual and cardiovascular dysfunctions. These changes significantly affect the overall quality of life of individuals with spinal cord injury. One cardiovascular dysfunction that commonly develops following high spinal cord injury is called autonomic dysreflexia. Autonomic dysreflexia is a life-threatening condition that is characterized by sudden increases in blood pressure triggered by normal touch below the level of injury. These episodes can be extremely uncomfortable for patients as they are often accompanied by pounding headaches, upper body flushing and feelings of anxiety. Furthermore, as these episodes are often triggered by routine daily events, such as catheterization, they can significantly interfere with rehabilitation programs and work schedules. The cause of autonomic dysreflexia is unknown. In her research, Jessica is looking at how spinal cord injury changes sympathetic nerve cells – cells that are involved in regulating blood pressure by speeding up the heart and contracting blood vessels. One possibility is that there are unusual new connections formed between sensory and sympathetic nerve cells after spinal cord injury; so that a normal touch, which did not cause increased blood pressure before injury, is abnormally connected to sympathetic nerve cells after injury, causing increased blood pressure. Ultimately, Jessica hopes her research will help lead to the development of therapeutic strategies to prevent autonomic dysreflexia’s devastating effects on people with spinal cord injury.
An investigation of the basis of aminoglycoside resistance in the Burkholderia cepacia complex
Cystic fibrosis and chronic granulomatous disease are both life-threatening genetic disorders. Cystic fibrosis is the most common life-shortening genetic disorder affecting Caucasians, with the median survival age being only about 37 years in North America. A genetic mutation results in the buildup of sticky, dehydrated mucus in the airways of the lungs, leading to an inability to clear many microorganisms. The resulting persistent infections gradually destroy lung function. Individuals with chronic granulomatous disease are also susceptible to chronic bacterial and other infections, because a genetic mutation impairs the protective functions of certain immune cells, causing them to be unable to effectively kill infectious organisms. A group of bacteria that commonly cause severe and fatal infections in these patients is the Burkholderia cepacia complex (BCC). These bacteria represent a significant threat because they are highly resistant to many antimicrobial drugs. Recently, researchers in Agatha Jassem’s lab discovered B. vietnamiensis bacteria, a member of the BCC, which are sensitive to a particular group of antibiotics called aminoglycosides. This presents an opportunity to undertake comparative studies between drug resistant and susceptible strains of the BBC. Jassem believes the outer cell wall permeability of the newly discovered B. vietnamiensis bacteria may be responsible for its susceptibility to the aminoglycosides group of antibiotics. To establish this, she is first evaluating the level of resistance of the B. vietnamiensis bacteria to a variety of antibiotics. Then, she is carrying out molecular studies of the outer cell wall of these bacteria to clarify the mechanisms that affect their permeability and thus their susceptibility or resistance to antibiotics. Ultimately, Jassem hopes her research will lead to the development of new therapies for treatment in cystic fibrosis and chronic granulomatous disease.
Using real-time fMRI to modulate metacognitive thought processes in patients with recurrent unipolar depression
About 15 per cent of adults experience major depression at some time in their lives. This debilitating mental disorder can cause depressed moods, loss of energy, insomnia and, in severe cases, suicidal ideas and acts. Although current treatments such as antidepressant drugs and psychotherapy help a majority of patients, a significant number of people have a high rate of relapse. In recent years, several cognitive therapies have been developed to try to prevent relapse. One successful method trains patients to increase their ability to reflect on and change the direction of their own thoughts (called meta-cognitive awareness). Depression involves a reduction in certain parts of the brain. Functional Magnetic Resonance Imaging (fMRI) scans show depressed people have abnormally low activity in the front part of the prefrontal cortex, a region of the brain involved in planning cognitive behaviours and pleasure. fMRI scans also show an increased activation in this area of the brain when patients use reflective thinking. Kamyar Keramatian is investigating whether normal subjects and patients with depression can be trained to improve their own brain activation, by combining self-reflective therapy with real-time fMRI; a new tool that allows patients and researchers to see brain activation data as it is collected. If so, this approach could be an effective way to treat people who do not respond to conventional therapies.
Involvement of ErbB4 in excitatory and inhibitory synapse maturation
Synapses are the junctions across which signals are passed from one neuron to another. Generally, the type of input received through synapses can be classified into two categories: excitatory input increases the signal transmission, while inhibitory input reduces signal transmission. Problems that disrupt the coordination of excitatory and inhibitory inputs have been associated with the development of many severe psychiatric disorders, including schizophrenia. Recently, genetic analysis of families with a history of schizophrenia identified two genes potentially responsible for the onset of the disorder: Neuregulin1 (NRG1) and its protein receptor ErbB4. Daria Krivosheya’s recent research indicates that the ErbB4 protein receptor may help to stabilize existing synapses. Previous research has shown that ErbB4 interacts with PSD-95, a protein involved in regulating other proteins involved with excitatory synapses. Krivosheya believes interaction of the ErbB4 protein receptor with the PSD-95 protein may regulate the number of excitatory and inhibitory synapses formed by the nerve cell, while interaction with the NRG1 gene may stabilize synapses and promote branching out of dendrites, extensions of a nerve cell that conduct impulses from neighbouring cells. Krivosheya is investigating the role of NRG1-ErbB4 interaction at the synapse, as well as involvement of PSD-95 in mediating this interaction. Her goal is to explain the mechanism through which these molecules control excitatory and inhibitory synaptic balance. She hopes her research will ultimately help explain some of the physical or behavioral abnormalities associated with schizophrenia, and lead to the development of new therapies.
The role of toll-like receptors in autoimmunity in non-obese diabetic mice
More than 180 million people worldwide have either type 1 or type 2 diabetes. People with this condition are unable to maintain normal blood sugar levels due to a lack of, or insensitivity to, insulin, a hormone that regulates blood sugar levels. Whereas type 2 diabetes is usually caused by eating an unhealthy diet, type 1 diabetes is an autoimmune disease in which the affected person’s own immune system destroys the insulin-producing islet cells in the pancreas. Research shows that killer T cells (immune cells that normally attack virus-infected cells) cause type 1 diabetes by destroying islet cells. However, there has been little research completed to date regarding what causes T cells to attack the body’s cells. It has been hypothesized that sensors that recognize microbes like bacteria and viruses, called TLRs (toll-like receptors), may play a role. TLRs activate the immune system to fight off microbes; however, TLRs are also suspected of playing a role in the onset of type 1 diabetes. Andrew Lee is investigating whether a group of TLRs activate or accelerate the destruction of healthy cells in autoimmune diseases. Lee will also determine whether older, anti-malaria drugs and new designer DNA drugs can block these TLRs. Since symptoms of type 1 diabetes only appear when the pancreas is irreversibly damaged, this research could be used to identify people at risk of developing type 1 diabetes, and lead to new ways of preventing and treating the disease.
The role of the Rap1 GTPase in mediating the inflammatory and anti-microbial functions of macrophages
Large, white blood cells (called macrophages) play a crucial role in protecting the body against harmful viruses, bacteria and other substances, such as pollen, that the immune system recognizes as foreign. These cells trap the foreign substance and signal other cells in the immune system to start the inflammatory process needed to destroy them. Normally, the body tightly regulates the process ensuring that once the invader is destroyed, the inflammatory process is shut down to minimize damage to and promote healing in surrounding tissue. However, sometimes the process goes awry, such that the inflammatory process persists, which can lead to a variety of autoimmune diseases, including hay fever, atherosclerosis, and rheumatoid arthritis. Victor Lei is exploring whether a protein called Rap 1 is involved in activating the immune response to microbial infections by helping white blood cells find infected tissue and initiate inflammation. He is looking in particular to discover whether appropriate Rap1 levels create an effective response to infection, while excessive levels contribute to chronic inflammatory response that could lead to autoimmune diseases. The results of this research could help in the development of drugs that control Rap 1 activity to more effectively combat infections and prevent or minimize the chronic inflammation responsible for arthritis and other conditions.
Study of intercellular barrier alterations in enterocytes during Campylobacter jejuni pathogenesis
Campylobacter jejuni (Cj) is the leading cause of bacterial food poisoning in the world. Each year about 300,000 Canadians are infected by these highly invasive bacteria through ingestion of undercooked meats or dairy products. An acute infection causes diarrhea, fever, vomiting, and, occasionally, death. Cj infection may also lead to Guillain-Barré Syndrome, an autoimmune disease that causes weakness or tingling in the legs and arms. In some cases, symptoms can become so severe that the patient is almost totally paralyzed. Most people recover, although some continue to have some degree of weakness. Ann Lin is researching how Cj bacteria cause disease in the gastrointestinal tract. Cj is predominantly found in the first and last sections of the small intestine and the colon. The bacteria penetrate layers of cells in the intestine and infect underlying tissues. Lin is examining whether this process disrupts the intercellular junctions that provide integrity for host epithelial cells. Disrupting this barrier is believed to contribute to diarrhea, but the molecular process is not well understood. Lin will determine whether Cj causes gastrointestinal disease by damaging the barrier. Ultimately, her findings could lead to the development of new methods of preventing Cj infection.