The ability of an organism to perceive its environment and to respond accordingly is a key survival factor for any species. An important example of environmental sensing is the evolution of antibiotic resistance among bacteria, which is a significant challenge for fighting and containing infections in hospital and community settings. These adaptations by disease-causing bacteria allow them to sense the presence of drugs and respond by producing agents to resist the antibiotic. Multidrug resistant bacterial strains have emerged and are increasing in frequency, making treatment more costly and such infections more lethal. Dr. Gerd Prehna is studying the structures and pathways within bacteria that enable this to happen. He is studying in salmonella a novel antivirulence pathway that regulates bacterial populations within the host. Disruption of this process would lead to an unorganized effort by a bacterial infection to maintain itself within a host, reducing its ability to cause illness. He is also studying methicillin resistant staphylococcus aureus, or MRSA, which has evolved a complex sensor molecule that binds to antibiotics and then relays a signal for the bacteria to express resistance factors. By solving the complete three-dimensional structure of this antibiotic sensor, he hopes to determine the mechanism by which this signal is relayed. By learning more about how disease-causing bacteria detect antibiotics, communicate with each other, and collectively mount a defense against these drugs, Prehna hopes this knowledge might be exploited to block sensory and communication pathways, making the bacteria once more susceptible to antibiotics.
Program: Trainee
Structural and kinetic studies into eukaryotic sialyltransferases
The outer surfaces of mammalian cells are covered with a dense and complex array of sugar molecules. These sugars are important in many essential biological processes such as cell recognition, communication, neuron growth and immune defence. However, they are also used as attachment sites by a diverse range of disease-causing microbes and their toxins, and have been implicated in tumour cell metastasis. Many of these sugar-containing structures contain an essential sugar, sialic acid. The enzymes that transfer sialic acid onto these sugar structures are known as sialyltransferases. These enzymes are able to recognize numerous different types of sugar configurations. In fact, the human genome encodes at least 20 distinct sialyltransferases. Despite the importance of these enzymes, researchers know little about their molecular structure, their mechanisms, how they recognize their targets or how they are regulated. Dr. Francesco Rao is investigating the structure and mechanism of a mammalian sialyltransferase. This will give, for the first time, insight into how such enzymes work at the molecular level. This information could also be used to determine ways these enzymes could be therapeutically inhibited to combat infection or cancer metastasis.
Engineering of carbohydrate processing enzymes for generation of therapeutic glycoproteins with increased serum halflife
Biopharmaceuticals are molecules produced using biotechnology, rather than chemistry, for therapeutic purposes. Biotechnology uses microorganisms (such as bacteria or yeasts) or biological substances (such as enzymes) to manufacture pharmaceutical compounds. Many biopharmaceuticals are very large proteins, which show considerable promise in the treatment of a wide range of diseases. Unfortunately, owing to the complex mechanisms that the body requires to regulate its own proteins in the bloodstream, foreign proteins in the form of medicines are typically rapidly destroyed or removed from the circulation by the body. Sugars found on the surface of mammalian proteins protect provide protection from destruction by circulating protein-degrading enzymes. They also provide a signal when it is time for a protein to be removed from the blood. Dr. Jamie Rich is investigating whether adding specific sugars to protein drugs could help them last longer in the bloodstream and be more effective. He is working to develop an enzyme that can “build” a particular type of sulphur-containing sugar onto the surface of the protein drug. This promises to protect the protein from degradation, prevent the exposure of sugar-based clearance signals, and allow the protein to function normally as an effective long-lasting drug. Creating longer-lasting drugs would reduce the required amount and frequency of dosages, resulting in reduced drug costs. If successful, this approach could be applied to a wide range of proteins that are currently used as drugs or are in the drug development stage.
Chondrogenic gene expression in repetitive-use tendon injury
Tendon has to withstand high tensile forces to do its job properly, acting as a mechanical link between muscle and bone to allow joint movement. Repetitive-use tendon injury, known as tendinopathy, affects workers in many key Canadian industries, as well as professional and recreational athletes. Standard anti-inflammatory treatments are unsuccessful in treating tendinopathy, and new treatments are needed to relieve the burden of chronic tendon pain. Normal tendon is composed of rope-like molecules (type I collagen). In contrast, in tendinopathy the collagen can become spongey – like in cartilage (type II collagen). The tendon becomes less able to resist tensile forces, and more prone to microtearing, pain and rupture. Dr. Alexander Scott is investigating what triggers tendon cells to switch their metabolism to produce less type I collagen and more type II collagen. Scott is conducting a combination of molecular and biomechanical studies both with tendon fibroblasts and with tendon progenitor cells. Scott is also studying transcriptional regulation during tendon injury using a transgenic reporter system, and in patients with tendinopathy. Scott’s research is aimed at developing evidence-based treatments for chronically painful tendons. Ultimately, this could open up new therapeutic options for restoring tendon health.
In vivo analysis of novel neuronal synapse promoting proteins
Brain cells communicate with each other at junctions called synapses. Changes in synapses underlie important cognitive processes such as learning and memory. Synapse development requires communication proteins on either side of a synaptic junction. Previous research has identified genes called leucine-rich repeat transmembrane (LRRTMs) proteins, which promote formation of mammalian synapses. These novel genes are able to promote synapse formation between neighbouring cells. LRRTMs have recently been shown to be associated with neurological disorders, including schizophrenia and late-onset Alzheimer’s disease. Mutations in functionally-related proteins have also been directly been linked to autism and mental retardation. Dr. Tabrez Siddiqui is studying how synapses are formed and modified by experience. He is working to fully characterize LRRTMs in mouse models, studying the role of LRRTMs in brain morphology and synapse development. He will also identify proteins that interact with LRRTMs across the synaptic junction. A detailed study of LRRTMs and their binding partners will lead to a greater understanding of how brain cells interact with each other, and will shed light on the molecular basis of neurological disorders.
Predicting treatment response in Hodgkin Lymphoma by identifying new molecular markers
Hodgkin lymphoma is the most common type of malignant lymphoma in young people in the Western world. Despite modern treatments, about 20 per cent of patients die. Present studies have tried to identify ways to predict which patients are likely to be cured, using characteristics such as age, stage (degree of spread of the lymphoma), blood tests and x-rays or scans. However, these predictions are often inaccurate. Other genetic approaches to testing have proved difficult because malignant cells are present in very low numbers. Dr. Christian Steidl’s research focuses on developing tests to identify patients who will not be cured with current standard therapy, so that they may enrol in clinical trials testing innovative, new treatments. He is using a laser beam to capture individual malignant cells within lymph nodes so they can be studied separately from the surrounding non-malignant cells. This enables him to investigate how the genetic material in the malignant and non-malignant cells is altered and how this affects the behaviour of these cells – leading to the identification of markers that can predict treatment response. With a better understanding of the markers that can predict treatment response, physicians will be able to choose the right therapies for patients with Hodgkin lymphoma. This will help prevent both insufficient treatment and excessive treatment, which can lead to toxic side-effects. Identification of genes that are important for the malignant cells to survive will also help to develop new drugs that specifically target these cells.
Pharmacogenomics of anthracycline-induced cardiotoxicity in childhood
Serious adverse drug reactions (ADRs) are the fourth leading cause of death and illness in the developed world, claiming many lives and costing billions of dollars each year. Children are especially at risk for ADRs: an estimated 15 per cent of all children admitted to hospitals get ADRs. Although many factors influence the effect of drugs, such as age, weight and organ function, genetic factors account for a great proportion. Small genetic differences between patients can cause serious ADRs. One group of drugs, called anthracyclines, are an effective treatment for many children and adults with cancer. However, they can sometimes be very harmful or damaging to the heart (cardiotoxicity), resulting in life-long drug treatment, the need for heart transplantation, or death. Dr. Henk Visscher is working to find the genetic factors behind this phenomenon. He is comparing gene variants between children who have experienced severe cardiotoxicity after receiving anthracyclines with children who did not. Using high-tech machines, he can screen for thousands of gene variants at the same time, making it more likely to find the gene(s) involved. Once identified, he will conduct a number of studies to confirm that the identified gene variants are the “culprits.” Visscher plans to create a diagnostic test based on the variants that can predict cardiotoxicity in patients taking anthracyclines. This would enable physicians to identify at-risk patients before they take the drugs, allowing them to adjust the dose, choose a different drug or monitor a high-risk patient more closely. Ultimately, this may help prevent potentially fatal heart disease among cancer survivors.
Functional analysis of the tumour suppressor ING1b Ser126 phosphorylation
In 2006, it was estimated that 153,100 new cancer cases were diagnosed in Canada, and 70,400 patients died of cancer. Improving our understanding of the molecular changes in cancer development is essential for designing more effective strategies for cancer prevention and treatment. In the past few years, studies on the biological functions of the tumour suppressor ING1b have attracted much attention in the scientific community. Dr. Aijaz Wani and his colleagues have found that ING1b can enhance DNA repair and promote programmed cell death – key biological functions that prevent cancer cells from developing and growing. However, information on the regulation of ING1b expression and its activity is lacking. Wani’s recent studies have uncovered that that the amino acid serine 126 attaches a phosphate group to ING1b, a process known as phosphorylation. He also confirmed that serine 126 phosphorylation is essential for ING1b protein stability. Now, he is investigating in detail how serine 126 phosphorylation of ING1b regulates the biological functions of this tumour suppressor. Wani’s research will provide new insights into the mechanisms on the regulation of ING1b activity and its biological functions. Ultimately, this work may lead to novel strategies for cancer prevention and treatment.
Conditional genetic screens to define gene-gene and gene-drug interactions in normal and malignant human cells
Approximately eight per cent of breast cancers are caused by inherited mutations in genes called BRCA1 and BRCA2 (BReast CAncer 1 and 2). Since the BRCA genes were first identified in patients with inherited breast cancer, it has become obvious that they are also mutated in many non-inherited cancers. Understanding their function in normal and tumour cells is therefore an important problem in breast cancer research. Genes usually carry out their functions through interactions with other genes, organizing the different steps into pathways. Cells often use two or more different pathways to respond to the same stimulus. For example, there are multiple pathways that repair damaged DNA; one involves BRCA2, while a gene called PARP1 is involved in other pathways. Even when radiation and chemotherapy disable the BRCA-2 pathway, the intact PARP1 repair pathways may compensate and enable the cancer cells to survive. PARP1 inhibitors are currently undergoing clinical trials at various centres, including the BC Cancer Agency. Dr. Hong Xu is identifying interactions between the BRCA2 and PARP1 DNA repair pathways. She is also screening for gene mutations that make normal and BRCA2-mutated breast cells more sensitive to PARP1 inhibitors, which could help physicians determine appropriate doses based on a tumour’s genetic profile. Xu’s work will enhance our understanding of the roles of BRCA2 and PARP1, and accelerate the development of new individually tailored therapeutic treatments for breast cancer.
Cognitive contributions to checking compulsions
Obsessive-compulsive disorder (OCD) is an anxiety disorder that afflicts three percent of all Canadians. The disorder is characterized by intrusive and unwanted thoughts, images or impulses that cause anxiety, and that are temporarily relieved by the execution of specific compulsions. Obsessions and compulsions can occupy a large proportion of individuals’ time and energy and can interfere with daily routines, functioning at work, social activities and relationships with others. Checking compulsions are among the most common manifestations of OCD. Individuals with checking compulsions have intrusive concerns that they have failed to perform some task (such as locking the door or turning off the stove) and feel compelled to repeatedly check to ensure that the task was indeed completed. Preliminary evidence suggests that impaired prospective memory may play an important role in checking compulsions. Prospective memory is the ability to remember plans and intentions at a later moment. Everyday life and clinical observations show that checkers’ compulsions are related to this future-oriented aspect of memory and that the types of activities that tend to trigger checking compulsions are prospective memory tasks. Dr. Carrie Cuttler was previously supported by MSFHR with two research training awards. Her current work continues her exploration of whether individuals with checking compulsions have a cognitive deficit related to prospective memory. She hypothesizes that checking compulsions may develop to compensate for an impairment in prospective memory. In other words, individuals who frequently forget to perform tasks may develop a strategy of repeatedly checking to ensure that important tasks are not forgotten. Cuttler’s research focuses on improving our understanding of the mechanisms underlying OCD. The results will improve the quality of OCD patients’ lives by setting the stage for more effective treatments for reducing the frequency of checking compulsions.