The Role of beta-catenin Stabilization in the Synaptic Pathology of Alzheimer’s Disease

Alzheimer’s disease (AD) is a devastating neurological disorder characterized by the loss of cognitive function and an inability to process and store new memories, caused by the progressive death of neurons (brain cells). It is becoming increasingly evident that before neurons die, changes can be observed at their synapses – the junction between neurons across which information is transmitted. Deficits in synaptic function, loss of synapses, and a reduced ability to form new synapses are the major correlates of dementia. It is therefore crucial to understand the basic biology of synapses, and how these processes are affected in AD. The cadherin family of cell adhesion molecules and their intracellular partner, b-catenin, play a critical role in regulating the formation and remodelling of synapses. Both molecules also associate with presenilin-1 (PS1), a protein that normally degrades (breaks down) b-catenin. Mutations in the PS1 gene account for nearly 70 per cent of early-onset familial AD cases. Fergil Mills is investigating the effects on neurons when b-catenin is not normally degraded by PS1. Using isolated neurons and a mouse model, he is characterizing the synaptic consequences of stabilizing (maintaining) b-catenin in neurons, and determining the molecular mechanisms of b-catenin in the development of synaptic structures. These studies will help determine whether b-catenin stabilization leads to the synaptic pathology and cognitive deficits seen in AD. Mills’ studies will further our understanding of synapse pathology and cognitive deficits, and could lead to new treatments for patients with AD or other neurological disorders.

Exposure to asbestos in the slums of a sub-population of migrant ship dismantlers in Bangladesh

“Shipbreaking” is the dismantling and recycling of obsolete vessels, their hulls and superstructures. In Bangladesh, this work is carried out on beaches. Salvaged items are resold in local markets and workers and their families live in adjacent slums. Ships often contain hazardous substances such as polychlorinated biphenyls, heavy metals and asbestos, which are all recognized carcinogens. Most work is done without adequate training or protection, and there is high potential for exposures to toxic materials in the shipyards, shops and the community itself. According to the International Labour Organization, shipbreaking is one of the world’s most dangerous occupations. On average, one worker dies every week; the long-term consequences of mortality due to cancer and other chronic illnesses are unknown. Few studies have been performed in Bangladesh on the environmental impact of dismantling ships, the health of shipbreakers, or the impact on the surrounding community and maritime environment. Working in collaboration with local university and non-governmental organization researchers, Midori Courtice is measuring the concentration of asbestos in workers’ living quarters, in shops selling salvaged items, and in areas downwind of ship-dismantling operations. She will interview people about their knowledge, attitudes and practices with respect to their handling of, and hazards associated with, asbestos. Courtice’s findings will be made available to the participants and the local community, and her recommendations could inform local workshops on hazards and reducing risk. Her work will also provide the basis to approach policy makers and strengthen the link between research and policy, to raise awareness of personal health and safety among workers, and to build local capacity for future research on sustainable solutions related to the shipbreaking industry.

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.

Somatic and gametic loss of imprinting (LOI) in mammalian development: studies using a novel imprinted transgene on the mouse distal chromosome 7 (MMU7) imprinted region

Genetic inheritance primarily results from the interplay of dominant and recessive genes between two parents. With certain genes, however, gene expression is parent-of-origin-specific: these genes will always be expressed from either the maternal or paternal chromosome. This process is known as genomic imprinting, which creates a mark, or “imprint”, on the chromosome. Gametes are reproductive cells, such as sperm or eggs, which contain a single set of chromosomes. During their maturation, their imprints are erased then re-established. Between the erasure and re-establishment phases is a transitional loss of imprinting (LOI) state. Problems with the erasure or re-establishment of imprints in gametes can result in a number of human genetic disorders, including Prader-Willi, Angelmann, Silever-Russell, and Beckwith-Wiedemann Syndromes. In non-gamete tissues, on the other hand, imprints are generally thought to be maintained throughout life and LOI is often considered to be an abnormal condition. Both loss of epigenetic marks and loss of parent-specific gene expression are observed frequently in many types of cancers, but whether this is a cause or an effect of this abnormal growth is unclear. Meaghan Jones was previously supported by MSFHR for her early PhD studies in genomic imprinting. She is now working to determine more about what causes LOI events in both gametic and non-gametic tissues. She is using a model of Beckwith-Wiedemann Syndrome to determine when LOI occurs in cells, with the hope of pinpointing factors that can cause LOI. An understanding of normal LOI in development could help alleviate the risk of imprinting defects, and could improve effectiveness of medical technologies including assisted reproductive technologies, stem cells, nuclear transfer, and cloning.

Impact of maternal fatty acid nutrition in early development – a basic science and clinical approach

There is a growing appreciation that the n-3 fatty acids, particularly docosahexaenoic acid (DHA), are important for brain development and influence cognitive, behavioural and visual function. The richest source of DHA is found in fatty fish, leading to considerable interest in the importance of fish consumption during pregnancy. Important new data shows that about 40 per cent of British Columbian women have DHA intakes below projected requirements for fetal development, and that DHA levels in BC women’s breast milk are among the lowest in the world. During early human development, DHA is delivered from mother to baby by placental transfer (before birth) and via breast milk (after birth). Maternal intake of DHA affects the supply of DHA available to the developing fetus and infant. Currently, little is known about how DHA is transferred from mother to infant before birth, or what dietary DHA intake best supports human growth and development, and the secretion of DHA in human milk. Elizabeth Novak is conducting clinical projects to pinpoint how DHA is transported from mother to baby and to determine how much dietary DHA a mother must consume to achieve optimal levels of DHA in her baby both before and after birth. She is conducting a randomized controlled trial that tests supplementation with DHA during pregnancy. This will allow her to track maternal dietary DHA intake, blood levels of DHA, and newborn and infant blood levels of DHA and biomarkers. Novak’s studies on human milk will also involve collecting and analyzing human milk. She is also studying animal models to address questions regarding the importance of DHA in the developing fetal and neonatal liver. Ultimately, this research will result in dietary recommendations for n-3 fatty acids that support optimal development in babies.

Multimodal Imaging Instrumentation for Non-Invasive Functional Retinal Imaging

With an aging population comes an increase in a number of diseases and conditions of the eye. A recent advance in imaging – called optical coherence tomography (OCT) – provides a non-invasive way to create high resolution, cross-sectional images of inside the eye. OCT is particularly useful in providing these images of the retina, showing cross sectional images of the various layers with resolution equivalent to a low-power microscope and better than other imaging techniques such as magnetic resonance imaging (MRI).

A new technological development called Fourier Domain (FD) OCT provides these images much more quickly than existing systems. It has also been successful in creating three-dimensional images of the retina, which were previously not possible to obtain. However, clinical use of FD OCT is limited as it generates only an image of the eye’s structures, without providing any functional information about the biological processes at play.

Dr. Marinko Sarunic’s research builds on earlier work where he successfully combined FD OCT imaging with molecular contrast capabilities to provide functional information. He is now using this technology to determine its usefulness in retinal diagnostics, the study of disease processes, and the testing of new drugs and therapies. Development of FD OCT imaging techniques will help physicians better understand and manage ophthalmic conditions, through high resolution visualization and improved minimally-invasive, image-guided procedures.

Regulation of the Jun Transcription Factors in B Lymphocytes by the NEDD4 Family E3 Ubiquitin Ligase, Itch

Ubiquitin is a small protein found in all cells containing a nucleus. A key function for this protein is ubiquitylation, the process by which ubiquitin attaches to target proteins to “mark” them for degradation (breaking down) and removal from the cell. Ubiquitylation is an important process for maintaining proper levels of cellular proteins and removing mis-folded proteins to ensure proper cellular function and to prevent disease. E3 Ub ligases are important regulators of the ubiquitylation process because they select the specific proteins (substrates) that are to be degraded. Itch is an E3 Ub ligase that is important in the immune system, as mice deficient in Itch (Itchy mice) develop a fatal autoimmune-like disease. The Jun transcription factors, c-Jun and JunB, are found to be deregulated in the T cells of these mice, and this is believed to contribute to the disease. These proteins are also important for the proper function of B cells and their deregulation has been implicated in some B cell cancers, such as Hodgkin lymphoma. Joel Pearson is determining whether Itch also regulates the Jun proteins in B cells, and how this may contribute to the autoimmune-like disease of Itchy mice. He is also investigating whether Itch regulates the Jun proteins in B and T cell lymphomas where these proteins are expressed at unusually high levels. His hypothesis is that Itch is an important regulator of the Jun proteins in B cells. Furthermore, he believes that Itch is also an important regulator of the Jun proteins in B and T cell lymphomas where these proteins are over-expressed. Understanding how the Jun proteins are regulated in these cells is important for understanding how the autoimmune-like disease of Itch-deficient mice may arise. Deregulation of the Jun proteins also contributes to the pathogenesis of some types of B and T cell lymphomas. Because of this, understanding how they are regulated is important for understanding how these cancers arise and persist. It could also lead to the development of novel ways to treat these cancers.

The immunomodulatory effects of host defence peptides on dendritic cells

Modern day vaccines are effective at preventing infections such as tetanus, influenza, polio and many others. To ensure full protection from illness, some vaccines require more than one immunization. This is commonly known as a booster shot. In developed countries, getting vaccinated usually means nothing more than going to the clinic. In developing countries the process is not so straight forward. Limited access to, and availability of vaccines makes widespread immunization a difficult process. The fact that people may have to return for a booster shot only compounds the problem. For all of the above reasons, there is clearly a need for improved vaccines in developing countries. Our laboratory is studying ways to create effective single-dose neonatal vaccines for developing countries. This means the vaccine would be given shortly after birth, and there is no need for a booster shot to ensure complete protection. Such a vaccine would alleviate the previously described difficulties. Specifically, our lab is developing more effective vaccine adjuvants. An adjuvant is simply any component added to a vaccine that will interact with the immune system to improve protection. We believe that a class of proteins known as host defence peptides (HDPs) will act as effective vaccine adjuvants. HDPs are short proteins, found almost ubiquitously in nature (microorganisms, insects, plants and mammals for example). Historically, the function of HDPs has been primarily to kill invading bacteria and viruses. Recent research conclusively shows that some HDPs are capable of altering the way in which immune system responds to an infection. My research will focus on how HDPs interact with and important type of immune cell known as a dendritic cell. Dendritic cells (DCs) circulate in the body in an “”immature”” form. When they encounter anything foreign (for example, bacteria or viruses), they become “”activated,”” capture the invader, and alert the immune system so it can mount a full response. They are now said to be “”mature.”” For this reason, DCs are a very unique type of cell. They are part of the front line of defence, yet they are also critical in generating the full immune response, which develops shortly after. We believe that HDPs will influence DCs in such a way that they will promote an efficient immune response in the context of vaccination. I hypothesize that HDPs impact DC function, activation, and maturation by altering specific genes and proteins important to DCs. This hypothesis has lead me to develop five goals to guide my research. I will provide an overview of these goals: 1) Bioinformatics. My preliminary experiments have tracked how HDPs influence the expression of 16,000 genes in mouse DCs. Such a large amount of data needs to be handled by a computer. Using specially designed programs, I am able to sort through the vast amounts of data and determine the broad trends occurring in response to HDPs. Furthermore, I am able to look at how small groups of genes behave in the context of their larger gene families; 2) IRAK-4. Results show that one peptide altered the behaviour of an important protein called IRAK-4. IRAK-4 is known to be important for specific immune responses. I will further analyze how this protein functions in the presence and absence of HDPs and other immune stimuli in DCs. I will also determine how proteins related to, and dependent on IRAK-4 will behave in response to HDPs; 3) Lyn Kinase. Another interesting finding was the altered production of Lyn, another protein important for proper DC function. I will continue analyzing the behaviour of Lyn in DCs in response to HDPs. I will also study the consequences of Lyn deficiency and determine its effects on HDP function. 4) DC Type. There are different types of DCs depending on where in the body you look, each performing similar, yet distinct functions. Currently it is not known how different types of DCs respond to HDPs. A lot of DC research is done with mouse DCs because they are relatively easy to generate compared to their human counterparts. The comparative responses of human and mouse DCs to HDPs are not well understood. For these reasons, I will be experimenting in multiple DC types, and in both human and mouse DCs. 5) In vivo peptide effects. Using the previously described experiments as a guide, I will examine how HDPs affect whole mice. We have access to mice deficient in all of the genes listed above, and this will be useful in determining the role of specific genes on the scale of a whole animal. At the completion of this project, I will have gained a comprehensive understanding of how HDPs influence DCs, with the goal of using this information to provide better vaccine adjuvant candidates aimed at developing countries.

Development of a pipeline for the analysis of flow cytometry data

Flow cytometry (FCM) is a method of sorting and measuring types of cells by fluorescent labelling of markers on the surface of the cells. It plays a critical role in basic research and clinical therapy in the areas of cancer, HIV and stem cell manipulation. For example, it can be used to diagnose some types of cancer, based on which labelled antibodies bind to a particular cell’s surface. It is widely recognized that one of the main stumbling blocks for FCM analysis is in data processing and interpretation, which heavily relies on manual processes to identify particular cell populations and to find correlations between these cell populations and their clinical diagnosis and outcome (e.g. survival). Manual analysis of FCM data is a process that is highly tedious, time-consuming (to the level of impracticality for some datasets), subjective and based on intuition rather than standardized statistical inference. Dr. Ali Bashashati has developed a “pipeline” for automatic analysis of FCM data – a computational platform that can identify cell populations, find biomarkers that correlate with clinical outcomes, and label the samples as normal or diseased. Preliminary evaluations of this pipeline have shown accuracy levels of more than 90 per cent in identifying some sub-types of lymphoma. Moreover, a biomarker that contributes to a more aggressive behaviour of a specific sub-type of lymphoma has been discovered. Bashashati is now testing and refining the platform to improve its analytical power and applicability to a range of FCM data, testing its performance across a number of ongoing FCM studies in BC. Ultimately, he hopes to provide an accurate, powerful computational platform to increase the efficiency of using FCM for research and clinical purposes.

Modulation of ocular motor decisions by reward: an investigation of neural processes using converging methods

The prospect of reward or punishment is known to affect how people make decisions. However, it is not clear which neural systems are involved in this process. This is an important topic in healthcare, because impaired processing of reward information is known to affect the decision-making abilities of many people, including those with damage to the frontal lobe of their brains, Parkinson’s disease, depression/anxiety, obsessive compulsive disorder, and even normal aging. A striking example of this situation occurs among some people with Parkinson’s disease, who can develop pathological gambling behaviours as a result of taking dopaminergic drugs. An effective way to study these neural systems is to track eye movement decisions – in other words where people focus their visual attention. Typically, people are faster to make an eye movement and are more accurate in their eye positions when the movement is rewarded by monetary gain. However, these effects are degraded in certain psychiatric conditions, such as anxiety and depression. Dr. Linda Lanyon is investigating the brain circuits that mediate these reward-related decisions in healthy humans. Her findings will enable her to develop a computer model of the brain circuitry and function that is able to simulate the behaviours observed in humans. In addition to demonstrating how these systems operate in healthy humans, the computer model can also be selectively damaged in order to simulate pathological behaviours observed in patients. By using healthy subjects to create a computer model for decision-making, Linda hopes to improve the understanding of the pathology of neurologically-impaired circuits.