The role of secreted protein acidic rich in cysteines (SPARC) in neurogenesis and gliogenesis in the embryonic and adult mouse brain: applications to models of Cerebral Ischemia Reperfusion Injury

Stroke is the primary cause of adult disability in Canada. Recovering brain function after stroke is dependent on the brain’s ability to rewire itself and replace tissue that has died during the stroke – something that is difficult to achieve in the adult brain. Rewiring the brain requires that existing neurons sprout new fibres (axons) and connect to other neurons in a way that allows proper functioning of neural circuitry. Recovery also involves the birth of new cells to replace dead cells and to form functioning connections with new and existing neurons. These processes all occur within the extracellular matrix (ECM) – a network of fibrous proteins, gel-like sugars and linking molecules – and are promoted by a large number of growth factors and intercellular signalling molecules. Anthony Berndt’s research focuses on the role of the SPARC protein in the generation of new neurons. SPARC binds to the ECM and regulates the potency of growth factors that normally promote cell division and migration. Berndt is examining the influence of SPARC on the development of the embryonic brain and on the generation of new neurons in the adult brain. His studies will determine if SPARC’s presence or absence affects the rate or manner in which brain tissue regenerates after stroke. He hopes to formulate an approach that will prompt neural stem cells normally found in the adult brain to follow the developmental steps required to form functional tissue after stroke. By understanding the function of SPARC after brain injury, he could also determine at what point of recovery such an intervention would be of greatest use. By understanding the role of SPARC, Berndt’s research could eventually lead to improved therapies for treating major brain injuries by augmenting the body’s natural repair processes.

Peripheral neurophysiological basis of sensorimotor deficits in individuals with essential tremor

Essential tremor (ET) is a neurological disorder characterized by shaking of the hands (and sometimes other parts of the body) that occurs with voluntary movement. Often mistaken for Parkinson’s disease, it is the most common tremor disorder. Approximately 75 per cent of people living with ET experience some limitation in their activities, and these limitations typically get worse with increasing age. Therapies for essential tremor focus on tremor reducing medications, but effective treatments remain limited. Consequently, new insights into disease mechanisms are needed to guide the development of more effective therapies. The origins of essential tremor are believed to involve abnormal rhythmic activity in the brain, which then travels down to the peripheral nervous system. However, the specific neural pathways that the tremor travels, as well as how ET influences the recruitment of muscles for movement, remains unclear. Also unknown is the impact of tremor on sensory receptors found within skeletal muscles, which provide the sense of position and movement of the limbs. Dr. Martin Héroux is conducting studies on British Columbians with ET to determine how their muscles and sensory receptors are affected by abnormal rhythmic activities of essential tremor. He hopes these studies will increase our knowledge of the neural mechanisms involved in the generation of essential tremor and provide a better understanding of the motor-sensory deficits associated with tremor disorders. Ultimately, this knowledge could contribute to the development of more effective anti-tremor therapies.

Regulation of T Cell Development, Function and Transformation by Interleukin-7.

Immune disorders – such as immunodeficiencies, leukemia and lymphoma, autoimmunity, and allergy – are significant health problems. For example, every year 5,600 Canadians people die of cancers of the immune system, such as leukemia and lymphoma, and these cancers account for 42% of all cancers in children. Current treatments for these cancers, such as chemotherapy and radiation therapy, have significant shortcomings. To improve recovery rates and reduce unwanted side effects, researchers need to develop new, specifically targeted treatment approaches. Treating diseases with few side effects requires knowing the signals involved in disease development. Dr. Ninan Abraham is focusing his research on understanding how a cytokine called interleukin-7 (IL-7) regulates immune cells by interacting with proteins to trigger biochemical pathways that control normal cell development and function. IL-7 is an essential growth factor that promotes the development of T cells and memory T cells, which are both essential for the body’s response to pathogens that lead to disease or infection. Being able to enhance development or survival of T cells by manipulating IL-7 could lead to the creation of more effective vaccines to boost the body’s immune response to disease. Conversely, since over-expression of IL-7 is associated with several forms of human T cell lymphoma, being able to limit this cytokine’s activity could also be important. By identifying how IL-7 promotes the development or survival of T cells and memory T cells, Abraham hopes for new strategies for treating these cancers and enhancing vaccines for long-term immunity.

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.

Examining the role of N-linked glycosylation on the maturation and cell surface trafficking of hyperpolarization-activated cyclic nucleotide-gated (HCN) pacemaker channels

Cardiovascular disease remains the number one killer in British Columbia. These diseases include cardiac arrhythmias, which cause the heart to beat too slowly, too quickly, or in an uncoordinated fashion. Arrhythmias arise from dysfunction of the heart’s natural pacemaker: the sinoatrial node. The sinoatrial node consists of a group of cells responsible for generating the electrical impulse that controls normal rhythmic contraction and relaxation of the heart. In order to generate these electrical impulses, these cells possess a group of proteins known as ion channels. These proteins allow ions to selectively cross the cell membrane barrier, generating an electrical impulse that spreads to neighbouring cells. One particularly important family of ion channels are the HCN or ‘pacemaker’ channels which are responsible for generating the spontaneous activity of the sinoatrial node. The assembly and trafficking of these channels to the cell membrane is vital for ensuring our hearts beat in a regular fashion. How the cell accomplishes this task remains an unanswered question. Hamed Nazzarisedeh’s research attempts to uncover the underlying mechanisms that help regulate or contribute to the trafficking of HCN channels in the heart. Specifically, he is examining the role in which N-linked glycosylation of these proteins may factor in this regulation. His research will contribute to further our knowledge about how various forms of cardiovascular disease associated with HCN channel disruption arise in the heart. Ultimately, this work could aid in the discovery of novel treatment strategies.

Viral host interactions of the Dicistroviridae family

All successful viruses have evolved strategies to infect host cells and disrupt normal cell functions. However, the host can counteract these strategies by using its natural antiviral responses to detect and defend against viruses. Revealing the molecular mechanisms between the battle of the virus and host is vital in the fight against many of today’s viruses. Some viruses use an internal ribosome entry site (IRES) to infect cells. Molecular machines in cells called ribosomes translate genes into proteins, but viruses with an IRES can hijack the ribosome to replicate their viral proteins instead. IRESs are found in a number of human viruses, including polio, hepatitis C, herpes and HIV, but there is limited understanding of how these mechanisms work. Understanding the ways in which a virus hijacks the ribosome function is the focus of Dr. Eric Jan’s laboratory. He uses a unique IRES found in an insect virus called the cricket paralysis virus (CrPV). Jan’s previous work was critical in delineating important CrPV IRES functions. Building on this work, he plans to map the specific IRES elements that interact with the ribosome. He will also determine how CrPV disrupts cellular function that leads to IRES activity in Drosophila (fruit fly) cells, and elucidate the host antiviral response in these cells. The study of Drosophila antiviral responses will contribute to knowledge about fundamental virus-host interactions in humans. The research could lead to new drug targets for inhibiting viral IRESs and therapies that can augment antiviral responses. An exciting future goal will be to exploit viral IRESs to prompt the destruction of virus-infected cells – taking advantage of a viral mechanism against itself.

Wnt signalling during avian facial morphogenesis

It is estimated that 1 in 800 babies is born with cleft lip with or without a cleft palate, making CL/P the most common craniofacial malformation in humans. The lip forms during the early embryonic period in utero, at which time the face is very different from its appearance after birth. Initially, there are separate swellings that surround the oral cavity, several of which grow together and fuse in order to make a continuous smooth upper lip. Dr. Poongodi Geetha-Loganathan is determining the molecules that are required for normal lip fusion, focusing the roles of Wnt genes in the control of facial growth. She is using chickens as a model for facial development, observing through windows made in the shell how the beak develops, and the role of different proteins or DNA. This work will help researchers find those changes in genes that give rise to clefts. In the long term these discoveries will lead to identification of new genes that cause human orofacial clefts, potentially suggesting ways to prevent this common birth defect.

Neuroimaging and quality of life of children with developmental coordination disorder

Developmental coordination disorder (DCD) affects six to 15 per cent of children aged five to 11. In BC, up to 48,000 of children may meet the diagnostic criteria for DCD. Children with DCD have significant motor coordination difficulties that interfere with their academic achievement and/or activities of daily living. While it was once believed that children with DCD would outgrow their motor difficulties, research suggests that these difficulties persist into adolescence and adulthood. Individuals with DCD tend to avoid social and physical activities, are at higher risk for obesity and coronary vascular disease, and experience social and emotional difficulties. There is some suggestion that DCD is related to differences in brain development, but this has yet to be confirmed. No studies have been conducted to determine how the brains of children with DCD differ from those of typically developing children, and few studies have explored the quality of life of children with this disorder. Jill Zwicker is exploring the neurobiological explanations for children with DCD, and studying how DCD impacts their quality of life. She is examining patterns of brain activation of children with and without DCD using neuroimaging techniques to determine differences in brain anatomy and activation during a fine-motor task. Zwicker will also be interviewing school-age children with DCD to determine how the disorder affects their quality of life. Zwicker’s findings will be used to educate physicians and therapists in BC and beyond regarding DCD. In the longer term, these efforts will lead to the development of scientifically grounded rehabilitation approaches specifically targeted towards enhancing brain activity, function and quality of life for children with DCD.

Expiratory flow limitation, dynamic hyperinflation and respiratory muscle fatigue during exercise in men and women

The act of breathing is a complex physiological process involving the interaction of numerous respiratory muscles and a neural control network. These respiratory muscles are the only skeletal muscles in the body whose functioning is necessary to sustain human life, making their ability to resist fatigue very important. Despite this, research has shown that high intensity exercise can induce respiratory muscle fatigue. Given the life-sustaining role of the respiratory muscles, it is important to understand the mechanisms of fatigue, how it is best detected, and how the human body responds and adapts to fatigue. Also, research suggests that physiological and anatomical differences may make women more susceptible to respiratory muscle fatigue compared to men. However, there are no studies that have systematically examined sex-based differences in respiratory muscle fatigue, and the “normal” pulmonary response to exercise in women is not well understood. Jordan Guenette was previously funded by MSFHR for his early PhD work identifying the respiratory limitations women face as they age. Now, he is examining the mechanisms and consequences of respiratory muscle fatigue in men and women during whole body exercise. His study will determine if the smaller lungs and airways in women cause greater respiratory muscle fatigue compared to men. He will also investigate whether high levels of respiratory muscle work reduce blood flow to other parts of the body and are responsible for impairment of whole body exercise performance. Guenette’s project will address questions significant to both basic and clinical science, outlining how men and women differ with respect to the normal pulmonary physiology of exercise. His findings have the potential to influence exercise rehabilitation programs for a variety of patient populations, and exercise prescription to prevent disease in healthy individuals.

Inhibition of productive influenza A virus (H5N1) infection by secretory pathway SERine Protease INhibitors (serpins): A basis for the development of novel antiviral therapy

The potential for a pandemic outbreak of highly pathogenic avian influenza A strains, such as H5N1 or H7N3, is a serious and growing public health threat. Currently, a major limitation in pandemic preparedness is the difficulty associated with the timely development and distribution of a vaccine, as it is impossible to precisely predict the nature of a coming virus until a pandemic has already begun. Moreover, current antiviral treatments that target influenza virus components can be toxic, and can be overcome if the virus develops drug resistance. An alternative approach to antiviral drug design is to target host cell components that are required for viral infection, which eliminates the chance of antiviral resistance. A key step during influenza infection is entry of the virus into the host cell via fusion of viral and host cell surfaces. This process relies on the cutting and structural change of a virus surface protein, which in avian influenza strains is accomplished by an enzyme from the host cell. Recently, a novel, naturally-occurring inhibitor of this host enzyme was discovered in fruit flies. Heather Braybrook is investigating whether this inhibitor can prevent H5N1 virus entry and subsequent widespread infection. She will evaluate its effectiveness and toxicity in a cell culture model of influenza infection and study the mechanism of inhibition in further detail. Her studies will shed light on whether this type of inhibition could be used to reduce avian influenza infection in humans. Braybrook’s research may contribute to the development of novel and diverse antiviral therapeutics in the face of a potential influenza pandemic.