Parvoviruses are small, single stranded DNA viruses that must enter the nucleus of their host cells in order to replicate. Because of their ability to target and kill rapidly dividing cancer cells, parvoviruses have recently gained attention as potential vectors (carriers) for use in cancer gene therapy. Although research has led to a better understanding of cell entry and trafficking of parvoviruses, little is known about how parvoviruses are imported into the nucleus. Sarah Cohen is continuing her earlier MSFHR-funded research which examined how a specific parvovirus, Minute virus of mice (MVM), enters the cell nucleus. Cohen’s research discovered that MVM selectively breaks down the membranes surrounding the nucleus, the nuclear envelope (NE), in the early stages of infection. Now, she is investigating how parvoviruses disrupt the nuclear envelope of host cells and whether this disruption allows the MVM access into the cell nucleus. Cohen’s goal is to determine whether parvoviruses initiate the process leading to cell death (apoptosis) early in an infection. If so, it may be possible to boost the anti-cancer activity of parvoviruses, by engineering them to produce additional proteins that can kill cancer cells. Ultimately, this research could show MVM is a viable anti-cancer agent for clinical studies.
Research Pillar: Biomedical
The regulatory role of matrix metalloproteinase-8 in inflammation and autoimmunity
Rheumatoid arthritis affects one in six people. Although the specific trigger is unclear, the condition occurs when the immune system mistakenly attacks tissue within the joints. Symptoms include swelling, pain, stiffness and redness caused by an accumulation of white blood cells in and around the joint. When the inflammation persists for a long time, it may cause irreversible cartilage damage and bone erosion, leading to deformity and disability. In her previous MSFHR-funded research, Jennifer Cox examined molecular influences on the immune system. Now she is focusing on understanding the inflammatory process in the development of arthritis. Jennifer is studying MMP-8, a member of a family of enzymes called matrix metalloproteinases that function to break down proteins in the body. This process, called proteolysis, is essential for normal immune responses. However, an unusually high level of MMPs may contribute to diseases such as arthritis and cancer. For example, elevated levels of MMP-8 are present in patients with rheumatoid arthritis. Jennifer is researching whether MMP-8 contributes to the progression and severity of the disease, or conversely if the high levels of enzyme are protecting against inflammation. Her findings will contribute to a better understanding of the inflammatory process and potentially to new methods for treating rheumatoid arthritis.
Epigenomic variation in normal and cancer cells
Tumour suppressor genes (TSGs) are DNA blueprints for proteins that stop cells from dividing and increasing in numbers. Each TSG comes in pairs called alleles: one from the mother and one from the father. Cancer is caused by the uncontrolled division of cells; in order for cancers to grow, both tumour suppressor alleles need to be turned off. It was previously thought that the only way to turn off genes like TSGs was through permanent changes to the normal DNA sequence, called mutations. However, another way to turn off genes is to add small chemical “tags” – called methyl groups – to a gene. This causes the DNA blueprints to fold up and become unreadable. Another complexity is that some regions of DNA that are normally folded up because of methylation become de-methylated as cancer progresses. This turns on cancer-promoting genes and increases DNA instability. Therefore, it is important to determine the DNA methylation patterns of all DNA in cancer cells in order to know what and how genes are turned on and off. Jonathan Davies previously received a Junior Graduate Studentship from MSFHR. Now funded with at Senior Graduate Studentship, he is researching techniques to identify genes and regions in normal and cancer genomes that may be turned on or off by DNA methylation. These techniques could be used to tailor treatments to individual patients, leading to improved recovery rates, and avoiding costly and ineffectual treatments.
In vivo imaging of neuronal growth and connectivity during activity-dependent learning within the developing brain – exploring the link between morphology and function
In development, neurons form complex connections within the brain that ultimately determine how you think, how you feel, how you act and how your body communicates with itself. In the past, researchers believed that our genes were the main determinants of brain development. Now an increasing number of studies show that conditions in our surroundings can influence our internal brain plan during early life and in later years. One of the most interesting questions in brain development is whether the shape and structure of individual neurons is connected to the function that those neurons play within our brains. Using real-time imaging of the shape and structure of single neurons during development, Derek Dunfield is investigating how neurons grow and connect with each other and how external activity influences these connections. His studies include using external activity to modify the functions of neurons and see if this affects their structure. By developing a better understanding of the connection between a neuron’s function and its growth or ability to form brain circuit connections, Dunfield’s research could provide useful knowledge about how information is stored within our brains. The study of how external activity modifies both the structure and function of neurons may shed light on how aberrant brain circuits form and can lead to disabling brain disorders later in life.
In Vivo Evaluation of the Potential Role of Anti-Inflammatory Factors Involved in the Survival and Mechanism of Action of hRPE-Cell Implants for Parkinson's Disease
Parkinson’s disease is a neurodegenerative disorder that causes tremors, muscular rigidity, slowness of movement and postural instability. Affecting up to three per cent of the elderly population, Parkinson’s is characterized by depletion of the neurotransmitter dopamine and chronic inflammation in the substantia nigra region of the brain. While various pharmacological treatments alleviate symptoms of the disease, these medications eventually lose effectiveness and cause debilitating side effects. Cell-based transplantation therapies are being studied as alternative treatment options for Parkinson’s disease, but the routine use of these therapies has been delayed by mixed clinical results, safety and logistical concerns, and ethical issues. Recently, human retinal pigment epithelial (hRPE) cells have been proposed as a tissue transplant alternative for Parkinson’s disease and are currently being used in Phase II clinical trials. Found in the inner retina, hRPE cells are easily grown in culture so that a single donor can provide sufficient tissue for multiple recipients. Several studies have shown sustained reversal of Parkinsonian symptoms after hRPE implants with minimal side effects. Especially interesting is early evidence suggesting that transplanted cells may have the potential for long-term survival without requiring immunosuppressive drugs. However, little is known about the mechanisms of action of hRPE cells. Joseph Flores is researching the survival of implanted hRPE cells and the ability of implanted hRPE cells to replace depleted dopamine and induce a long-term anti-inflammatory response. A better understanding of hRPE-cell implants may lead to its routine use as a therapeutic alternative for Parkinson’s disease and improved outcomes for patients.
Genetic and epigenetic studies of innate immunity related genes in the development of asthma in childhood: the role of airway epithelial cells
Asthma is the most common chronic disease in children. It affects eight to 10 per cent of the population in developed countries, and rates are increasing. Susceptibility to asthma and other allergic diseases runs in families, which indicates that genes influence its development. However, numerous studies examining the influence of changes in the genetic code have led to inconsistent results. A possible explanation for the inconsistency is a failure to account for epigenetics. This emerging field of study involves investigating the basis of inherited traits that affect how genes function without affecting the sequence of the underlying genetic code. The airway lining cells, or epithelium, are a promising cell type in which to identify novel mechanisms of asthma. Jian-Qing He is studying cultured airway epithelial cells from 150 asthmatic and non-asthmatic children to explore whether a combination of genetic and epigenetic changes in immunity-related genes are central to the development of childhood asthma. Results from this study will allow for a better understanding of how genetic and epigenetic differences in epithelial cells are related to the development of asthma. Potentially, such knowledge could contribute to the development of more effective methods of screening for susceptibility to asthma and better preventive strategies.
The excitatory and inhibitory synaptic balance in neurodevelopmental disorders: the role of neuroligins
Neurodevelopmental disorders result from gaps, delays or variations in the way a child’s brain develops, often interfering with learning, behaviour and adaptability. Research has shown that neurodevelopmental disorders have a strong genetic basis, yet the genes involved have not been clearly identified. The onset of disorders such as autism, fragile-x and Rett syndrome occurs after neurons have developed, during the time connections between neurons (synapses) are being formed to facilitate transmission of signals from one neuron to another. These disorders may, therefore, result from altered synapse formation and maintenance. Some of the genes thought to be associated with these disorders produce proteins involved in synapse formation and maintenance. Alterations in the size, form and structure of synaptic components have been demonstrated in fragile-x syndrome, Rett syndrome and autistic spectrum disorders. This suggests that these diseases are associated with abnormal or halted synaptic development and maturation. Building on her MSFHR-funded Master’s research, Rochelle Hines is studying specific proteins involved in synapse formation and maintenance to assess whether and how they contribute to the development of neurodevelopmental disorders.
Elucidating the function of Bardet-Biedl Syndrome (BBS) proteins in Intraflagellar Transport (IFT)
Cilia are fine, hairlike projections that protrude from most cells of the human body. Many of these cilia perform sensory roles such as detecting light, sensing temperature and perceiving smell. Dysfunction of cilia is implicated in a number of conditions, most notably polycystic kidney disease. The less common Bardet-Biedl Syndrome (BBS) reflects the effects of complete loss of cilia function throughout the body. Patients with this condition suffer from obesity, polydactyly (more than 20 fingers/toes), cystic kidneys, infertility and many other conditions. Analysis of cilia structures in a tiny worm called nematode Caenorhabditis elegans has provided tremendous insight into the function of BBS proteins. Research has revealed that BBS proteins are involved in the process of intraflagellar transport (IFT), the dynamic mechanism through which cilia are built and maintained. An absence of BBS proteins appears to impair cilia function, apparently by causing the IFT machinery to split apart, although other deficiencies are highly likely. Peter Inglis has developed a new approach in studying the interaction of BBS proteins within the IFT complex, focusing on how BBS proteins are involved in the rearrangement of core IFT proteins. He will dissect BBS function and assemble a general model for the role of BBS proteins in IFT. Ultimately, his work promises to shed significant light on a cellular mechanism implicated in a wide variety of human disorders.
Investigation of the Mechanisms of Hematopoietic Cell Generation from Human Embryonic Stem Cells
Human embryonic stem cells (ES cells) — cells obtained from an embryo when they are only a few days old — are unique because they can become any type of cell. They can also multiply in the laboratory for very long periods of time without losing this special ability. ES cells offer huge medical potential, both in research and clinical applications. They could, for example, be turned into cells affected by cancers, such as blood cells or brain cells, then genetically altered to become cancer-like and studied to identify potential drug targets or other unique characteristics. Human ES cells could also be used as a cell source for many different kinds of transplantation. One of the biggest hurdles to overcome in working with human ES cells is increasing understanding of how these cells turn into specific kinds of cells. Because they can become anything, ES cells often become many different things at once, which makes them difficult to study and potentially inappropriate for transplantation. A better understanding of the mechanisms an ES cell uses to turn into different kinds of cells would help ES cell differentiation be better controlled and directed towards cell types of interest. Building on her previous MSFHR-funded research, Melanie Kardel is researching how ES cells turn into blood cells. Kardel’s focus is on determining how many blood cells can be produced from a single ES cell, and what genes can influence either the number of blood cells produced or how long it takes to produce them. The research could contribute to more standard, controlled procedures for high efficiency blood cell production from human ES cells.
The molecular characterization of murine hematopoietic stem cell self-renewal divisions
Every day, billions of new blood cells are produced in the human body. The origin of these cells, which are produced in the bone marrow, can be traced back to a tiny population of self-maintaining cells known as blood stem cells. Drugs used in current cancer treatments cause considerable damage to these stem cells and this can prevent more effective doses from being used for treating a number of cancers. Better ways to protect blood stem cells or to increase their numbers in a controlled fashion are needed. Additionally, many types of leukemia are known to be sustained by mutated blood stem cells. More detailed understanding of the mechanisms that regulate normal blood stem cells and how they become mutated is needed to determine how leukemia arises and how the many types of the disease can be treated more effectively. David Kent and his colleagues have recently developed a technique that allows them to isolate nearly pure populations of normal blood stem cells from the many different cell types (blood stem cells are at a frequency of between 1 in 10,000 and 1 in 15,000 cells) present in the bone marrow of adult mice. They are now able to stimulate these cells to behave differently (i.e.: to give rise to a daughter stem cell or not) in short term cell culture using different growth factors. Kent is comparing the sets of genes in these purified and differentially manipulated blood stem cell populations to identify genes that are involved in the regulation of normal blood stem cell expansion. He hopes his work will facilitate further research into the controlled expansion of stem cells and other blood cell types, and offer insight into the mechanisms by which stem cells mutate and replicate as cancer cells. He also hopes to expand fundamental knowledge of stem cells as a potential source of treatments for multiple cancers.