Hepatits C virus (HCV) causes chronic liver disease, such as cirrhosis (liver disease) and hepatocarcinoma (liver cancer), an irreversible condition that results in liver failure. There is no vaccine or drug available to prevent or treat this infection, which makes HCV the number one cause of liver transplantation in North America. Host proteins are involved in feeding and sheltering organisms such as viruses. Structural and functional studies revealed that a host protein, glyceraldehydes-3-phosphate (GAPDH) interacts with 3’ non-coding region (NCR) of the HCV genome. This multifunctional protein is also shown to associate with genome of several other RNA viruses, such as hepatitis A virus, hepatitis D virus, human parainfluenza virus type 3, and hepatitis B virus, but its function in the virus life cycle is uncertain. Independent of its glycolitic function, this multifunctional protein is also shown to play a role as an apoptosis mediator upon oxidative stress, and is shown to be essential in endoplasmic reticulum (ER) to Golgi transport. This suggests that GAPDH may be involved in several stages of HCV life cycle, such as regulation of translation and replication by interacting with HCV 3’NCR, modulation of liver damage from oxidative stress imposed by HCV encoded proteins, and formation of new virus partivles by budding of nascent HCV genome through the ER. Meera Raj is researching the biological role of GAPDH in the HCV life cycle, which may include regulating viral replication, facilitating viral assembly and modulating viral release from the host cell. In order to show that GAPDH plays a role in HCV life cycle, Meera has prepared human hepatoma (liver) cells showing reduction in GAPDH expression. Her next step is to study the effects of GAPDH reduction on HCV life-cycle. In order to find other host factors that may play a key role in the HCV life-cycle, she will use microarray to study changes in gene expression within HCV infected cells. Her study will provide insight into the HCV biology, host-viral interaction and may provide a potential new strategy for HCV treatment. Establishing GAPDH as a therapeutic target may also provide a broad base therapy for other infections, because targeting host proteins can affect the life cycles of many other viruses.
Research Pillar: Biomedical
Acute lung injury: FasL, apoptosis and protection by erythropoietin
Acute Respiratory Distress Syndrome (ARDS) is a common catastrophic lung condition that complicates critical illnesses of many types, most commonly severe infections. In ARDS, the cells that line the airspaces of the lung are injured and die. As a result, the lungs flood with fluid, becoming stiff, scarred and unable to transport oxygen into the bloodstream. Half of all patients with ARDS die, and there are currently no specific therapies to treat the condition, other than to provide supportive care. Erthropoieten (EPO) is a natural hormone that regulates the production of red blood cells in bone marrow. Injecting EPO is an established and safe therapy for anemia in patients with kidney failure, and it has been shown to protect against cell death in experimental models of stroke and heart attack. Patients with critical illness in the intensive care unit have abnormally low levels of EPO in their blood, leading to the hypothesis that low levels of EPO in the lung might contribute to cell injury and death in ARDS. Dr. Ruth MacRedmond’s research is the first to study the presence and activity of EPO in the lung. She is examining the ability of EPO treatment to prevent cell death caused by infection and the protective properties of EPO treatment in preventing ARDS. This project will expand our understanding of the mechanisms of cellular injury and death in ARDS, and explore the potential of EPO to act as a novel and important therapy for this devastating disease.
Bioinformatics of sequence indels: Novel applications for protein network analysis, drug target identification and drug development
Infectious diseases continue to be a huge threat worldwide. The effectiveness of current antibiotics is declining as many life-threatening bacteria have developed resistance to existing drugs, giving rise to the need for a new generation of antibiotics. An important factor responsible for emerging bacterial resistance is that conventional antibiotic drugs are designed to disable proteins on bacteria that allow it to infect host cells. These particular proteins mutate readily, which enhances their potential to develop resistance mechanisms against antibiotic treatment. An alternative strategy in antibiotic development would be to target “conserved” proteins – fundamental proteins that are resistant to mutations, because they perform essential functions that keep the bacteria alive. Michael Hsing’s research is focused on developing antibiotics that selectively target conserved and essential proteins in pathogens. To do this, he is investigating the important biological phenomenon of protein insertions and deletions (referred to as indels) and combining this approach with the latest computational tools to develop novel antibiotics that are more rapid and effective than the conventional approach. His goal is the development of an effective and economical method of developing antibiotic drugs to treat existing and emerging pathogens.
Mechanism of androgen regulated expression of SESN1, a potential tumor suppressor
Male sex hormones (androgens) regulate tumour growth in prostate cancer. The only effective treatment for advanced prostate cancer is the removal of androgens using medication, or the surgical removal of the testes — treatments that cause impotence and a decreased sex drive. The results are usually temporary since some tumour cells survive, become independent of androgens, and continue to grow. Prostate cancer cells depend primarily on the androgen receptor, which encodes genetic information, for growth and survival. Gang Wang is studying how the androgen receptor decreases the expression of the SESN1 gene — a gene that may inhibit the growth of prostate tumour cells. Wang believes the SESN1 gene is no longer repressed when patients receive hormone therapy. This would explain the initial suppression of prostate cancer cells seen in these patients and the subsequent reappearance of cancer cells which later follows. Wang will confirm if the androgen receptor begins lowering the gene following therapy, allowing the cancer cells to grow. If so, the SESN1 gene could be a promising therapeutic target for treating prostate cancer.
Structural analysis of the molecular machinery involved in protein secretion, membrane protein assembly and protein processing
The ability for proteins to travel across cell membranes is critical to the life of all cells, yet research shows that bacterial cells differ from human cells in some of the components necessary for this movement to occur. In previous work supported by an MSFHR Scholar award, Dr. Mark Paetzel uncovered the three-dimensional structure of proteins that make up the molecular machinery involved in this movement in bacterial cells. Now a Senior Scholar, Dr. Paetzel will continue this work with the goal of learning more about these structures in order to determine how to inhibit the movement of proteins across cell membranes in bacteria. He will use X-ray crystallography to investigate the proteins involved in protein targeting, translocation, and membrane protein assembly in bacteria. Dr. Paetzel is also investigating a particular enzyme that functions at the membrane surface — one that causes the cleaving of interior peptide bonds in a protein. Understanding how to inhibit this enzyme and its role in bacterial cell movement could lead to the development of a novel class of antibiotics — a strategy that is required to meet the ever-increasing challenge of antibiotic resistance.
Genetic Factors in Premature Ovarian Failure
Although the average age of menopause is 51 years, approximately one per cent of women will experience menopause before the age of 40, a condition known as premature ovarian failure. Working on the hypothesis that multiple genetic factors may combine and interact in a single individual to determine the rate of reproductive aging, Karla Bretherick is examining the molecular genetic differences between women with normal reproductive function and women with premature ovarian failure. She hopes her work identifying specific genetic factors that contribute to early menopause may lead to the development of both treatment options for affected individuals and predictive testing for those at risk.
Molecular Basis of Cancer Cell Invasion
Tumour invasion is the cellular process that initiates the spread of cancer cells from the primary tumour to new sites in a patient’s body (metastasis). Inhibiting this process is important, as solid tumours are much more readily surgically removed if metastasis hasn’t yet occurred. Researchers have identified Dihydromotuporamine C (dhMotC) as a novel tumour invasion inhibitor that may have therapeutic potential. Lianne McHardy is investigating the molecular mechanisms of this compound, focusing specifically on how the protein SNF7 is involved in these mechanisms. SNF7 is normally required for the sorting of intracellular vesicles, which are a basic tool of the cell for organizing metabolism, transport, enzyme storage, as well as being chemical reaction chambers. Lianne will investigate a potential link between the mechanisms controlling vesicle sorting and the invasion abilities of a tumour cell. By pinpointing the mechanisms that allow for metastasis, her studies may aid in the development of dhMotC as a potential drug candidate for metastatic cancers.
Entry of Dendritic Cells into the Brain: Regulation by Endothelial Cell Adhesion Molecules and Chemokines
Immune reactions in the central nervous system (CNS) – the brain and spinal cord – differ from other organs. Under normal conditions, the endothelial cells lining blood vessels in the brain act as a “blood-brain barrier” to block the entry of most immune cells into the CNS. In some CNS diseases like multiple sclerosis, and in trauma, stroke and infections, this barrier is compromised. As a result, immune cells migrate to the brain in large numbers causing inflammation, which can lead to serious consequences. Azadeh Arjmandi is studying how immune cells gain access to the brain and spinal cord in infectious, inflammatory and autoimmune diseases. Immune cells called dendritic cells have been found in the central nervous systems of patients with these diseases and their numbers increase with more chronic conditions. Azadeh is examining dendritic cell trafficking across the blood-brain barrier in order to further characterize the molecular mechanisms of inflammation in the brain. This will provide important information about how certain CNS diseases develop and may contribute to more effective treatments.
Intestinal Goblet Cells and Their Role in Host Defense Against Enteric Bacterial Pathogens
An important role of intestinal goblet cells is to secrete mucus into the gut, which is believed to act as a barrier, preventing contents in the intestine from damaging intestinal tissue. However, researchers have also hypothesized that mucus secretion by goblet cells may also serve as a defense mechanism against bacterial pathogens such as enterohemmorhagic E. coli (EHEC), a bacteria that causes diarrhea and inflammation in humans. Kirk Bergstrom is investigating if, and how, goblet cells may also secrete toxins to combat infecting microbes. With a better understanding of how these cells respond to bacterial pathogens, he hopes his research may lead to new treatment options to combat bacterial diseases of the intestine.
Role of Notch-1 in Neurodegeneration and Neuroprotection
Alzheimer’s disease is a neurodegenerative disorder that causes deficits in memory, language and other cognitive functions. A family history increases the risk for Alzheimer’s by about four-fold. Early onset, familial Alzheimer’s disease (FAD) runs in families, and strikes under the age of 60. Brain cells shrink or disappear, and are replaced by irregularly shaped spots, called amyloid beta plaques (A-beta). A-beta is normally found in brain cells, but harmfully accumulates in FAD – a process that is facilitated by “presenilin” proteins. FAD has been linked to multiple genetic mutations, including defects in these proteins. These proteins also decrease the production of Notch-1, a brain receptor involved in learning and memory. Notch-1 is essential for normal development, but its role in the mature brain is unknown. Kelley Bromley is investigating the ability of Notch-1 to protect brain cells from the toxic effects of A-beta plaques, and how levels of Notch-1 change during the aging process. Her research could help explain how Alzheimer’s disease develops and potentially lead to new treatments for the condition.