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Title: Discovering plant-specific mechanisms underlying endomembrane-actin interactions and metabolic signaling
Creator: Cao, Pengfei
Date: 2019
Collection: Electronic Theses & Dissertations
Description: In eukaryotic cells, the endomembrane system compartments, including the endoplasmic reticulum, the vacuole and several other types of membrane-enclosed vesicles, are indispensable organelles and together exert essential cellular functions. In plant cells, the endomembranes interact extensively with the actin cytoskeleton, rather than the microtubules in mammalian cells, proposing significant questions of how the plant-specific endomembrane-actin interactions are established and regulated. My...
Show moreIn eukaryotic cells, the endomembrane system compartments, including the endoplasmic reticulum, the vacuole and several other types of membrane-enclosed vesicles, are indispensable organelles and together exert essential cellular functions. In plant cells, the endomembranes interact extensively with the actin cytoskeleton, rather than the microtubules in mammalian cells, proposing significant questions of how the plant-specific endomembrane-actin interactions are established and regulated. My research identified the first ER-actin anchor protein in plant cells. Moreover, the research presented in this dissertation discovered that the abundance of certain cellular nutrients stimulates the metabolic signaling and subsequently triggers re-organization of the actin cytoskeleton and actin-associated endomembranes. This revealed signaling transduction from metabolites and raw materials to manufacturing endomembrane compartments is arguably the first identified regulatory mechanism of such kind in all eukaryotes. Furthermore, additional data and considerations are expected to contribute further mechanistic understandings of the plant-specific endomembrane-actin interactions in a broad context of organelle morphogenesis, cellular functions, and plant growth.
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Title: Metabolic regulation of the methylerythritol 4-phosphate (MEP) pathway : specific role of deoxy-D-xylulose 5-phosphate synthase (DXS)
Creator: Banerjee, Aparajita
Date: 2015
Collection: Electronic Theses & Dissertations
Description: The 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway is an important pathway for the biosynthesis of isopentenyl diphosphate (IDP) and dimethylallyl diphosphate (DMADP), the precursors of isoprenoids. Isoprenoids are ubiquitous natural products present in all different forms of life and have a wide variety of structures and functions. Some isoprenoids are involved in primary metabolic processes like photosynthesis, respiration, regulation of growth and development whereas many others have...
Show moreThe 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway is an important pathway for the biosynthesis of isopentenyl diphosphate (IDP) and dimethylallyl diphosphate (DMADP), the precursors of isoprenoids. Isoprenoids are ubiquitous natural products present in all different forms of life and have a wide variety of structures and functions. Some isoprenoids are involved in primary metabolic processes like photosynthesis, respiration, regulation of growth and development whereas many others have important roles in secondary metabolism. In addition, isoprenoids have numerous commercial applications as flavor and fragrance molecules, drugs, pigments, natural polymers, agrichemicals, cosmetics, biofuels, etc. Isoprene, the smallest member of the isoprenoid family, has different adverse effects on atmospheric chemistry. Despite having diverse functions, all isoprenoids are structurally based on C5 isoprenoid units. It was believed for a long time that the mevalonate (MVA) pathway is the only route for the biosynthesis of IDP. In early 1990s, it was discovered that an alternative (MEP) pathway exists for the biosynthesis of both IDP and DMADP. Soon after its discovery, the various enzymes and metabolites involved in this pathway were elucidated. However, not much was known about the metabolic regulation of this pathway. Considering the numerous applications of isoprenoids, it was important to understand the metabolic regulation of the MEP pathway. Earlier studies suggested that DXS might play an important role in the regulation of the MEP pathway. The research work presented in this dissertation mainly involves the study of the metabolic regulation of this pathway by focusing on the kinetic behavior of 1-deoxy-D-xylulose-5-phosphate synthase (DXS). A liquid chromatography-tandem mass spectrometry (LC-MS/MS) based assay was developed for DXS to study its kinetics in presence of different metabolites of the MEP pathway. It was observed that recombinant DXS from Populus trichocarpa (PtDXS) is feedback-inhibited by IDP and DMADP, the two end products of this pathway. Mechanistic studies of this inhibition showed that both IDP and DMADP compete with thiamin diphosphate (ThDP) for binding at the active site of the enzyme. Feedback regulation of DXS plays an important role in controlling the carbon flux through this pathway and thus constitutes a significant regulatory mechanism of this pathway. A modified PtDXS, which would exhibit reduced binding affinity for IDP/DMADP and thereby relieving the feedback inhibition partially or completely, would be important for biotechnological uses. Site-directed mutagenesis was used to engineer an improved PtDXS that has reduced affinity for IDP and DMADP. This engineered PtDXS was also shown to have higher Km for ThDP than the WT enzyme. Therefore, this mutant of PtDXS would be important for biotechnological applications if high concentration of ThDP is maintained.
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Title: Role of the sphingomyelin/ceramide pathway in diabetic retinopathy
Creator: Opreanu, Madalina
Date: 2010
Collection: Electronic Theses & Dissertations

Title: The role of altered sphingolipid metabolism in the development of diabetic retinopathy
Creator: Chakravarthy, Harshini
Date: 2015
Collection: Electronic Theses & Dissertations
Description: Diabetic retinopathy (DR) is a vision-threatening microvascular complication of diabetes mellitus, and around 67% of patients have some degree of retinopathy after ten years of diabetes [1]. In spite of decades of investigations, the precise molecular mechanisms involved in the pathogenesis of DR have not been completely deciphered. The main aim of this dissertation is to provide an important molecular link connecting diabetic dyslipidemia with retinal vascular degeneration associated with...
Show moreDiabetic retinopathy (DR) is a vision-threatening microvascular complication of diabetes mellitus, and around 67% of patients have some degree of retinopathy after ten years of diabetes [1]. In spite of decades of investigations, the precise molecular mechanisms involved in the pathogenesis of DR have not been completely deciphered. The main aim of this dissertation is to provide an important molecular link connecting diabetic dyslipidemia with retinal vascular degeneration associated with diabetes. Our studies reveal a central pathway of sphingolipid metabolism involved in the development of DR, concurrently affecting function of bone marrow (BM)-derived inflammatory cells contributing to retinal inflammation and microvascular injury, and negatively affecting repair of retinal vasculature by BM-derived circulating angiogenic cells (CAC). Notably, we reveal that normalizing the pro-inflammatory and reparative functions of these BM-derived cells by modulating their lipid metabolism improves the outcomes of DR.First, we explored the link between bone marrow and DR using a mouse model of diabetes, stably engrafted with GFP+ bone marrow. We demonstrated that diabetes has a significant long-term effect on the BM-derived inflammatory monocytes as well as reparative circulating angiogenic cells (CAC) that circulate in the blood, localize to the retina and undergo further differentiation. Our findings indicate that BM-derived cells could play a central role in the development of DR. Secondly, we investigated the role of altered sphingolipid metabolism in DR. We addressed the hypothesis that perturbation of a specific sphingolipid pathway in BM-derived cells may contribute to inflammation and vascular damage in the diabetic retina. We demonstrated that activation of an essential enzyme of sphingolipid metabolism, acid sphingomyelinase (ASM) in BM-derived cells plays a crucial role in retinal microvascular deterioration associated with diabetes. Inhibition of ASM in the diabetic BM prevented activation of BM-derived microglia-like cells and normalized retinal levels of proinflammatory cytokines. Notably, ASM also caused accumulation of ceramide on cell membrane of BM-derived reparative CACs, thereby reducing membrane fluidity and impairing CAC migration. Inhibition of ASM in these reparative cells improved membrane fluidity and homing of these cells to damaged retinal vessels in a mouse model of DR.Finally, to demonstrate the effect of diabetes on the in vivo homing ability of CACs, we injected purified GFP-expressing CACs into the vitreous of healthy mice. We observed that increased numbers of diabetic CACs remained trapped in the retina without returning to their BM niche, implying impaired migration and homing efficiency of the diabetic CACs. However, inhibition of ASM in diabetic CACs improved their clearance from retina and homing into the BM niche, demonstrating that ASM upregulation in diabetes contributes to impaired migration and homing of reparative CACs.Collectively, these findings indicate that modulation of sphingolipid metabolism in dysfunctional BM-derived cell populations could normalize the reparative/pro-inflammatory cell balance and can be explored as a novel therapeutic strategy for treating DR.
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Title: Lipid trafficking and lipid breakdown in Chlamydomonas
Creator: Warakanont, Jaruswan
Date: 2015
Collection: Electronic Theses & Dissertations
Description: With their high photosynthetic efficiency and the ability to synthesize triacylglycerol (TAG), unicellular microalgae have an important ecological role, as well as value for production of triacylglycerol lipids that can be converted to biodiesel. The recent state of knowledge about microalgal lipid metabolism had been deduced from that of a model seed plant, Arabidopsis. However, recent studies have revealed that aspects of lipid metabolism differ between microalgae and Arabidopsis....
Show moreWith their high photosynthetic efficiency and the ability to synthesize triacylglycerol (TAG), unicellular microalgae have an important ecological role, as well as value for production of triacylglycerol lipids that can be converted to biodiesel. The recent state of knowledge about microalgal lipid metabolism had been deduced from that of a model seed plant, Arabidopsis. However, recent studies have revealed that aspects of lipid metabolism differ between microalgae and Arabidopsis. Investigating these differences was a cornerstone of this study, using Chlamydomonas, a representative of microalgae, and Arabidopsis. Two major approaches were undertaken: forward and reverse genetics. The forward genetic screening used insertional mutagenesis of Chlamydomonas and focused on a knockout mutation of a gene, which proved to be an orthologue of the Arabidopsis TRIGALACTOSYLDIACYLGLYCEROL 2 (TGD2). The tgd2 mutant exhibits increases in cellular concentrations of phosphatidic acid (PtdOH) and triacylglycerol (TAG); the latter contains signature fatty acids of monogalactosyldiacylglycerol (MGDG), pointing to its likely origin of synthesis. The mutant also experiences low viability in extended culture. Similar to AtTGD2, CrTGD2 is located in the chloroplast inner envelope membrane and binds PtdOH in vitro. Radioactive labeling experiments suggest that CrTGD2 functions in transferring a lipid precursor, presumably PtdOH, from the outer chloroplast envelope into the chloroplast. This study shows that, in contrast to prevailing assumptions, Chlamydomonas is able to import lipids from the endoplasmic reticulum (ER) to the chloroplast, and utilizes the eukaryotic pathway to synthesize galactoglycerolipids. The reverse genetics investigation focused on CrLIP4, a putative TAG lipase. CrLIP4 is an orthologue of a major Arabidopsis TAG lipase. Reverse transcription PCR revealed that the CrLIP4 transcript is reduced in abundance during N deprivation when TAG accumulates. Down-regulation of this gene through an artificial microRNA construct resulted in delayed TAG degradation. Expression of CrLIP4 in Escherichia coli alters the pattern of neutral lipids. Recombinant CrLIP4 exhibited TAG lipase activity. These results show that CrLIP4 has TAG lipase activity both in in vitro and in vivo. In summary, two Arabidopsis orthologues in Chlamydomonas were characterized through forward and reverse genetic approaches. The results elaborate and refine our understanding of Chlamydomonas lipid metabolism, and are likely relevant for other unicellular microalgae.
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Title: Variations in the basal metabolism of four young women of different races
Creator: Lingaiah, Sushela
Date: 1950
Collection: Electronic Theses & Dissertations

Title: The dietary procedures employed in conducting a non-clinical metabolic balance study
Creator: Friedemann, Carolyn Mae
Date: 1965
Collection: Electronic Theses & Dissertations

Title: Information-entropy concepts for nutritional systems
Creator: Harper, Jerome Paul, 1948-
Date: 1976
Collection: Electronic Theses & Dissertations

Title: Pancreatic secretions and their effect on circulatory and immune cells
Creator: Entwistle, Kristen
Date: 2016
Collection: Electronic Theses & Dissertations
Description: Diabetes mellitus is a metabolic disease characterized by chronic hyperglycemia and insulin dysfunction, which often results in secondary complications associated with blood flow. Four major types of diabetes are defined by the American Diabetes Association: type 1 diabetes (T1D, insulin insufficiency), type 2 diabetes (T2D, insulin resistance), gestational diabetes (occurring during pregnancy), and other types, which includes cystic fibrosis related diabetes (CFRD). Although each of these...
Show moreDiabetes mellitus is a metabolic disease characterized by chronic hyperglycemia and insulin dysfunction, which often results in secondary complications associated with blood flow. Four major types of diabetes are defined by the American Diabetes Association: type 1 diabetes (T1D, insulin insufficiency), type 2 diabetes (T2D, insulin resistance), gestational diabetes (occurring during pregnancy), and other types, which includes cystic fibrosis related diabetes (CFRD). Although each of these types of diabetes is associated with insulin dysfunction, it is important to note that the treatment of oral medications or exogenous insulin, although sufficient to effectively manage blood glucose levels, is not sufficient to completely cure diabetes. Secondary complications resulting from diabetes include retinopathy, nephropathy and neuropathy, along with dysfunctions in immune response. In recent years, a surge in the research of C-peptide, the 31 amino acid peptide co-secreted with insulin, has revealed that C-peptide may actually help to ameliorate some of these secondary complications, including neuropathy and immune response. Although initial studies revealed promising results, a phase 2b clinical trial was shut down in 2014 due to indistinguishable results in placebo and treatment groups in T1D patients. To enhance our knowledge of these downstream problems, we here report the effect of C-peptide/zinc/albumin on RBCs and peripheral neutrophils (an immune cell) that mimic those from CF/CFRD patients using a chemical inhibitor (CFTRinh-172). C-peptide and zinc binding to RBCs confirms previously published data, and binding to CFTR-inhibited RBCs is increased from the control, however, the molar binding ratio of C-peptide to zinc remains 1:1. ATP release is increased in control and CFTR-inhibited cells only in the presence of the ensemble of C-peptide/zinc/albumin, but is abolished when any one of these components is missing. Similarly, in neutrophils, we observe a 1:1 molar binding ratio of C-peptide to zinc when albumin is present in both control and CFTR-inhibited cells. We also observed a significant increase in intracellular calcium, intracellular NO, extracellular NO, glucose uptake, and rate of chemotaxis in neutrophils that had been treated with the ensemble, but not when any one component was missing. In both RBCs and neutrophils, we observed an increase in membrane expression of glucose transporter 1 (GLUT1) only when C-peptide, zinc and albumin were present. Insulin did not have this effect. The results reported here are the first to indicate that C-peptide may be acting on cells that contain primarily GLUT1, and that the mechanism of action may be similar to the way that insulin acts in muscle and fat cells, by translocating GLUT4 to the plasma membrane. These results are also the first to suggest that C-peptide may directly be affecting peripheral neutrophils, which could have significant implications in the treatment of immune complications in all forms of diabetes. Additionally, these results are the first to examine the effect this peptide and its metal may have on patients who have CF, and may point to its use a potential therapy in both T2D and CFRD.
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Title: Some aspects of the carbohydrate metabolism of certain trichomonads
Creator: Lindblom, Gordon Paul
Date: 1957
Collection: Electronic Theses & Dissertations

Title: The riboflavin metabolism of college women on a weight reduction diet
Creator: Chang, Irene Hwei-lin
Date: 1951
Collection: Electronic Theses & Dissertations

Title: Effect of two types of fat supplements differing in saturation on production performance and energy partitioning
Creator: Liu, Enhong
Date: 2015
Collection: Electronic Theses & Dissertations
Description: Our objective was to examine the effect of trans-10, cis-12 conjugated linoleic acid (CLA) on production performance and energy partitioning. Holstein cows (n=32; 93±35 DIM) were randomly assigned to treatment sequence in a crossover design experiment and fed iso-energetic diets containing fat supplements differing in saturation. Treatment diets contained 2.5% palmitic acid-enriched triglyceride (BergaFat T-300, SAT) or 2.5% soybean oil (UNSAT), with 25% NDF, 32% starch, 18% CP, and 4.6% FA ...
Show moreOur objective was to examine the effect of trans-10, cis-12 conjugated linoleic acid (CLA) on production performance and energy partitioning. Holstein cows (n=32; 93±35 DIM) were randomly assigned to treatment sequence in a crossover design experiment and fed iso-energetic diets containing fat supplements differing in saturation. Treatment diets contained 2.5% palmitic acid-enriched triglyceride (BergaFat T-300, SAT) or 2.5% soybean oil (UNSAT), with 25% NDF, 32% starch, 18% CP, and 4.6% FA (DM basis). Treatment periods were 28 d in length with the final 5 d used for sample and data collection. The statistical model included the random effect of cow and fixed effects of treatment and period. Compared to the SAT treatment, UNSAT did not alter dry matter intake (DMI), energy intake, or milk yield but decreased milk fat concentration and yield, with reduced de novo fatty acid (FA) and 16-carbon FA yield. UNSAT also decreased fat-corrected milk (FCM) and energy-corrected milk (ECM). UNSAT increased body weight (BW) gain but did not alter body condition score (BCS) or fat thickness over the rump and rib. UNSAT tended to reduce NDF digestibility and increased FA digestibility in period 1 but not in period 2. UNSAT increased plasma insulin, NEFA, and triglyceride concentrations, with increased milk trans-10 C18:1 and trans-10, cis-12 C18:2. In conclusion, with similar NEL intake, the SAT diet containing the palmitic acid-enriched triglyceride partitioned more energy toward milk, while the UNSAT diet containing soybean oil partitioned more energy toward body gain.
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Title: The metabolic assessment of elite male and female swimmers using a continually adjusted tethered swim protocal
Creator: Kurowski, Thomas T.
Date: 1987
Collection: Electronic Theses & Dissertations

Title: Variations in the calcium metabolism of preschool children
Creator: Hiller, Veda E.
Date: 1932
Collection: Electronic Theses & Dissertations

Title: Variations in the calcium metabolism of pre-school children on a medium protein diet
Creator: Wilde, Marjorie Olson
Date: 1936
Collection: Electronic Theses & Dissertations

Title: Studies on high protein diets
Creator: Ferguson, Mary H.
Date: 1930
Collection: Electronic Theses & Dissertations

Title: Ferulate cross-linking and conjugations : the role of ferulate in the grass cell wall and specialized metabolism
Creator: Frankman, Emily
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Members of the Poaceae include many of the most economically important plants, such as maize, rice, wheat, and sorghum. These grasses not only account for approximately half of the human diet, they are also a likely source of renewable bioenergy. An impediment to using biomass for the production of biofuels and other produces is the recalcitrance of the plant cell to enzymatic digestion. The cell wall is vital for plant strength in that it allows the plant to grow upright, and acts as...
Show moreMembers of the Poaceae include many of the most economically important plants, such as maize, rice, wheat, and sorghum. These grasses not only account for approximately half of the human diet, they are also a likely source of renewable bioenergy. An impediment to using biomass for the production of biofuels and other produces is the recalcitrance of the plant cell to enzymatic digestion. The cell wall is vital for plant strength in that it allows the plant to grow upright, and acts as protection against pests and the environment. Grasses have a unique cell wall that contain glucuronoarabinoxylan instead of xyloglucan and has a large amount of esterified hydroxycinnamic acid. Hydroxycinnamates are derived from phenylalanine in the phenylpropanoid pathway and serve many roles in the plant, including cell wall biosynthesis and specialized metabolism. One of these hydroxycinnamates, namely ferulate, can modify the arabinose side-chain of xylan. These feruloylated arabinoxylan moieties are able to dimerize via radical coupling to form diferulates, resulting in cross-links between xylan polymers and between xylan and lignin. Cross-linking in monocots likely contributes to cell wall strength, but the lack of identified genes involved in this pathway limit our understanding of this monocot-specific modification. The enzyme that adds ferulate to arabinoxylan is currently unidentified preventing alteration of the amount of ferulate in the wall by reverse genetic methods. In order to better understand ferulate-mediated cross-linking in grasses, our goal has been to find the gene encoding the enzyme responsible for adding ferulate onto arabinose residues in arabinoxylan, namely the arabinoxylan ferulate acyltransferase (AraFAT). To accomplish this goal we selected candidates from a grass-specific BAHD acyltransferase clade that were highly differentially expressed in monocots compared to dicots, produced proteins from these genes, and then assayed these proteins with arabinose-containing substrates and feruloyl-CoA. We also explored wheat seedling protein extractions as a method of determining a testable assay for AraFAT. During our search for the AraFAT gene, we discovered that one of our candidate genes, Bradi1g36980, is able to add ferulate to phenylamines to create phenylamides or hydroxycinnamic acid amide conjugates. These phenylamides have several functions in plants that include defense responses to pathogens and wounding. Phenylamides also play an important role in the plant cell wall, providing crosslinks between polymers that add rigidity and strength. The Bradi1g36980 enzyme has activity with donor substrate feruloyl-CoA and the acceptors tyramine, 2-phenyl-ethylamine, tryptamine, and serotonin. To our knowledge, this is the first time a BAHD acyl-transferase has been shown to use tryptamine or serotonin as a substrate. The true substrates of this enzymes have not been established by mutational analysis. Because these hydroxycinnamic acid amides are known to increase in plants exposed to jasmonate, a hormone involved in wound response pathways, we subjected Brachypodium seedlings to methyl-jasmonate and measured the relative expression level of Bradi1g36980 at various time points. We observed a slight increase in Bradi1g36980 expression occurred from methyl-jasmonate exposure, and are investigating the role of the phytohormone ethylene in its regulation.
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Title: Interactions of dissolved and particulate nitrogen in lake metabolism
Creator: Manny, Bruce Andrew
Date: 1971
Collection: Electronic Theses & Dissertations

Title: Deconstructing the correlated nature of ancient and emergent traits : an evolutionary investigation of metabolism, morphology, and mortality
Creator: Grant, Nkrumah Alions
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Phenotypic correlations are products of genetic and environmental interactions, yet the nature of these correlations is obscured by the multitude of genes organisms possess. My dissertation work focused on using 12 populations of Escherichia coli from Richard Lenski's long-term evolution experiment (LTEE) to understand how genetic correlations facilitate or impede an organism's evolution. In chapter 1, I describe how ancient correlations between aerobic and anaerobic metabolism have...
Show morePhenotypic correlations are products of genetic and environmental interactions, yet the nature of these correlations is obscured by the multitude of genes organisms possess. My dissertation work focused on using 12 populations of Escherichia coli from Richard Lenski's long-term evolution experiment (LTEE) to understand how genetic correlations facilitate or impede an organism's evolution. In chapter 1, I describe how ancient correlations between aerobic and anaerobic metabolism have maintained - and even improved - the capacity of E. coli to grow in an anoxic environment despite 50,000 generations of relaxed selection for anaerobic growth. I present genomic evidence illustrating substantially more mutations have accumulated in anaerobic-specific genes and show parallel evolution at two genetic loci whose protein products regulate the aerobic-to-anaerobic metabolic switch. My findings reject the "if you don't use it, you lose it" notion underpinning relaxed selection and show modules with deep evolutionary roots can overlap more, hence making them harder to break. In chapter 2, I revisit previous work in the LTEE showing that the fitness increases measured for the 12 populations positively correlated with an increase in cell size. This finding was contrary to theory predicting smaller cells should have evolved. Sixty thousand generations have surpassed since that initial study, and new fitness data collected for the 12 populations show fitness has continued to increase over this period. Here, I asked whether cell size also continued to increase. To this end, I measured the size of cells for each of the 12 populations spanning 50,000 generations of evolution using a particle counter, microscopy, and machine learning. I show cell size has continued to increase and that it remains positively correlated with fitness. I also present several other observations including heterogeneity in cell shape and size, parallel mutations in cell-shape determining genes, and elevated cell death in the single LTEE population that evolved a novel metabolism - namely the ability to grow aerobically on citrate. This last observation formed the basis of my chapter 3 research where my collaborators and I fully examine the cell death finding and the associated genotypic and phenotypic consequences of the citrate metabolic innovation.
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Title: Targeting metabolic vulnerabilities in breast cancer subtypes
Creator: Ogrodzinski, Martin Peter
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Breast cancer is a highly prevalent and deadly disease. Globally, it is the most diagnosed cancer in women and is responsible for the most cancer-related deaths among women. Breast cancer is also a remarkably heterogeneous disease, with clear variability in clinical parameters including histological presentation, receptor status, and gene expression patterns that differ between patients. A significant amount of effort has been spent characterizing breast cancer into subtypes, with the main...
Show moreBreast cancer is a highly prevalent and deadly disease. Globally, it is the most diagnosed cancer in women and is responsible for the most cancer-related deaths among women. Breast cancer is also a remarkably heterogeneous disease, with clear variability in clinical parameters including histological presentation, receptor status, and gene expression patterns that differ between patients. A significant amount of effort has been spent characterizing breast cancer into subtypes, with the main goal of improving patient outcomes by: 1) designing targeted therapies, and 2) improving our ability to determine patient prognosis. While scientists have made significant strides in meeting these goals, we still lack targeted therapies for some subtypes of breast cancer, and current therapies often fail to provide a lasting cure. Thus, additional research is needed to improve patient care. One promising area in breast cancer research is cancer metabolism. Using metabolism as a therapeutic target is rapidly gaining traction, as it is now widely appreciated that cancer cells exhibit significant differences in metabolism compared to normal cells. The primary goal of this dissertation is to study the metabolism of distinct subtypes of breast cancer and identify metabolic vulnerabilities that can be used to effectively treat each subtype.This thesis will begin with a review of current classification strategies for breast cancer subtypes and knowledge regarding subtype-specific metabolism. It will also consider modern techniques for targeting breast cancer metabolism for therapeutic benefit. Breast cancer heterogeneity and metabolism are investigated using cell lines and tumors derived from the MMTV-Myc mouse model, which mimics the complexity observed in human disease. Cell lines derived from two histologically defined subtypes, epithelial-mesenchymal transition (EMT) and papillary, are used to establish clear metabolic profiles for each subtype. Metabolic vulnerabilities are identified in glutathione biosynthesis and the tricarboxylic acid cycle in the EMT subtype and nucleotide biosynthesis is determined to be a metabolic weakness in the papillary subtype. It is further shown that pharmacologically targeting each of these metabolic pathways has the greatest effect on reducing proliferation when used against the vulnerable subtype. These in vitro findings are then expanded upon by integrating genomic and metabolomic data acquired from in vivo tumors. In vivo experiments reveal that the EMT and papillary tumors prefer parallel pathways to generate nucleotides, with the EMT subtype preferring to salvage nucleotides while the papillary subtype prefers to produce nucleotides de novo. CRISPR/Cas9 gene editing is used to functionally characterize the metabolic effects of targeting nucleotide salvage and de novo biosynthesis in the EMT and papillary subtypes, and determine that targeting the preferred pathway of each subtype is most effective at slowing tumor growth.Overall, this work demonstrates the power of using metabolism as a therapeutic target of breast cancer, and further shows that metabolic vulnerabilities specific to individual subtypes can be used effectively to guide personalized medicine.
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