Molecular, Genetic, and Biochemical Nutrition Commons^™

Studies Of The Role Of Mtorc1 In Modulating Intestinal Epithelial Barrier Function, Isaac Adediji

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Mechanistic target of rapamycin complex 1 (mTORC1) signaling impacts intestinal inflammation by modulating the production of cytokines in both intestinal epithelial cells and macrophages. Recent evidence revealed that THP-1-derived macrophages with elevated mTORC1 activity (THP-1shTSC2 macrophages), exhibited increased proinflammatory cytokine production when stimulated with lipopolysaccharide (LPS) compared to counterpart macrophages with repressed or baseline mTORC1 activity. Furthermore, it has been shown that mTORC1 governs intestinal barrier function as evidenced by elevated transepithelial electrical resistance (TEER) and para/transcellular permeability in Raptor-depleted Caco-2 cells (cells with repressed mTORC1 activity) compared to Caco-2 cells with elevated or baseline mTORC1 activity. The present study …

Bovine Mammary Alveolar Mac-T Cells Afford A Tool For Studies Of Bovine Milk Exosomes In Drug Delivery., Mojisola Ogunnaike

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Bovine milk exosomes (BMEs) have attracted attention as vehicles for delivering RNA therapeutics. BMEs originate in mammary alveolar cells. Here, we determined whether bovine mammary alveolar MAC-T cells are a promising tool to assess RNA delivery by BMEs. MAC-T cells exosomes (MAC-T BMEs) and BMEs were harvested by differential ultracentrifugation. Exosome size, morphology, microRNA content and marker proteins were assessed using nanoparticle tracking analysis, transmission electron microscopy, real-time PCR and immunoblot analysis, respectively. MAC-T cells were genetically engineered to secrete MAC-T BMEs endogenously labeled with a near-infrared fluorescent protein and tissue distribution was compared to fluorophore-labeled BMEs following intravenous injection …

Transport And Distribution Of Bovine Milk Exosomes And Mir-34a Cargo In Murine Cerebral Cortex Endothelial Bend.3 Cells And Bv2 Microglia, Pearl Ebea

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

The blood-brain barrier (BBB) poses an obstacle in the delivery of drugs to the brain. Bovine milk exosomes (BME) are explored for delivering antisense oligonucleotides to tumors, because BME are bioavailable and protect RNA cargos against degradation in the gastrointestinal tract. This study had the following objectives: 1) assess the transport kinetics of BME and their RNA cargos and secretion of RNA across the apical membrane in murine cerebral cortex endothelial bEnd.3 cells and 2) determine whether murine brain BV2 microglia have the potential to accumulate and, therefore, eliminate BME that crossed the BBB. The uptake of BME labeled with …

Inhibitory Effects Of Shiitake-Derived Exosome-Like Nanoparticles On Nlrp3 Inflammasome Activation, Yizhu Lu

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

The NLRP3 inflammasome is a critical mediator of inflammation and consists of the sensor NOD-like receptor family, pyrin domain containing 3 (NLRP3), the adaptor apoptotic speck protein containing a caspase recruitment domain (ASC), and the effector caspase-1. Dysregulated or excessive activation of the NLRP3 inflammasome contributes to pathogenesis of diverse inflammatory diseases such as Type 2 diabetes and atherosclerosis. Therefore, the NLRP3 inflammasome is a promising therapeutic target for treating these diseases. Extracellular vesicles (EVs) are membrane-enclosed tiny particles released by almost any type of cells and they are involved in the intercellular communication by transferring their cargos including RNAs, …

Effects Of Vagotomy And Fenugreek On Hyperlipidemia And Insulin Resistance, Rituraj Khound

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Hyperlipidemia is the impairment of lipid metabolism marked by abnormally high levels of lipid in circulation. This has been implicated in a number of metabolic diseases including diabetes, cardiovascular diseases, and nonalcoholic fatty liver disease. Insulin resistance is the impairment of insulin action, which leads to several diseases such as obesity and type 2 diabetes. New clinical and therapeutic approaches are warranted for the prevention and treatment of hyperlipidemia and insulin resistance. In our study, we investigated the mechanism underlying the effect of complete disruption of the sub-diaphragmatic vagus nerve (vagotomy) on hyperlipidemia and insulin sensitivity. We observed that vagotomy …

Red Grain Sorghum Whole Kernel Crude Lipid Protects Energy Metabolism And Short Chain Fatty Acid Profile In A Hamster Model To Minimize Intestinal Stress Caused By A High Fat Diet, Haowen Qiu

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Multiple studies have shown throughout the past 10+ years that grain sorghum (GS) lipid extract protects against high plasma and hepatic cholesterol and, to a lesser degree, positively modulate the gut microbiota in response to a high fat (HF) diet. However, the impact of GS lipids on intestinal stress induced by such a diet remains largely unknown. The objective of this project was to determine the ability of GS crude lipid (GS-CL) obtained from the surface of GS whole kernel to protect energy metabolism and short chain fatty acid (SCFA) profile produced by the gut microbiome that may be negatively …

Mechanism Of Triglyceride Lowering Action Of Akkermansia Muciniphila And Fenugreek In A Genetic Induced Hyperlipidemia, Jing Shen

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Hyperlipidemia is a condition of abnormally elevated levels of lipids and/or lipoproteins in the blood circulation. It is usually accompanied with obesity, type 2 diabetes, insulin resistance, hypertension and non-alcoholic fatty liver diseases (NAFLD) and has become a great threat to human health. New therapeutic strategies are needed for the prevention and treatment of both genetic intervention-induced hyperlipidemia and environmentally induced hyperlipidemia. In this study, we determined the therapeutic effects of a diseaseprotecting gut bacteria, Akkermansia muciniphila, and an annual legume, fenugreek, on hypertriglyceridemia induced by genetic depletion of cAMP responsive binding protein H (CREBH KO) in mice. We found …

Characterization Of Extraction Methods To Recover Phenolic-Rich Extracts From Black Beans (Phaseolus Vulgaris) That Inhibit Alpha-Amylase And Alpha-Glucosidase Using Response Surface Approaches, Mazen Alharbi

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Black beans contain high phenolic contents that are considered potent antioxidants. Relatively little is known about their ability to inhibit the carbohydrate-hydrolyzing enzymes α-amylase and α-glucosidase from releasing glucose from starch and/or disaccharides. The objective of this project was to determine the optimum procedures for extracting total phenols (TP), total flavonoids (TF) and total condensed tannins (TCT) from black beans (Phaseolus vulgaris), and then to determine the ability of the phenolic rich extracts to inhibit α-amylase and α-glucosidase. Due to their high phenolic levels, it was hypothesized that black beans would be an effective inhibitor of α-amylase and α-glucosidase, which …

Attenuation Of Mtorc1-Driven Secretion Of Lipoproteins And Triacylglycerides By Short Chain Fatty Acids: Mechanistic Insight Into The Pathogenesis Of Hypertriglyceridemia, Joseph L. Roberts

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

The mechanistic target of rapamycin complex 1 (mTORC1) is a serine/threonine kinase that drives several anabolic processes including lipid synthesis, protein synthesis, and adipogenesis. mTORC1 is highly active in the livers of obese rodents, in overnutrition, and is implicated in the development of obesity related metabolic disorders, including the overproduction of atherogenic lipoproteins. Direct inhibition of mTORC1 is not a viable treatment strategy because it prevents feedback inhibition of the insulin-signaling cascade, leading to increased lipid synthesis and secretion of lipoproteins. Thus, therapeutic approaches that drive catabolic pathways are considered promising mechanisms for overcoming mTORC1-driven anabolism. Human liver HepG2 cells …

Stability And Biological Activity Of Dietary Micrornas, Katherine Howard

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

MicroRNAs play important roles in gene regulation by binding to complimentary sites at the 3’ untranslated region of target mRNA molecules. Binding results in inhibition or degradation of target mRNA. Many bovine and chicken microRNA are homologous with human counterparts enabling gene regulation. A recent study in our lab provided undisputable evidence that endogenous milk microRNAs are bioavailable in humans; resulting in regulation of human gene expression. Based on these findings, we wanted to explore the possibility that other exogenous food borne microRNAs are able to be absorbed through the diet. My thesis surrounds two aims: 1) assessing the stability …

Micrornas Are Absorbed In Biologically Meaningful Amounts From Nutritionally Relevant Doses Of Cow’S Milk And Chicken Eggs And Affect Gene Expression In Peripheral Blood Mononuclear Cells, Cell Cultures, And Mouse Livers, Scott Baier

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Throughout the twenty-first century, evidence has been continually increasing to show the importance of epigenetic regulation in health. While the term “epigenetics” can be applied to many different processes, the focus of this dissertation will be on microRNAs and chromatin structure. Ultimately, both of these forms of epigenetic regulation can be used to fine tune gene expression based on environmental cues. The first three chapters of the dissertation focus on microRNA bioavailability, stability, and function from two commonly consumed food products: cow’s milk and chicken eggs. This important work has been the first of its kind to demonstrate the bioavailability …

Studies On The Regulation Of Fgf21 Gene Expression By (R)-Α-Lipoic Acid: Mechanistic Insight Into The Lipid Lowering Properties Of A Dithiol Dietary Molecule, Xiaohua Yi

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Controlling blood lipids is a major public health challenge of our time. The pleiotropic hormone-like polypeptide fibroblast growth factor 21 (FGF21) was recently recognized as a potent modulator of lipid and glucose metabolism and a promising treatment strategy for obesity related metabolic disorders, including dyslipidemia. A cost effective and practical alternative to the administration of recombinant FGF21 is to stimulate endogenous FGF21 production through diet. Our research identified (R)-a-lipoic acid (LA), a naturally occurring enzyme cofactor and dietary molecule found in green leafy vegetable and red meat, as an inducer of FGF21 expression. LA stimulated FGF21 production, demonstrated by a …

Biotinylation Of The C-Myc Promoter Binding Protein Mbp-1 Decreases C-Myc And Cox-2 Expression In Mammary Carcinoma Mcf-7 Cells, Jie Zhou

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Biotin feeding in a Balb/c mouse model of breast cancer suggest that the tumor load is ~100% greater in biotin-deficient mice compared with biotin-sufficient controls, and that the increase is associated with metastasis rather than new tumors. The oncogenes c-Myc and COX-2 are implicated in cancer metastasis, and their expressions are repressed by binding of MBP-1 to the promoter. Mass spectrometry studies, designed to discover novel biotin-containing proteins, suggest that lysine residues K10 and K12 in the c-Myc promoter binding protein (MBP-1) contains covalently bound biotin (MBP-1bio). We hypothesized that biotinylation of MBP-1 increases the binding of MBP-1 to the …

Effects Of Single Nucleotide Polymorphisms In The Human Holocarboxylase Synthetase Gene On Catalytic Activity, Shingo Esaki

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Holocarboxylase synthetase (HCS) catalyzes the covalent binding of biotin to carboxylases and histones in eukaryotic cells. Biotinylated carboxylases play essential roles in the metabolism of fatty acids, amino acids, and glucose; biotinylated histones play essential roles in gene regulation and genome stability. HCS null individuals are not viable whereas HCS deficiency is linked to developmental delays and phenotypes such as short life span and low stress resistance. Greater than 2,500 single nucleotide polymorphisms (SNPs) have been reported for HCS, but the biological importance of these polymorphisms is unknown. We hypothesized that some of these SNPs impair catalytic activity and that …

Regulation Of Sterol Transport By Dietary Phytosterol Esters, Trevor J. Carden

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

LDL cholesterol is associated with the development of atherosclerosis and is therefore considered an important target for intervention to prevent cardiovascular diseases. The inhibition of cholesterol absorption in the small intestine is an attractive approach to lowering plasma cholesterol, one that is exploited by drug therapy as well as dietary supplementation with plant sterols. The mechanism of action of plant sterol esters (PSE) is still incompletely understood, therefore this study was conducted to test the hypothesis that hydrolysis of plant sterol esters is necessary for their cholesterol-lowering effects to be realized.

Male Syrian hamsters were fed diets containing no PSE, …

Mechanisms Of Decreased Cholesterol Absorption Mediated By Phytosterols In The Intestinal Lumen, Andrew W. Brown

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Phytosterols and their fatty acyl esters have been known for decades to lower LDL cholesterol, making them powerful nutraceuticals in lowering cardiovascular disease risk. The mechanisms by which phytosterols lower cholesterol, though, have been incompletely characterized. Three studies were executed to examine three aspects of cholesterol and phytosterol interactions in the intestinal lumen. In the first study, the ability of pancreatic cholesterol esterase to hydrolyze phytosterol esters was examined. Pancreatic cholesterol esterase hydrolyzed phytosterol esters, but the rate of hydrolysis proved sensitive to the structures of both the sterol and ester components. In the second study, cholesterol micellarization was challenged …

Regulation Of Atp Binding Cassette Transporter A1 And G1 Expression By Fatty Acids, Chai Siah Ku

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

High density lipoprotein (HDL) is an atheroprotective element which is critical in the reverse cholesterol transport (RCT) pathway to eliminate excess cholesterol from the periphery of the body. A low plasma HDL cholesterol levels indicate a higher risk of getting cardiovascular diseases (CVD). Formation and metabolism of HDL largely rely on ATP binding cassette transporter A1 (ABCA1) and G1 (ABCG1) that are transporters to facilitate the efflux of cellular cholesterol to outside of cells. ABCA1 in the liver and small intestine is the major contributing factor for HDL formation. On the other hand, ABCA1 and ABCG1 present in macrophages contribute …

Holocarboxylase Synthetase-Dependent Biotinylation Of Histone H4, Luisa F. Rios Avila

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Holocarboxylase synthetase (HCS) catalyzes the binding of biotin to lysine (K) residues in histones H3 and H4. Histone biotinylation marks play important roles in the repression of genes and retrotransposons. Preliminary studies suggested that K16 in histone H4 is a target for biotinylation by HCS. Here we demonstrated that H4K16bio is overrepresented in repeat regions {pericentromeric alpha satellite repeats; long terminal repeats (LTR)} compared with euchromatin promoters. H4K16bio was also enriched in the repressed interleukin-2 gene promoter. The enrichment at LTR22 and promoter 1 of the sodium-dependent multivitamin transporter (SMVT) depended on biotin supply; and was significantly lower in fibroblasts …

Modulation Of Lipid Metabolism By Phytosterol Stearates And Black Raspberry Seed Oils, Mark Mckinley Ash

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Naturally occurring compounds and lifestyle modifications as combination and mono-therapy are increasingly used for dyslipidemia. Specficially, phytosterols and fatty acids have demonstrated an ability to modulate cholesterol and triglyceride metabolism in different fashions. In two separate studies, the lipid-lowering effects of black raspberry seed oil and three different phytosterol stearates were examined in order to elucidate the effects of these dietary components and the factors influencing their therapeutic actions.

The first study examined high cholesterol diets supplemented with crude and refined black raspberry seed oils, coconut oil or soybean oil. The crude and refined raspberry seed oil (RSO) treatments significantly …