Medicine and Health Sciences Commons^™

Iron-Dependent Gene Expression In Actinomyces Oris, Matthew P. Mulé, David Giacalone, Kayla Lawlor, Alexa Golden, Caroline Cook, Thomas Lott, Elizabeth Aksten, George A. O'Toole, Lori J. Bergeron

Dartmouth Scholarship

Actinomyces oris is a Gram-positive bacterium that has been associated with healthy and diseased sites in the human oral cavity. Most pathogenic bacteria require iron to survive, and in order to acquire iron in the relatively iron-scarce oral cavity A. oris has been shown to produce iron-binding molecules known as siderophores. The genes encoding these siderophores and transporters are thought to be regulated by the amount of iron in the growth medium and by the metal-dependent repressor, AmdR, which we showed previously binds to the promoter of proposed iron-regulated genes.

Systemic Insulin Sensitivity And Skeletal Muscle Akt Signaling In Rats Artificially Selected For Low And High Aerobic Capacity, Kyle Levi Fulghum

MSU Graduate Theses

The mechanism(s) linking physical inactivity, obesity, and type-II diabetes are unclear. I hypothesized low intrinsic aerobic capacity is associated with reduced systemic insulin sensitivity via skeletal muscle insulin signaling. After 34 generations of selective breeding, high aerobic capacity (HCR) rats exhibited an 8-fold increase in running distance vs low aerobic capacity (LCR) rats (n=14 per group). LCR rats had higher rates of weight gain vs HCR (p<0.05) though food consumption was constant (p=0.86) over a 12-week study. Rats were divided into 4 groups: 1) LCR-Sham Surgery, 2) LCR-Catheterization, 3) HCR-Sham Surgery or 4) HCR-Catheterization (n=7 per group). Euglycemic-hyperinsulinemic clamps on catheterized rats tested insulin sensitivity while sham LCR and HCR were used for basal tissue analysis. Plasma insulin levels did not differ during the clamps, but LCR required lower glucose infusion rates than HCR (p<0.05). Upon insulin stimulation, both absolute and normalized phospho-Akt(Ser473) of soleus muscle were significantly increased in HCR above basal group (p<0.05), but not in LCR. No difference was observed between insulin-stimulated phospho-Akt(Ser473) of HCR and LCR groups . These data support that LCR is linked to a reduction in insulin sensitivity in vivo without impairments of insulin-stimulated skeletal muscle phospho-Akt(Ser473) vs HCR rats.

Cyclin-Dependent Kinase Inhibitor P1446a Induces Apoptosis In A Jnk/P38 Mapk-Dependent Manner In Chronic Lymphocytic Leukemia B-Cells, Cody Paiva, J. Claire Godbersen, Ryan S. Soderquist, Taylor Rowland, Sumner Kilmarx

Dartmouth Scholarship

CDK (cyclin-dependent kinase) inhibitors have shown remarkable activity in CLL, where its efficacy has been linked to inhibition of the transcriptional CDKs (7 and 9) and deregulation of RNA polymerase and short-lived pro-survival proteins such as MCL1. Furthermore, ER (endoplasmic reticulum) stress has been implicated in CDK inhibition in CLL. Here we conducted a pre-clinical study of a novel orally active kinase inhibitor P1446A in CLL B-cells. P1446A inhibited CDKs at nanomolar concentrations and induced rapid apoptosis of CLL cells in vitro, irrespective of chromosomal abnormalities or IGHV mutational status. Apoptosis preceded inactivation of RNA polymerase, and was accompanied by …

13C Tracer Studies Of Metabolism In Mouse Tumor Xenografts, Andrew N. Lane, Jun Yan, Teresa W-M Fan

Toxicology and Cancer Biology Faculty Publications

Mice are widely used for human tumor xenograft studies of cancer development and drug efficacy and toxicity. Stable isotope tracing coupled with metabolomic analysis is an emerging approach for assaying metabolic network activity. In mouse models there are several routes of tracer introduction, which have particular advantages and disadvantages that depend on the model and the questions addressed. This protocol describes the bolus i.v. route via repeated tail vein injections of solutions of stable isotope enriched tracers including ¹³C₆-glucose and ¹³C₅,¹⁵N₂-glutamine. Repeated injections give higher enrichments and over longer labeling …

Eisosomes Provide Membrane Reservoirs For Rapid Expansion Of The Yeast Plasma Membrane, Ruth Kabeche, Louisa Howard, James B. Moseley

Dartmouth Scholarship

Cell surface area rapidly increases during mechanical and hypoosmotic stresses. Such expansion of the plasma membrane requires 'membrane reservoirs' that provide surface area and buffer membrane tension, but the sources of this membrane remain poorly understood. In principle, the flattening of invaginations and buds within the plasma membrane could provide this additional surface area, as recently shown for caveolae in animal cells. Here, we used microfluidics to study the rapid expansion of the yeast plasma membrane in protoplasts, which lack the rigid cell wall. To survive hypoosmotic stress, yeast cell protoplasts required eisosomes, protein-based structures that generate long invaginations at …

Role Of The Dna Sensor Sting In Protection From Lethal Infection Following Corneal And Intracerebral Challenge With Herpes Simplex Virus 1, Zachary M. Parker, Aisling A. Murphy, David. A. Leib

Dartmouth Scholarship

STING is a protein in the cytosolic DNA and cyclic dinucleotide sensor pathway that is critical for the initiation of innate responses to infection by various pathogens. Consistent with this, herpes simplex virus 1 (HSV-1) causes invariable and rapid lethality in STING-deficient (STING(-/-)) mice following intravenous (i.v.) infection. In this study, using real-time bioluminescence imaging and virological assays, as expected, we demonstrated that STING(-/-) mice support greater replication and spread in ocular tissues and the nervous system. In contrast, they did not succumb to challenge via the corneal route even with high titers of a virus that was routinely lethal …

A Self-Lysis Pathway That Enhances The Virulence Of A Pathogenic Bacterium, Kirsty A. Mcfarland, Emily L. Dolben, Michele Leroux, Tracy K. Kambara, Kathryn Ramsey, Robin Kirkpatrick, Joseph Mougous, Deborah Hogan, Simon Dove

Dartmouth Scholarship

In mammalian cells, programmed cell death (PCD) plays important roles in development, in the removal of damaged cells, and in fighting bacterial infections. Although widespread among multicellular organisms, there are relatively few documented instances of PCD in bacteria. Here we describe a potential PCD pathway in Pseudomonas aeruginosa that enhances the ability of the bacterium to cause disease in a lung infection model. Activation of the system can occur in a subset of cells in response to DNA damage through cleavage of an essential transcription regulator we call AlpR. Cleavage of AlpR triggers a cell lysis program through de-repression of …

Links Between Anr And Quorum Sensing In Pseudomonas Aeruginosa Biofilms, John H. Hammond, Emily F. Dolben, T. Jarrod Smith, Sabin Bhuju, Deborah Hogan

Dartmouth Scholarship

In Pseudomonas aeruginosa, the transcription factor Anr controls the cellular response to low oxygen or anoxia. Anr activity is high in oxygen-limited environments, including biofilms and populations associated with chronic infections, and Anr is necessary for persistence in a model of pulmonary infection. In this study, we characterized the Anr regulon in biofilm-grown cells at 1% oxygen in the laboratory strain PAO1 and in a quorum sensing (QS)-deficient clinical isolate, J215. As expected, transcripts related to denitrification, arginine fermentation, high-affinity cytochrome oxidases, and CupA fimbriae were lower in the Δanr derivatives. In addition, we observed that transcripts associated with quorum …

Association Between Chlorinated Pesticides In The Serum Of Prepubertal Russian Boys And Longitudinal Biomarkers Of Metabolic Function, Jane Burns, Paige Williams, Susan Korrick, Russ Hauser, Oleg Sergeyev, Boris Revich, Thuy Lam, Mary Lee

Mary M. Lee

Organochlorine pesticides (OCPs) have been linked to adult metabolic disorders; however, few studies have examined these associations in childhood. We prospectively evaluated the associations of baseline serum OCPs (hexachlorobenzene, beta-hexachlorocyclohexane, and p,p'-dichlorodiphenyldichloroethylene) in Russian boys with subsequent repeated measurements of serum glucose, insulin, lipids, leptin, and calculated homeostatic model assessment of insulin resistance (IR). During 2003-2005, we enrolled 499 boys aged 8-9 years in a prospective cohort; 318 had baseline serum OCPs and serum biomarkers measured at ages 10-13 years. Multivariable generalized estimating equation and mediation regression models were used to examine associations and direct and indirect (via body mass …

Coculture Of Staphylococcus Aureus With Pseudomonas Aeruginosa Drives S. Aureus Towards Fermentative Metabolism And Reduced Viability In A Cystic Fibrosis Model, Laura M. Filkins, Jyoti A. Graber, Daniel G. Olson, Emily L. Dolben, Lee Lynd, Sabin Bhuju, George A. O'Toole

Dartmouth Scholarship

The airways of patients with cystic fibrosis are colonized with diverse bacterial communities that change dynamically during pediatric years and early adulthood. Staphylococcus aureus is the most prevalent pathogen during early childhood, but during late teens and early adulthood, a shift in microbial composition occurs leading to Pseudomonas aeruginosa community predominance in ∼50% of adults. We developed a robust dual-bacterial in vitro coculture system of P. aeruginosa and S. aureus on monolayers of human bronchial epithelial cells homozygous for the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) mutation to better model the mechanisms of this interaction. We show that P. …

Sec17 Can Trigger Fusion Of Trans-Snare Paired Membranes Without Sec18, Michael Zick, Amy Orr, Matthew L. Schwartz, Alexey J. Merz, William Wickner

Dartmouth Scholarship

Sec17 [soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein; α-SNAP] and Sec18 (NSF) perform ATP-dependent disassembly of cis-SNARE complexes, liberating SNAREs for subsequent assembly of trans-complexes for fusion. A mutant of Sec17, with limited ability to stimulate Sec18, still strongly enhanced fusion when ample Sec18 was supplied, suggesting that Sec17 has additional functions. We used fusion reactions where the four SNAREs were initially separate, thus requiring no disassembly by Sec18. With proteoliposomes bearing asymmetrically disposed SNAREs, tethering and trans-SNARE pairing allowed slow fusion. Addition of Sec17 did not affect the levels of trans-SNARE complex but triggered sudden fusion of trans-SNARE paired proteoliposomes. …

Fungal Mediator Tail Subunits Contain Classical Transcriptional Activation Domains, Zhongle Liu, Lawrence C. Myers

Dartmouth Scholarship

Classical activation domains within DNA-bound eukaryotic transcription factors make weak interactions with coactivator complexes, such as Mediator, to stimulate transcription. How these interactions stimulate transcription, however, is unknown. The activation of reporter genes by artificial fusion of Mediator subunits to DNA binding domains that bind to their promoters has been cited as evidence that the primary role of activators is simply to recruit Mediator. We have identified potent classical transcriptional activation domains in the C termini of several tail module subunits of Saccharomyces cerevisiae, Candida albicans, and Candida dubliniensis Mediator, while their N-terminal domains are necessary and sufficient for their …

Systems Level Analysis Of Systemic Sclerosis Shows A Network Of Immune And Profibrotic Pathways Connected With Genetic Polymorphisms, J. Matthew Mahoney, Jaclyn Taroni, Viktor Martyanov, Tammara A. A. Wood, Casey S. Greene, Patricia A. Pioli, Monique E. Hinchcliff, Michael L. Whitfield

Dartmouth Scholarship

Systemic sclerosis (SSc) is a rare systemic autoimmune disease characterized by skin and organ fibrosis. The pathogenesis of SSc and its progression are poorly understood. The SSc intrinsic gene expression subsets (inflammatory, fibroproliferative, normal-like, and limited) are observed in multiple clinical cohorts of patients with SSc. Analysis of longitudinal skin biopsies suggests that a patient's subset assignment is stable over 6-12 months. Genetically, SSc is multi-factorial with many genetic risk loci for SSc generally and for specific clinical manifestations. Here we identify the genes consistently associated with the intrinsic subsets across three independent cohorts, show the relationship between these genes …

Mcl1 Enhances The Survival Of Cd8+ Memory T Cells After Viral Infection, Jingang Gui, Zhuting Hu, Ching-Yi Tsai, Tian Ma, Yan Song, Amanda Morales, Li-Hao Huang, Ethan Dmitrovsky, Ruth Craig, Edward Usherwood

Dartmouth Scholarship

Viral infection results in the generation of massive numbers of activated effector CD8+ T cells that recognize viral components. Most of these are short-lived effector T cells (SLECs) that die after clearance of the virus. However, a small proportion of this population survives and forms antigen-specific memory precursor effector cells (MPECs), which ultimately develop into memory cells. These can participate in a recall response upon reexposure to antigen even at protracted times postinfection. Here, antiapoptotic myeloid cell leukemia 1 (MCL1) was found to prolong survival upon T cell stimulation, and mice expressing human MCL1 as a transgene exhibited a skewing …

Strategies For Preventing Age And Neurodegenerative Disease-Associated Mitochondrial Dysfunction, Vedad Delic

USF Tampa Graduate Theses and Dissertations

Mitochondrial dysfunction plays a pivotal role in the development of aging phenotypes and aging-associated neurodegenerative disorders, such as Alzheimer’s disease (AD), Parkinson’s disease (PD) and Amyotrophic lateral sclerosis (ALS). Strategies that restore mitochondrial dysfunction may rescue the deficits of central metabolism in these disorders and improve cell survival. For example, we found that modulating the mTOR signaling pathway in a tissue culture model of aging-induced mitochondrial DNA mutation enhanced mitochondrial function as evidenced by increased oxygen consumption. Our previous melatonin studies also led us to hypothesize that caloric restriction and the hormone melatonin would reverse brain mitochondrial dysfunction in animal …

The Metabolism Of Alcohol: Risk And Protective Factors, Sydney E. Levan, Amy Adkins, Danielle Dick, Karen G. Chartier

Undergraduate Research Posters

Purpose: Abstract for poster submission to VCU Poster Symposium for

Undergraduate Research and Creativity

Title: The Metabolism of Alcohol: Risk and Protective Factors

Background: In 2002, it was reported by the National Institutes of Health that

60.3% of college aged students (18-22) drank alcohol in the past month of being

asked, as compared to 51.9% of those not in college. They also found that 20% of

college students met the criteria for at least one alcohol use disorder (AUDs)1.

Many genes have been linked to an increased risk for AUDs and how individuals

with various ethnic backgrounds respond to alcohol. …

Metabolic And Oxidative Regulation Of Neuronal Autophagy And Survival, Matthew Dodson

All ETDs from UAB

Neurodegenerative diseases, such as Parkinson's disease, Alzheimer's disease and Huntington's disease are all characterized by metabolic dysfunction, increased oxidative damage to proteins and organelles, formation of proteinaceous inclusions, decreased autophagic and proteasomal function, and eventual neuronal and glial cell death. While our understanding of the mechanisms that underlie many of these pathologies is constantly growing, their exact cause, onset, interplay and progression still remain unclear. The gap between the description of disease pathologies and understanding the fundamental mechanisms of disease pathogenesis, progression and potential therapeutics to mitigate disease progression is still large. Based on the observation that altered glucose utilization, …

The Alpha-Glucosidase Inhibitor Acarbose As A Calorie Restriction Mimetic To Modify Metabolic Outcomes In Mice, Rachel Ann Brewer

All ETDs from UAB

Age-related diseases continue to be a leading cause of death. One of the only replicable methods proven to decrease age-related morbidity and mortality in multiple species is calorie restriction (CR). CR is difficult for human populations to implement, and has a number of associated risks and side effects. A CR mimetic could provide the healthspan- and lifespan-extending benefits of CR without the limitations. Acarbose (ACA), an α-glucosidase and α-amylase inhibitor approved to treat type 2 diabetes in humans, was recently identified as able to extend lifespan in healthy mice. The purpose of this research was to determine the effects of …

Energy Metabolism Of Platelets During Activation, Oxidative Stress And Storage, Saranya Ravi

All ETDs from UAB

The principal function of platelets is to regulate hemostasis, and dysfunction of platelet aggregation or activation can lead to either excessive thrombotic or hemorrhagic complications. It has been shown that the ability to generate ATP and exposure to oxidative stress can affect platelet thrombotic potential. While platelet metabolism has been extensively studied, the importance of substrate availability and metabolic plasticity in regulating aggregation under physiological or pathological conditions is not well understood. In this dissertation, we examined the reliance of platelets on different metabolic substrates, the importance of ATP production for aggregation in response to thrombin stimulation, metabolic stress following …