PI: Jeff Davidson, Ph.D., Professor of Pathology, Microbiology and Immunology
The Role of Cardiac Ankyrin Repeat Protein in Wound Healing
The overall goal of my project is to study the role cardiac ankyrin repeat protein (Ankrd1/CARP) plays in tissue repair. Data from Ankrd1/CARP overexpression and deletion showed Ankrd1/CARP involvement in neovascularization, a critical aspect of the wound healing process. Studies in our lab have shown that Ankrd1/CARP is capable of stimulating neovascularization in a number of wound-healing models. We hypothesize that Ankrd1/CARP utilizes novel signaling pathways for its proangiogenic effects. One of my research objectives is to determine how Ankrd1/CARP affects tissue repair through provisionally identified targets such as integrins and matrix metalloproteinases. Results derived from this study can lead to the delineation of new mechanisms that regulate wound angiogenesis.
PI: James Patton, Ph.D., Stevenson Professor of Biological Sciences
Small RNA Regulation of Gene Expression in Zebrafish
RNA Interference (RNAi) is an umbrella term that involves the use of small RNAs to mediate gene silencing. Silencing RNAs (siRNAs) and endogenous micro RNAs (miRNAs) use a common pathway to knockdown gene expression in a sequence-specific manner. I am studying two different mechanisms of gene silencing in zebrafish. The first is to elucidate the role that miRNAs play in regulating early development. Global analysis of miRNA expression patterns during early development showed dynamic changes in miRNA expression and my focus is to identify the mRNAs targets for specific miRNAs using gain-of-function and loss-of-function experiments. My second project is to develop a novel strategy allowing gene silencing in zebrafish in an RNAi-dependent manner. The use of siRNAs in zebrafish is controversial with numerous reports claiming nonspecific gene knockdown. I am testing a new silencing mechanism in which convergent mRNA transcripts produce nuclear double stranded RNAs that ultimately cause sequence-specific gene silencing via chromatin modification. I seek to determine whether specific histone modifications underlie gene silencing as a result of convergent transcription.
PI: Irina Kaverina, Ph.D., Associate Professor of Cell and Developmental Biology
Mechanism and Regulation of Proto-oncogene Src Trafficking
My research focuses on determining the underlying mechanism by which the proto-oncogene Src is trafficked by the underlying microtubule and actin cytoskeleton. My work focuses on identifying the key molecular players that regulate and coordinate this concerted effort for the efficient delivery of Src, as well as how regulation of Src trafficking by the cytoskeleton influences the formation of degradative actin-rich structures, podosomes.
Additionally, I am also examining the role and function of the tumor suppressor RASSF1A. My work focuses on determining the mechanism by which RASSF1A exerts its tumor suppressor function through interaction with the microtubule network.
PI: Simon Hayward, Ph.D., Professor of Cancer Biology
The Role of NF-kB Activation in Prostate Hyperplastic Growth
NF-kB is a nuclear transcription factor that responds to a variety of stimuli including cytokines and stress and which in turn influences the immune and inflammatory systems. Altered NF-kB regulation is associated with inflammation and a host of human disease processes. Elevated NF-kB activation is seen in BPH and is associated with inflammatory responses. However, little is known about the mechanisms linking NF-kB activation with hyperplastic growth in the prostatic stroma and epithelium which lead to BPH. Therefore, this project is aimed to address the question of whether chronic activation of NF-kB signaling in human prostatic cells will result in hyperplasia of both the stromal and epithelium tissues. BHPrE1, BPH-1, NHPrE1, and BHPrS1 cells will be transduced with a dominant active (DA) form of IKK2 which results in constitutive activation of NF-kB.
PI: Barbara Fingleton, Ph.D., Assistant Professor of Cancer Biology
Matrix Metalloproteinase 2 Contributions to Tumor Cell Proliferation in Breast Cancer
My studies are centered on the role of host cell matrix metalloproteinase 2 (MMP2) contributions to tumor cell proliferation in breast cancer. MMP2 is an enzyme that is upregulated in many cancers and has multiple functions. Our preliminary data in mouse models demonstrate that there is reduced tumor cell growth in animals lacking MMP2 compared to wild type animals. This suggests that host stromal cells facilitate the growth of tumor cells in vivo. Our present focus is to determine the cells responsible for mediating tumor cell proliferation, the means by which this is accomplished, and whether or not this is MMP2 dependent. Because our in vitro studies suggest that MMP2 does not directly induce tumor cell growth and current literature suggests that fibroblasts support the growth of tumor cells in vivo, we hypothesize that MMP2 dependent fibroblast support of tumor cells mediates tumor cell growth in vivo.
PI: Julie Sterling, Ph.D.,Assistant Professor of Medicine, Assistant Professor of Cancer Biology
The Role of Myeloid-Derived Suppressor Cells (MDSCs) in the Tumor Microenvironment
The Sterling lab studies the mechanisms that enable certain cancer types to metastasize to bone. These include breast, lung, oral, renal, and prostate cancer. One of my goals for my graduate studies is to understand the role of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment and their contribution to bone metastasis in breast cancer. The hypothesis is that these cells initiate the metastatic niche and dictate where it establishes. By understanding how these cells affect the different cell signaling pathways within the tumor microenvironment, such as the TGF-β pathway, it will give a better idea of how early bone metastatic disease occurs. The more that is known about the tumor microenvironment the more opportunity there is to create targeted novel therapies.
PI: Chee Lim, Ph.D., Assistant Professor of Medicine, Assistant Professor of Molecular Physiology and Biophysics
Post-transcriptional Regulation of Titan in the Cardiac Sarcomere
The Lim laboratory studies the maintenance and organizational properties of the cardiac sarcomere. The cardiac sarcomere is the contracting unit in a cardiomyocyte. Together, these cells work in rhythm to promote cardiac muscle contraction. During human life, the heart continuously beats; however, over time the sarcomere proteins are worn out/damaged. Our lab focuses on understanding the molecular events that mediate sarcomere turnover in a functional contracting heart. We are specifically interested in the protein titin. Titin is important to the sarcomere since it provides a scaffold for myosins and other sarcomere signaling proteins. My project focuses on the post-transcriptional regulation of titin.
PI: Larry Marnett, Ph.D., University Professor of Biochemistry and Chemistry, Mary Geddes Stahlman Chair in Cancer Research, Professor of Chemistry, Professor of Pharmacology
Modification of the Cell Cycle by 4-hydroxynonenal (HNE).
4-hydroxynonenal (HNE) is a product of lipid peroxidation that occurs as a result of high levels of oxidative stress. My work focuses on the covalent modification of proteins by HNE that can alter protein function resulting in the dysregulation of cellular pathways. Through previous mass spectrometry analysis, our group has shown that HNE can covalently modify CDK2, a main cell cycle regulator in the G1/S transition. The goal of my project is to determine how modification of CDK2 by HNE results in alteration of the cell cycle.
PI: Julie Sterling, Ph.D.,Assistant Professor of Medicine, Assistant Professor of Cancer Biology
Molecular Mechanisms Facilitating Metastasis of Oral Squamous Carcinoma
In the Sterling lab we study the mechanisms that enable certain cancer types to metastasize to bone. These include breast, lung, oral, renal, and prostate cancer. My projects mainly involve oral squamous cellular carcinoma and molecular mechanisms facilitating its metastasis to the lower jaw. We are especially interested in understanding the role of bone rigidity and PTHrP (Para Thyroid Hormone related Protein) in cancer progression in the bone microenvironment. Our lab utilizes basic bench research techniques, such as RT-PCR as well as pre-clinical systems using mouse models and sophisticated imaging equipment to conduct our research.
PI: Anne Kenworthy, Ph.D., Associate Professor of Molecular Physiology and Biophysics; Associate Professor of Cell and Developmental Biology
Role of Caveolin-1 Mutations in Pulmonary Arterial Hypertension
I work in the lab of Dr. Anne Kenworthy where some main interests are microscopy, lipid rafts, autophagy, and endocytosis. Recently, we began collaborating with researchers who are working on Pulmonary Arterial Hypertension (PAH). My thesis project focuses on the membrane protein Caveolin-1 which is involved in endocytosis amongst other things. The Cav-1 mutation we study is associated with PAH, and we would like to better understand the role of this mutated protein in the pathogenesis of the disease.
Chemical and Physical Biology
PI: Brian Welch, Ph.D., Assistant Professor of Radiology and Radiological Sciences
Characterization of Adipose Tissue Before and After Roux-en-Y Gastric Bypass Surgery
Morbid obesity is an increasing epidemic in the US and is the leading factor in the development of cardiovascular diseases such as coronary atherosclerosis, hypertension, dyslipidemia, and Type 2 diabetes (T2DM). Currently, gastrointestinal bypass surgery, specifically Roux-en-Y bypass (RGBP) surgery, is the most established and effective treatment for substantial and sustained weight loss in morbidly obese subjects. However, the mechanism in which the tissue of the adipose organ changes is not well understood.
Our goal is to investigate adipose tissue (AT) using MRI and PET imaging on obese rats before and after RGBP surgery and determine: size, type and localization of the districts adipose tissues (brown and white) using fat-water MRI, and R2* relaxation time within AT to detect inflammation associated adipose tissue.
Many advances have been made in understanding the underlying mechanism of prolonged weight loss after RGBP, but characterization of AT, specifically spatial distribution, triglyceride composition, inflammation status and mitochondrial density before and after surgery, has not been previously measured in a single imaging-based study. Investigating the role played by AT in combination with hormone and cellular signaling will provide a better understanding of weight loss mechanisms after gastrointestinal (GI) bypass intervention.
PI: Jonathan Irish, Ph.D., Assistant Professor of Cancer Biology, Assistant Professor of Pathology, Microbiology, and Immunology
Systems Biology Approach to Melanoma Treatment
The goal of my project is to improve current methods of treatment for melanoma by using a systems biology approach. I measure abnormal cell signaling events that improve incidences of proliferation and apoptosis evasion using phosphoflow cytometry. Cytoplasmic signaling is a mechanism that cells use to respond to their environment and regulate their biological activity. Cancer cells are unusual because they have discovered a way to make minor modifications of their signaling processing circuitry to stay alive. I focus on measuring signaling in melanoma, because it should provide a comprehensive view of cellular processes necessary for therapeutic resistance.
PI: Rebecca Sappington, Ph.D., Assistant Professor of Ophthalmology and Visual Sciences, Assistant Professor of Pharmacology
Role of IL-6 in the Progression of Glaucoma
I work in the lab of Dr. Rebecca Sappington looking at the effect of neuronal-glial signaling in glaucoma, the leading cause of irreversible blindness worldwide. Vision loss in glaucoma is attributed to the degeneration of retinal ganglion cells (RGC) and their axons and is often associated with elevation in intraocular pressure (IOP). Although glaucoma primarily targets RGCs, glial cells, which are responsible for supporting RGC health, may be involved in disease onset and development. Currently, I’m focused on interleukin-6 (IL-6), a cytokine released by glial cells with both pro- and anti-inflammatory properties, and its impact on RGC health and the progression of glaucoma in vivo.
PI: Rebecca Ihrie, Ph.D., Assistant Professor of Cancer Biology, Assistant Professor of Neurological Surgery
Stem Cells and Brian Tumor Development
My project is focused on understanding the stem cells of the brain, how they function in the normal brain, and how mutations that disrupt the normal functioning of these cells may result in brain tumor development. Recently, we have found that stem cells in different locations within the brain respond to different signals, meaning that stem cells in a specific position seem to make specific types of neurons. My project will dissect a specific pathway’s effects on neuron production, and ask if the same positional pattern is true for a developmental disorder. Are stem or progenitor cells in a specific location particularly susceptible to specific mutations, and can we use this information to improve treatment of the tumors that result?
PI: Sachin Patel, M.D., Ph.D., Assistant Professor of Psychiatry, Assistant Professor of Molecular Physiology and Biophysics
Cannabinoid Receptor 1 Signaling in the Amygdala
My thesis research project focuses on the role of the endocannabinoid system in stress-induced maladaptations in the mouse brain, specifically the amygdala. By investigating stress-induced changes in the amygdala, mechanisms that underlie stress-related neuronal plasticity and remodeling leading to fear and anxiety can be determined. In this research project, I will investigate the molecular mechanisms involving the endocannabinoid system, specifically signaling through cannabinoid receptor 1 (CB1R), which underlie the development and exacerbation of anxiety-like behaviors in rodents. These investigations will involve the use of electrophysiological recordings in brain slices and a variety of behavioral and biochemical techniques.
PI: F. Peter Guengerich, Ph.D. Professor of Biochemistry, Harry Pearson Broquist Professorship in Biochemistry
Hydroxylation and Lyase Activities of Human Cytochrome P450 17A1
Human cytochrome P450 17A1 is a monooxygenase enzyme that catalyzes both the 17a-hydroxylation and 17,20-lyase reactions in the steroid hormone biosynthetic pathway. While only the former function is required for the production of glucocorticoids, both are vital for the synthesis of the sex hormones: androgens and estrogens, which creates a unique issue when targeting the enzyme to treat sex steroid responsive cancers without hindering the production of essential glucocorticoids. Identification of the specific structural regions, peptides and/or amino acids in enzyme that distinguish between the 17a-hydroxylation and 17,20-lyase activities is the primary interest of my investigation. In this structure/function investigation, I will conduct kinetic and structural analyses on clinically reported and naturally evolved P450 17A1 variants. The methods employed will include substrate binding analysis, steady-state and rapid reaction kinetic measurements (e.g. stopped-flow, rapid-quench), crystallography, etc. Additionally, I will examine the mechanism by which the lyase-specific inhibitor, Orteronel, impedes only the 17,20-lyase function.
PI: Utpal Dave, M.D., Assistant Professor of Medicine, Assistant Professor of Cancer Biology
B-cell Development and T-cell Acute Lymphobastic Leukemia
The maintenance of the hematopoietic system depends on the ability of hematopoietic stem cells (HSCs) to self-renew and differentiate into all blood cell lineages. When hematopoiesis is blocked in differentiation or has deregulated self-renewal, leukemia or lymphoma can result. The hematopoetically expressed homeobox (Hhex) is important for normal B-cell development and is also activated along with Lmo2 in T-cell acute lymphoblastic leukemia (T-ALL). However, the mechanism by which Hhex operates in normal and malignant hematopoiesis is not well understood. My research seeks to understand the roles of Hhex in B-cell development and T-ALL induction.
PI: Claus Schneider, Ph.D., Professor of Pharmacology
Oxidative Metabolites of Curcumin and their Bioactivity
My graduate work is focused on the oxidative metabolism curcumin, a natural chemopreventive agent. We hypothesize that the oxidative metabolites are direct mediators of some of curcumin's many bioactivities. The approach in testing this hypothesis has been to isolate and identify the oxidative metabolites from in vitro reactions; to determine the formation of these metabolites in vivo; and to assess the bioactivities of the metabolites against known curcumin targets using cell culture systems. Our aim is towards improving the therapeutic efficacy of curcumin.
PI: Katherine Friedman, Ph.D., Associate Professor of Biological Sciences
Maintenance of chromosome ends by telomerase in Saccharomyces cerevisiae
The ends of chromosomes (telomeres) constitute a tiny fraction of DNA in a cell, but play a central role in genome stability and cellular lifespan. Following conventional DNA replication, processing of the leading strand results in chromosome shortening. A ribonucleoprotein enzyme, telomerase, replenishes these terminal sequences. Yeast telomerase contains an RNA that provides the template for addition of DNA to chromosome ends, a catalytic protein subunit (Est2p), and other essential protein components (Est1p and Est3p). Telomerase activity is tightly regulated in the cell cycle, occurring only in late S phase. We have shown that Est1p is degraded by the proteasome during G1 phase, precluding telomerase assembly. Inhibiting Est1p degradation allows Est1p to associate with the catalytic core of the telomerase complex and simultaneously recruits Est3p. Our current work is directed toward understanding the regulation of Est1p degradation, determining the mechanism through which Est1p recruits Est3p to the telomerase complex, and examining the role of Est3p in telomerase activation.
PI: Alyssa Hasty, Ph.D., Associate Professor of Molecular Physiology and Biophysics
inflammatory Macrophage Survival in Obese Adipose Tissue
Obesity has become a major worldwide health issue over the past few years that can lead to insulin resistance (IR) and type 2 diabetes. Macrophage inflammation in adipose tissue (AT) is thought to contribute to the development of IR in obese individuals. My research investigates the role of NF-κB in inflammatory adipose tissue macrophage (ATM) survival in obese adipose tissue. ATM inflammation is thought to contribute to the chronic inflammation in obese tissue that ultimately contributes to the development of insulin resistance and type 2 diabetes. Understanding the mechanisms by which NF-κB can help prolong ATM survival could help develop new therapies against these diseases.
PI: Charles Sanders, Ph.D., Professor of Biochemistry
Molecular Biophysical Basis of Diseases Involving Membrane Protein Dysfunction
A number of diseases involve missense mutations in genes encoding membrane proteins that result in protein dysfunction and/or misfolding and mistrafficking early in the secretory pathway. The Sanders lab seeks to elucidate the molecular biophysical mechanisms by which such mutations result in these defects. We are pursuing several systems, including Long QT Syndrome mutant forms of both the human potassium KCNQ1 channel and a modulatory partner, KCNE1. Mutations in either of these proteins result in altered channel functional properties that throw off the timing and electrical properties of the cardiac action potential in a way that can result in serious, even fatal arrhythmias. Our approach is to carry out studies of purified membrane proteins using solution NMR spectroscopy and then correlate observations from these studies with what is known about the behavior of the corresponding mutant protein in vivo.
PI: BethAnn McLaughlin, Ph.D., Assistant Professor of Neurology, Assistant Professor of Pharmacology
Cell Signaling Pathways Related to Neurodegeneration and Protection
The goal of research in the McLaughlin lab is to understand the endogenous pathways associated with neurodegeneration and protection to develop novel therapeutics for stroke, cerebral palsy and other degenerative conditions. Studies in the lab include understanding how classical biochemical changes in ion homeostasis (specifically zinc, calcium and potassium homeostasis) induce the molecular pathways associated with apoptotic cell death. In this work we established a novel link between ROS and zinc induced activation of MAPKs and opening of potassium channels that are associated with apoptotic cell death. In addition, these studies investigate signaling pathways which provide protective mechanisms against other forms of cell death.
Molecular Physiology and Biophysics
PI: David Harrison, M.D., Betty and Jack Bailey Chair in Cardiology, Professor of Medicine, Professor of Molecular Physiology and Biophysics, Professor of Pharmacology, Director, Division of Clinical Pharmacology
Role of Inflammation in Hypertension
Hypertension is one the leading causes of mortality in the US. One in three people suffer from high blood pressure, which is correlated to the development of other diseases such as diabetes, renal damage, and obesity. My laboratory has shown that T cells play an important role in hypertension, but the mechanisms by which they are activated remains undefined. Dendritic cells present antigens and secrete cytokines that modify T cell polarization. The NADPH oxidase contributes to hypertension via multiple mechanisms. Hypertensive mice have high levels of superoxides. Superoxide catalyzes the formation of H2-isoprostanes, which rearrange to form reactive γ-ketoaldehydes termed isoketals that adduct to protein lysines which renders them immunogenic. We hypothesize that oxidative stress catalyzes the formation of isoketals, which alters the function of dendritic cells leading to inflammation and hypertension. Therefore, my project focuses on identifying the molecular and physiological mechanism by which isoketals function during hypertension.
PI: Michael Freeman, Ph.D., Professor of Radiation Oncology, Professor of Radiology and Radiological Sciences, Professor of Cancer Biology
The Role of Lipid Oxidation after Radiation-induced Pulmonary Injury.
Normal tissue toxicity is a limiting factor in radiation therapy in advanced stage lung cancer. Subsets of patients who have undergone radiation therapy develop radiation-induced pulmonary injury. It is well-established that ionizing radiation induces oxidative stress that generates lipid oxidation products. Lipid oxidation products have been shown to react with protein, lipid membranes and DNA. What is not well understood, are the specific types of lipid products formed after ionizing radiation, their targets, and their role in radiation-induced pulmonary injury. This research seeks to understand the role of lipid oxidation products which occur after ionizing radiation in the context of pulmonary-injury. The goal of this project is to identify novel targets to help decrease normal tissue damage after lung cancer radiation therapy.
PI: Billy Hudson, Ph.D., Elloitt V. Newman Professor of Medicine, Professor of Biochemistry, Professor of Pathology, Microbiology and Immunology
The Role of Sulfilimine Crosslinks in Tissue Genesis and Tumorigenesis and Progression
Collagen IV extracellular scaffolds are a principal component of the basement membrane (BM), a specialized form of extracellular matrix (ECM) that effects tissue tension, cell polarity, and cell-microenvironment relationships. During tissue generation and tumorigenesis, collagen IV scaffolds are assembled to support cellular proliferation, survival, and migration. Our lab has recently discovered a unique sulfilimine crosslink of collagen IV that reinforces the scaffold network. My study focuses on determining the role of the collagen IV sulfilimine crosslinks in epithelial arrangement. Additionally, I am investigating the role of sulfimine crosslinks in tumor supportive BM assembly and remodeling, which is required for tumorigenesis and progression.
PI: Chris Williams, M.D., Ph.D., Assistant Professor of Medicine, Assistant Professor of Cancer Biology
Role of BVES, a Tight Junction Protein, in Cancer.
I am interested in junctional biology and cancer. Tight junctions between epithelial cells regulate the passage of molecules through the epithelial barrier. Dysregulation of junctional complexes plays a role in cancer development. Recent studies from our lab have shown that BVES, a tight junction protein, is down regulated in colon cancer and restoring expression of BVES in cancer cell lines promotes epithelial-like features. The main goal of my project is to understand how BVES and BVES-interacting proteins are regulated in cancer. I am using complimentary mouse and cell culture models to understand BVES mediated signaling events in cancer.
Molecular Physiology and Bioophysics
PI: Kasey Vickers, Ph.D., Assistant Professor of Medicine, Assistant Professor of Molecular Physiology and Biophysics
Communication by HDL-miRNAs in Type 2 Diabetes
MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally repress gene expression and are found in both cells and extracellular fluids, including plasma. Extracellular miRNAs are protected from circulating nucleases through their association with lipid and protein carriers, specifically exosomes and lipoproteins.. Currently, I am studying the role of high-density lipoproteins (HDL)-miRNAs as cell-to-cell messengers in a novel endocrine-like communication pathway within Type 2 diabetes. We found that many of the most abundant miRNAs on HDL are also enriched in insulin-producing β-cells in the islets of Langerhans. Additionally, we found that the miRNA signature on HDL is significantly altered in rat models of Type 2 diabetes; therefore, the goal of my project is to investigate the molecular mechanisms by which the β-cell-originating miRNAs control gene expression in distal tissues and how this pathway regulates systemic lipid and glucose metabolism. Using high-throughput genomics, I aim to decode and control miRNA intercellular communication to better understand and treat type 2 diabetes, including developing biomarkers to predict pre-diabetes.
PI: Jennifer Pietenpol, Ph.D., Benjamin F. Byrd Jr. Endowed Chair in Oncology, Professor of Biochemistry, Professor of Cancer Biology, Director of the Vanderbilt Ingram Cancer Center
The Role of p73 during Organ Development
The p53 family of proteins; p53, p63 and p73; are sequence-specific transcription factors that genes involved in cell cycle arrest, DNA repair, apoptosis, development and cell differentiation. p73, unlike p53, is rarely mutated in human cancers, which makes p73 a good therapeutic target. Using our genetically engineered p73 knockout mice, we will determine the role of p73 during normal development and determine signaling mechanisms by which p73 regulates organ function.
PI: Tina Iverson, Ph.D., Associate Professor of Pharmacology
Mechanism of Covalent Flavin Attachment to Metabolic Enzyme Complex II
Complex II is an essential metabolic enzyme that functions in both the Krebs cycle and the electron transport chain in mitochondria, coupling succinate oxidation to fumarate with ubiquinone reduction to ubiquinol. Covalent FAD attachment in the flavoprotein subunit of this hetertrimeric complex is essential for succinate oxidation and mutations that abrogate this covalent linkage and result in pheochromocytoma-paraganglioma syndrome in humans have been identified, although the underlying biochemistry is currently undefined. In addition, assembly factors have recently been identified that are required for the covalent flavin attachment, and mutations in the assembly factors present with the same clinical symptoms as mutations in Complex II. Understanding the mechanism of covalent flavin attachment is vital to understanding the function of Complex II and how this unique enzyme has adapted utilization of an FAD cofactor to couple two essential respiratory processes. My work utilizes a combination of structural, biochemical and biophysical methods to investigate this mechanism, the underpinnings of which are highly conserved from bacteria to complex mammals. Mutagenesis and structural studies will also allow me to probe the role of specific mutations in Complex II malfunction in disease.
PI: John Penn, Ph.D., Professor of Ophthalmology and Visual Sciences, Professor of Cell and Developmental Biology, Phyllis G. and William B. Snyder, MD Endowed Chair in Ophthalmology and Visual Sciences, Professor of Medical Education and Administration, Assistant Dean for Faculty Development
Nuclear Accumulation of GAPDH and Decreased Cell Viability in Human Retinal Pericytes Exposed to Diabetic Conditions
One of the earliest pathological features of diabetic retinopathy (DR) is the death of retinal pericytes. Retinal pericyte death follows in endothelial cell dropout, acelluar retinal capillaries, and ultimately, to hypoxia-induced retinal neovascularization. Two enzymes with known roles in cell death in other disease states are GAPDH and Siah-1. Once the enzymes bind each other, GAPDH stabilizes Siah-1 causing nuclear translocation of GAPDH. This stabilization affects the degradation of target proteins, which results in apoptosis. The purpose of my research is to determine whether or not, and to what extent, GAPDH and Siah-1 are involved in the cell death response of retinal pericytes exposed to diabetes-relevant pathological conditions in vitro.
PI: Brandt Eichman, Ph.D., Associate Professor of Biological Sciences, Associate Professor of Biochemsitry
Structural Biology of DNA Replication and Repair
DNA damage can be caused by exposure to environmental toxins and by cellular metabolites. This damage, or chemical modification of DNA bases, can cause errors in DNA replication and lead to stalled replication forks which can then lead to genomic instability, cell death, and even cancer. The lab uses the tools of biochemistry and structural biology, primarily X-ray crystallography, to study the mechanisms of proteins involved in various DNA damage response pathways. Current work is focused on DNA glycosylases involved in base excision repair of alkylated DNA, and on DNA translocases involved in stalled replication fork stabilization and regression. These studies will ultimately allow us to understand the fundamental processes and mechanisms of DNA repair and genome maintenance and to develop new therapeutic strategies to target genetic diseases.
PI: Todd Edwards, Ph.D., M.S., Assistant Professor of Medicine, Center for Human Genetics Research, Division of Epidemiology
Genetic Determinants of Complex Diseases and Racial Health Disparities
Vanderbilt University has the largest collection of electronic medical records linked with patient genetic information in a database called BioVU. This impressive resource enables me to investigate the complex determinants of diseases - in particular uterine fibroids and keloids - that have a disproportionally large burden in African Americans. Most of my analyses look at distributions of genetic loci across populations, as determined through techniques like genome-wide association studies (GWAS) and exome genotyping, to look for heritable factors that modiulate disease risk. I also employ large-scale epidemiology study design and computational biostatistics approaches to model clinical factors that lead to stratification of health outcomes in the context of racial health disparities.
PI: Daniel Moore, M.D., Ph.D., Assistant Professor of Pediatrics, Assistant Professor of Pathology, Microbiology and Immunology
Defective Regulation of Auto-Reactive Lymphocytes in Type I Diabetes
Type 1 diabetes is a prototypical example of an organ specific autoimmune disease. During the progression of disease in susceptible individuals, T and B lymphocytes become activated to destroy insulin-producing beta cells; meanwhile, these same highly aggressive effector lymphocytes leave other cells of the pancreas untouched. Recent studies have suggested that this is due to an inability to regulate auto-reactive lymphocytes through central and peripheral immunosuppressive mechanisms. We propose that this may be due in part to a defect in B-regulatory cells. We study a model of induced tolerance in which B lymphocytes are absolutely required for specific and permanent acceptance of an allograft in the C57/Bl6(B6) mouse. This tolerance induction, as well as many others, is dysfunctional in the NOD mouse, a model for autoimmune diabetes.
In my study we hypothesize that changes in signaling downstream of the BCR caused by anti-CD45RB therapy define tolerant B-cells. Using NOD mice as a model for a system in which tolerance induction is dysfunctional we will define abnormally regulated signaling pathways by RNA sequencing of purified B-cells. We will then assess the activity of these pathways and their interactors in B-cells of the B6 and NOD mice by phos-flow cytometry.
PI: Susan Wente, Ph.D., Professor of Cell and Developmental Biology, Senior Associate Dean for Biomedical Sciences, Associate Vice Chancellor for Research
Directionality of mRNA export Regulated by DEAD-box Helicases
Regulation of directionality of mRNA export is controlled through remodeling of the
mRNPs at the cytoplasmic face of the NPC, where the actions of the essential Dbp5 and Gle1 proteins remodel and release the mRNP into the cytoplasm. Dbp5 is a DEAD-box protein belonging to the RNA helicase superfamily II that binds to the nucleoporin Nup159 on the cytoplasmic filaments of the NPC. Gle1 also binds at the cytoplasmic filaments and, along with its cofactor inositol hexakisphosphate (IP6), specifically stimulates the RNA-dependent ATPase activity of Dbp5. It is the resulting
ADP-bound form of Dbp5 that triggers remodeling of the mRNP. The release of bound ADP from Dbp5 is then stimulated by Nup159. We speculate that this mechanism for regulation of Dpb5 activity may represent a conserved paradigm for the regulation of other DEAD-box helicases. Currently, I am exploring the potential conservation of function and regulation through biochemical characterization of the two human paralogues for Dbp5, DDX19 and DDX25.
PI: Neil Osheroff, Ph.D., Professor of Biochemisty, John Coniglio Chair in Biochemistry, Professor of Medicine
Mechanism of Action of Natural Products against Topoisomerase II
Topoisomerase II is a ubiquitous enzyme that removes knots and tangles from the genetic material. In order to carry out these physiological functions, the enzyme generates transient double-stranded breaks in the DNA. Thus, while essential to cell survival, topoisomerase II has the potential to fragment the genome.
Beyond its critical cellular functions, topoisomerase II is the target for a number of widely prescribed anticancer drugs and dietary chemopreventative agents that act by increasing levels of enzyme-mediated DNA strand breaks. Many of these compounds are derived from natural sources. My research focuses on characterizing the mechanism by which a select group of natural products converts human topoisomerase II into a cellular toxin.