Digital Commons Network^™

Cdc42 Antagonizes Rho1 Activity At Adherens Junctions To Limit Epithelial Cell Apical Tension, Stephen J. Warner, Gregory D. Longmore

Open Access Publications

In epithelia, cells are arranged in an orderly pattern with a defined orientation and shape. Cadherin containing apical adherens junctions (AJs) and the associated actomyosin cytoskeleton likely contribute to epithelial cell shape by providing apical tension. The Rho guanosine triphosphatases are well known regulators of cell junction formation, maintenance, and function. Specifically, Rho promotes actomyosin activity and cell contractility; however, what controls and localizes this Rho activity as epithelia remodel is unresolved. Using mosaic clonal analysis in the Drosophila melanogaster pupal eye, we find that Cdc42 is critical for limiting apical cell tension by antagonizing Rho activity at AJs. Cdc42 …

Mitochondrial Mislocalization Underlies Abeta42-Induced Neuronal Dysfunction In A Drosophila Model Of Alzheimer's Disease., Kanae Iijima-Ando, Stephen A Hearn, Christopher Shenton, Anthony Gatt, Lijuan Zhao, Koichi Iijima

Department of Biochemistry and Molecular Biology Faculty Papers

The amyloid-beta 42 (Abeta42) is thought to play a central role in the pathogenesis of Alzheimer's disease (AD). However, the molecular mechanisms by which Abeta42 induces neuronal dysfunction and degeneration remain elusive. Mitochondrial dysfunctions are implicated in AD brains. Whether mitochondrial dysfunctions are merely a consequence of AD pathology, or are early seminal events in AD pathogenesis remains to be determined. Here, we show that Abeta42 induces mitochondrial mislocalization, which contributes to Abeta42-induced neuronal dysfunction in a transgenic Drosophila model. In the Abeta42 fly brain, mitochondria were reduced in axons and dendrites, and accumulated in the somata without severe mitochondrial …

Revealing Genes Associated With Vitellogenesis In The Liver Of The Zebrafish (Danio Rerio) By Transcriptome Profiling., Liraz Levi, Irena Pekarski, Ellen Gutman, Paolo Fortina, Terry Hyslop, Jakob Biran, Berta Levavi-Sivan, Esther Lubzens

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

BACKGROUND: In oviparous vertebrates, including fish, vitellogenesis consists of highly regulated pathways involving 17beta-estradiol (E2). Previous studies focused on a relatively small number of hepatic expressed genes during vitellogenesis. This study aims to identify hepatic genes involved in vitellogenesis and regulated by E2, by using zebrafish microarray gene expression profiling, and to provide information on functional distinctive genes expressed in the liver of a vitellogenic female, using zebrafish as a model fish. RESULTS: Genes associated with vitellogenesis were revealed by the following paired t-tests (SAM) comparisons: a) two-month old vitellogenic (Vit2) females were compared with non-vitellogenic (NV) females, showing 825 …

Developing Tta Transgenic Rats For Inducible And Reversible Gene Expression., Hongxia Zhou, Cao Huang, Min Yang, Carlisle P Landel, Pedro Yuxing Xia, Yong-Jian Liu, Xu Gang Xia

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

To develop transgenic lines for conditional expression of desired genes in rats, we generated several lines of the transgenic rats carrying the tetracycline-controlled transactivator (tTA) gene. Using a vigorous, ubiquitous promoter to drive the tTA transgene, we obtained widespread expression of tTA in various tissues. Expression of tTA was sufficient to strongly activate its reporter gene, but was below the toxicity threshold. We examined the dynamics of Doxycycline (Dox)-regulated gene expression in transgenic rats. In the two transmittable lines, tTA-mediated activation of the reporter gene was fully subject to regulation by Dox. Dox dose-dependently suppressed tTA-activated gene expression. The washout …

Micrornas: Key Modulators Of Posttranscriptional Gene Expression., Steven P. O'Hara, Justin L. Mott, Patrick L. Splinter, Gregory J. Gores, Nicholas F. Larusso

Journal Articles: Biochemistry & Molecular Biology

No abstract provided.

Mitochondrial Fragmentation Is Involved In Methamphetamine-Induced Cell Death In Rat Hippocampal Neural Progenitor Cells., Changhai Tian, L. Charles Murrin, Jialin C. Zheng

Journal Articles: Pharmacology & Experimental Neuroscience

Methamphetamine (METH) induces neurodegeneration through damage and apoptosis of dopaminergic nerve terminals and striatal cells, presumably via cross-talk between the endoplasmic reticulum and mitochondria-dependent death cascades. However, the effects of METH on neural progenitor cells (NPC), an important reservoir for replacing neurons and glia during development and injury, remain elusive. Using a rat hippocampal NPC (rhNPC) culture, we characterized the METH-induced mitochondrial fragmentation, apoptosis, and its related signaling mechanism through immunocytochemistry, flow cytometry, and Western blotting. We observed that METH induced rhNPC mitochondrial fragmentation, apoptosis, and inhibited cell proliferation. The mitochondrial fission protein dynamin-related protein 1 (Drp1) and reactive oxygen …

Functional Interleukin-17 Receptor A Is Expressed In Central Nervous System Glia And Upregulated In Experimental Autoimmune Encephalomyelitis., Jayasri Das Sarma, Bogoljub Ciric, Ryan Marek, Sanjoy Sadhukhan, Michael L. Caruso, Jasmine Shafagh, Denise C. Fitzgerald, Kenneth S. Shindler, Am Rostami

Department of Neurology Faculty Papers

BACKGROUND: Interleukin-17A (IL-17A) is the founding member of a novel family of inflammatory cytokines that plays a critical role in the pathogenesis of many autoimmune diseases, including multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). IL-17A signals through its receptor, IL-17RA, which is expressed in many peripheral tissues; however, expression of IL-17RA in the central nervous system (CNS) and its role in CNS inflammation are not well understood.

METHODS: EAE was induced in C57Bl/6 mice by immunization with myelin oligodendroglial glycoprotein. IL-17RA expression in the CNS was compared between control and EAE mice using RT-PCR, in situ …

Effector Memory T Cell Responses Are Associated With Protection Of Rhesus Monkeys From Mucosal Simian Immunodeficiency Virus Challenge., Scott G. Hansen, Cassandra Vieville, Nathan Whizin, Lia Coyne-Johnson, Don C. Siess, Derek D. Drummond, Alfred W. Legasse, Michael K. Axthelm, Kelli Oswald, Charles M. Trubey, Michael Piatak, Jeffrey D. Lifson, Jay A. Nelson, Michael A. Jarvis, Louis J. Picker

School of Biomedical Sciences

The rapid onset of massive, systemic viral replication during primary HIV or simian immunodeficiency virus (SIV) infection and the immune evasion capabilities of these viruses pose fundamental problems for vaccines that depend upon initial viral replication to stimulate effector T cell expansion and differentiation. We hypothesized that vaccines designed to maintain differentiated effector memory T cell (TEM cell) responses at viral entry sites might improve efficacy by impairing viral replication at its earliest stage, and we have therefore developed SIV protein-encoding vectors based on rhesus cytomegalovirus (RhCMV), the prototypical inducer of life-long TEM cell responses. RhCMV vectors expressing SIV Gag, …

The Eagleville Times,Volume 6, Issue 24, Debbie Ryan

Eagleville Times

No abstract provided.

Identification Of G1-Regulated Genes In Normally Cycling Human Cells, Maroun J. Beyrouthy, Karen E. Alexander, Amy Baldwin, Michael L. Whitfield, Hank W. Bass, Dan Mcgee, Myra M. Hurt

Dartmouth Scholarship

Background: Obtaining synchronous cell populations is essential for cell-cycle studies. Methods such as serum withdrawal or use of drugs which block cells at specific points in the cell cycle alter cellular events upon re-entry into the cell cycle. Regulatory events occurring in early G1 phase of a new cell cycle could have been overlooked. Methodology and Findings: We used a robotic mitotic shake-off apparatus to select cells in late mitosis for genome-wide gene expression studies. Two separate microarray experiments were conducted, one which involved isolation of RNA hourly for several hours from synchronous cell populations, and one experiment which examined …

Clustering Neural Spike Trains With Transient Responses, John D. Hunter, Jianhong Wu, John Milton

WM Keck Science Faculty Papers

The detection of transient responses, i.e. nonstationarities, that arise in a varying and small fraction of the total number of neural spike trains recorded from chronically implanted multielectrode grids becomes increasingly difficult as the number of electrodes grows. This paper presents a novel application of an unsupervised neural network for clustering neural spike trains with transient responses. This network is constructed by incorporating projective clustering into an adaptive resonance type neural network (ART) architecture resulting in a PART neural network. Since comparisons are made between inputs and learned patterns using only a subset of the total number of available dimensions, …

Glypican-1 Modulates The Angiogenic And Metastatic Potential Of Human And Mouse Cancer Cells, Takuma Aikawa, Chery A. Whipple, Martha E. Lopez, Jason Gunn, Alison Young, Arthur D. Lander, Murray Korc

Dartmouth Scholarship

Cells isolated from many types of human cancers express heparin-binding growth factors (HBGFs) that drive tumor growth, metastasis, and angiogenesis. The heparan sulfate proteoglycan glypican-1 (GPC1) is a coreceptor for HBGFs. Here we show that both cancer cell–derived and host-derived GPC1 are crucial for efficient growth, metastasis, and angiogenesis of human and mouse cancer cells. Thus downregulation of GPC1 in the human pancreatic cancer cell line PANC-1, using antisense approaches, resulted in prolonged doubling times and decreased anchorage-independent growth in vitro as well as attenuated tumor growth, angiogenesis, and metastasis when these cells were transplanted into athymic mice. Moreover, athymic …

Genomic Rna Profiling And The Programme Controlling Preimplantation Mammalian Development., Christine E Bell, Michele D Calder, Andrew J Watson

Obstetrics & Gynaecology Publications

Preimplantation development shifts from a maternal to embryonic programme rapidly after fertilization. Although the majority of oogenetic products are lost during the maternal to embryonic transition (MET), several do survive this interval to contribute directly to supporting preimplantation development. Embryonic genome activation (EGA) is characterized by the transient expression of several genes that are necessary for MET, and while EGA represents the first major wave of gene expression, a second mid-preimplantation wave of transcription that supports development to the blastocyst stage has been discovered. The application of genomic approaches has greatly assisted in the discovery of stage specific gene expression …

Aluminum Bioavailability From Tea Infusion, Robert A. Yokel, Rebecca L. Florence

Pharmaceutical Sciences Faculty Publications

The objective was to estimate oral Al bioavailability from tea infusion in the rat, using the tracer ²⁶Al. ²⁶Al citrate was injected into tea leaves. An infusion was prepared from the dried leaves and given intra-gastrically to rats which received concurrent intravenous ²⁷Al infusion. Oral Al bioavailability (F) was calculated from the area under the ²⁶Al, compared to ²⁷Al, serum concentration × time curves. Bioavailability from tea averaged 0.37%; not significantly different from water (F = 0.3%), or basic sodium aluminum phosphate (SALP) in cheese (F = 0.1 to 0.3%), but greater than acidic SALP …

Meeting Report: Methylmercury In Marine Ecosystems—From Sources To Seafood Consumers, Celia Y. Chen, Nancy Serrell, David C. Evers, Bethany J. Fleishman, Kathleen F. Lambert, Jeri Weiss, Robert P. Mason, Michael S. Bank

Dartmouth Scholarship

Mercury and other contaminants in coastal and open-ocean ecosystems are an issue of great concern globally and in the United States, where consumption of marine fish and shellfish is a major route of human exposure to methylmercury (MeHg). A recent National Institute of Environmental Health Sciences–Superfund Basic Research Program workshop titled “Fate and Bioavailability of Mercury in Aquatic Ecosystems and Effects on Human Exposure,” convened by the Dartmouth Toxic Metals Research Program on 15–16 November 2006 in Durham, New Hampshire, brought together human health experts, marine scientists, and ecotoxicologists to encourage cross-disciplinary discussion between ecosystem and human health scientists and …

The Eagleville Times,Volume 6 , Issue 23, Debbie Ryan

Eagleville Times

No abstract provided.

Manufactured Aluminum Oxide Nanoparticles Decrease Expression Of Tight Junction Proteins In Brain Vasculature, Lei Chen, Robert A. Yokel, Bernhard Hennig, Michal Toborek

Pharmaceutical Sciences Faculty Publications

Manufactured nanoparticles of aluminum oxide (nano-alumina) have been widely used in the environment; however, their potential toxicity provides a growing concern for human health. The present study focuses on the hypothesis that nano-alumina can affect the blood-brain barrier and induce endothelial toxicity. In the first series of experiments, human brain microvascular endothelial cells (HBMEC) were exposed to alumina and control nanoparticles in dose- and time-responsive manners. Treatment with nano-alumina markedly reduced HBMEC viability, altered mitochondrial potential, increased cellular oxidation, and decreased tight junction protein expression as compared to control nanoparticles. Alterations of tight junction protein levels were prevented by cellular …

Is There A Visitor Effect On Abyssinian Ground Hornbills (Bucorvus Abyssinicus), Papuan Wreathed Hornbills (Aceros Plicatus), Wrinkled Hornbills (Aceros Corrugatus) And Toco Toucans (Ramphastos Toco) In A Captive Zoo Environment?, Susanna Frances Thicks

The Plymouth Student Scientist

Research into the possible effects that zoo visitors have on the captive animals they come to visit is still relatively poorly understood. Most of the studies all ready completed have used non-human primate subjects, but there is a distinct lack of studies using non-primate species. One of the groups that are in particular need of this kind of research is birds. This study examines a potential visitor effect in captive Abyssinian Ground Hornbills (Bucorvus abyssinicus), Papuan Wreathed Hornbills (Aceros plicatus), Wrinkled Hornbills (Aceros corrugatus) and Toco Toucans (Ramphastos toco) at Paignton Zoo Environmental Park®. This study also investigates the evenness …

Retinoid X Receptor And Peroxisome Proliferator-Activated Receptor-Gamma Agonists Cooperate To Inhibit Matrix Metalloproteinase Gene Expression, Peter S. Burrage, Adam C. Schmucker, Yanqing Ren, Michael B. Sporn, Constance E. Brinckerhoff

Dartmouth Scholarship

We recently described the ability of retinoid X receptor (RXR) ligand LG100268 (LG268) to inhibit interleukin-1-beta (IL-1-β)-driven matrix metalloproteinase-1 (MMP-1) and MMP-13 gene expression in SW-1353 chondrosarcoma cells. Other investigators have demonstrated similar effects in chondrocytes treated with rosiglitazone, a ligand for peroxisome proliferator-activated receptor-gamma (PPARγ), for which RXR is an obligate dimerization partner. The goals of this study were to evaluate the inhibition of IL-1--induced expression of MMP-1andMMP-13 by combinatorial treatment with RXR and PPAR  ligands and to investigate the molecular mechanisms of this inhibition.

Increased Myocardial Susceptibility To Repetitive Ischemia With High-Fat–Diet-Induced Obesity, Geeta D Thakker, Nikolaos G Frangogiannis, Pawel T Zymek, Saumya Sharma, Joe L Raya, Philip M Barger, Heinrich Taegtmeyer, Mark L Entman, Christie M Ballantyne

Faculty, Staff and Student Publications

Obesity and diabetes are frequently associated with cardiovascular disease. When a normal heart is subjected to brief/sublethal repetitive ischemia and reperfusion (I/R), adaptive responses are activated to preserve cardiac structure and function. These responses include but are not limited to alterations in cardiac metabolism, reduced calcium responsiveness, and induction of antioxidant enzymes. In a model of ischemic cardiomyopathy inducible by brief repetitive I/R, we hypothesized that dysregulation of these adaptive responses in diet-induced obese (DIO) mice would contribute to enhanced myocardial injury. DIO C57BL/6J mice were subjected to 15 min of daily repetitive I/R while under short-acting anesthesia, a protocol …

Coordinated Changes In Mrna Turnover, Translation, And Rna Processing Bodies In Bronchial Epithelial Cells Following Inflammatory Stimulation, Yuxin Zhai, Zhenping Zhong, Chyi-Ying A Chen, Zhenfang Xia, Ling Song, Michael R Blackburn, Ann-Bin Shyu

Faculty, Staff and Student Publications

Bronchial epithelial cells play a pivotal role in airway inflammation, but little is known about posttranscriptional regulation of mediator gene expression during the inflammatory response in these cells. Here, we show that activation of human bronchial epithelial BEAS-2B cells by proinflammatory cytokines interleukin-4 (IL-4) and tumor necrosis factor alpha (TNF-alpha) leads to an increase in the mRNA stability of the key chemokines monocyte chemotactic protein 1 and IL-8, an elevation of the global translation rate, an increase in the levels of several proteins critical for translation, and a reduction of microRNA-mediated translational repression. Moreover, using the BEAS-2B cell system and …

Extended Kalman Filter For Estimation Of Parameters In Nonlinear State-Space Models Of Biochemical Networks, Xiaodian Sun, Li Jin, Momiao Xiong

Faculty, Staff and Student Publications

It is system dynamics that determines the function of cells, tissues and organisms. to develop mathematical models and estimate their parameters are an essential issue for studying dynamic behaviors of biological systems which include metabolic networks, genetic regulatory networks and signal transduction pathways, under perturbation of external stimuli. In general, biological dynamic systems are partially observed. Therefore, a natural way to model dynamic biological systems is to employ nonlinear state-space equations. Although statistical methods for parameter estimation of linear models in biological dynamic systems have been developed intensively in the recent years, the estimation of both states and parameters of …

The Eagleville Times,Volume 6 Issue 22, Debbie Ryan

Eagleville Times

No abstract provided.

The Parkinson's Disease Protein Α-Synuclein Disrupts Cellular Rab Homeostasis, Aaron D. Gitler, Brooke J. Bevis, James Shorter, Katherine E. Strathearn, Shusei Hamamichi, Linhui Julie Su, Kim A. Caldwell, Guy A. Caldwell, Jean-Christophe Rochet, J. Michael Mccaffrey, Charles Barlowe, Susan Lindquist

Dartmouth Scholarship

α-Synuclein (α-syn), a protein of unknown function, is the most abundant protein in Lewy bodies, the histological hallmark of Parkinson's disease (PD). In yeast α-syn inhibits endoplasmic reticulum (ER)-to-Golgi (ER→Golgi) vesicle trafficking, which is rescued by overexpression of a Rab GTPase that regulates ER→Golgi trafficking. The homologous Rab1 rescues α-syn toxicity in dopaminergic neuronal models of PD. Here we investigate this conserved feature of α-syn pathobiology. In a cell-free system with purified transport factors α-syn inhibited ER→Golgi trafficking in an α-syn dose-dependent manner. Vesicles budded efficiently from the ER, but their docking or fusion to Golgi membranes was inhibited. Thus, …

Differential Gene Expression Associated With Postnatal Equine Articular Cartilage Maturation, Michael J. Mienaltowski, Liping Huang, Arnold J. Stromberg, James N. Macleod

Veterinary Science Faculty Publications

BACKGROUND: Articular cartilage undergoes an important maturation process from neonate to adult that is reflected by alterations in matrix protein organization and increased heterogeneity of chondrocyte morphology. In the horse, these changes are influenced by exercise during the first five months of postnatal life. Transcriptional profiling was used to evaluate changes in articular chondrocyte gene expression during postnatal growth and development.

METHODS: Total RNA was isolated from the articular cartilage of neonatal (0-10 days) and adult (4-5 years) horses, subjected to one round of linear RNA amplification, and then applied to a 9,367-element equine-specific cDNA microarray. Comparisons were made with …

Evolution Acts On Enhancer Organization To Fine-Tune Gradient Threshold Readouts, Justin Crocker, Yoichiro Tamori, Albert Erives

Dartmouth Scholarship

The elucidation of principles governing evolution of gene regulatory sequence is critical to the study of metazoan diversification. We are therefore exploring the structure and organizational constraints of regulatory sequences by studying functionally equivalent cis-regulatory modules (CRMs) that have been evolving in parallel across several loci. Such an independent dataset allows a multi-locus study that is not hampered by nonfunctional or constrained homology. The neurogenic ectoderm enhancers (NEEs) of Drosophila melanogaster are one such class of coordinately regulated CRMs. The NEEs share a common organization of binding sites and as a set would be useful to study the relationship …

Technical Variables In High-Throughput Mirna Expression Profiling: Much Work Remains To Be Done, Peter T. Nelson, Wang-Xia Wang, Bernard R. Wilfred, Guiliang Tang

Pathology and Laboratory Medicine Faculty Publications

MicroRNA (miRNA) gene expression profiling has provided important insights into plant and animal biology. However, there has not been ample published work about pitfalls associated with technical parameters in miRNA gene expression profiling. One source of pertinent information about technical variables in gene expression profiling is the separate and more well-established literature regarding mRNA expression profiling. However, many aspects of miRNA biochemistry are unique. For example, the cellular processing and compartmentation of miRNAs, the differential stability of specific miRNAs, and aspects of global miRNA expression regulation require specific consideration. Additional possible sources of systematic bias in miRNA expression studies include …

Caveolin-1, Tgf-Β Receptor Internalization, And The Pathogenesis Of Systemic Sclerosis, Francesco Del Galdo, Michael P. Lisanti, Sergio A. Jimenez

Jefferson Institute of Molecular Medicine Papers and Presentations

PURPOSE OF REVIEW: To review the scientific literature supporting the participation of caveolin-1 in the pathogenesis of tissue fibrosis and the notion that modulation of the caveolin-1 pathway may represent a novel treatment for systemic sclerosis and other fibrotic diseases.

RECENT FINDINGS: Caveolin-1 plays an important role in the regulation of transforming growth factor-beta (TGF-beta) signaling owing to its participation in TGF-beta receptor internalization. TGF-beta receptor internalized through caveolin-1 lipid rafts undergoes rapid degradation, effectively decreasing TGF-beta signaling. Studies have shown that caveolin-1 knockdown in vitro markedly increased collagen gene expression in normal human lung fibroblasts. Caveolin-1 was reduced in …

The Eagleville Times,Volume 6, Issue 21, Debbie Ryan

Eagleville Times

No abstract provided.

Focus On Rna Isolation: Obtaining Rna For Microrna (Mirna) Expression Profiling Analyses Of Neural Tissue, Wang-Xia Wang, Bernard R. Wilfred, Donald A. Baldwin, R. Benjamin Isett, Na Ren, Arnold J. Stromberg, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are present in all known plant and animal tissues and appear to be somewhat concentrated in the mammalian nervous system. Many different miRNA expression profiling platforms have been described. However, relatively little research has been published to establish the importance of 'upstream' variables in RNA isolation for neural miRNA expression profiling. We tested whether apparent changes in miRNA expression profiles may be associated with tissue processing, RNA isolation techniques, or different cell types in the sample. RNA isolation was performed on a single brain sample using eight different RNA isolation methods, and results were correlated using a conventional …