Medical Genetics Commons^™

Genetic Analysis Of Hereditary Gingival Fibromatosis Associated Sos1 Missense Variants Of Uncertain Significance In Caenorhabditis Elegans, Himani Patel

Theses

Hereditary gingival fibromatosis (HGF) is a disease that can present as benign overgrowth of gingival tissue in the mouth. The overgrowth can enclose the entire mouth and teeth in severe cases or present itself in a concentrated area. Researchers have identified that mutations in the SOS1 gene can be responsible for HGF. This disease can impair basic functions related to the mouth. Eating, smiling, speaking can all be affected. Additionally, excess inflammation can cause periodontal disease because of the difficulty in maintaining proper oral health. Periodontal disease can lead to severe bone loss which can lead to complete loss of …

Enpp1 Variants In Patients With Gaci And Pxe Expand The Clinical And Genetic Heterogeneity Of Heritable Disorders Of Ectopic Calcification., Douglas Ralph, Yvonne Nitschke, Michael A Levine, Matthew Caffet, Tamara Wurst, Amir Hossein Saeidian, Leila Youssefian, Hassan Vahidnezhad, Sharon F Terry, Frank Rutsch, Jouni Uitto, Qiaoli Li

Department of Medicine Faculty Papers

Pseudoxanthoma elasticum (PXE) and generalized arterial calcification of infancy (GACI) are clinically distinct genetic entities of ectopic calcification associated with differentially reduced circulating levels of inorganic pyrophosphate (PPi), a potent endogenous inhibitor of calcification. Variants in ENPP1, the gene mutated in GACI, have not been associated with classic PXE. Here we report the clinical, laboratory, and molecular evaluations of ten GACI and two PXE patients from five and two unrelated families registered in GACI Global and PXE International databases, respectively. All patients were found to carry biallelic variants in ENPP1. Among ten ENPP1 variants, one homozygous variant demonstrated uniparental disomy …

Rnase Κ Promotes Robust Pirna Production By Generating 2',3'-Cyclic Phosphate-Containing Precursors, Megumi Shigematsu, Takuya Kawamura, Keisuke Morichika, Natsuko Izumi, Takashi Kiuchi, Shozo Honda, Venetia Pliatsika, Ryuma Matsubara, Isidore Rigoutsos, Susumu Katsuma, Yukihide Tomari, Yohei Kirino

Computational Medicine Center Faculty Papers

In animal germlines, PIWI proteins and the associated PIWI-interacting RNAs (piRNAs) protect genome integrity by silencing transposons. Here we report the extensive sequence and quantitative correlations between 2′,3′-cyclic phosphate-containing RNAs (cP-RNAs), identified using cP-RNA-seq, and piRNAs in the Bombyx germ cell line and mouse testes. The cP-RNAs containing 5′-phosphate (P-cP-RNAs) identified by P-cP-RNA-seq harbor highly consistent 5′-end positions as the piRNAs and are loaded onto PIWI protein, suggesting their direct utilization as piRNA precursors. We identified Bombyx RNase Kappa (BmRNase κ) as a mitochondria-associated endoribonuclease which produces cP-RNAs during piRNA biogenesis. BmRNase κ-depletion elevated transposon levels and disrupted a piRNA-mediated …

Deficient Histone H3 Propionylation By Brpf1-Kat6 Complexes In Neurodevelopmental Disorders And Cancer., Kezhi Yan, Justine Rousseau, Keren Machol, Laura A. Cross, Katherine E. Agre, Cynthia Forster Gibson, Anne Goverde, Kendra Engleman, Hannah Verdin, Elfride De Baere, Lorraine Potocki, Dihong Zhou, Maxime Cadieux-Dion, Gary A. Bellus, Monisa D. Wagner, Rebecca J. Hale, Natacha Esber, Alan F. Riley, Benjamin D. Solomon, Megan T. Cho, Kirsty Mcwalter, Roy Eyal, Meagan K. Hainlen, Bryce A. Mendelsohn, Hillary M. Porter, Brendan C. Lanpher, Andrea M. Lewis, Juliann Savatt, Isabelle Thiffault, Bert Callewaert, Philippe M. Campeau, Xiang-Jiao Yang

Manuscripts, Articles, Book Chapters and Other Papers

Lysine acetyltransferase 6A (KAT6A) and its paralog KAT6B form stoichiometric complexes with bromodomain- and PHD finger-containing protein 1 (BRPF1) for acetylation of histone H3 at lysine 23 (H3K23). We report that these complexes also catalyze H3K23 propionylation in vitro and in vivo. Immunofluorescence microscopy and ATAC-See revealed the association of this modification with active chromatin. Brpf1 deletion obliterates the acylation in mouse embryos and fibroblasts. Moreover, we identify BRPF1 variants in 12 previously unidentified cases of syndromic intellectual disability and demonstrate that these cases and known BRPF1 variants impair H3K23 propionylation. Cardiac anomalies are present in a subset of the …

Frontotemporal Dementia Nonsense Mutation Of Progranulin Rescued By Aminoglycosides, Lisha Kuang, Kei Hashimoto, Eric J. Huang, Matthew S. Gentry, Haining Zhu

Molecular and Cellular Biochemistry Faculty Publications

Frontotemporal dementia (FTD) is an early onset dementia and is characterized by progressive atrophy of the frontal and/or temporal lobes. FTD is highly heritable with mutations in progranulin accounting for 5-26% of cases in different populations. Progranulin is involved in endocytosis, secretion and lysosomal processes, but its function under physiological and pathological conditions remains to be defined. Many FTD-causing nonsense progranulin mutations contain a premature termination codon (PTC), thus progranulin haploinsufficiency has been proposed as a major disease mechanism. Currently, there is no effective FTD treatment or therapy.

Aminoglycosides are a class of antibiotics that possess a less known function …

H3k27m Induces Defective Chromatin Spread Of Prc2-Mediated Repressive H3k27me2/Me3 And Is Essential For Glioma Tumorigenesis., Ashot S. Harutyunyan, Brian Krug, Haifen Chen, Simon Papillon-Cavanagh, Michele Zeinieh, Nicolas De Jay, Shriya Deshmukh, Carol C L Chen, Jad Belle, Leonie G. Mikael, Dylan M. Marchione, Rui Li, Hamid Nikbakht, Bo Hu, Gael Cagnone, Warren A. Cheung, Abdulshakour Mohammadnia, Denise Bechet, Damien Faury, Melissa K. Mcconechy, Manav Pathania, Siddhant U. Jain, Benjamin Ellezam, Alexander G. Weil, Alexandre Montpetit, Paolo Salomoni, Tomi Pastinen, Chao Lu, Peter W. Lewis, Benjamin A. Garcia, Claudia L. Kleinman, Nada Jabado, Jacek Majewski

Manuscripts, Articles, Book Chapters and Other Papers

Lys-27-Met mutations in histone 3 genes (H3K27M) characterize a subgroup of deadly gliomas and decrease genome-wide H3K27 trimethylation. Here we use primary H3K27M tumor lines and isogenic CRISPR-edited controls to assess H3K27M effects in vitro and in vivo. We find that whereas H3K27me3 and H3K27me2 are normally deposited by PRC2 across broad regions, their deposition is severely reduced in H3.3K27M cells. H3K27me3 is unable to spread from large unmethylated CpG islands, while H3K27me2 can be deposited outside these PRC2 high-affinity sites but to levels corresponding to H3K27me3 deposition in wild-type cells. Our findings indicate that PRC2 recruitment and propagation on …

Precision Medicine In Pediatric Cancer: Current Applications And Future Prospects., Atif Ahmed, Divya S. Vundamati, Midhat S. Farooqi, Erin M. Guest

Manuscripts, Articles, Book Chapters and Other Papers

Precision oncologic medicine is an emerging approach for cancer treatment that has recently taken giant steps in solid clinical practice. Recent advances in molecular diagnostics that can analyze the individual tumor's variability in genes have provided greater understanding and additional strategies to treat cancers. Although tumors can be tested by several molecular methods, the use of next-generation sequencing (NGS) has greatly facilitated our understanding of pediatric cancer and identified additional therapeutic opportunities. Pediatric tumors have a different genetic make-up, with a fewer number of actionable targets than adult tumors. Nevertheless, precision oncology in the pediatric population has greatly improved the …

The Zinc Transporter Zipt-7.1 Regulates Sperm Activation In Nematodes, Yanmei Zhao, Chieh-Hsiang Tan, Amber Krauchunas, Andrea Scharf, Nicholas Dietrich, Kurt Warnhoff, Zhiheng Yuan, Marina Druzhinina, Sam Guoping Gu, Long Miao, Andrew Singson, Ronald E Ellis, Kerry Kornfeld

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Sperm activation is a fascinating example of cell differentiation, in which immotile spermatids undergo a rapid and dramatic transition to become mature, motile sperm. Because the sperm nucleus is transcriptionally silent, this transition does not involve transcriptional changes. Although Caenorhabditis elegans is a leading model for studies of sperm activation, the mechanisms by which signaling pathways induce this transformation remain poorly characterized. Here we show that a conserved transmembrane zinc transporter, ZIPT-7.1, regulates the induction of sperm activation in Caenorhabditis nematodes. The zipt-7.1 mutant hermaphrodites cannot self-fertilize, and males reproduce poorly, because mutant spermatids are defective in responding to activating …

Hypotonia And Intellectual Disability Without Dysmorphic Features In A Patient With Pign-Related Disease., Isabelle Thiffault, Britton Zuccarelli, Holly Welsh, Xuan Yuan, Emily Farrow, Lee Zellmer, Neil Miller, Sarah Soden, Ahmed Abdelmoity, Robert A Brodsky, Carol Saunders

Manuscripts, Articles, Book Chapters and Other Papers

BACKGROUND: Defects in the human glycosylphosphatidylinositol anchor biosynthetic pathway are associated with inherited glycosylphosphatidylinositol (GPI)-deficiencies characterized by a broad range of clinical phenotypes including multiple congenital anomalies, dysmorphic faces, developmental delay, hypotonia, and epilepsy. Biallelic variants in PIGN, encoding phosphatidylinositol-glycan biosynthesis class N have been recently associated with multiple congenital anomalies hypotonia seizure syndrome.

CASE PRESENTATION: Our patient is a 2 year old male with hypotonia, global developmental delay, and focal epilepsy. Trio whole-exome sequencing revealed heterozygous variants in PIGN, c.181G > T (p.Glu61*) and c.284G > A (p.Arg95Gln). Analysis of FLAER and anti-CD59 by flow-cytometry demonstrated a shift in this patient's …

A Novel Compound-Heterozygous Epithelial Cell Adhesion Molecule Mutation In Tufting Enteropathy., Valentina Shakhnovich, Darrell Dinwiddie, Amber Hildreth, Thomas M. Attard, Stephen Kingsmore

Manuscripts, Articles, Book Chapters and Other Papers

No abstract provided.

Biallelic Mutations In Tbcd, Encoding The Tubulin Folding Cofactor D, Perturb Microtubule Dynamics And Cause Early-Onset Encephalopathy., Elisabetta Flex, Marcello Niceta, Serena Cecchetti, Isabelle Thiffault, Margaret G. Au, Alessandro Capuano, Emanuela Piermarini, Anna A. Ivanova, Joshua W. Francis, Giovanni Chillemi, Balasubramanian Chandramouli, Giovanna Carpentieri, Charlotte A. Haaxma, Andrea Ciolfi, Simone Pizzi, Ganka V. Douglas, Kara Levine, Antonella Sferra, Maria Lisa Dentici, Rolph R. Pfundt, Jean-Baptist Lepichon, Emily G. Farrow, Frank Baas, Fiorella Piemonte, Bruno Dallapiccola, John M. Graham, Carol J. Saunders, Enrico Bertini, Richard A. Kahn, David A. Koolen, Marco Tartaglia

Manuscripts, Articles, Book Chapters and Other Papers

Microtubules are dynamic cytoskeletal elements coordinating and supporting a variety of neuronal processes, including cell division, migration, polarity, intracellular trafficking, and signal transduction. Mutations in genes encoding tubulins and microtubule-associated proteins are known to cause neurodevelopmental and neurodegenerative disorders. Growing evidence suggests that altered microtubule dynamics may also underlie or contribute to neurodevelopmental disorders and neurodegeneration. We report that biallelic mutations in TBCD, encoding one of the five co-chaperones required for assembly and disassembly of the αβ-tubulin heterodimer, the structural unit of microtubules, cause a disease with neurodevelopmental and neurodegenerative features characterized by early-onset cortical atrophy, secondary hypomyelination, microcephaly, thin …

Identical Mutation In A Novel Retinal Gene Causes Progressive Rod-Cone Degeneration In Dogs And Retinitis Pigmentosa In Humans, Barbara Zangerl, Orly Goldstein, Alisdair R. Philip, Sarah J. P Lindauer, Susan E. Pearce-Kelling, Roberts F. Mullins, Alexander S. Graphodatsky, Daniel Ripoll, Jeanette S. Felix, Edwin M. Stone, Gregory M. Acland, Gustavo D. Aguirre

Gustavo D. Aguirre, VMD, PhD

Progressive rod–cone degeneration (prcd) is a late-onset, autosomal recessive photoreceptor degeneration of dogs and a homolog for some forms of human retinitis pigmentosa (RP). Previously, the disease-relevant interval was reduced to a 106-kb region on CFA9, and a common phenotype-specific haplotype was identified in all affected dogs from several different breeds and breed varieties. Screening of a canine retinal EST library identified partial cDNAs for novel candidate genes in the disease-relevant interval. The complete cDNA of one of these, PRCD, was cloned in dog, human, and mouse. The gene codes for a 54-amino-acid (aa) protein in dog and human and …

Exome Screening To Identify Loss-Of-Function Mutations In The Rhesus Macaque For Development Of Preclinical Models Of Human Disease, Adam Cornish, Robert M. Gibbs, Robert B. Norgren

Journal Articles: Genetics, Cell Biology & Anatomy

BACKGROUND: Exome sequencing has been utilized to identify genetic variants associated with disease in humans. Identification of loss-of-function mutations with exome sequencing in rhesus macaques (Macaca mulatta) could lead to valuable animal models of genetic disease. Attempts have been made to identify variants in rhesus macaques by aligning exome data against the rheMac2 draft genome. However, such efforts have been impaired due to the incompleteness and annotation errors associated with rheMac2. We wished to determine whether aligning exome reads against our new, improved rhesus genome, MacaM, could be used to identify high impact, loss-of-function mutations in rhesus macaques that would …

Recessive Mutations In Polr1c Cause A Leukodystrophy By Impairing Biogenesis Of Rna Polymerase Iii., Isabelle Thiffault, Nicole I Wolf, Diane Forget, Kether Guerrero, Luan T. Tran, Karine Choquet, Mathieu Lavallée-Adam, Christian Poitras, Bernard Brais, Grace Yoon, Laszlo Sztriha, Richard I. Webster, Dagmar Timmann, Bart P. Van De Warrenburg, Jürgen Seeger, Alíz Zimmermann, Adrienn Máté, Cyril Goizet, Eva Fung, Marjo S. Van Der Knaap, Sébastien Fribourg, Adeline Vanderver, Cas Simons, Ryan J. Taft, John R. Yates, Benoit Coulombe, Geneviève Bernard

Manuscripts, Articles, Book Chapters and Other Papers

A small proportion of 4H (Hypomyelination, Hypodontia and Hypogonadotropic Hypogonadism) or RNA polymerase III (POLR3)-related leukodystrophy cases are negative for mutations in the previously identified causative genes POLR3A and POLR3B. Here we report eight of these cases carrying recessive mutations in POLR1C, a gene encoding a shared POLR1 and POLR3 subunit, also mutated in some Treacher Collins syndrome (TCS) cases. Using shotgun proteomics and ChIP sequencing, we demonstrate that leukodystrophy-causative mutations, but not TCS mutations, in POLR1C impair assembly and nuclear import of POLR3, but not POLR1, leading to decreased binding to POLR3 target genes. This study is the first …

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 …

A Patient With Polymerase E1 Deficiency (Pole1): Clinical Features And Overlap With Dna Breakage/Instability Syndromes., Isabelle Thiffault, Carol Saunders, Janda Jenkins, Nikita Raje, Kristi Canty, Mukta Sharma, Lauren Grote, Holly I. Welsh, Emily Farrow, Greyson Twist, Neil Miller, David Zwick, Lee Zellmer, Stephen F. Kingsmore, Nicole P. Safina

Manuscripts, Articles, Book Chapters and Other Papers

BACKGROUND: Chromosome instability syndromes are a group of inherited conditions associated with chromosomal instability and breakage, often leading to immunodeficiency, growth retardation and increased risk of malignancy.

CASE PRESENTATION: We performed exome sequencing on a girl with a suspected chromosome instability syndrome that manifested as growth retardation, microcephaly, developmental delay, dysmorphic features, poikiloderma, immune deficiency with pancytopenia, and myelodysplasia. She was homozygous for a previously reported splice variant, c.4444 + 3A > G in the POLE1 gene, which encodes the catalytic subunit of DNA polymerase E.

CONCLUSION: This is the second family with POLE1-deficency, with the affected individual demonstrating a more …

Analysis Of Candida Albicans Mutants Defective In The Cdk8 Module Of Mediator Reveal Links Between Metabolism And Biofilm Formation, Allia K. Lindsay, Diana K. Morales, Zhongle Liu, Nora Grahl, Anda Zhang, Sven D. Willger, Lawrence C. Myers, Deborah A. Hogan

Dartmouth Scholarship

Candida albicans biofilm formation is a key virulence trait that involves hyphal growth and adhesin expression. Pyocyanin (PYO), a phenazine secreted by Pseudomonas aeruginosa, inhibits both C. albicans biofilm formation and development of wrinkled colonies. Using a genetic screen, we identified two mutants, ssn3Δ/Δ and ssn8Δ/Δ, which continued to wrinkle in the presence of PYO. Ssn8 is a cyclin-like protein and Ssn3 is similar to cyclin-dependent kinases; both proteins are part of the heterotetrameric Cdk8 module that forms a complex with the transcriptional co-regulator, Mediator. Ssn3 kinase activity was also required for PYO sensitivity as a kinase dead mutant maintained …

Structure-Functional Prediction And Analysis Of Cancer Mutation Effects In Protein Kinases, Anshuman Dixit, Gennady M. Verkhivker

Mathematics, Physics, and Computer Science Faculty Articles and Research

A central goal of cancer research is to discover and characterize the functional effects of mutated genes that contribute to tumorigenesis. In this study, we provide a detailed structural classification and analysis of functional dynamics for members of protein kinase families that are known to harbor cancer mutations. We also present a systematic computational analysis that combines sequence and structure-based prediction models to characterize the effect of cancer mutations in protein kinases. We focus on the differential effects of activating point mutations that increase protein kinase activity and kinase-inactivating mutations that decrease activity. Mapping of cancer mutations onto the conformational …

Novel Napi-Iic Mutations Causing Hhrh And Idiopathic Hypercalciuria In Several Unrelated Families: Long-Term Follow-Up In One Kindred., Y Yu, S R. Sanderson, M Reyes, A Sharma, N Dunbar, Tarak Srivastava, H Jüppner, C Bergwitz

Manuscripts, Articles, Book Chapters and Other Papers

Homozygous and compound heterozygous mutations in SLC34A3, the gene encoding the sodium-dependent co-transporter NaPi-IIc, cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH), a disorder characterized by renal phosphate-wasting resulting in hypophosphatemia, elevated 1,25(OH)(2) vitamin D levels, hypercalciuria, rickets/osteomalacia, and frequently kidney stones or nephrocalcinosis. Similar albeit less severe biochemical changes are also observed in heterozygous carriers, which are furthermore indistinguishable from those encountered in idiopathic hypercalciuria (IH). We now searched for SLC34A3 mutations (exons and introns) in two previously not reported HHRH kindreds, which resulted in the identification of three novel mutations. The affected members of kindred A were compound heterozygous …

The Dermatan Sulfate Proteoglycan Decorin Modulates Α2Β1 Integrin And The Vimentin Intermediate Filament System During Collagen Synthesis., Oliver Jungmann, Katerina Nikolovska, Christian Stock, Jan-Niklas Schulz, Beate Eckes, Christoph Riethmüller, Rick T Owens, Renato V Iozzo, Daniela G Seidler

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Decorin, a small leucine-rich proteoglycan harboring a dermatan sulfate chain at its N-terminus, is involved in regulating matrix organization and cell signaling. Loss of the dermatan sulfate of decorin leads to an Ehlers-Danlos syndrome characterized by delayed wound healing. Decorin-null (Dcn(-/-)) mice display a phenotype similar to that of EDS patients. The fibrillar collagen phenotype of Dcn(-/-) mice could be rescued in vitro by decorin but not with decorin lacking the glycosaminoglycan chain. We utilized a 3D cell culture model to investigate the impact of the altered extracellular matrix on Dcn(-/-) fibroblasts. Using 2D gel electrophoresis followed by mass spectrometry, …

Aberrations Of A Putative Tumor Suppressor Gene Sel1l In Pancreatic Ductal Adenocarcinoma, Qian Liu

Dissertations & Theses (Open Access)

Introduction: Pancreatic cancer is the fourth leading cause of cancer-related death among males and females in the United States. Sel-1-like (SEL1L) is a putative tumor suppressor gene that is downregulated in a significant proportion of human pancreatic ductal adenocarcinoma (PDAC). It was hypothesized that SEL1L expression could be down-modulated by somatic mutation, loss of heterozygosity (LOH), CpG island hypermethylation and/or aberrantly expressed microRNAs (miRNAs).

Material and methods: In 42 PDAC tumors, the SEL1L coding region was amplified using reverse transcription polymerase chain reaction (RT-PCR), and analyzed by agarose gel electrophoresis and sequenced to search for mutations. Using fluorescent …

Rho Activation Of Mdia Formins Is Modulated By An Interaction With Inverted Formin 2 (Inf2), Hua Sun, Johannes S. Schlondorff, Elizabeth J. Brown, Henry N. Higgs, Martin R. Pollak

Dartmouth Scholarship

Inverted formin 2 (INF2) encodes a member of the diaphanous subfamily of formin proteins. Mutations in INF2 cause human kidney disease characterized by focal and segmental glomerulosclerosis. Disease-causing mutations occur only in the diaphanous inhibitory domain (DID), suggesting specific roles for this domain in the pathogenesis of disease. In a yeast two-hybrid screen, we identified the diaphanous autoregulatory domains (DADs) of the mammalian diaphanous-related formins (mDias) mDia1, mDia2, and mDia 3 as INF2_DID-interacting partners. The mDias are Rho family effectors that regulate actin dynamics. We confirmed in vitro INF2_DID/mDia_DAD binding by biochemical assays, confirmed the in vivo interaction of these …

Transgenic Rat Model Of Neurodegeneration Caused By Mutation In The Tdp Gene., Hongxia Zhou, Cao Huang, Han Chen, Dian Wang, Carlisle P Landel, Pedro Yuxing Xia, Robert Bowser, Yong-Jian Liu, Xu Gang Xia

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

TDP-43 proteinopathies have been observed in a wide range of neurodegenerative diseases. Mutations in the gene encoding TDP-43 (i.e., TDP) have been identified in amyotrophic lateral sclerosis (ALS) and in frontotemporal lobe degeneration associated with motor neuron disease. To study the consequences of TDP mutation in an intact system, we created transgenic rats expressing normal human TDP or a mutant form of human TDP with a M337V substitution. Overexpression of mutant, but not normal, TDP caused widespread neurodegeneration that predominantly affected the motor system. TDP mutation reproduced ALS phenotypes in transgenic rats, as seen by progressive degeneration of motor neurons …

Interconnections Between Sigma B, Agr, And Proteolytic Activity In Staphylococcus Aureus Biofilm Maturation, Katherine J. Lauderdale, Blaise R. Boles, Ambrose L. Cheung, Alexander R. Horswill

Dartmouth Scholarship

Staphylococcus aureus is a proficient biofilm former on host tissues and medical implants. We mutagenized S. aureus strain SH1000 to identify loci essential for ica-independent mechanisms of biofilm maturation and identified multiple insertions in the rsbUVW-sigB operon. Following construction and characterization of a sigB deletion, we determined that the biofilm phenotype was due to a lack of sigma factor B (SigB) activity. The phenotype was conserved in a sigB mutant of USA300 strain LAC, a well-studied community-associated methicillin-resistant S. aureus isolate. We determined that agr RNAIII levels were elevated in the sigB mutants, and high levels of RNAIII expression are …

The Cytoplasmic Tail Of The Rabies Virus G Protein Is An Essential Domain Controlling Death/Survival In Human Neuronal Cells, Christophe Prehaud, Mireille Lafage, Gene S. Tan, Françoise Mégret, Pauline Ménager, Matthias Schnell, Henri Buc, Monique Lafon

Department of Microbiology and Immunology Faculty Papers

Poster presentation.

Abeta42 Mutants With Different Aggregation Profiles Induce Distinct Pathologies In Drosophila., Koichi Iijima, Hsueh-Cheng Chiang, Stephen A Hearn, Inessa Hakker, Anthony Gatt, Christopher Shenton, Linda Granger, Amy Leung, Kanae Iijima-Ando, Yi Zhong

Department of Biochemistry and Molecular Biology Faculty Papers

Aggregation of the amyloid-beta-42 (Abeta42) peptide in the brain parenchyma is a pathological hallmark of Alzheimer's disease (AD), and the prevention of Abeta aggregation has been proposed as a therapeutic intervention in AD. However, recent reports indicate that Abeta can form several different prefibrillar and fibrillar aggregates and that each aggregate may confer different pathogenic effects, suggesting that manipulation of Abeta42 aggregation may not only quantitatively but also qualitatively modify brain pathology. Here, we compare the pathogenicity of human Abeta42 mutants with differing tendencies to aggregate. We examined the aggregation-prone, EOFAD-related Arctic mutation (Abeta42Arc) and an artificial mutation (Abeta42art) that …

The Pseudomonas Aeruginosa Secreted Protein Pa2934 Decreases Apical Membrane Expression Of The Cystic Fibrosis Transmembrane Conductance Regulator, Daniel P. Maceachran, Siying Ye, Jennifer M. Bomberger, Deborah A. Hogan, Agnieszka Swiatecka-Urban, Bruce Stanton, George A. O'Toole

Dartmouth Scholarship

We previously reported that Pseudomonas aeruginosa PA14 secretes a protein that can reduce the apical membrane expression of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Here we report that we have used a proteomic approach to identify this secreted protein as PA2934 [corrected], and we have named the gene cif, for CFTR inhibitory factor. We demonstrate that Cif is a secreted protein and is found associated with outer membrane-derived vesicles. Expression of Cif in Escherichia coli and purification of the C-terminal six-His-tagged Cif protein showed that Cif is necessary and sufficient to mediate the reduction in apical membrane expression …

The Myc Transactivation Domain Promotes Global Phosphorylation Of The Rna Polymerase Ii Carboxy-Terminal Domain Independently Of Direct Dna Binding, Victoria H. Cowling, Michael D. Cole

Dartmouth Scholarship

Myc is a transcription factor which is dependent on its DNA binding domain for transcriptional regulation of target genes. Here, we report the surprising finding that Myc mutants devoid of direct DNA binding activity and Myc target gene regulation can rescue a substantial fraction of the growth defect in myc^−/− fibroblasts. Expression of the Myc transactivation domain alone induces a transcription-independent elevation of the RNA polymerase II (Pol II) C-terminal domain (CTD) kinases cyclin-dependent kinase 7 (CDK7) and CDK9 and a global increase in CTD phosphorylation. The Myc transactivation domain binds to the transcription initiation sites of these promoters …

The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding, Marta Hristova, Darcy Birse, Yang Hong, Victor Ambros

Dartmouth Scholarship

A temporal gradient of the novel nuclear protein LIN-14 specifies the timing and sequence of stage-specific developmental events in Caenorhabditis elegans. The profound effects of lin-14 mutations on worm development suggest that LIN-14 directly or indirectly regulates stage-specific gene expression. We show that LIN-14 can associate with chromatin in vivo and has in vitro DNA binding activity. A bacterially expressed C-terminal domain of LIN-14 was used to select DNA sequences that contain a putative consensus binding site from a pool of randomized double-stranded oligonucleotides. To identify candidates for genes directly regulated by lin-14, we employed DNA microarray hybridization to compare …

A Three-Component Regulatory System Regulates Biofilm Maturation And Type Iii Secretion In Pseudomonas Aeruginosa, Sherry L. Kuchma, John P. Connolly, George A. O'Toole

Dartmouth Scholarship

Biofilms are structured communities found associated with a wide range of surfaces. Here we report the identification of a three-component regulatory system required for biofilm maturation by Pseudomonas aeruginosa strain PA14. A transposon mutation that altered biofilm formation in a 96-well dish assay originally defined this locus, which is comprised of genes for a putative sensor histidine kinase and two response regulators and has been designated sadARS. Nonpolar mutations in any of the sadARS genes result in biofilms with an altered mature structure but do not confer defects in growth or early biofilm formation, swimming, or twitching motility. After …