Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 27 of 27
Full-Text Articles in Life Sciences
Coupling Between Cytoplasmic Concentration Gradients Through Local Control Of Protein Mobility In The Caenorhabditis Elegans Zygote, Youjun Wu, Huaiying Zhang, Erik E. Griffin
Coupling Between Cytoplasmic Concentration Gradients Through Local Control Of Protein Mobility In The Caenorhabditis Elegans Zygote, Youjun Wu, Huaiying Zhang, Erik E. Griffin
Dartmouth Scholarship
Cell polarity is characterized by the asymmetric distribution of factors at the cell cortex and in the cytoplasm. Although mechanisms that establish cortical asymmetries have been characterized, less is known about how persistent cytoplasmic asymmetries are generated. During the asymmetric division of the Caenorhabditis elegans zygote, the PAR proteins orchestrate the segregation of the cytoplasmic RNA-binding proteins MEX-5/6 to the anterior cytoplasm and PIE-1, POS-1, and MEX-1 to the posterior cytoplasm. In this study, we find that MEX-5/6 control the segregation of GFP::PIE-1, GFP::POS-1, and GFP::MEX-1 by locally increasing their mobility in the anterior cytoplasm. Remarkably, PIE-1, POS-1, and MEX-1 …
The Formin Fmnl3 Assembles Plasma Membrane Protrusions That Participate In Cell–Cell Adhesion, Timothy J. Gauvin, Lorna E. Young, Henry N. Higgs
The Formin Fmnl3 Assembles Plasma Membrane Protrusions That Participate In Cell–Cell Adhesion, Timothy J. Gauvin, Lorna E. Young, Henry N. Higgs
Dartmouth Scholarship
FMNL3 is a vertebrate-specific formin protein previously shown to play a role in angiogenesis and cell migration. Here we define the cellular localization of endogenous FMNL3, the dynamics of GFP-tagged FMNL3 during cell migration, and the effects of FMNL3 suppression in mammalian culture cells. The majority of FMNL3 localizes in a punctate pattern, with >95% of these puncta being indistinguishable from the plasma membrane by fluorescence microscopy. A small number of dynamic cytoplasmic FMNL3 patches also exist, which enrich near cell–cell contact sites and fuse with the plasma membrane at these sites. These cytoplasmic puncta appear to be part of …
Redox-Dependent Stability, Protonation, And Reactivity Of Cysteine-Bound Heme Proteins, Fangfang Zhong, George P. Lisi, Daniel P. Collins, John H. Dawson, Ekaterina V. Pletneva
Redox-Dependent Stability, Protonation, And Reactivity Of Cysteine-Bound Heme Proteins, Fangfang Zhong, George P. Lisi, Daniel P. Collins, John H. Dawson, Ekaterina V. Pletneva
Dartmouth Scholarship
Cysteine-bound hemes are key components of many enzymes and biological sensors. Protonation (deprotonation) of the Cys ligand often accompanies redox transformations of these centers. To characterize these phenomena, we have engineered a series of Thr78Cys/Lys79Gly/Met80X mutants of yeast cytochrome c (cyt c) in which Cys78 becomes one of the axial ligands to the heme. At neutral pH, the protonation state of the coordinated Cys differs for the ferric and ferrous heme species, with Cys binding as a thiolate and a thiol, respectively. Analysis of redox-dependent stability and alkaline transitions of these model proteins, as well as comparisons to Cys …
An Expanded View Of The Eukaryotic Cytoskeleton, James B. Moseley
An Expanded View Of The Eukaryotic Cytoskeleton, James B. Moseley
Dartmouth Scholarship
A rich and ongoing history of cell biology research has defined the major polymer systems of the eukaryotic cytoskeleton. Recent studies have identified additional proteins that form filamentous structures in cells and can self-assemble into linear polymers when purified. This suggests that the eukaryotic cytoskeleton is an even more complex system than previously considered. In this essay, I examine the case for an expanded definition of the eukaryotic cytoskeleton and present a series of challenges for future work in this area.
Bioengineered Lysozyme Reduces Bacterial Burden And Inflammation In A Murine Model Of Mucoid Pseudomonas Aeruginosa Lung Infection, Charlotte C. Teneback, Thomas C. Scanlon, Matthew J. Wargo, Jenna L. Bement, Karl E. Griswold, Laurie W. Leclair
Bioengineered Lysozyme Reduces Bacterial Burden And Inflammation In A Murine Model Of Mucoid Pseudomonas Aeruginosa Lung Infection, Charlotte C. Teneback, Thomas C. Scanlon, Matthew J. Wargo, Jenna L. Bement, Karl E. Griswold, Laurie W. Leclair
Dartmouth Scholarship
The spread of drug-resistant bacterial pathogens is a growing global concern and has prompted an effort to explore potential adjuvant and alternative therapies derived from nature's repertoire of bactericidal proteins and peptides. In humans, the airway surface liquid layer is a rich source of antibiotics, and lysozyme represents one of the most abundant and effective antimicrobial components of airway secretions. Human lysozyme is active against both Gram-positive and Gram-negative bacteria, ac
Force Generation By Kinesin And Myosin Cytoskeletal Motor Proteins, F. Jon Kull, Sharyn A. Endow
Force Generation By Kinesin And Myosin Cytoskeletal Motor Proteins, F. Jon Kull, Sharyn A. Endow
Dartmouth Scholarship
Kinesins and myosins hydrolyze ATP, producing force that drives spindle assembly, vesicle transport and muscle contraction. How do motors do this? Here we discuss mechanisms of motor force transduction, based on their mechanochemical cycles and conformational changes observed in crystal structures. Distortion or twisting of the central β-sheet - proposed to trigger actin-induced Pi and ADP release by myosin, and microtubule-induced ADP release by kinesins - is shown in a movie depicting the transition between myosin ATP-like and nucleotide-free states. Structural changes in the switch I region form a tube that governs ATP hydrolysis and Pi release by the motors, …
Auf1/Hnrnp D Represses Expression Of Vegf In Macrophages, Abigail Fellows, Mary E. Griffin, Brenda L. Petrella, Lihui Zhong, Fatemeh P. Parvin-Nejad, Roy Fava, Peter Morganelli, R. Brooks Robey, Ralph C. Nichols
Auf1/Hnrnp D Represses Expression Of Vegf In Macrophages, Abigail Fellows, Mary E. Griffin, Brenda L. Petrella, Lihui Zhong, Fatemeh P. Parvin-Nejad, Roy Fava, Peter Morganelli, R. Brooks Robey, Ralph C. Nichols
Dartmouth Scholarship
Vascular endothelial growth factor (VEGF) is a regulator of vascularization in development and is a key growth factor in tissue repair. In disease, VEGF contributes to vascularization of solid tumors and arthritic joints. This study examines the role of the mRNA-binding protein AUF1/heterogeneous nuclear ribonucleoprotein D (AUF1) in VEGF gene expression. We show that overexpression of AUF1 in mouse macrophage-like RAW-264.7 cells suppresses endogenous VEGF protein levels. To study 3′ untranslated region (UTR)–mediated regulation, we introduced the 3′ UTR of VEGF mRNA into a luciferase reporter gene. Coexpression of AUF1 represses VEGF-3′ UTR reporter expression in RAW-264.7 cells and in …
Splice Variant–Specific Cellular Function Of The Formin Inf2 In Maintenance Of Golgi Architecture, Vinay Ramabhadran, Farida Korobova, Gilbert J. Rahme, Henry N. Higgs
Splice Variant–Specific Cellular Function Of The Formin Inf2 In Maintenance Of Golgi Architecture, Vinay Ramabhadran, Farida Korobova, Gilbert J. Rahme, Henry N. Higgs
Dartmouth Scholarship
INF2 is a unique formin that can both polymerize and depolymerize actin filaments. Mutations in INF2 cause the kidney disease focal and segmental glomerulosclerosis. INF2 can be expressed as two C-terminal splice variants: CAAX and non-CAAX. The CAAX isoform contains a C-terminal prenyl group and is tightly bound to endoplasmic reticulum (ER). The localization pattern and cellular function of the non-CAAX isoform have not been studied. Here we find that the two isoforms are expressed in a cell type-dependent manner, with CAAX predominant in 3T3 fibroblasts and non-CAAX predominant in U2OS, HeLa, and Jurkat cells. Although INF2-CAAX is ER localized …
Differential Interactions Of The Formins Inf2, Mdia1, And Mdia2 With Microtubules, Jeremie Gaillard, Bvinay Ramabhadran, Emmanuelle Neumanne, Pinar Gurel, Laurent Blanchoin, Marylin Vantard, Henry N. Higgs
Differential Interactions Of The Formins Inf2, Mdia1, And Mdia2 With Microtubules, Jeremie Gaillard, Bvinay Ramabhadran, Emmanuelle Neumanne, Pinar Gurel, Laurent Blanchoin, Marylin Vantard, Henry N. Higgs
Dartmouth Scholarship
A number of cellular processes use both microtubules and actin filaments, but the molecular machinery linking these two cytoskeletal elements remains to be elucidated in detail. Formins are actin-binding proteins that have multiple effects on actin dynamics, and one formin, mDia2, has been shown to bind and stabilize microtubules through its formin homology 2 (FH2) domain. Here we show that three formins, INF2, mDia1, and mDia2, display important differences in their interactions with microtubules and actin. Constructs containing FH1, FH2, and C-terminal domains of all three formins bind microtubules with high affinity (K(d) < 100 nM). However, only mDia2 binds microtubules at 1:1 stoichiometry, with INF2 and mDia1 showing saturating binding at approximately 1:3 (formin dimer:tubulin dimer). INF2-FH1FH2C is a potent microtubule-bundling protein, an effect that results in a large reduction in catastrophe rate. In contrast, neither mDia1 nor mDia2 is a potent microtubule bundler. The C-termini of mDia2 and INF2 have different functions in microtubule interaction, with mDia2's C-terminus required for high-affinity binding and INF2's C-terminus required for bundling. mDia2's C-terminus directly binds microtubules with submicromolar affinity. These formins also differ in their abilities to bind actin and microtubules simultaneously. Microtubules strongly inhibit actin polymerization by mDia2, whereas they moderately inhibit mDia1 and have no effect on INF2. Conversely, actin monomers inhibit microtubule binding/bundling by INF2 but do not affect mDia1 or mDia2. These differences in interactions with microtubules and actin suggest differential function in cellular processes requiring both cytoskeletal elements.
Serum- And Glucocorticoid-Induced Kinase 3 In Recycling Endosomes Mediates Acute Activation Of Na+/H+ Exchanger Nhe3 By Glucocorticoids, Peijian He, Sei-Jung Lee, Songbai Lin, Ursula Seidler, Florian Lang, Geza Fejes-Toth, Aniko Naray-Fejes-Toth, C. Chris Yun
Serum- And Glucocorticoid-Induced Kinase 3 In Recycling Endosomes Mediates Acute Activation Of Na+/H+ Exchanger Nhe3 By Glucocorticoids, Peijian He, Sei-Jung Lee, Songbai Lin, Ursula Seidler, Florian Lang, Geza Fejes-Toth, Aniko Naray-Fejes-Toth, C. Chris Yun
Dartmouth Scholarship
Na(+)/H(+) exchanger 3 (NHE3) is the major Na(+) transporter in the intestine. Serum- and glucocorticoid-induced kinase (SGK) 1 interacts with NHE regulatory factor 2 (NHERF2) and mediates activation of NHE3 by dexamethasone (Dex) in cultured epithelial cells. In this study, we compared short-term regulation of NHE3 by Dex in SGK1-null and NHERF2-null mice. In comparison to wild-type mice, loss of SGK1 or NHERF2 significantly attenuated regulation of NHE3 by Dex but did not completely obliterate the effect. We show that transfection of SGK2 or SGK3 in PS120 cells resulted in robust activation of NHE3 by Dex. However, unlike SGK1 or …
A Kinesin Motor In A Force-Producing Conformation, Elisabeth Heuston, C. Eric Bronner, F Jon Kull, Sharyn A. Endow
A Kinesin Motor In A Force-Producing Conformation, Elisabeth Heuston, C. Eric Bronner, F Jon Kull, Sharyn A. Endow
Dartmouth Scholarship
Kinesin motors hydrolyze ATP to produce force and move along microtubules, converting chemical energy into work by a mechanism that is only poorly understood. Key transitions and intermediate states in the process are still structurally uncharacterized, and remain outstanding questions in the field. Perturbing the motor by introducing point mutations could stabilize transitional or unstable states, providing critical information about these rarer states.
Ceramide Kinase Regulates Phospholipase C And Phosphatidylinositol 4, 5, Bisphosphate In Phototransduction, Ujjaini Dasgupta, Takeshi Bamba, Salvatore Chiantia, Pusha Karim, Ahmad N. Abou Tayoun
Ceramide Kinase Regulates Phospholipase C And Phosphatidylinositol 4, 5, Bisphosphate In Phototransduction, Ujjaini Dasgupta, Takeshi Bamba, Salvatore Chiantia, Pusha Karim, Ahmad N. Abou Tayoun
Dartmouth Scholarship
Phosphoinositide-specific phospholipase C (PLC) is a central effector for many biological responses regulated by G-protein-coupled receptors including Drosophila phototransduction where light sensitive channels are activated downstream of NORPA, a PLCbeta homolog. Here we show that the sphingolipid biosynthetic enzyme, ceramide kinase, is a novel regulator of PLC signaling and photoreceptor homeostasis. A mutation in ceramide kinase specifically leads to proteolysis of NORPA, consequent loss of PLC activity, and failure in light signal transduction. The mutant photoreceptors also undergo activity-dependent degeneration. Furthermore, we show that a significant increase in ceramide, resulting from lack of ceramide kinase, perturbs the membrane microenvironment of …
Insulin Stimulates The Phosphorylation Of The Exocyst Protein Sec8 In Adipocytes, Patrick D. Lyons, Grantley R. Peck, Arminja N. Kettenbach, Scott A. Gerber, Liya Roudaia, Gustav E. Lienhard
Insulin Stimulates The Phosphorylation Of The Exocyst Protein Sec8 In Adipocytes, Patrick D. Lyons, Grantley R. Peck, Arminja N. Kettenbach, Scott A. Gerber, Liya Roudaia, Gustav E. Lienhard
Dartmouth Scholarship
The signal transduction pathway leading from the insulin receptor to stimulate the fusion of vesicles containing the glucose transporter GLUT4 with the plasma membrane in adipocytes and muscle cells is not completely understood. Current evidence suggests that in addition to the Rab GTPase-activating protein AS160, at least one other substrate of Akt (also called protein kinase B), which is as yet unidentified, is required. Sec8 is a component of the exocyst complex that has been previously implicated in GLUT4 trafficking. In the present study, we report that insulin stimulates the phosphorylation of Sec8 on Ser-32 in 3T3-L1 adipocytes. On the …
A Conserved Cam- And Radial Spoke–Associated Complex Mediates Regulation Of Flagellar Dynein Activity, Erin E. Dymek, Elizabeth F. Smith
A Conserved Cam- And Radial Spoke–Associated Complex Mediates Regulation Of Flagellar Dynein Activity, Erin E. Dymek, Elizabeth F. Smith
Dartmouth Scholarship
For virtually all cilia and eukaryotic flagella, the second messengers calcium and cyclic adenosine monophosphate are implicated in modulating dynein- driven microtubule sliding to regulate beating. Calmodulin (CaM) localizes to the axoneme and is a key calcium sensor involved in regulating motility. Using immunoprecipitation and mass spectrometry, we identify members of a CaM-containing complex that are involved in regulating dynein activity. This complex includes flagellar-associated protein 91 (FAP91), which shares considerable sequence similarity to AAT-1, a protein originally identified in testis as an A-kinase anchor protein (AKAP)- binding protein. FAP91 directly interacts with radial spoke protein 3 (an AKAP), which …
Stoichiometric Controls Of Mercury Dilution By Growth, Roxanne Karimi, Celia Y. Chen, Paul C. Pickhardt, Nicholas S. Fisher, Carol L. Folt
Stoichiometric Controls Of Mercury Dilution By Growth, Roxanne Karimi, Celia Y. Chen, Paul C. Pickhardt, Nicholas S. Fisher, Carol L. Folt
Dartmouth Scholarship
Rapid growth could significantly reduce methylmercury (MeHg) concentrations in aquatic organisms by causing a greater than proportional gain in biomass relative to MeHg (somatic growth dilution). We hypothesized that rapid growth from the consumption of high-quality algae, defined by algal nutrient stoichiometry, reduces MeHg concentrations in zooplankton, a major source of MeHg for lake fish. Using a MeHg radiotracer, we measured changes in MeHg concentrations, growth and ingestion rates in juvenile Daphnia pulex fed either high (C:P = 139) or low-quality (C:P = 1317) algae (Ankistrodesmus falcatus) for 5 d. We estimated Daphnia steady-state MeHg concentrations, using a …
The Allantois And Chorion, When Isolated Before Circulation Or Chorio-Allantoic Fusion, Have Hematopoietic Potential, Brandon M. Zeigler, Daisuke Sugiyama, Michael Chen, Yalin Guo, K. M. Downs, N. A. Speck
The Allantois And Chorion, When Isolated Before Circulation Or Chorio-Allantoic Fusion, Have Hematopoietic Potential, Brandon M. Zeigler, Daisuke Sugiyama, Michael Chen, Yalin Guo, K. M. Downs, N. A. Speck
Dartmouth Scholarship
The chorio-allantoic placenta forms through the fusion of the allantois (progenitor tissue of the umbilical cord), with the chorionic plate. The murine placenta contains high levels of hematopoietic stem cells, and is therefore a stem cell niche. However, it is not known whether the placenta is a site of hematopoietic cell emergence, or whether hematopoietic cells originate from other sites in the conceptus and then colonize the placenta. Here, we show that the allantois and chorion, isolated prior to the establishment of circulation, have the potential to give rise to myeloid and definitive erythroid cells following explant culture. We further …
Dictyostelium Myosin-Ie Is A Fast Molecular Motor Involved In Phagocytosis, Ulrike Durrwang, Setsuko Fujita-Becker, Muriel Erent, F. Jon Kull
Dictyostelium Myosin-Ie Is A Fast Molecular Motor Involved In Phagocytosis, Ulrike Durrwang, Setsuko Fujita-Becker, Muriel Erent, F. Jon Kull
Dartmouth Scholarship
Class I myosins are single-headed motor proteins, implicated in various motile processes including organelle translocation, ion-channel gating, and cytoskeleton reorganization. Here we describe the cellular localization of myosin-IE and its role in the phagocytic uptake of solid particles and cells. A complete analysis of the kinetic and motor properties of Dictyostelium discoideum myosin-IE was achieved by the use of motor domain constructs with artificial lever arms. Class I myosins belonging to subclass IC like myosin-IE are thought to be tuned for tension maintenance or stress sensing. In contrast to this prediction, our results show myosin-IE to be a fast motor. …
Phylogenetic Analysis Of The Formin Homology 2 Domain, Henry N. Higgs, Kevin J. Peterson
Phylogenetic Analysis Of The Formin Homology 2 Domain, Henry N. Higgs, Kevin J. Peterson
Dartmouth Scholarship
Formin proteins are key regulators of eukaryotic actin filament assembly and elongation, and many species possess multiple formin isoforms. A nomenclature system based on fundamental features would be desirable, to aid the rapid identification and characterization of novel formins. In this article, we attempt to systematize the formin family by performing phylogenetic analyses of the formin homology 2 (FH2) domain, an independently folding region common to all formins, which alone can influence actin dynamics. Through database searches, we identify 101 FH2 domains from 26 eukaryotic species, including 15 in mice. Sequence alignments reveal a highly conserved yeast-specific insert in the …
The Kini Kinesin Kif2a Is Required For Bipolar Spindle Assembly Through A Functional Relationship With Mcak, Neil J. Ganem, Duane A. Compton
The Kini Kinesin Kif2a Is Required For Bipolar Spindle Assembly Through A Functional Relationship With Mcak, Neil J. Ganem, Duane A. Compton
Dartmouth Scholarship
Although the microtubule-depolymerizing KinI motor Kif2a is abundantly expressed in neuronal cells, we now show it localizes to centrosomes and spindle poles during mitosis in cultured cells. RNAi-induced knockdown of Kif2a expression inhibited cell cycle progression because cells assembled monopolar spindles. Bipolar spindle assembly was restored in cells lacking Kif2a by treatments that altered microtubule assembly (nocodazole), eliminated kinetochore–microtubule attachment (loss of Nuf2), or stabilized microtubule plus ends at kinetochores (loss of MCAK). Thus, two KinI motors, MCAK and Kif2a, play distinct roles in mitosis, and MCAK activity at kinetochores must be balanced by Kif2a activity at poles for spindle …
Pv1 Is A Key Structural Component For The Formation Of The Stomatal And Fenestral Diaphragms, Radu V. Stan, Eugene Tkachenko, Ingrid R. Niesman
Pv1 Is A Key Structural Component For The Formation Of The Stomatal And Fenestral Diaphragms, Radu V. Stan, Eugene Tkachenko, Ingrid R. Niesman
Dartmouth Scholarship
PV1 is an endothelial-specific integral membrane glycoprotein associated with the stomatal diaphragms of caveolae, transendothelial channels, and vesiculo-vacuolar organelles and the diaphragms of endothelial fenestrae. Multiple PV1 homodimers are found within each stomatal and fenestral diaphragm. We investigated the function of PV1 within these diaphragms and their regulation and found that treatment of endothelial cells in culture with phorbol myristate acetate (PMA) led to upregulation of PV1. This correlated with de novo formation of stomatal diaphragms of caveolae and transendothelial channels as well as fenestrae upon PMA treatment. The newly formed diaphragms could be labeled with anti-PV1 antibodies. The upregulation …
The C. Elegans Heterochronic Gene Lin-46 Affects Developmental Timing At Two Larval Stages And Encodes A Relative Of The Scaffolding Protein Gephyrin, A. S.-R. Pepper, Jill E. Mccane, Kevin Kemper, Dennis Au Yeung, Rosalind C. Lee, Victor Ambros, Eric G. Moss
The C. Elegans Heterochronic Gene Lin-46 Affects Developmental Timing At Two Larval Stages And Encodes A Relative Of The Scaffolding Protein Gephyrin, A. S.-R. Pepper, Jill E. Mccane, Kevin Kemper, Dennis Au Yeung, Rosalind C. Lee, Victor Ambros, Eric G. Moss
Dartmouth Scholarship
The succession of developmental events in the C. elegans larva is governed by the heterochronic genes. When mutated, these genes cause either precocious or retarded developmental phenotypes, in which stage-specific patterns of cell division and differentiation are either skipped or reiterated, respectively. We identified a new heterochronic gene, lin-46, from mutations that suppress the precocious phenotypes caused by mutations in the heterochronic genes lin-14 and lin-28. lin-46 mutants on their own display retarded phenotypes in which cell division patterns are reiterated and differentiation is prevented in certain cell lineages. Our analysis indicates that lin-46 acts at a step immediately downstream …
A Subgroup Algorithm To Identify Cross-Rotation Peaks Consistent With Non-Crystallographic Symmetry, Ryan H. Lilien, Chris Bailey-Kellogg, Amy C. Anderson, Bruce R. Donald
A Subgroup Algorithm To Identify Cross-Rotation Peaks Consistent With Non-Crystallographic Symmetry, Ryan H. Lilien, Chris Bailey-Kellogg, Amy C. Anderson, Bruce R. Donald
Dartmouth Scholarship
Molecular replacement (MR) often plays a prominent role in determining initial phase angles for structure determination by X-ray crystallography. In this paper, an efficient quaternion-based algorithm is presented for analyzing peaks from a cross-rotation function in order to identify model orientations consistent with proper non-crystallographic symmetry (NCS) and to generate proper NCS-consistent orientations missing from the list of cross-rotation peaks. The algorithm, CRANS, analyzes the rotation differences between each pair of cross-rotation peaks to identify finite subgroups. Sets of rotation differences satisfying the subgroup axioms correspond to orientations compatible with the correct proper NCS. The CRANS algorithm was first …
Minus-End Capture Of Preformed Kinetochore Fibers Contributes To Spindle Morphogenesis, Alexey Khodjakov, Lily Copenagle, Michael B. Gordon, Duane A. Compton, Tarun M. Kapoor
Minus-End Capture Of Preformed Kinetochore Fibers Contributes To Spindle Morphogenesis, Alexey Khodjakov, Lily Copenagle, Michael B. Gordon, Duane A. Compton, Tarun M. Kapoor
Dartmouth Scholarship
Near-simultaneous three-dimensional fluorescence/differential interference contrast microscopy was used to follow the behavior of microtubules and chromosomes in living alpha-tubulin/GFP-expressing cells after inhibition of the mitotic kinesin Eg5 with monastrol. Kinetochore fibers (K-fibers) were frequently observed forming in association with chromosomes both during monastrol treatment and after monastrol removal. Surprisingly, these K-fibers were oriented away from, and not directly connected to, centrosomes and incorporated into the spindle by the sliding of their distal ends toward centrosomes via a NuMA-dependent mechanism. Similar preformed K-fibers were also observed during spindle formation in untreated cells. In addition, upon monastrol removal, centrosomes established a transient …
Meiotic Cohesion Requires Accumulation Of Ord On Chromosomes Before Condensation, Eric M. Balicky, Matthew W. Endres, Cary Lai, Sharon E. Bickel
Meiotic Cohesion Requires Accumulation Of Ord On Chromosomes Before Condensation, Eric M. Balicky, Matthew W. Endres, Cary Lai, Sharon E. Bickel
Dartmouth Scholarship
Cohesion between sister chromatids is a prerequisite for accurate chromosome segregation during mitosis and meiosis. To allow chromosome condensation during prophase, the connections that hold sister chromatids together must be maintained but still permit extensive chromatin compaction. In Drosophila, null mutations in the orientation disruptor (ord) gene lead to meiotic nondisjunction in males and females because cohesion is absent by the time that sister kinetochores make stable microtubule attachments. We provide evidence that ORD is concentrated within the extrachromosomal domains of the nuclei ofDrosophila primary spermatocytes during early G2, but accumulates on the meiotic chromosomes by …
A Novel Iron-Regulated Metal Transporter From Plants Identified By Functional Expression In Yeast., David Eide, Margaret Broderius, Jeanette Fett, Mary Lou Guerinot
A Novel Iron-Regulated Metal Transporter From Plants Identified By Functional Expression In Yeast., David Eide, Margaret Broderius, Jeanette Fett, Mary Lou Guerinot
Dartmouth Scholarship
Iron is an essential nutrient for virtually all organisms. The IRT1 (iron-regulated transporter) gene of the plant Arabidopsis thaliana, encoding a probable Fe(II) transporter, was cloned by functional expression in a yeast strain defective for iron uptake. Yeast expressing IRT1 possess a novel Fe(II) uptake activity that is strongly inhibited by Cd. IRT1 is predicted to be an integral membrane protein with a metal-binding domain. Data base comparisons and Southern blot analysis indicated that IRT1 is a member of a gene family in Arabidopsis. Related sequences were also found in the genomes of rice, yeast, nematodes, and humans. In Arabidopsis, …
Binding Of Matrix Attachment Regions To Lamin Polymers Involves Single-Stranded Regions And The Minor Groove., M. E. Eva Ludérus, Jan L. Den Blaauwen, Oncko J. De Smit, Duane A. Compton, Roel Van Driel
Binding Of Matrix Attachment Regions To Lamin Polymers Involves Single-Stranded Regions And The Minor Groove., M. E. Eva Ludérus, Jan L. Den Blaauwen, Oncko J. De Smit, Duane A. Compton, Roel Van Driel
Dartmouth Scholarship
Chromatin in eukaryotic nuclei is thought to be partitioned into functional loop domains that are generated by the binding of defined DNA sequences, named MARs (matrix attachment regions), to the nuclear matrix. We have previously identified B-type lamins as MAR-binding matrix components (M. E. E. Ludérus, A. de Graaf, E. Mattia, J. L. den Blaauwen, M. A. Grande, L. de Jong, and R. van Driel, Cell 70:949-959, 1992). Here we show that A-type lamins and the structurally related proteins desmin and NuMA also specifically bind MARs in vitro. We studied the interaction between MARs and lamin polymers in molecular detail …
Differential Regulation Of Collagenase Gene Expression By Retinoic Acid Receptors--Alpha, Beta And Gamma, Luying Pan, Stephen H. Chamberlain, David T. Auble, Constance E. Brinckerhoff
Differential Regulation Of Collagenase Gene Expression By Retinoic Acid Receptors--Alpha, Beta And Gamma, Luying Pan, Stephen H. Chamberlain, David T. Auble, Constance E. Brinckerhoff
Dartmouth Scholarship
The mechanisms involved in retinoic acid (RA)-mediated regulation of the collagenase gene in a rabbit synovial fibroblast cell line (HIG82) were investigated. When HIG82 cells are cotransfected with expression vectors containing cDNAs for retinoic acid receptor (RAR) α1, β2, or γ1 and collagenase promoter-driven CAT reporter constructs, only RAR-γ1 represses basal CAT expression upon RA treatment, while RAR-α1, β2, and γ1 all suppress phorbol-induced CAT expression. Thus, transcriptional regulation of collagenase by RA is mediated by RARs in an RAR-type specific manner. Using mutatlonal and deletional analysis, we find that interaction between elements within 182 bp collagenase promoter plays an …