bluuebunny/crossref_metadata_2025 huggingface dataset:
The
Escherichia coli
MG1655
in silico
metabolic genotype: Its definition, characteristics, and capabilities
Authors: Edwards J. S. , Palsson B. O.
Published: July 2002

The
Escherichia coli
MG1655 genome has been completely sequenced. The annotated sequence, biochemical information, and other information were used to reconstruct the
E. coli
metabolic map. The stoichiometric coefficients for each metabolic enzyme in the
E. coli
metabolic map were assembled to construct a genome-specific stoichiometric matrix. The
E. coli
stoichiometric matrix was used to define the system's characteristics and the capabilities of
E. coli
metabolism. The effects of gene deletions in the central metabolic pathways on the ability of the
in silico
metabolic network to support growth were assessed, and the
in silico
predictions were compared with experimental observations. It was shown that based on stoichiometric and capacity constraints the
in silico
analysis was able to qualitatively predict the growth potential of mutant strains in 86% of the cases examined. Herein, it is demonstrated that the synthesis of
in silico
metabolic genotypes based on genomic, biochemical, and strain-specific information is possible, and that systems analysis methods are available to analyze and interpret the metabolic phenotype.
Identification of a nuclear domain with deacetylase activity
Authors: Downes Michael , Ordentlich Peter , Kao Hung-Ying , Alvarez Jacqueline G. A. , Evans Ronald M.
Published: July 2002

Here, we describe the identification and characterization of a nuclear body (matrix-associated deacetylase body) whose formation and integrity depend on deacetylase activity. Typically, there are 20–40 0.5-μM bodies per nucleus, although the size and number can vary substantially. The structure appears to contain both class I and the recently described class II histone deacetylases (HDAC)5 and 7 along with the nuclear receptor corepressors SMRT (silencing mediator for retinoid and thyroid receptor) and N-CoR (nuclear receptor corepressor). Addition of the deacetylase inhibitors trichostatin A and sodium butyrate completely disrupt these nuclear bodies, providing a demonstration that the integrity of a nuclear body is enzyme dependent. We demonstrate that HDAC5 and 7 can associate with at least 12 distinct proteins, including several members of the NuRD and Sin3A repression complexes, and appear to define a new but related complex.
sqv-3
,
-7
, and -
8
, a set of genes affecting morphogenesis in
Caenorhabditis elegans
, encode enzymes required for glycosaminoglycan biosynthesis
Authors: Bulik Dorota A. , Wei Ge , Toyoda Hidenao , Kinoshita-Toyoda Akiko , Waldrip W. Ross , Esko Jeffrey D. , Robbins Phillips W. , Selleck Scott B.
Published: July 2002

sqv
(
squashed vulva
) genes comprise a
set of eight independent loci in
Caenorhabditis
elegans
required zygotically for the invagination of vulval
epithelial cells and maternally for normal oocyte formation and
embryogenesis. Sequencing of
sqv-3
,
sqv-7
, and
sqv-8
suggested a role for the
encoded proteins in glycolipid or glycoprotein biosynthesis. Using a
combination of
in vitro
analysis of SQV enzymatic
activities,
sqv
+
-
mediated
rescue of vertebrate cell lines, and biochemical characterization of
sqv
mutants, we show that
sqv-3
,
-7
, and
-8
all affect the biosynthesis of
glycosaminoglycans and therefore compromise the
function of one specific class of glycoconjugates, proteoglycans. These
findings establish the importance of proteoglycans and their associated
glycosaminoglycans in epithelial morphogenesis and
patterning during
C. elegans
development.
DNA condensation in two dimensions
Authors: Koltover Ilya , Wagner Kathrin , Safinya Cyrus R.
Published: July 2002

We have found that divalent electrolyte counterions common in
biological cells (Ca
2+
, Mg
2+
, and
Mn
2+
) can condense anionic DNA molecules confined to
two-dimensional cationic surfaces. DNA-condensing agents
in
vivo
include cationic histones and polyamines spermidine and
spermine with sufficiently high valence (Z) 3 or larger.
In
vitro
studies show that electrostatic forces between DNA chains
in bulk aqueous solution containing divalent counterions remain purely
repulsive, and DNA condensation requires counterion valence Z ≥
3. In striking contrast to bulk behavior, synchrotron x-ray diffraction
and optical absorption experiments show that above a critical divalent
counterion concentration the electrostatic forces between DNA chains
adsorbed on surfaces of cationic membranes reverse from repulsive to
attractive and lead to a chain collapse transition into a condensed
phase of DNA tethered by divalent counterions. This demonstrates the
importance of spatial dimensionality to intermolecular interactions
where nonspecific counterion-induced electrostatic attractions between
the like-charged polyelectrolytes overwhelm the electrostatic
repulsions on a surface for Z = 2. This new phase, with a
one-dimensional counterion liquid trapped between DNA chains at a
density of 0.63 counterions per DNA bp, represents the most compact
state of DNA on a surface
in vitro
and suggests
applications in high-density storage of genetic information and
organo-metallic materials processing.
APC
mutations in sporadic colorectal tumors: A mutational “hotspot” and interdependence of the “two hits”
Authors: Rowan A. J. , Lamlum H. , Ilyas M. , Wheeler J. , Straub J. , Papadopoulou A. , Bicknell D. , Bodmer W. F. , Tomlinson I. P. M.
Published: July 2002

Although
APC
mutations occur at a high frequency in
colorectal cancers, few studies have performed a comprehensive analysis
by screening the whole gene for mutations and assessing allelic loss.
APC
seems to act as a tumor-suppressor gene in a
“nonclassical” fashion: data from familial adenomatous polyposis
(FAP) show that the site of the germ-line mutation determines the type
of “second hit” in FAP tumors, and simple protein inactivation is
selected weakly, if at all. In this study, we screened the entire
coding region of
APC
for mutations and assessed allelic
loss in a set of 41 colorectal cancer cell lines. Of 41 cancers, 32
(83%) showed evidence of
APC
mutation and/or allelic
loss. We identified several
APC
mutations and found a
“hotspot” for somatic mutation in sporadic colorectal tumors at
codon 1,554. Our results suggest that
APC
mutations
occur in the great majority of colorectal cancers, the exceptions
almost all being RER+ tumors, which may substitute for altered
APC
function by mutations in β-catenin and/or at
other loci. When combined with previously published data, our results
show that there is interdependence of the “two hits” at
APC
in sporadic colorectal tumors as well as in FAP.
APC
mutations in the “mutation cluster region,”
especially those close to codon 1,300, are associated with allelic
loss, whereas tumors with mutations outside this region tend to harbor
truncating mutations. The causes of this phenomenon are probably
selection for retained N-terminal and lost C-terminal APC functions,
effects on β-catenin levels, and APC protein stability.
Expression of sterol regulatory element-binding protein 1c (SREBP-1c) mRNA in rat hepatoma cells requires endogenous LXR ligands
Authors: DeBose-Boyd Russell A. , Ou Jiafu , Goldstein Joseph L. , Brown Michael S.
Published: July 2002

The current paper describes a line of cultured rat hepatoma cells
(McA-RH7777 cells) that mimics the behavior of rat liver by producing
an excess of mRNA for sterol regulatory element-binding protein 1c
(SREBP-1c) as opposed to SREBP-1a. These two transcripts are derived
from a single gene by use of alternative promoters that are separated
by many kilobases in the genome. The high level of SREBP-1c mRNA is
abolished when cholesterol synthesis is blocked by compactin, an
inhibitor of 3-hydroxy-3-methylglutaryl CoA (HMG CoA) reductase that
inhibits cholesterol synthesis. Levels of SREBP-1c mRNA are restored by
mevalonate, the product of the HMG CoA reductase reaction, and by
ligands for the nuclear hormone receptor LXR, including
22(
R
)-hydroxycholesterol and T0901317. These data
suggest that transcription of the SREBP-1c gene in hepatocytes requires
tonic activation of LXR by an oxysterol intermediate in the cholesterol
biosynthetic pathway. Reduction of this intermediate lowers SREBP-1c
levels, and this in turn is predicted to lower the rates of fatty acid
biosynthesis in liver.
Contributing to world development: Research activities of the International Union of Psychological Science
Authors: Ritchie Pierre L.‐J. , Sabourin Michel
Published: July 2002

Research activities of the International Union of Psychological Science are reviewed from the perspective of their broader contribution to world development. Characterized by diversity, they are also engendered by the Union's collaboration with major international organizations. Several recent projects are elaborated. The challenges of facilitating research and research networks on a global scale are also noted.
The UN activities of the International Union of Psychological Science in 2001
Authors: Sabourin Michel
Published: July 2002

The major thrust of the IUPsyS activities at the UN this year has been the establishment, in early 2001, of a permanent team of New York area psychologists willing to voluntarily represent the Union at the different meetings held throughout the year at the UN Secretariat in New York under the auspices of the UN Department of Public Information, the Economic and Social Council (ECOSOC), as well as some of the other UN agencies also active in New York, such as UNICEF and UNESCO. With the help of the International Affairs Office of the American Psychological Association, which we would like to thank, we had access to the names of New York area psychologists who were interested in doing UN representation for psychology. Four of them were identified as prime candidates and were interviewed. Their nomination as UN/NGO representatives was approved by the Executive Committee of the Union. I am very happy to inform our national members and affiliate organizations that Dr. Fritz Galette, Dr. Margarita Garcia‐Estevez, Dr. Douglas Y Seiden and Ms. Carolee E. Iltis have generously accepted to act as the Union's NGO representatives in New York. The decision to appoint four representatives was determined by the workload associated with the activities of the UN Secretariat (e.g., Dept of Public Information ‐NGO Briefings every week, multiple meetings of numerous committees dealing with mental health, health, ageing, children, human rights, women issues), plus numerous Preparatory Committees for General Assembly Summits (presently, three upcoming summits on racism, children and women that we will briefly discuss later in this report). Therefore, we felt it was important to be realistic and to appoint several individuals who are ready to share the work to be done and provide 1–2 days per month of their time.
Bringing the world to your desk: Evolution of an international resource*
Authors: Overmier Judith A. , Overmier J. Bruce
Published: July 2002

Traces the historical development of an international resource as it has evolved through seven versions from International Directory of Psychologists published as a book in 1958 to Psychology: IUPsyS Global Resource published as a CD‐ROM in 2001 to address the communication needs of the international psychology community in particular and the scholarly community in general.
Cognitive Enhancement: An Everyday Event?
Authors: White Norman M.
Published: July 2002

The hypothesis presented here has three parts. First, cognitive enhancement is not only possible, but is an everyday reality. Several common substances, including caffeine and sugar, improve the retention of new memories, a form of cognitive enhancement. Second, data from experiments on memory enhancement, taken together with estimates of the information‐processing capacity of the human brain, suggest that many individuals may already be functioning cognitively at or very close to the maximum level possible. If this is true then only relatively small enhancing effects would be expected. Third, the existing relatively modest instances of cognitive enhancement may represent what can be expected from this phenomenon.
Suicide and Parasuicide in London: A Small-area Study
Authors: Congdon Peter
Published: July 2002

This study discusses variability in the spatial prevalence of suicide and parasuicide across small areas in London in relation to the social and demographic composition of their populations. The focus is on the relative importance in explaining suicidal outcomes of variables representing respectively social deprivation, psychiatric morbidity and anomie (or community fragmentation), and of differentiation in the effects of these factors across sub-populations. There is strong evidence for such contextual effects—namely, varying effects of these socio-economic factors according to geographical setting—as well as for differential associations by age group, sex and type of outcome (suicide vs parasuicide).
Motivational Patterns in Disaffected School Students: Insights from pupil referral unit clients
Authors: Solomon Yvette , Rogers Colin
Published: July 2002

Abstract This recently completed small‐scale study investigated perceptions of the circumstances of pupils registered with Pupil Referral Units. Questionnaires were administered to all pupils registered, covering a range of perceptions of their current circumstances, history and prospects. The questionnaire also contained scales from the Patterns of Adaptive Learning Survey, enabling assessments of pupil motivation. Interviews were conducted with a sample of pupils and practitioners who work with them. These included school teachers, tutorial centre teachers, and service managers. The article explores the variety of views expressed and concludes that there is little evidence to support the claim that disaffection experienced by these pupils is the result of an inappropriate curriculum. Rather, it reflects a deficiency of motivational and coping strategies perhaps not best dealt with in ‘out‐of‐school’ contexts.
Children’s Revision of Textual Flaws
Authors: Cameron Catherine Ann , Edmunds Gail , Wigmore Barbara , Hunt Anne Kathryn , Linton M. J.
Published: July 2002

Two studies are reported here that investigated elementary school children’s text revision. In the first experiment, both semantic and surface flaws were inserted in texts that varied in reading difficulty. Second-grade through fifth-grade students revised these experimenter-generated passages, presented as examples of submissions to a class newspaper. Differences in text reading difficulty did not affect revision effectiveness, nor were the semantic flaws especially difficult to detect and revise. An age effect showed growth in the revision of both semantic and surface errors from grades 2 to 4 with 2nd-graders revising one-third of the inserted errors, and 4th- and 5th-graders revising three-quarters of them. Revision and cloze reading comprehension skills were correlated. A second study compared students’ revision of their own as well as another’s text flaws. Fifth-graders wrote a narrative for a classroom anthology, and they revised both their own and inserted flaws. Their writing was evaluated holistically. Rates of both semantic and surface revision were somewhat lower for their own as opposed to another’s text errors, but revision rates were nevertheless relatively high, and they correlated with writing quality; that is, children who wrote high-quality texts also revised more errors, especially experimenter-inserted flaws. These data confirm that children respond positively to writing challenges in the area of revision, a skill in process of development, which is amenable to inspection and appears ripe for facilitation.
Comparison of Northern Irish Children’s Attitudes to War and Peace Before and After the Paramilitary Ceasefires
Authors: McLernon Frances , Ferguson Neil , Cairns Ed
Published: July 2002

This study compares the attitudes of young people in Northern Ireland to conflict and conflict resolution, before and after the 1994 ceasefire announcements. Content analysis on the responses of 117 adolescents aged 14-15 years showed differences in their attitudes to war and peace and in their strategies to attain peace. Concepts of war as static and unchanging showed a significant difference after the ceasefire. In addition, the perception of war as a struggle between national leaders before the ceasefire shifted significantly to a more general view of war in terms of war activities and their negative consequences. Perceptions of peace as “active” showed a marked swing after the ceasefire to a more abstract view of peace as freedom, justice, and liberty after the ceasefire. Before the ceasefire, adolescents were reluctant to provide strategies to attain peace, but after the ceasefire, strategies were suggested with more confidence. Results also indicated that adolescents prefer an alternative to violence in the resolution of conflict. Although the proportion of adolescents who said the country was at peace did not change significantly after the ceasefire, the percentage who expressed ambivalent feelings about the status of Northern Ireland in terms of peace increased significantly. This suggests that, at the time of this study, many young people had not fully accepted the reality of the peace process.
Divergent Validity and the Measurement of Processing Capacity
Authors: Pulos Steven
Published: July 2002

This study examines the divergent validity of the neo-Piagetian measures of processing capacity by reanalysing two factor-analytic studies of processing capacity (Case & Globerson, 1974; Morra, 1994). The reanalyses found that the assumption of orthogonal, independent, factors used in the studies was not warranted. Rather, it appears that although processing capacity tasks do fall on one factor, this factor is highly related to a factor traditionally identified as fluid/spatial intelligence. Implications for neo-Piagetian theory and research are discussed.
Genetic and Environmental In‘uences on Personality in Adult Russian Twins
Authors: Saudino Kimberly J. , Gagne Jeffrey R. , Grant Julie , Ibatoulina Anna , Marytuina Tatinana , Ravich-Scherbo Inna , Whitfield Keith
Published: July 2002

The present study explored genetic and environmental contributions to personality in a sample of twins participating in the Adult Russian Twin Study (ARTS). Subjects included 79 monozygotic (MZ) and 51 dizygotic (DZ) twin-pairs residing in the metropolitan Moscow area, Russia (mean age 42.2 years). Twins completed self-report questionnaires assessing the personality dimensions of neuroticism, extraversion, monotony avoidance, and impulsivity. For all four dimensions, model-”tting analyses yielded estimates of heritability consistent with previous behavioural genetic findings ( h2 ranging from .49 to .59). Also consistent with previous research is the finding that shared environmental variance is negligible for each dimension. These results suggest that the factors that influence individual differences in personality in the Russian culture do not substantially differ from those that influence personality in more Western cultures.
Self-concept and Anxiety in Immigrant Children
Authors: Roebers Claudia M. , Schneider Wolfgang
Published: July 2002

In a longitudinal study of acculturation in Germany, a total sample ( N 364) of immigrant and nonimmigrant elementary schoolchildren were tested in regard to achievement related personality variables, such as self-concept, anxiety, and peer relations. The participants belonged to one of four subgroups: (1) nonimmigrants from the Western region of Germany; (2) nonimmigrants from the Eastern region; (3) German-speaking immigrants from the former German Democratic Republic; and (4) immigrants with poor German language skills from the former USSR. Migration did not seem to lead to a global decrease of self-concept or to an increase of general anxiety. However, the immigrant children did differ in their self-concept in the German language and in test anxiety from the nonimmigrant children. The chosen parameters proved to be fairly stable over time in the German-speaking groups and in the immigrant group with poor German language skills, the self-concept was more stable with a longer stay in Germany. Overall, comparing the immigrants with the nonimmigrants: (a) an acceleration in the development of self-evaluations; and (b) an interruption in the gradual stabilisation of the personality became apparent.
In Vitro Models to Study Hepatotoxicity
Authors: Groneberg David A. , Grosse-Siestrup Christian , Fischer Axel
Published: July 2002

Drug discovery and development consists of a series of processes starting with the demonstration of pharmacologica l effects in experimental cell and animal models and ending with drug safety and effi cacy studies in patients. A main limitation is often the unacceptabl e level of toxicity with the liver as the primary target organ. Therefore, approaches to study hepatic toxicity in the early phase of drug discovery represent an important step towards rational drug development. A variety of in vitro liver model s have been developed in the past years. Next to their use in drug development, they can also be applied to study environmental toxins and their hepatotoxicity. The 3 main approache s are ex vivo isolated and perfused organ models, precision-cut liver slices and cell culture models. Although the advantage of whole organ perfusions is based on the assessment of physiologic parameters such as bile production and morphologic parameters such as tissue histology, cell culture models can be effi ciently used to assess cellular metabolism, cytotoxicity and genotoxicity. The advantage of precision-cut liver slices is based on the juxtaposition of cellular assays and tissue morphology. None of these model s can be compared as they all focus on different fi elds of hepatoxicolog y. For the future, the ideal setup for testing the hepatic toxicity of a new compound could of primary studies in cell or slice cultures to assess cellular effects and secondary studies using ex vivo perfused organs to examine gross organ function parameters and histology.
L‐NAME causes antinociception by stimulation of the arginine‐NO‐cGMP pathway
Authors: Duarte I. D. G. , Ferreira S. H.
Published: July 2002

NG‐nitro‐L‐arginine methyl ester (L‐NAME) has been used extensively as a paradigmatic inhibitor of NO synthase and has been shown to cause antinociception in several experimental models. We describe here how L‐NAME produced a dose‐dependent anti‐nociceptive effect when injected intraperitoneally in the mouse after acetic acid induced writhings, or intraplantarly in the rat paw pressure hyperalgesia induced by carrageenin or prostaglandin E2. In contrast another NO synthase inhibitor, NG‐monomethyl‐L‐arginine (L‐NMMA), had no significant effect per se but inhibited L‐NAME systemic induced antinociception in mice and local induced antinociception in the rat paw hyperalgesia test. D‐NAME had no anti‐nociceptive effect upon carrageenin‐induced hyperalgesia. Pretreatment of the paws with two inhibitors of guanylate cyclase, methylene blue (MB) and 1H‐:[1,2,4]‐oxadiazolo‐:[4,3‐a] quinoxalin–1‐one (ODQ) abolished the antinociceptive effect of L‐NAME. L‐Arginine and the cGMP phosphodiesterase inhibitor, MY 5445 significantly enhanced the L‐NAME antinociceptive effect. The central antinociceptive effect of L‐NAME was blocked by co‐administration of L‐NMMA, ODQ and MB. The present series of experiments shows that L‐NAME, but not L‐NMMA, has an antinociceptive effect. It can be suggested that L‐NAME causes the antinociceptive effect by stimulation of the arginine/NO/cGMP pathway, since the antinociceptive effect of L‐NAME can be antagonized by L‐NMMA and abolished by the guanylate cyclase inhibitors (MB and ODQ). In addition, the NO synthase substrate, L‐arginine and the cGMP phosphodiesterase inhibitor, MY5445 were seen to potentiate the effects of L‐NAME. Thus, L‐NAME used alone, has limitations as a specific inhibitor of the arginine‐NOcGMP pathway and may therefore be a poor pharmacological tool for use in characterising participation in pathophysiological processes.
The Effect of Sertraline on Methadone Plasma Levels in Methadone‐Maintenance Patients
Authors: Hamilton Steven P. , Nunes Edward V. , Janal Malvin , Weber Laurie
Published: July 2002

The authors examine methadone plasma levels in 31 depressed methadone‐maintained opiate addicts enrolled in a 12‐week placebo‐controlled, double‐blind study of sertraline. Between baseline and week 6, patients on sertraline showed a mean increase in methadone plasma level/dose (P/D) ratio of 26% (SD = 43%, range −32% to +118%), while patients on placebo showed a mean decrease of 16% (SD = 27%, range −62% to +50%). This difference was significant (p < 0.02). The sertraline and placebo groups did not differ in reported side effects or methadone dose adjustments. Between weeks 6 and 12, methadone P/D in the sertraline group decreased back towards baseline, and the treatment groups did not differ significantly at week 12. The results suggest sertraline may produce a modest increase in methadone serum levels over the first six weeks of treatment. Depression and anxiety disorders are common in methadone‐maintained patients. Serotonin uptake inhibitors are attractive choices for treatment due to their low toxicity and low abuse potential, but these agents variously inhibit isoenzymes responsible for the metabolism of methadone. Clinicians treating depressed or anxious methadone patients with second‐generation antidepressants should monitor for clinical signs of increased or decreased methadone levels and consider monitoring serum methadone levels.
Motivational Interviewing with Psychiatrically Ill Substance Abusing Patients
Authors: Martino Steve , Carroll Kathleen M. , O'Malley Stephanie S. , Rounsaville Bruce J.
Published: July 2002

This pilot study reports the relative efficacy of a one‐session preadmission motivational interview (n = 13) compared to a standard preadmission interview (n = 10) for psychiatrically ill substance abusing patients in a partial hospital program.
Nitric oxide and cirrhosis of the liver
Authors: López‐Novoa José M. , García‐Estañ J.
Published: July 2002

A major characteristic of patients with liver cirrhosis is a marked peripheral and splanchnic vasodilatation that is the origin of many clinical problems associated with chronic liver damage, such as water and sodium retention, ascites and renal failure. There are several lines of evidence suggesting a role for nitric oxide (NO), a gaseous substance with potent vasodilator effects, in the peripheral vasodilatation associated with hepatic cirrhosis. In experimental models of cirrhosis in rats, most studies have reported an increased NO release by the endothelium of different arteries, which precedes the development of the systemic hyperdynamic circulation. In addition, the endothelium‐derived increased production of NO seems to be responsible for the lower than normal pressor response to vasoconstrictors in the mesenteric bed, kidney and in aortic rings of cirrhotic rats. The hyperdynamic circulation is partially reversed by NO synthesis inhibition. Thus, in experimental models of cirrhosis, most studies suggest a primary role of NO in the pathogenesis of the arterial vasodilatation. In humans, studies are scarce and not so homogeneous. Although there are some studies showing increased plasma NO levels in cirrhotic patients, there is not full agreement on the role of increased NO production in the maintenance of peripheral vasodilatation. Thus, despite some contradictory results, we can conclude that an increased production of NO, mainly of constitutive and endothelial origin, is an important factor that contributes to the cardiovascular and renal alterations observed in cirrhotic patients or in experimental models of liver cirrhosis. Whether this enhanced production of NO is the cause of these alterations or a secondary effect in compensation to the elevated levels of the vasoconstrictor and antinatriuretic hormones is not yet known.
Book and Media Reviews
Authors: Ball David
Published: July 2002

Book reviewed in this article:

Book reviews in this column will primar ily be of titles focusing completely, or in part, on biolog ical aspects of addiction. However, significant titles of general relevance to the addictions field will also be included, even if they are not “biological”, as will titles of general methodological and clinical relevance, even if they are not on “addictions”. Similar considerations will apply to other media (software, audio tapes and CDs, videos, etc.). However, specific “addictions” software applications seem to be relatively uncommon and, as these items are rarely reviewed elsewhere, we will endeavour to include reviews of some of the older programmes that are still useful, as well as new titles that appear. I would appreciate suggestions of any items suitable for reviews, but especially software and other media of specific relevance to the addictions. Please contact: Dr David Ball, National Addiction Centre, 4 Windsor Walk, London SE5 8AF, UK. Email: media@addictionbiology.com

Handbook of Alcoholism GERALD ZERNIG, ALOIS SARIA, MARTIN KURZ & STEPHANIE O'MALLEY (Eds)

New Medications for Drug Abuse S. G. GLICK & I. M. MAISONNEUVE (Eds)

Essential Psychopharmacology of Depression and Bipolar Disorder STEPHEN M. STAHL

The Neurochemistry of Drugs of Abuse SYED F. ALI (Ed.)

Psychiatric Genetics JOHN I. NURNBERGER Jr & WADE BERRETTINI (Eds)

Alcohol: The Ambiguous Molecule GRIFFITH EDWARDS
Cofilin Changes the Twist of F-Actin: Implications for Actin Filament Dynamics and Cellular Function
Authors: McGough Amy , Pope Brian , Chiu Wah , Weeds Alan
Published: July 2002

Cofilin is an actin depolymerizing protein found widely distributed in animals and plants. We have used electron cryomicroscopy and helical reconstruction to identify its binding site on actin filaments. Cofilin binds filamentous (F)-actin cooperatively by bridging two longitudinally associated actin subunits. The binding site is centered axially at subdomain 2 of the lower actin subunit and radially at the cleft between subdomains 1 and 3 of the upper actin subunit. Our work has revealed a totally unexpected (and unique) property of cofilin, namely, its ability to change filament twist. As a consequence of this change in twist, filaments decorated with cofilin have much shorter ‘actin crossovers' (∼75% of those normally observed in F-actin structures). Although their binding sites are distinct, cofilin and phalloidin do not bind simultaneously to F-actin. This is the first demonstration of a protein that excludes another actin-binding molecule by changing filament twist. Alteration of F-actin structure by cofilin/ADF appears to be a novel mechanism through which the actin cytoskeleton may be regulated or remodeled.
The Amino-terminal Domain of Desmoplakin Binds to Plakoglobin and Clusters Desmosomal Cadherin–Plakoglobin Complexes
Authors: Kowalczyk Andrew P. , Bornslaeger Elayne A. , Borgwardt Jeffrey E. , Palka Helena L. , Dhaliwal Avninder S. , Corcoran Connie M. , Denning Mitchell F. , Green Kathleen J.
Published: July 2002

The desmosome is a highly organized plasma membrane domain that couples intermediate filaments to the plasma membrane at regions of cell–cell adhesion. Desmosomes contain two classes of cadherins, desmogleins, and desmocollins, that bind to the cytoplasmic protein plakoglobin. Desmoplakin is a desmosomal component that plays a critical role in linking intermediate filament networks to the desmosomal plaque, and the amino-terminal domain of desmoplakin targets desmoplakin to the desmosome. However, the desmosomal protein(s) that bind the amino-terminal domain of desmoplakin have not been identified. To determine if the desmosomal cadherins and plakoglobin interact with the amino-terminal domain of desmoplakin, these proteins were co-expressed in L-cell fibroblasts, cells that do not normally express desmosomal components. When expressed in L-cells, the desmosomal cadherins and plakoglobin exhibited a diffuse distribution. However, in the presence of an amino-terminal desmoplakin polypeptide (DP-NTP), the desmosomal cadherins and plakoglobin were observed in punctate clusters that also contained DP-NTP. In addition, plakoglobin and DP-NTP were recruited to cell–cell interfaces in L-cells co-expressing a chimeric cadherin with the E-cadherin extracellular domain and the desmoglein-1 cytoplasmic domain, and these cells formed structures that were ultrastructurally similar to the outer plaque of the desmosome. In transient expression experiments in COS cells, the recruitment of DP-NTP to cell borders by the chimera required co-expression of plakoglobin. Plakoglobin and DP-NTP co-immunoprecipitated when extracted from L-cells, and yeast two hybrid analysis indicated that DP-NTP binds directly to plakoglobin but not Dsg1. These results identify a role for desmoplakin in organizing the desmosomal cadherin–plakoglobin complex and provide new insights into the hierarchy of protein interactions that occur in the desmosomal plaque.
Recruitment of Phosphorylated Chromatin Assembly Factor 1 to Chromatin after UV Irradiation of Human Cells
Authors: Martini Emmanuelle , Roche Danièle M.J. , Marheineke Kathrin , Verreault Alain , Almouzni Geneviève
Published: July 2002

The subcellular distribution and posttranslational modification of human chromatin assembly factor 1 (CAF-1) have been investigated after UV irradiation of HeLa cells. In an asynchronous cell population only a subfraction of the two large CAF-1 subunits, p150 and p60, were found to exist in a chromatin-associated fraction. This fraction is most abundant during S phase in nonirradiated cells and is much reduced in G2 cells. After UV irradiation, the chromatin-associated form of CAF-1 dramatically increased in all cells irrespective of their position in the cell cycle. Such chromatin recruitment resembles that seen for PCNA, a DNA replication and repair factor. The chromatin-associated fraction of p60 was predominantly hypophosphorylated in nonirradiated G2 cells. UV irradiation resulted in the rapid recruitment to chromatin of phosphorylated forms of the p60 subunit. Furthermore, the amount of the p60 and p150 subunits of CAF-1 associated with chromatin was a function of the dose of UV irradiation. Consistent with these in vivo observations, we found that the amount of CAF-1 required to stimulate nucleosome assembly during the repair of UV photoproducts in vitro depended upon both the number of lesions and the phosphorylation state of CAF-1. The recruitment of CAF-1 to chromatin in response to UV irradiation of human cells described here supports a physiological role for CAF-1 in linking chromatin assembly to DNA repair.
The Vitronectin Receptor and its Associated CD47 Molecule Mediates Proinflammatory Cytokine Synthesis in Human Monocytes by Interaction with Soluble CD23
Authors: Hermann P. , Armant M. , Brown E. , Rubio M. , Ishihara H. , Ulrich D. , Caspary R.G. , Lindberg F.P. , Armitage R. , Maliszewski C. , Delespesse G. , Sarfati M.
Published: July 2002

The vitronectin receptor, αvβ3 integrin, plays an important role in tumor cell invasion, angiogenesis, and phagocytosis of apoptotic cells. CD47, a member of the multispan transmembrane receptor family, physically and functionally associates with vitronectin receptor (VnR). Although vitronectin (Vn) is not a ligand of CD47, anti-CD47 and β3 mAbs suppress Vn, but not fibronectin (Fn) binding and function. Here, we show that anti-CD47, anti-β3 mAb and Vn, but not Fn, inhibit sCD23-mediated proinflammatory function (TNF-α, IL-12, and IFN-γ release). Surprisingly, anti-CD47 and β3 mAbs do not block sCD23 binding to αv+β3+ T cell lines, whereas Vn and an αv mAb (clone AMF7) do inhibit sCD23 binding, suggesting the VnR complex may be a functional receptor for sCD23. sCD23 directly binds αv+β3+/CD47− cell lines, but coexpression of CD47 increases binding. Moreover, sCD23 binds purified αv protein and a single human αv chain CHO transfectant. We conclude that the VnR and its associated CD47 molecule may function as a novel receptor for sCD23 to mediate its proinflammatory activity and, as such, may be involved in the inflammatory process of the immune response.
The Receptor Recycling Pathway Contains Two Distinct Populations of Early Endosomes with Different Sorting Functions
Authors: Sheff David R. , Daro Elizabeth A. , Hull Michael , Mellman Ira
Published: July 2002

Receptor recycling involves two endosome populations, peripheral early endosomes and perinuclear recycling endosomes. In polarized epithelial cells, either or both populations must be able to sort apical from basolateral proteins, returning each to its appropriate plasma membrane domain. However, neither the roles of early versus recycling endosomes in polarity nor their relationship to each other has been quantitatively evaluated. Using a combined morphological, biochemical, and kinetic approach, we found these two endosome populations to represent physically and functionally distinct compartments. Early and recycling endosomes were resolved on Optiprep gradients and shown to be differentially associated with rab4, rab11, and transferrin receptor; rab4 was enriched on early endosomes and at least partially depleted from recycling endosomes, with the opposite being true for rab11 and transferrin receptor. The two populations were also pharmacologically distinct, with AlF4 selectively blocking export of transferrin receptor from recycling endosomes to the basolateral plasma membrane. We applied these observations to a detailed kinetic analysis of transferrin and dimeric IgA recycling and transcytosis. The data from these experiments permitted the construction of a testable, mathematical model which enabled a dissection of the roles of early and recycling endosomes in polarized receptor transport. Contrary to expectations, the majority (>65%) of recycling to the basolateral surface is likely to occur from early endosomes, but with relatively little sorting of apical from basolateral proteins. Instead, more complete segregation of basolateral receptors from receptors intended for transcytosis occurred upon delivery to recycling endosomes.
CRM1-mediated Recycling of Snurportin 1 to the Cytoplasm
Authors: Paraskeva Efrosyni , Izaurralde Elisa , Bischoff F. Ralf , Huber Jochen , Kutay Ulrike , Hartmann Enno , Lührmann Reinhard , Görlich Dirk
Published: July 2002

Importin β is a major mediator of import into the cell nucleus. Importin β binds cargo molecules either directly or via two types of adapter molecules, importin α, for import of proteins with a classical nuclear localization signal (NLS), or snurportin 1, for import of m3G-capped U snRNPs. Both adapters have an NH2-terminal importin β–binding domain for binding to, and import by, importin β, and both need to be returned to the cytoplasm after having delivered their cargoes to the nucleus. We have shown previously that CAS mediates export of importin α. Here we show that snurportin 1 is exported by CRM1, the receptor for leucine-rich nuclear export signals (NESs). However, the interaction of CRM1 with snurportin 1 differs from that with previously characterized NESs. First, CRM1 binds snurportin 1 50-fold stronger than the Rev protein and 5,000-fold stronger than the minimum Rev activation domain. Second, snurportin 1 interacts with CRM1 not through a short peptide but rather via a large domain that allows regulation of affinity. Strikingly, snurportin 1 has a low affinity for CRM1 when bound to its m3G-capped import substrate, and a high affinity when substrate-free. This mechanism appears crucial for productive import cycles as it can ensure that CRM1 only exports snurportin 1 that has already released its import substrate in the nucleus.
Nuclear Import of the TATA-binding Protein: Mediation by the Karyopherin Kap114p and a Possible Mechanism for Intranuclear Targeting
Authors: Pemberton Lucy F. , Rosenblum Jonathan S. , Blobel Günter
Published: July 2002

Binding of the TATA-binding protein (TBP) to the promoter is the first and rate limiting step in the formation of transcriptional complexes. We show here that nuclear import of TBP is mediated by a new karyopherin (Kap) (importin) family member, Kap114p. Kap114p is localized to the cytoplasm and nucleus. A complex of Kap114p and TBP was detected in the cytosol and could be reconstituted using recombinant proteins, suggesting that the interaction was direct. Deletion of the KAP114 gene led to specific mislocalization of TBP to the cytoplasm. We also describe two other potential minor import pathways for TBP. Consistent with other Kaps, the dissociation of TBP from Kap114p is dependent on RanGTP. However, we could show that double stranded, TATA-containing DNA stimulates this RanGTP-mediated dissociation of TBP, and is necessary at lower RanGTP concentrations. This suggests a mechanism where, once in the nucleus, TBP is preferentially released from Kap114p at the promoter of genes to be transcribed. In this fashion Kap114p may play a role in the intranuclear targeting of TBP.
The Ribosome Regulates the Gtpase of the β-Subunit of the Signal Recognition Particle Receptor
Authors: Bacher Gerald , Pool Martin , Dobberstein Bernhard
Published: July 2002

Protein targeting to the membrane of the ER is regulated by three GTPases, the 54-kD subunit of the signal recognition particle (SRP) and the α- and β-subunit of the SRP receptor (SR). Here, we report on the GTPase cycle of the β-subunits of the SR (SRβ). We found that SRβ binds GTP with high affinity and interacts with ribosomes in the GTP-bound state. Subsequently, the ribosome increases the GTPase activity of SRβ and thus functions as a GTPase activating protein for SRβ. Furthermore, the interaction between SRβ and the ribosome leads to a reduction in the affinity of SRβ for guanine nucleotides. We propose that SRβ regulates the interaction of SR with the ribosome and thereby allows SRα to scan membrane-bound ribosomes for the presence of SRP. Interaction between SRP and SRα then leads to release of the signal sequence from SRP and insertion into the translocon. GTP hydrolysis then results in dissociation of SR from the ribosome, and SRP from the SR.
Essential Role of Voltage-Dependent Anion Channel in Various Forms of Apoptosis in Mammalian Cells
Authors: Shimizu Shigeomi , Matsuoka Yosuke , Shinohara Yasuo , Yoneda Yoshihiro , Tsujimoto Yoshihide
Published: July 2002

Through direct interaction with the voltage-dependent anion channel (VDAC), proapoptotic members of the Bcl-2 family such as Bax and Bak induce apoptogenic cytochrome c release in isolated mitochondria, whereas BH3-only proteins such as Bid and Bik do not directly target the VDAC to induce cytochrome c release. To investigate the biological significance of the VDAC for apoptosis in mammalian cells, we produced two kinds of anti-VDAC antibodies that inhibited VDAC activity. In isolated mitochondria, these antibodies prevented Bax-induced cytochrome c release and loss of the mitochondrial membrane potential (Δψ), but not Bid-induced cytochrome c release. When microinjected into cells, these anti-VDAC antibodies, but not control antibodies, also prevented Bax-induced cytochrome c release and apoptosis, whereas the antibodies did not prevent Bid-induced apoptosis, indicating that the VDAC is essential for Bax-induced, but not Bid-induced, apoptogenic mitochondrial changes and apoptotic cell death. In addition, microinjection of these anti-VDAC antibodies significantly inhibited etoposide-, paclitaxel-, and staurosporine-induced apoptosis. Furthermore, we used these antibodies to show that Bax- and Bak-induced lysis of red blood cells was also mediated by the VDAC on plasma membrane. Taken together, our data provide evidence that the VDAC plays an essential role in apoptogenic cytochrome c release and apoptosis in mammalian cells.
The lipid phosphatase activity of PTEN is critical for stabilizing intercellular junctions and reverting invasiveness
Authors: Kotelevets Larissa , van Hengel Jolanda , Bruyneel Erik , Mareel Marc , van Roy Frans , Chastre Eric
Published: July 2002

To analyze the implication of PTEN in the control of tumor cell invasiveness, the canine kidney epithelial cell lines MDCKras-f and MDCKts-src, expressing activated Ras and a temperature-sensitive v-Src tyrosine kinase, respectively, were transfected with PTEN expression vectors. Likewise, the human PTEN-defective glioblastoma cell lines U87MG and U373MG, the melanoma cell line FM-45, and the prostate carcinoma cell line PC-3 were transfected. We demonstrate that ectopic expression of wild-type PTEN in MDCKts-src cells, but not expression of PTEN mutants deficient in either the lipid or both the lipid and protein phosphatase activities, reverted the morphological transformation, induced cell–cell aggregation, and suppressed the invasive phenotype in an E-cadherin–dependent manner. In contrast, overexpression of wild-type PTEN did not counteract Ras-induced invasiveness of MDCKras-f cells expressing low levels of E-cadherin. PTEN effects were not associated with marked changes in accumulation or phosphorylation levels of E-cadherin and associated catenins. Wild-type, but not mutant, PTEN also reverted the invasive phenotype of U87MG, U373MG, PC-3, and FM-45 cells. Interestingly, PTEN effects were mimicked by N-cadherin–neutralizing antibody in the glioblastoma cell lines. Our data confirm the differential activities of E- and N-cadherin on invasiveness and suggest that the lipid phosphatase activity of PTEN exerts a critical role in stabilizing junctional complexes and restraining invasiveness.
c-erbB-3
Authors: Offterdinger Martin , Schöfer Christian , Weipoltshammer Klara , Grunt Thomas W.
Published: July 2002

c-erbB receptors are usually located in cell membranes and are activated by extracellular binding of EGF-like growth factors. Unexpectedly, using immunofluorescence we found high levels of c-erbB-3 within the nuclei of MTSV1-7 immortalized nonmalignant human mammary epithelial cells. Nuclear localization was mediated by the COOH terminus of c-erbB-3, and a nuclear localization signal was identified by site-directed mutagenesis and by transfer of the signal to chicken pyruvate kinase. A nuclear export inhibitor caused accumulation of c-erbB-3 in the nuclei of other mammary epithelial cell lines as demonstrated by immunofluorescence and biochemical cell fractionation, suggesting that c-erbB-3 shuttles between nuclear and nonnuclear compartments in these cells. Growth of MTSV1-7 on permeable filters induced epithelial polarity and concentration of c-erbB-3 within the nucleoli. However, the c-erbB-3 ligand heregulin β1 shifted c-erbB-3 from the nucleolus into the nucleoplasm and then into the cytoplasm. The subcellular localization of c-erbB-3 obviously depends on exogenous stimuli and on the stage of epithelial polarity and challenges the specific function of c-erbB-3 as a transmembrane receptor protein arguing for additional, as yet unidentified, roles of c-erbB-3 within the nucle(ol)us of mammary epithelial cells.