bluuebunny/crossref_metadata_2025 huggingface dataset:
Leukemia inhibitory factor induces differentiation of pituitary corticotroph function: an immuno-neuroendocrine phenotypic switch.
Authors: Stefana B , Ray D W , Melmed S
Published: July 2002

Leukemia inhibitory factor (LIF) promotes differentiated cell function in several systems. We recently reported LIF and LIF receptor expression in human fetal pituitary corticotrophs in vivo and demonstrated LIF stimulation of adrenocorticotrophin (ACTH) transcription in vitro, suggesting a role for LIF in corticotroph development. We therefore assessed the action of LIF on proliferating murine corticotroph cells (AtT20). LIF impairs proliferation of AtT20 cells (25% reduction versus control, P < 0.03), while simultaneously enhancing ACTH secretion (2-fold, P < 0.001) and augmenting ACTH responsiveness to corticotrophin-releasing hormone (CRH) action (4-fold, P < 0.001). This attenuation of cell growth is due to a block of cell cycle progression from G1 into S phase, as measured by flow cytometric analysis (24 +/- 0.8 versus 11.57 +/- 1.5, P < 0.001). Using bromodeoxyuridine incorporation assays, loss of cells in S phase was confirmed (25 +/- 0.08 to 9.4 +/- 1.4, P < 0.008). In contrast, CRH induced the G2/M phase (3.6 +/- 0.2 to 15.4 +/- 3, P < 0.001). This effect was blunted by LIF (P < 0.001 versus CRH alone). Cyclin A mRNA levels, which decline in S phase, were stimulated 3.5-fold by LIF and markedly suppressed by CRH. These results indicate a LIF-induced cell cycle block occurring at G1/S in corticotroph cells. Thus, LIF reduces proliferation, enhances ACTH secretion, and potentiates effects of CRH on ACTH secretion while blocking effects of CRH on the cell cycle. Responses of these three markers of differentiated corticotroph function indicate LIF to be a differentiation factor for pituitary corticotroph cells by preferential phenotypic switching from proliferative to synthetic.
Sucrose biosynthesis in a prokaryotic organism: Presence of two sucrose-phosphate synthases in
Anabaena
with remarkable differences compared with the plant enzymes
Authors: Porchia Andrea C. , Salerno Graciela L.
Published: July 2002

Biosynthesis of sucrose-6-P catalyzed by sucrose-phosphate synthase
(SPS), and the presence of sucrose-phosphate phosphatase (SPP) leading
to the formation of sucrose, have both been ascertained in a
prokaryotic organism:
Anabaena
7119, a filamentous
heterocystic cyanobacterium. Two SPS activities (SPS-I and SPS-II) were
isolated by ion-exchange chromatography and partially purified. Four
remarkable differences between SPSs from
Anabaena
and
those from higher plants were shown: substrate specificity, effect of
divalent cations, native molecular mass, and oligomeric composition.
Both SPS-I and SPS-II accept Fru-6-P (
K
m
for
SPS-I = 0.8 ± 0.1 mM;
K
m
for
SPS-II = 0.7 ± 0.1 mM) and UDP-Glc as substrates
(
K
m
for SPS-I = 1.3 ± 0.4 mM;
K
m
for SPS-II = 4.6 ± 0.4 mM),
but unlike higher plant enzymes, they are not specific for UDP-Glc.
GDP-Glc and TDP-Glc are also SPS-I substrates
(
K
m
for GDP-Glc = 1.2 ± 0.2 mM
and
K
m
for TDP-Glc = 4.0 ± 0.4
mM), and ADP-Glc is used by SPS-II (
K
m
for
ADP-Glc = 5.7 ± 0.7 mM). SPS-I has an absolute dependence
toward divalent metal ions (Mg
2+
or Mn
2+
) for
catalytic activity, not found in plants. A strikingly smaller native
molecular mass (between 45 and 47 kDa) was determined by gel filtration
for both SPSs, which, when submitted to SDS/PAGE, showed a monomeric
composition. Cyanobacteria are, as far as the authors know, the most
primitive organisms that are able to biosynthesize sucrose as higher
plants do.
Expression of galanin and a galanin receptor in several sensory systems and bone anlage of rat embryos
Authors: Xu Zhi-Qing , Shi Tie-Jun , Hökfelt Tomas
Published: July 2002

Using
in situ
hybridization and
immunohistochemistry the expression of, respectively, prepro-galanin
(prepro-GAL) mRNA and GAL receptor-1 mRNA, as well as GAL-like and GAL
message-associated peptide-like immunoreactivities, were studied in
rats from embryonic day 14 (E14) to postnatal day 1. GAL expression was
observed already at E14 in trigeminal and dorsal root ganglion neurons
and at E15 in the sensory epithelia in developing ear, eye, and nose,
as well as at E19 during bone formation. Also, GAL receptor-1 mRNA was
expressed in the sensory ganglia of embryos but appeared later than the
ligand. These findings suggest that GAL and/or GAL message-associated
peptide may have a developmental role in several sensory systems and
during bone formation.
GSP-1 genes are linked to the grain hardness locus (Ha) on wheat chromosome 5D.
Authors: Jolly C J , Glenn G M , Rahman S
Published: July 2002

An important determinant of wheat grain quality is the hardness of the grain. The trait is controlled by a major locus, Ha, on the short arm of chromosome 5D. Purified starch granules from soft-grained wheats have associated with them 15-kDa polypeptides called grain softness proteins (GSPs) or "friabilins." Genes that encode one family of closely related GSP polypeptides - GSP-1 genes - were mapped using chromosome substitution lines to the group 5 chromosomes. An F2 population segregating for hard and soft alleles at the Ha locus on a near-isogenic background was used in a single-seed study of the inheritance of grain softness and of GSP-1 alleles. Grain softness versus grain hardness was inherited in a 3:1 ratio. The presence versus absence of GSPs in single seed starch preparations was coinherited with grain softness versus hardness. This showed that grain softness is primarily determined by seed, and not by maternal, genotype. In addition, no recombination was detected in 44 F2 plants between GSP-1 restriction fragment length polymorphisms and Ha alleles. Differences between hard and soft wheat grains in membrane structure and lipid extractability have been described and, of the three characterized proteins that are part of the mixture of 15-kDa polypeptides called GSPs, at least two, and probably all three, are proteins that bind polar lipids. The data are interpreted to suggest that the Ha locus may encode one or more members of a large family of lipid-binding proteins.
Total chemical synthesis of enzymatically active human type II secretory phospholipase A
2
Authors: Hackeng Tilman M. , Mounier Carine M. , Bon Cassian , Dawson Philip E. , Griffin John H. , Kent Stephen B. H.
Published: July 2002

Human group II secretory phospholipase A
2
(sPLA
2
) is an enzyme found in the α granules of platelets and at inflammatory sites. Although its physiological function is unclear, sPLA
2
can inhibit blood coagulation reactions independent of its lipolytic action. To study the molecular basis of PLA
2
activities, we developed a total chemical synthesis of sPLA
2
by chemical ligation of large unprotected peptides. The synthetic segments PLA
2
-(1–58)-
α
COSCH
2
COOH and PLA
2
-(59–124) were prepared by stepwise solid-phase peptide synthesis and ligated to yield a peptide bond between Gly
58
and Cys
59
. The 124-residue polypeptide product (mass: 13,920 ± 2 Da) was folded to yield one major product (mass: 13,905 ± 1 Da), the loss of 15 ± 3 Da reflecting the formation of seven disulfide bonds. Circular dichroism studies of synthetic sPLA
2
showed α-helix, β-structure, and random coil contents consistent with those found in the crystal structure of sPLA
2
. Synthetic sPLA
2
had
k
cat
and
K
m
values identical to those of recombinant sPLA
2
for hydrolysis of 1,2-bis(heptanoylthio)-phosphatidylcholine. Synthetic sPLA
2
, like recombinant sPLA
2
, inhibited thrombin generation from prothrombinase complex (factors Xa, V, II, Ca
2+
, and phospholipids). In the absence of phospholipids, both synthetic and recombinant sPLA
2
inhibited by 70% prothrombin activation by factors Xa, Va, and Ca
2+
. Thus, synthetic sPLA
2
is a phospholipid-independent anticoagulant like recombinant or natural sPLA
2
. This study demonstrates that chemical synthesis of sPLA
2
yields a fully active native-like enzyme and offers a straightforward tool to provide sPLA
2
analogs for structure–activity studies of anticoagulant, lipolytic, or inflammatory activities.
Considerations of transcriptional control mechanisms: Do TFIID–core promoter complexes recapitulate nucleosome-like functions?
Authors: Hoffmann Alexander , Oelgeschläger Thomas , Roeder Robert G.
Published: July 2002

The general transcription initiation factor TFIID was originally
identified, purified, and characterized with a biochemical assay in
which accurate transcription initiation is reconstituted with multiple,
chromatographically separable activities. Biochemical analyses have
demonstrated that TFIID is a multiprotein complex that directs
preinitiation complex assembly on both TATA box-containing and
TATA-less promoters, and some TFIID subunits have been shown to be
molecular targets for activation domains in DNA-binding regulatory
proteins. These findings have most commonly been interpreted to support
the view that transcriptional activation by upstream factors is the
result of enhanced TFIID recruitment to the core promoter. Recent
insights into the architecture and cell-cycle regulation of the
multiprotein TFIID complex prompt both a reassessment of the functional
role of TFIID in gene activation and a review of some of the less
well-appreciated literature on TFIID. We present a speculative model
for diverse functional roles of TFIID in the cell, explore the merits
of the model in the context of published data, and suggest experimental
approaches to resolve unanswered questions. Finally, we point out how
the proposed functional roles of TFIID in eukaryotic class II
transcription fit into a model for promoter recognition and activation
that applies to both eubacteria and eukaryotes.
The mouse histone H2a gene contains a small element that facilitates cytoplasmic accumulation of intronless gene transcripts and of unspliced HIV-1-related mRNAs
Authors: Huang Yingqun , Carmichael Gordon G.
Published: July 2002

Histone mRNAs are naturally intronless and accumulate efficiently in the cytoplasm. To learn whether there are cis-acting sequences within histone genes that allow efficient cytoplasmic accumulation of RNAs, we made recombinant constructs in which sequences from the mouse H2a gene were cloned into a human β-globin cDNA. By using transient transfection and RNase protection analysis, we demonstrate here that a 100-bp sequence within the H2a coding region permits efficient cytoplasmic accumulation of the globin cDNA transcripts. We also show that this sequence appears to suppress splicing and can functionally replace Rev and the Rev-responsive element in the cytoplasmic accumulation of unspliced HIV-1-related mRNAs. Like the Rev-responsive element, this sequence acts in an orientation-dependent manner. We thus propose that the sequence identified here may be a member of the cis-acting elements that facilitate the cytoplasmic accumulation of naturally intronless gene transcripts.
Exploring the folding free energy surface of a three-helix bundle protein
Authors: Guo Zhuyan , Brooks Charles L. , Boczko Erik M.
Published: July 2002

The multidimensional free energy surface for a small fast folding helical protein is explored based on first-principle calculations. The model represents the 46-residue segment from fragment B of staphylococcal protein A. The relationship between collapse and tertiary structure formation, and the order of collapse and secondary structure formation, are investigated. We find that the initial collapse process gives rise to a transition state with about 30% of the native tertiary structure and 50–70% of the native helix content. We also observe two distinct distributions of native helix in this collapsed state (
R
g
≈ 12 Å), one with about 20% of the native helical hydrogen bonds, the other with near 70%. The former corresponds to a local minimum. The barrier from this metastable state to the native state is about 2 k
B
T. In the latter case, folding is essentially a downhill process involving topological assembly. In addition, the order of formation of secondary structure among the three helices is examined. We observe cooperative formation of the secondary structure in helix I and helix II. Secondary structure in helix III starts to form following the formation of certain secondary structure in both helix I and helix II. Comparisons of our results with those from theory and experiment are made.
Correction of the X-linked immunodeficiency phenotype by transgenic expression of human Bruton tyrosine kinase under the control of the class II major histocompatibility complex Ea locus control region
Authors: Drabek Dubravka , Raguz Selina , De Wit Ton P. M. , Dingjan Gemma M. , Savelkoul Huub F. J. , Grosveld Frank , Hendriks Rudolf W.
Published: July 2002

Bruton tyrosine kinase (Btk) is essential for the development of pre-B cells to mature B cell stages.Btk-deficient mice manifest an X-linked immunodeficiency (xid) defect characterized by a reduction of peripheral IgMlowIgDhighB cells, a lack of peritoneal CD5+B cells, low serum levels of IgM and IgG3, and impaired responses to T cell independent type II (TI-II) antigens. We have generated transgenic mice in which expression of the humanBtkgene is driven by the murine class II major histocompatibility complex Ea gene locus control region, which provides gene expression from the pre-B cell stage onwards. When these transgenic mice were mated onto aBtk−background, correction of thexidB cell defects was observed: B cells differentiated to mature IgMlowIgDhighstages, peritoneal CD5+B cells were present, and serum Ig levels andin vivoresponses to TI-II antigens were in the normal ranges. A comparable rescue by transgenicBtkexpression was also observed in heterozygousBtk+/−female mice in those B-lineage cells that wereBtk-deficient as a result of X chromosome inactivation. These findings indicate that theBtk−phenotype in the mouse can be corrected by expression of humanBtkfrom the pre-B cell stage onwards.
A point mutation in the
MET
oncogene abrogates metastasis without affecting transformation
Authors: Giordano Silvia , Bardelli Alberto , Zhen Zhu , Menard Sylvie , Ponzetto Carola , Comoglio Paolo M.
Published: July 2002

The
MET
oncogene encodes the tyrosine kinase receptor for hepatocyte growth factor/scatter factor (HGF), known to stimulate invasive growth of epithelial cells.
MET
is overexpressed in a significant percentage of human cancers and is amplified during the transition between primary tumors and metastasis. To investigate whether this oncogene is directly responsible for the acquisition of the metastatic phenotype, we exploited a single-hit oncogenic version of
MET
, able to transform and to confer invasive and metastatic properties to nontumorigenic cells, both
in vitro
and in nude mice. We mutagenized the signal transducer docking site of Met (Y
1349
VHVX
3
Y
1356
VNV), which has the uncommon property of binding and activating multiple src homology region 2 (SH2)-containing intracellular effectors. Notably, a point mutation (H
1351
→ N) increased the transforming ability of the oncogene but abolished its metastatic potential. This mutation duplicates the Grb2 binding site, super-activating the Ras pathway and preventing the binding of the other intracellular transducers. Complementation in trans with another nonmetastatic mutant (N
1358
→ H), recruiting all the transducers downstream to Met except Grb2, rescued the invasive–metastatic phenotype. It is concluded that the metastatic potential of the
MET
oncogene relies on the properties of its multifunctional docking site, and that a single point mutation affecting signal transduction can dissociate neoplastic transformation from metastasis.
How
Escherichia coli
can bias the results of molecular cloning: Preferential selection of defective genomes of hepatitis C virus during the cloning procedure
Authors: Forns Xavier , Bukh Jens , Purcell Robert H. , Emerson Suzanne U.
Published: July 2002

Cloned PCR products containing hepatitis C virus (HCV) genomic fragments have been used for analyses of HCV genomic heterogeneity and protein expression. These studies assume that the clones derived are representative of the entire virus population and that subsets are not inadvertently selected. The aim of the present study was to express HCV structural proteins. However, we found that there was a strong cloning selection for defective genomes and that most clones generated initially were incapable of expressing the HCV proteins. The HCV structural region (C-E1-E2-p7) was directly amplified by long reverse transcription–PCR from the plasma of an HCV-infected patient or from a control plasmid containing a viable full-length cDNA of HCV derived from the same patient but cloned in a different vector. The PCR products were cloned into a mammalian expression vector, amplified in
Escherichia coli
, and tested for their ability to produce HCV structural proteins. Twenty randomly picked clones derived from the HCV-infected patient all contained nucleotide mutations leading to absence or truncation of the expected HCV products. Of 25 clones derived from the control plasmid, only 8% were fully functional for polyprotein synthesis. The insertion of extra nucleotides in the region just upstream of the start codon of the HCV insert led to a statistically significant increase in the number of fully functional clones derived from the patient (42%) and from the control plasmid (72–92%). Nonrandom selection of clones during the cloning procedure has enormous implications for the study of viral heterogeneity, because it can produce a false spectrum of genomic diversity. It can also be an impediment to the construction of infectious viral clones.
Introns and intein coding sequence in the ribonucleotide reductase genes of
Bacillus subtilis
temperate bacteriophage SPβ
Authors: Lazarevic Vladimir , Soldo Blazenka , Düsterhöft Andreas , Hilbert Helmut , Mauël Catherine , Karamata Dimitri
Published: July 2002

The two putative ribonucleotide reductase subunits of the
Bacillus subtilis
bacteriophage SPβ are encoded by the
bnrdE
and
bnrdF
genes that are highly similar to corresponding host paralogs, located on the opposite replication arm. In contrast to their bacterial counterparts,
bnrdE
and
bnrdF
each are interrupted by a group I intron, efficiently removed
in vivo
by mRNA processing. The
bnrdF
intron contains an ORF encoding a polypeptide similar to homing endonucleases responsible for intron mobility, whereas the
bnrdE
intron has no obvious trace of coding sequence. The downstream
bnrdE
exon harbors an intervening sequence not excised at the level of the primary transcript, which encodes an in-frame polypeptide displaying all the features of an intein. Presently, this is the only intein identified in bacteriophages. In addition,
bnrdE
provides an example of a group I intron and an intein coding sequence within the same gene.
Functional evidence for a nasopharyngeal carcinoma tumor suppressor gene that maps at chromosome 3p21.3
Authors: Cheng Yue , Poulos Nicholas E. , Lung Maria L. , Hampton Garret , Ou Baoxiang , Lerman Michael I. , Stanbridge Eric J.
Published: July 2002

Nasopharyngeal carcinoma is a malignancy that is prevalent among populations from Southeast Asia. Epidemiological studies indicate that genetic predisposition, Epstein–Barr virus, and environmental conditions may play a role in determining incidence. Molecular studies have implicated a tumor suppressor gene(s) on the short arm of chromosome 3. In this study we provide functional evidence, via monochromosome transfer, for a tumor suppressor gene(s) activity in chromosome 3p21.3.
Global flexibility of tertiary structure in RNA: Yeast tRNA
Phe
as a model system
Authors: Friederich Marisa W. , Vacano Elsi , Hagerman Paul J.
Published: July 2002

The study of RNA structure using x-ray crystallography or NMR has yielded a wealth of detailed structural information; however, such approaches do not generally yield quantitative information regarding long-range flexibility in solution. To address this issue, we describe a solution-based method that is capable of characterizing the global flexibilities of nonhelix elements in RNA, provided that such elements are flanked by helix (e.g., bulges, internal loops, or branches). The “phased τ ratio” method is based on the principle that, for RNA molecules possessing two variably phased bends, the relative birefringence decay times depend on the flexibility of each bend, not simply the mean bend angles. The method is used to examine the overall flexibility of the yeast tRNA
Phe
core (as unmodified transcript). In the presence of magnesium ions, the tRNA core is not significantly more flexible than an equivalent length of RNA helix. In the absence of divalent ions, the tRNA core gains flexibility under conditions where its secondary structure is likely to be largely preserved. The phased τ ratio approach should be broadly applicable to nonhelix elements in both RNA and DNA and to protein–nucleic acid interactions.
Targeting tumor vasculature endothelial cells and tumor cells for immunotherapy of human melanoma in a mouse xenograft model
Authors: Hu Zhiwei , Sun Ying , Garen Alan
Published: July 2002

An immunotherapy treatment for cancer that targets both the tumor vasculature and tumor cells has shown promising results in a severe combined immunodeficient mouse xenograft model of human melanoma. The treatment involves systemic delivery of an immunoconjugate molecule composed of a tumor-targeting domain conjugated to the Fc effector domain of human IgG1. The effector domain induces a cytolytic immune response against the targeted cells by natural killer cells and complement. Two types of targeting domains were used. One targeting domain is a human single-chain Fv molecule that binds to a chondroitin sulfate proteoglycan expressed on the surface of most human melanoma cells. Another targeting domain is factor VII (fVII), a zymogen that binds with high specificity and affinity to the transmembrane receptor tissue factor (TF) to initiate the blood coagulation cascade. TF is expressed by endothelial cells lining the tumor vasculature but not the normal vasculature, and also by many types of tumor cells including melanoma. Because the binding of a fVII immunoconjugate to TF might cause disseminated intravascular coagulation, the active site of fVII was mutated to inhibit coagulation without affecting the affinity for TF. The immunoconjugates were encoded as secreted molecules in a replication-defective adenovirus vector, which was injected into the tail vein of severe combined immunodeficient mice. The results demonstrate that a mutated fVII immunoconjugate, administered separately or together with a single-chain Fv immunoconjugate that binds to the tumor cells, can inhibit the growth or cause regression of an established human tumor xenograft. This procedure could be effective in treating a broad spectrum of human solid tumors that express TF on vascular endothelial cells and tumor cells.
A heterozygous mutation of β-actin associated with neutrophil dysfunction and recurrent infection
Authors: Nunoi Hiroyuki , Yamazaki Tsuyoshi , Tsuchiya Hiroyuki , Kato Seishi , Malech Harry L. , Matsuda Ichiro , Kanegasaki Shiro
Published: July 2002

A human disorder caused by mutation in nonmuscle actin has not been reported. We report here a variant of nonmuscle actin in a female patient with recurrent infections, photosensitivity, and mental retardation. She also had abnormalities in neutrophil chemotaxis, superoxide production, and membrane potential response. Two-dimensional PAGE analysis of proteins from neutrophils and other cell types from this patient demonstrated a unique protein spot migrating at 42 kDa with pI shifted slightly to neutral relative to normal β- and γ-actin. Digestion peptide mapping and Western blotting showed this spot to be an abnormal actin. A full-length cDNA library was constructed by using mRNA from patient’s cells and cDNA encoding the mutant β-actin molecule was identified by an
in vitro
translation method. Sequencing of the clones demonstrated a G-1174 to A substitution, predicting a glutamic acid-364 to lysine substitution in β-actin and eliminating a
Hin
fI DNase restriction site found in normal β-actin sequence. By
Hin
fI digestion and by sequencing, the mutation in one allele of patient’s genomic DNA was confirmed. Though no defect in cell-free polymerization of actin was detected, this defect lies in a domain important for binding to profilin and other actin-regulatory molecules. In fact, the mutant actin bound to profilin less efficiently than normal actin did. Heterozygous expression of mutant β-actin in neutrophils and other cells of this patient may act in a dominant–negative fashion to adversely affect cellular activities dependent on the function of nonmuscle actin.
Dose-response resistance to HIV-1/MuLV pseudotype virus
ex vivo
in a hairpin ribozyme transgenic mouse model
Authors: Andäng Michael , Hinkula Jorma , Hotchkiss Graham , Larsson Sten , Britton Sven , Wong-Staal Flossie , Wahren Britta , Ährlund-Richter Lars
Published: July 2002

We have investigated the efficacy of a hairpin ribozyme targeting the 5′ leader sequence of HIV-1 RNA in a transgenic model system. Primary spleen cells derived from transgenic or control mice were infected with HIV-1/MuLV pseudotype virus. A significantly reduced susceptibility to infection in ribozyme-expressing transgenic spleen cells (
P
= 0.01) was shown. Variation of transgene-expression levels between littermates revealed a dose response between ribozyme expression and viral resistance, with an estimated cut off value below 0.2 copies of hairpin ribozyme per cell. These findings open up possibilities for studies on ribozyme efficacy and anti-HIV-1 gene therapy.
Mutation analysis of the Pip interaction domain reveals critical residues for protein–protein interactions
Authors: Ortiz Maria Antonia , Light James , Maki Richard A. , Assa-Munt Nuria
Published: July 2002

The PU.1 interaction partner (Pip) is a member of the interferon regulatory factor family that regulates gene expression through heterodimerization with the ETS transcription factor PU.1. Binding of Pip alone to DNA is weak, and usually it is recruited by phosphorylated PU.1 to form a strong ternary complex with specific DNA sequences. An approach combining sequence homology analysis, secondary structure predictions, and a precise mutational strategy has been used to determine critical residues within the Pip heterodimerization domain that contribute to ternary complex formation. We have delimited the Pip interaction domain to residues 245–422 by using deletion analysis. Site-directed mutagenesis of conserved polar amino acids within two predicted α-helices contained in this region, and which are highly conserved in the IRF family, confirmed the importance of these residues for Pip–PU.1 interaction with DNA as well as for trans-activation activity. Our results suggest the existence of a functional epitope essential for heterodimerization between Pip and PU.1 and possibly, in general, between interferon regulatory factor family members and their partners.
SMRTe, a silencing mediator for retinoid and thyroid hormone receptors-extended isoform that is more related to the nuclear receptor corepressor
Authors: Park Eun-Ju , Schroen Daniel J. , Yang Maozhou , Li Hui , Li Li , Chen J. Don
Published: July 2002

SMRT (silencing mediator for retinoid and thyroid hormone receptors) and N-CoR (nuclear receptor copressor) mediate transcriptional repression of important regulators that are involved in many signaling pathways. SMRT and N-CoR are related proteins that form complexes with mSin3A/B and histone deacetylases to induce local chromatin condensation and transcriptional repression. However, SMRT is substantially smaller than N-CoR, lacking an N-terminal domain of approximately 1,000 aa that are present in N-CoR. Here, we report the identification of SMRT-extended (SMRTe), which contains an N-terminal sequence that shows striking similarity with N-CoR. As in N-CoR, this SMRTe-N-terminal domain also represses basal transcription. We find that SMRTe expression is regulated during cell cycle progression and SMRTe transcripts are present in many embryonic tissues. These data redefine a structurally and functionally more related nuclear receptor corepressor family and suggest an additional role for SMRTe in the regulation of cycle-specific gene expression in diverse signaling pathways.
Environmental variation shapes sexual dimorphism in red deer
Authors: Post Eric , Langvatn Rolf , Forchhammer Mads C. , Stenseth Nils Chr.
Published: July 2002

Sexual dimorphism results from dichotomous selection on male and female strategies of growth in relation to reproduction. In polygynous mammals, these strategies reflect sexual selection on males for access to females and competitive selection on females for access to food. Consequently, in such species, males display rapid early growth to large adult size, whereas females invest in condition and early sexual maturity at the expense of size. Hence, the magnitude of adult size dimorphism should be susceptible to divergence of the sexes in response to environmental factors differentially influencing their growth to reproduction. We show that divergent growth of male and female red deer after 32 years of winter warming and 15 years of contemporaneously earlier plant phenology support this prediction. In response to warmer climate during their early development, males grew more rapidly and increased in size, while female size declined. Conversely, females, but not males, responded to earlier plant phenology with increased investment in condition and earlier reproduction. Accordingly, adult size dimorphism increased in relation to warmer climate, whereas it declined in relation to forage quality. Thus, the evolutionary trajectories of growth related to reproduction in the sexes (
i
) originate from sexual and competitive selection, (
ii
) produce sexual size dimorphism, and (
iii
) are molded by environmental variation.
Involvement of protein kinase A in fibroblast growth factor-2-activated transcription
Authors: Pursiheimo Juha-Pekka , Jalkanen Markku , Taskén Kjetil , Jaakkola Panu
Published: July 2002

Polypeptide growth factors activate common signal transduction
pathways, yet they can induce transcription of different target genes.
The mechanisms that control this specificity are not completely
understood. Recently, we have described a fibroblast growth factor
(FGF)-inducible response element, FiRE, on the syndecan-1 gene. In NIH
3T3 cells, the FiRE is activated by FGF-2 but not by several other
growth factors, such as platelet-derived growth factor or epidermal
growth factor, suggesting that FGF-2 activates signaling pathways that
diverge from pathways activated by other growth factors. In this paper,
we report that the activation of FiRE by FGF-2 requires protein kinase
A (PKA) in NIH 3T3 cells. The PKA-specific inhibitor H-89
(
N
-[2-(
p
-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide)
blocked the FGF-2-induced activation of FiRE, the transcription of the
syndecan-1 gene, and cell proliferation. Also, expression of a
dominant-negative form of PKA inhibited the FGF-2-induced FiRE
activation and the transcription of the syndecan-1 gene. The binding of
activator protein-1 transcription-factor complexes, required for the
activation of FiRE, was blocked by inhibition of PKA activity before
FGF-2 treatment. In accordance with the growth factor specificity of
FiRE, the activity of PKA was stimulated by FGF-2 but not by
platelet-derived growth factor or epidermal growth factor. Furthermore,
a portion of the PKA catalytic subunit pool was translocated to the
nucleus by FGF-2. Noticeably, the total cellular cAMP concentration was
not affected by FGF-2 stimulus. We propose that the FGF-2-selective
transcriptional activation through FiRE is caused by the ability of
FGF-2 to control PKA activity.
Mobilization of stem/progenitor cells by sulfated polysaccharides does not require selectin presence
Authors: Sweeney Elizabeth A. , Priestley Gregory V. , Nakamoto Betty , Collins Robert G. , Beaudet Arthur L. , Papayannopoulou Thalia
Published: July 2002

Employing carbohydrate ligands, which have been extensively used to block selectin functionin vitroandin vivo, we have examined the involvement of such ligands in stem/progenitor cell mobilization in mice and monkeys. We found that sulfated fucans, branched and linear, are capable of increasing mature white cells in the periphery and mobilizing stem/progenitor cells of all classes (up to 32-fold) within a few hours posttreatment in a dose-dependent manner. To elicit the effect, the presence of sulfate groups was necessary, yet not sufficient, as certain sulfated hexosamines tested (chondroitin sulfates A or B) were ineffective. Significant mobilization of stem/progenitor cells and leukocytosis was elicited in selectin-deficient mice (L−/−, PE−/−, or LPE−/−) similar to that of wild-type controls, suggesting that the mode of action of sulfated fucans is not through blockade of known selectins. Other mechanisms have been entertained, in particular, the release of chemokines/cytokines, including some previously implicated in mobilization. Significant increases were documented in the levels of seven circulating chemokines/cytokines within a few hours after fucan sulfate treatment and support such a proposition. Additionally, an increase was noted in plasma metalloproteinase (MMP) 9, which might independently contribute to the mobilization process by enzymatically facilitating chemokine/cytokine release. Mobilization by sulfated polysaccharides provides a distinct paradigm in the mobilization process and uncovers an additional novelin vivobiological role for sulfated glycans. As similarly sulfated compounds were ineffectivein vivo, the data also underscore the fact that polysaccharides with similar structures may elicit diversein vivoeffects.
Population genetic implications from sequence variation in four Y chromosome genes
Authors: Shen Peidong , Wang Frank , Underhill Peter A. , Franco Claudia , Yang Wei-Hsien , Roxas Adriane , Sung Raphael , Lin Alice A. , Hyman Richard W. , Vollrath Douglas , Davis Ronald W. , Cavalli-Sforza L. Luca , Oefner Peter J.
Published: July 2002

Some insight into human evolution has been gained from the sequencing of four Y chromosome genes. Primary genomic sequencing determined geneSMCYto be composed of 27 exons that comprise 4,620 bp of coding sequence. The unfinished sequencing of the 5′ portion of geneUTY1was completed by primer walking, and a total of 20 exons were found. By using denaturing HPLC, these two genes, as well asDBYandDFFRY, were screened for polymorphic sites in 53–72 representatives of the five continents. A total of 98 variants were found, yielding nucleotide diversity estimates of 2.45 × 10−5, 5.07 × 10−5, and 8.54 × 10−5for the coding regions ofSMCY,DFFRY, andUTY1, respectively, with no variant having been observed inDBY. In agreement with most autosomal genes, diversity estimates for the noncoding regions were about 2- to 3-fold higher and ranged from 9.16 × 10−5to 14.2 × 10−5for the four genes. Analysis of the frequencies of derived alleles for all four genes showed that they more closely fit the expectation of a Luria–Delbrück distribution than a distribution expected under a constant population size model, providing evidence for exponential population growth. Pairwise nucleotide mismatch distributions date the occurrence of population expansion to ≈28,000 years ago. This estimate is in accord with the spread of Aurignacian technology and the disappearance of the Neanderthals.
Ski represses bone morphogenic protein signaling inXenopusand mammalian cells
Authors: Wang Wei , Mariani Francesca V. , Harland Richard M. , Luo Kunxin
Published: July 2002

The bone morphogenic proteins (BMPs) play important roles in vertebrate development. InXenopus, BMPs act as epidermal inducers and also as negative regulators of neurogenesis. Antagonism of BMP signaling results in neuralization. BMPs signal through the cell-surface receptors and downstream Smad molecules. Upon stimulation with BMP, Smad1, Smad5, and Smad8 are phosphorylated by the activated BMP receptors, form a complex with Smad4, and translocate into the nucleus, where they regulate the expression of BMP target genes. Here, we show that the Ski oncoprotein can block BMP signaling and the expression of BMP-responsive genes in bothXenopusand mammalian cells by directly interacting with and repressing the activity of BMP-specific Smad complexes. This ability to antagonize BMP signaling results in neuralization by Ski in theXenopusembryo and blocking of osteoblast differentiation of murine W-20-17 cells. Thus, Ski is able to repress the activity of all receptor-associated Smads and may regulate vertebrate development by modulating the signaling activity of transforming growth factor-β family members.
Evolutionary modification of development in mammalian teeth: Quantifying gene expression patterns and topography
Authors: Jernvall Jukka , Keränen Soile V. E. , Thesleff Irma
Published: July 2002

The study of mammalian evolution often relies on detailed analysis
of dental morphology. For molecular patterning to play a role in dental
evolution, gene expression differences should be linkable to
corresponding morphological differences. Because teeth, like many other
structures, are complex and evolution of new shapes usually involves
subtle changes, we have developed topographic methods by using
Geographic Information Systems. We investigated how genetic markers for
epithelial signaling centers known as enamel knots are associated with
evolutionary divergence of molar teeth in two rodent species, mouse and
vole. Our analysis of expression patterns of
Fgf4, Lef1,
p21
, and
Shh
genes in relation to digital
elevation models of developing tooth shapes shows that molecular
prepatterns predict the lateral cusp topography more than a day in
advance. A heterotopic shift in the molecular prepatterns can be
implicated in the evolution of mouse molar, changing locations from
which historically homologous cusps form. The subtle but measurable
heterotopic shifts may play a large role in the evolution of tooth cusp
topographies. However, evolutionary increase in the number of
longitudinal cusps in vole molar has involved accelerated longitudinal
growth and iterative addition of new cusps without changes in lateral
cusp topography. The iterative addition of cusps after the
establishment of lateral cusp topography may limit the independence of
individual morphological features used in evolutionary studies. The
diversity of mammalian molar patterns may largely result from the
heterotopic and iterative processes.
Identification of two novel transmembrane γ-carboxyglutamic acid proteins expressed broadly in fetal and adult tissues
Authors: Kulman John D. , Harris Jeff E. , Xie Ling , Davie Earl W.
Published: July 2002

The proline-rich γ-carboxyglutamic acid (Gla) proteins
(PRGPs) 1 and 2 are the founding members of a family of vitamin
K-dependent single-pass integral membrane proteins characterized by an
extracellular amino terminal domain of approximately 45 amino acids
that is rich in Gla. The intracellular carboxyl terminal region of
these two proteins contains one or two copies of the sequence PPXY, a
motif present in a variety of proteins involved in such diverse
cellular functions as signal transduction, cell cycle progression, and
protein turnover. In this report, we describe the cloning of the cDNAs
for two additional human transmembrane Gla proteins (TMG) of 20–24 kDa
named TMG3 and TMG4. These two proteins possess extracellular Gla
domains with 13 or 9 potential Gla residues, respectively,
followed by membrane-spanning hydrophobic regions and cytoplasmic
carboxyl terminal regions that contain PPXY motifs. This emerging
family of integral membrane Gla proteins includes proline-rich Gla
protein (PRGP) 1, PRGP2, TMG3, and TMG4, all of which are characterized
by broad and variable distribution in both fetal and adult tissues.
Members of this family can be grouped into two subclasses on the basis
of their gene organization and amino acid sequence. These observations
suggest novel physiological functions for vitamin K beyond its known
role in the biosynthesis of proteins involved in blood coagulation and
bone development. The identification and characterization of these
proteins may allow a more complete understanding of the teratogenic
consequences of exposure
in utero
to vitamin K
antagonists, such as warfarin-based anticoagulants.
Examen d'une erreur fondamentale dans la perception du hasard
Authors: Ladouceur Robert , Paquet Claude , Lachance Nadine , Dubé Dominique
Published: July 2002

Un des principaux facteurs expliquant le jeu excessif serait les perceptions erronées qu'entretiennent les individus concernant le hasard. Cet article vise à préciser les perceptions du joueur en analysant ses verbalisations lors de la production ou de la reconnaissance de suites aléatoires. Deux études empiriques ont été réalisées. E est prédit que la majorité des gens ont une perception erronée à l'égard du hasard et qu'il existe une relation entre le nombre d'issues possibles (par exemple deux lors du tir d'une pièce de monnaie ou six lors du tir d'un dé) et le nombre de verbalisations erronées faisant référence aux événements passés de la suite. Comme on le prévoyait, près de 70% des verbalisations sont l'expression d'une perception erronée, la plupart se référant à des liens de dépendance entre les événements de la suite. Cependant, l'augmentation du nombre d'issues possibles n'a pas d'effet significatif sur la proportion de perceptions erronées. La discussion met en relief les implications pratiques et théoriques des perceptions inadéquates des joueurs sur l'illusion du contrôle du jeu et des comportements excessifs en résultant.
Citizenship education in France and Britain: evolving theories and practices
Authors: Starkey Hugh
Published: July 2002

In the late 1990s both the British and the French governments gave new impetus to citizenship education. This article examines the theories and world views that underpin the formal syllabuses for citizenship education in England and France. It notes that whereas the English curriculum aspires to create a diverse society founded on multicultural citizenship, an insufficiently strongly agreed statement of values undermines the implementation of the project. The French syllabus, on the other hand, emphasizes a commitment to anti‐racism, human rights and civil action against injustice. Its theoretical basis in the French Republic, committed to individual equality without distinction, denies any recognition to the existence of social groups based on culture or ethnicity. This blindness to difference also tends to undermine citizenship education as a social project intended to promote integration through schools. Whereas French citizenship education is intended to integrate individuals into a predetermined, existing republican framework, English citizenship education apparently aims to create a new society and a new national identity. The article concludes that such a project requires an explicit commitment to and promotion of human rights as the basis for a social consensus and citizenship.
Public opinion and alcohol policy: comparisons of two Canadian general population surveys
Authors: GIESBRECHT NORMAN , KAVANAGH LYNN
Published: July 2002

In recent years increasing attention has been devoted to the association between public opinion and alcohol policy. This paper compares public opinion on alcohol policy questions in two national cross‐sectional surveys of representatives samples of the general population in Canada, with total Ns of 11 634 (1989) and 12 155 (1994). Views on the following topics are analysed: taxation of alcoholic beverages, the legal drinking age, beer and liquor store hours, government advertising against drinking, efforts to prevent drunken patrons from being served, adding warning labels on alcoholic beverage containers, selling alcohol in convenience (corner) stores, alcohol and drug education and treatment programs. Public support for current and potential alcohol policies is compared to actual changes in alcohol policy at the national level and to gradual or dramatic increases in access to alcohol in provincial contexts. Personal views on policies are placed into context by examining associations among support for policies, respondents' demographic characteristics and their drinking volumes and patterns. A decline in support for further or enhanced policy interventions is evident, although support remains high for several measures. In some instances public responses seemed to be a reaction to increased access, in others a confirmation of greater availability.
Making Sense of Adam Smith's Invisible Hand: Beyond Pareto Optimality and Unintended Consequences
Authors: Khalil Elias L.
Published: July 2002

Smith explicitly spells out the term “invisible hand” in only three texts, each in a different work. What is embarrassing to neoclassical welfare theory is that these explicit references have little to do with what came to be understood by the metaphor. In particular, the explicit reference to the invisible hand in The Wealth of Nations (WN) is not about the efficiency of the market in allocating resources. Rather, it is about, ironically, how impediments in the international capital market generate great benefits.
The Impact of Amphetamine‐Related Disorders on Community Psychiatric Emergency Services: 1993–1997
Authors: Leamon Martin H. , Canning Robert D. , Benjamin Lloyd
Published: July 2002

Trends in number, relative prevalence, and demographics of adult psychiatric admissions to the county psychiatric emergency service in Sacramento, California, for treatment of Amphetamine‐Related Disorders (ARDs) (N = 2,428) between July 1993 and July 1997 were examined. ARDs accounted for 11.2% of all emergency admissions (N = 21,615) and were the most frequent substance‐related disorder requiring admission during the study period. Patients with ARDs tended to be Caucasian or Hispanic males in their mid 30s. 38% of the ARD patients required further inpatient psychiatric care. The trends in numbers of ARDs tended to parallel other local and national non‐psychiatric indicators of amphetamine‐induced morbidity.
1956 and the PSI: The end of ‘ten winters’
Authors: Favretto Ilaria
Published: July 2002

The focus of this article is the revisionist course which the Italian Socialist Party embarked upon after 1956 and which led up to the first Centre-Left government. The article challenges two quite well established views. One view is that the transformation experienced by the PSI during the 1956-64 period was simply tactically expedient and devoid of any substance and consistency. This article argues, by contrast, that these years represented, in Alessandro Pizzorno's words, a veritable ‘Copernican revolution’. This period of revisionism was as important as the better-known revisionisms elaborated during the same period by other European Socialist parties such as the German SPD or British Labour. The second main argument is that ‘structural reformism’, the new strategy adopted by the PSI after 1956, was not, as it has often been described, an expression of ‘duplicity’ owing to the party's incapacity to behave like a genuinely reformist party - a phenomenon that has allegedly long characterized parties of the Left. Instead, the strategy was reflected in the changes to European socialism during the early 1960s. In particular, this period marked a contrast to the previous years which were characterized by the dominance of ideas of ‘redistributive’ socialism, à la Anthony Crosland. This period marked also a shift among Socialist parties towards the acceptance of greater state controls over the economy by way of public planning and ownership.