bluuebunny/crossref_metadata_2025_split huggingface dataset:
KRE5Gene Null Mutant Strains ofCandida albicansAre Avirulent and Have Altered Cell Wall Composition and Hypha Formation Properties
Authors: Herrero Ana B. , Magnelli Paula , Mansour Michael K. , Levitz Stuart M. , Bussey Howard , Abeijon Claudia 
Published: December 2004

ABSTRACTThe UDP-glucose:glycoprotein glucosyltransferase (UGGT) is an endoplasmic reticulum sensor for quality control of glycoprotein folding.Saccharomyces cerevisiaeis the only eukaryotic organism so far described lacking UGGT-mediated transient reglucosylation of N-linked oligosaccharides. The only gene inS. cerevisiaewith similarity to those encoding UGGTs isKRE5. S. cerevisiae KRE5deletion strains show severely reduced levels of cell wall β-1,6-glucan polymer, aberrant morphology, and extremely compromised growth or lethality, depending on the strain background. Deletion of both alleles of theCandida albicans KRE5gene gives rise to viable cells that are larger than those of the wild type (WT), tend to aggregate, have enlarged vacuoles, and show major cell wall defects.C. albicans kre5/kre5mutants have significantly reduced levels of β-1,6-glucan and more chitin and β-1,3-glucan and less mannoprotein than the WT. The remaining β-1,6-glucan, about 20% of WT levels, exhibits a β-1,6-endoglucanase digestion pattern, including a branch point-to-linear stretch ratio identical to that of WT strains, suggesting that Kre5p is not a β-1,6-glucan synthase.C. albicans KRE5is a functional homologue ofS. cerevisiae KRE5; it partially complements both the growth defect and reduced cell wall β-1,6-glucan content ofS. cerevisiae kre5viable mutants.C. albicans kre5/kre5homozygous mutant strains are unable to form hyphae in several solid and liquid media, even in the presence of serum, a potent inducer of the dimorphic transition. Surprisingly the mutants do form hyphae in the presence ofN-acetylglucosamine. Finally,C. albicans KRE5homozygous mutant strains exhibit a 50% reduction in adhesion to human epithelial cells and are completely avirulent in a mouse model of systemic infection.
Adenylyl Cyclase-Associated Protein Aca1 Regulates Virulence and Differentiation of
Cryptococcus neoformans
via the Cyclic AMP-Protein Kinase A Cascade
Authors: Bahn Yong-Sun , Hicks Julie K. , Giles Steven S. , Cox Gary M. , Heitman Joseph 
Published: December 2004

ABSTRACT

The evolutionarily conserved cyclic AMP (cAMP) signaling pathway controls cell functions in response to environmental cues in organisms as diverse as yeast and mammals. In the basidiomycetous human pathogenic fungus
Cryptococcus neoformans
, the cAMP pathway governs virulence and morphological differentiation. Here we identified and characterized adenylyl cyclase-associated protein, Aca1, which functions in parallel with the Gα subunit Gpa1 to control the adenylyl cyclase (Cac1). Aca1 interacted with the C terminus of Cac1 in the yeast two-hybrid system. By molecular and genetic approaches, Aca1 was shown to play a critical role in mating by regulating cell fusion and filamentous growth in a cAMP-dependent manner. Aca1 also regulates melanin and capsule production via the Cac1-cAMP-protein kinase A pathway. Genetic epistasis studies support models in which Aca1 and Gpa1 are necessary and sufficient components that cooperate to activate adenylyl cyclase. Taken together, these studies further define the cAMP signaling cascade controlling virulence of this ubiquitous human fungal pathogen.
Increased Genome Instability and Telomere Length in the
elg1
-Deficient
Saccharomyces cerevisiae
Mutant Are Regulated by S-Phase Checkpoints
Authors: Banerjee Soma , Myung Kyungjae 
Published: December 2004

ABSTRACT

Gross chromosomal rearrangements (GCRs) are frequently observed in cancer cells. Abnormalities in different DNA metabolism including DNA replication, cell cycle checkpoints, chromatin remodeling, telomere maintenance, and DNA recombination and repair cause GCRs in
Saccharomyces cerevisiae
. Recently, we used genome-wide screening to identify several genes the deletion of which increases GCRs in
S. cerevisiae
. Elg1, which was discovered during this screening, functions in DNA replication by participating in an alternative replication factor complex. Here we further characterize the GCR suppression mechanisms observed in the
elg1
Δ mutant strain in conjunction with the telomere maintenance role of Elg1. The
elg1
Δ mutation enhanced spontaneous DNA damage and resulted in GCR formation. However, DNA damage due to inactivation of Elg1 activates the intra-S checkpoints, which suppress further GCR formation. The intra-S checkpoints activated by the
elg1
Δ mutation also suppress GCR formation in strains defective in the DNA replication checkpoint. Lastly, the
elg1
Δ mutation increases telomere size independently of other previously known telomere maintenance proteins such as the telomerase inhibitor Pif1 or the telomere size regulator Rif1. The increase in telomere length caused by the
elg1
Δ mutation was suppressed by a defect in the DNA replication checkpoint, which suggests that DNA replication surveillance by Dpb11-Mec1/Tel1-Dun1 also has an important role in telomere length regulation.
Rad51 Protein from the Thermotolerant Yeast
Pichia angusta
as a Typical but Thermodependent Member of the Rad51 Family
Authors: Shalguev Valery I. , Kil Yury V. , Yurchenko Ludmila V. , Namsaraev Eugene A. , Lanzov Vladislav A. 
Published: December 2004

ABSTRACT

The Rad51 protein from the methylotrophic yeast
Pichia angusta
(Rad51
Pa
) of the taxonomic complex
Hansenula polymorpha
is a homolog of the RecA-RadA-Rad51 protein superfamily, which promotes homologous recombination and recombination repair in prokaryotes and eukaryotes. We cloned the
RAD51
gene from the cDNA library of the thermotolerant
P. angusta
strain BKM Y1397. Induction of this gene in a
rad51
-deficient
Saccharomyces cerevisiae
strain partially complemented the survival rate after ionizing radiation. Purified Rad51
Pa
protein exhibited properties typical of the superfamily, including the stoichiometry of binding to single-stranded DNA (ssDNA) (one protomer of Rad51
Pa
per 3 nucleotides) and DNA specificity for ssDNA-dependent ATP hydrolysis [poly(dC) > poly(dT) > φX174 ssDNA > poly(dA) > double-stranded M13 DNA]. An inefficient ATPase and very low cooperativity for ATP interaction position Rad51
Pa
closer to Rad51 than to RecA. Judging by thermoinactivation, Rad51
Pa
alone was 20-fold more thermostable at 37°C than its
S. cerevisiae
homolog (Rad51
Sc
). Moreover, it maintained ssDNA-dependent ATPase and DNA transferase activities up to 52 to 54°C, whereas Rad51
Sc
was completely inactive at 47°C. A quick nucleation and an efficient final-product formation in the strand exchange reaction promoted by Rad51
Pa
occurred only at temperatures above 42°C. These reaction characteristics suggest that Rad51
Pa
is dependent on high temperatures for activity.
UGD1
, Encoding the
Cryptococcus neoformans
UDP-Glucose Dehydrogenase, Is Essential for Growth at 37°C and for Capsule Biosynthesis
Authors: Moyrand Frédérique , Janbon Guilhem 
Published: December 2004

ABSTRACT

We report the identification and disruption of the
Cryptococcus neoformans
var.
grubii UGD1
gene encoding the UDP-glucose dehydrogenase, which catalyzes the conversion of UDP-glucose into UDP-glucuronic acid. Deletion of
UGD1
led to modifications in the cell wall, as revealed by changes in the sensitivity of
ugd1
Δ cells to sodium dodecyl sulfate, NaCl, and sorbitol. Moreover, two of the yeast's major virulence factors—capsule biosynthesis and the ability to grow at 37°C—were impaired in
ugd1
Δ strains. These results suggest that the UDP-dehydrogenase represents the major, and maybe only, biosynthetic pathway for UDP-glucuronic acid in
C. neoformans
. Consequently, deletion of
UGD1
blocked not only the synthesis of UDP-glucuronic acid but also that of UDP-xylose. To differentiate the phenotype(s) associated with the UDP-glucuronic acid defect alone from those linked to the UDP-xylose defect,
ugd1
Δ mutants were phenotypically compared to strains from which the gene encoding UDP-xylose synthase (i.e., that required for synthesis of UDP-xylose) had been deleted. Finally, studies of strains from which one of the four
CAP
genes (
CAP10
,
CAP59
,
CAP60
, or
CAP64
) had been deleted revealed common cell wall phenotypes associated with the acapsular state.
The Small-Subunit Processome Is a Ribosome Assembly Intermediate
Authors: Bernstein Kara A. , Gallagher Jennifer E. G. , Mitchell Brianna M. , Granneman Sander , Baserga Susan J. 
Published: December 2004

ABSTRACT

The small-subunit (SSU) processome is a large ribonucleoprotein required for the biogenesis of the 18S rRNA and likely corresponds to the terminal knobs visualized by electron microscopy on the 5′ end of nascent rRNAs. The original purification of the SSU processome of
Saccharomyces cerevisiae
resulted in the identification of 28 proteins. Here, we characterize 12 additional protein components, including five small-ribosomal-subunit proteins (Rps4, Rps6, Rps7, Rps9, and Rps14) that had previously been copurified. Our multiple criteria for including a component as a bona fide SSU processome component included coimmunoprecipitation with Mpp10 (an SSU processome component), the U3 snoRNA, and the anticipated pre-rRNAs. Importantly, the association of specific ribosomal proteins with the SSU processome suggests that the SSU processome has roles in both pre-rRNA processing and ribosome assembly. These ribosomal proteins may be analogous to the primary or secondary RNA binding proteins first described in bacterial in vitro ribosome assembly maps. In addition to the ribosomal proteins and based on the same experimental approach, we found seven other proteins (Utp18, Noc4, Utp20, Utp21, Utp22, Emg1, and Krr1) to be bona fide SSU processome proteins.
TAC1
, Transcriptional Activator of
CDR
Genes, Is a New Transcription Factor Involved in the Regulation of
Candida albicans
ABC Transporters
CDR1
and
CDR2
Authors: Coste Alix T. , Karababa Mahir , Ischer Françoise , Bille Jacques , Sanglard Dominique 
Published: December 2004

ABSTRACT

The ABC transporter genes
CDR1
and
CDR2
can be upregulated in
Candida albicans
developing resistance to azoles or can be upregulated by exposing cells transiently to drugs such as fluphenazine. The
cis
-acting drug-responsive element (DRE) present in the promoters of both genes and necessary for their upregulation contains 5′-CGG-3′ triplets that are often recognized by transcriptional activators with Zn(2)-Cys(6) fingers. In order to isolate regulators of
CDR1
and
CDR2
, the
C. albicans
genome was searched for genes encoding proteins with Zn(2)-Cys(6) fingers. Interestingly, three of these genes were tandemly arranged near the mating locus. Their involvement in
CDR1
and
CDR2
upregulation was addressed because a previous study demonstrated a link between mating locus homozygosity and azole resistance. The deletion of only one of these genes (orf19.3188) was sufficient to result in a loss of transient
CDR1
and
CDR2
upregulation by fluphenazine and was therefore named
TAC1
(transcriptional activator of
CDR
genes). Tac1p has a nuclear localization, and a fusion of Tac1p with glutathione
S
-transferase could bind the
cis
-acting regulatory DRE in both the
CDR1
and the
CDR2
promoters.
TAC1
is also relevant for azole resistance, since a
TAC1
allele (
TAC1-2
) recovered from an azole-resistant strain could trigger constitutive upregulation of
CDR1
and
CDR2
in an azole-susceptible laboratory strain. Transcript profiling experiments performed with a
TAC1
mutant and a revertant containing
TAC1-2
revealed not only
CDR1
and
CDR2
as targets of
TAC1
regulation but also other genes (
RTA3
,
IFU5
, and
HSP12
) that interestingly contained a DRE-like element in their promoters. In conclusion,
TAC1
appears to be the first
C. albicans
transcription factor involved in the control of genes mediating antifungal resistance.
Rabbit and Nonhuman Primate Models of Toxin-Targeting Human Anthrax Vaccines
Authors: Phipps Andrew J. , Premanandan Christopher , Barnewall Roy E. , Lairmore Michael D. 
Published: December 2004

SUMMARYThe intentional use ofBacillus anthracis, the etiological agent of anthrax, as a bioterrorist weapon in late 2001 made our society acutely aware of the importance of developing, testing, and stockpiling adequate countermeasures against biological attacks. Biodefense vaccines are an important component of our arsenal to be used during a biological attack. However, most of the agents considered significant threats either have been eradicated or rarely infect humans alive today. As such, vaccine efficacy cannot be determined in human clinical trials but must be extrapolated from experimental animal models. This article reviews the efficacy and immunogenicity of human anthrax vaccines in well-defined animal models and the progress toward developing a rugged immunologic correlate of protection. The ongoing evaluation of human anthrax vaccines will be dependent on animal efficacy data in the absence of human efficacy data for licensure by the U.S. Food and Drug Administration.
Little Lambda, Who Made Thee?
Authors: Gottesman Max E. , Weisberg Robert A. 
Published: December 2004

SUMMARYThe study of the bacteriophage λ has been critical to the discipline of molecular biology. It was the source of key discoveries in the mechanisms of, among other processes, gene regulation, recombination, and transcription initiation and termination. We trace here the events surrounding these findings and draw on the recollections of the participants. We show how a particular atmosphere of interactions among creative scientists yielded spectacular insights into how living things work.
Regulation of tissue factor-induced coagulation and platelet aggregation in flowing whole blood
Authors: Kuijpers Marijke , Nieuwenhuys Cécile , Feijge Marion , Kloots Willem , Giesen Peter , Jerling Johann , oude Egbrink Mirjam , Heemskerk Johan 
Published: December 2004

SummaryPhotochemically induced thrombosis (a thrombin-dependent process) was measured in rats treated with moderate doses of anticoagulants, but which appeared to be unchanged. We considered the possibility that platelet-inhibiting agents, which also indirectly inhibit coagulation, would act as more potent antithrombotic agents.Inhibitors used as such were prostaglandin E1 (PGE1), which elevates cyclic AMP levels, and the P2Y12 ADP-receptor antagonist,AR-C69931MX. Effects of these agents were investigated in an ex vivo model system, in which whole blood under coagulant conditions was perfused over fibrinogen at defined wall shear rate. Perfusion of blood (rat or human) in the presence of tissue factor resulted in deposition of activated platelets and subsequent aggregate formation, along with exposure of procoagulant phosphatidylserine (PS) on the platelet surface and formation of fibrin fibers. In the presence of PGE1 aggregation was completely inhibited,but platelet adhesion and PS exposure were only party reduced, while fibrin formation was hardly affected. Treatment with AR-C69931MX caused similar, but less complete effects.These results indicate that in tissue factor- triggered blood under conditions of flow:(i) the platelet procoagulant response is independent of aggregate formation; (ii) the platelet-inhibiting effect of PGE1 and AR-C69931MX is sufficient to suppress aggregation, but not platelet adhesion and coagulation. These platelet inhibitors thus maintain their aggregation- inhibiting effect at sites of thrombin formation.
Defective collagen-induced platelet activation in two patients with malignant haemopathies is related to a defect in the GPVI-coupled signalling pathway
Authors: Huisse Marie , Boval Bernadette , Hainaud Patricia , Robert Annie , Fauvel-Lafève Françoise , Jandrot-Perrus Martine , Bellucci Sylvia 
Published: December 2004

SummaryThe occurrence of a thrombocytopathy concomitantly to the development of a malignant haemopathy has been reported for some time, but little is known about the mechanism(s) involved in the platelet dysfunction. Platelet glycoprotein VI (GPVI) has now been identified as a principal platelet receptor for collagen. In this paper, we report the cases of two patients with a myelodysplasia and a B lymphopathy, respectively, who presented with thrombocytopathy in relation to a defective GPVI-mediated platelet reactivity to collagen. Thus, with regard to the different steps of adhesion, activation secretion or aggregation, patients’ platelet responses to collagen and to the GPVI specific agonists, collagen related peptide (CRP) or convulxin were null or dramatically impaired. Platelet responses to other agonists ADP, TRAP,Arachidonic acid were normal or showed only a moderate decrease. GPVI content was repeatedly normal, and binding of specific ligands, such as convulxin, satisfactory. Nevertheless, specific activating monoclonal antibodies and convulxin failed to induce platelet secretion; collagen, CRP or convulxin were unable to provoke calcium mobilisation. Furthermore, using a perfusion chamber model, we showed that ex vivo collagen-induced thrombi formation was very impaired.Taken together,these data provide evidence, for the first time, of an acquired defect in GPVI-mediated platelet reactivity to collagen, which reflects data observed in constitutional GPVI deficiencies, in two patients with malignant haemopathies.
Long lives, short indications
Authors: Ku Grace , Billett Henny 
Published: December 2004

SummaryVena cava filters have been in use for decades to prevent pulmonary embolization from deep venous thrombosis. These filters have been shown to be effective, with fairly low rates of filter migration, fracture and thrombosis. However considering that filters remain in situ for the life of the patient and that studies do not show increased longevity in patients with filters, any complications from filters are significant concerns. In addition, often patients require filters for only temporary indications, e.g. contraindication for anticoagulation because of impending procedures, or for only a transient risk period, as in trauma or pregnant patients. In these cases, removable filters may be more appealing. This review will examine the different types of removable filters and the indications in which removable filters may have an advantage over permanent filters.
Two parallel prothrombin activator systems in Australian rough-scaled snake, Tropidechis carinatus
Authors: Reza Md. Abu , Swarup Sanjay , Kini Manjunatha 
Published: December 2004

SummaryIt is uncommon for similar pathways/systems to be involved in highly divergent functions within single organisms. Earlier, we have shown that trocarin D, a venom prothrombin activator, from the Australian rough-scaled snake Tropidechis carinatus, is structurally and functionally similar to the blood coagulation factor Xa (FXa). The presence of a haemostatic system in these snakes implies that they have two parallel prothrombin activating systems: one in the plasma, that participates in the life saving process of blood clotting and the other in their venom, where it acts as a toxin. Here, we report the complete cDNA sequence encoding the blood coagulation factor X (FX) from the liver of T. carinatus. Deduced T. carinatus FX sequence shows ~80% identity with trocarin D but ~50% identity with the mammalian FX. Our present study confirms the presence of two separate genes – one each for FX and trocarin D, that code for similar proteins in T. carinatus snake. These two genes have different expression sites and divergent uses suggesting that snake venom prothrombin activators have probably evolved by the duplication of the liver FX gene and subsequently marked for tissue-specific expression in the venom gland.
Prevention of cardiovascular disease in type-2 diabetes: How to improve the clinical efficacy of aspirin
Authors: Totani Licia , Rotondo Serenella , Lorenzet Roberto , Tognoni Gianni , De Berardis Giorgia , Nicolucci Antonio , Evangelista Virgilio 
Published: December 2004

SummaryAtherosclerotic cardiovascular disease and its thrombotic complications are the principal causes of morbidity and mortality in patients with type-2 diabetes.Aspirin reduces the risk of thrombotic events in a broad range of patients with vascular disease and, in selected individuals, is beneficial for primary prevention. Although recommended by existing guidelines,in secondary and in primary prevention trials the clinical efficacy of low-dose aspirin in patients with diabetes appears to be substantially lower than in individuals without diabetes. In this review, we discuss possible mechanisms that may contribute to reduce the antithrombotic activity of aspirin in diabetes.We also discuss adjuvant therapies used in diabetic patients that may potentially improve the antithrombotic efficacy of aspirin.
Pharmacodynamic resistance to warfarin associated with a Val66Met substitution in vitamin K epoxide reductase complex subunit 1
Authors: Harrington Dominic , Underwood Sarah , Morse Colin , Shearer Martin , Tuddenham Edward , Mumford Andrew 
Published: December 2004

SummaryThe gene encoding vitamin K epoxide reductase complex subunit 1 (VKORC1), a component of the enzyme that is the therapeutic target site for warfarin, has recently been identified. In order to investigate the relationship betweenVKORC1 and warfarin dose response, we studied theVKORC1 gene (VKORC1) in patients with warfarin resistance. From a study group of 820 patients, we identified 4 individuals who required more than 25 mg of warfarin daily for therapeutic anticoagulation.Three of these had serum warfarin concentrations within the therapeutic range of 0.7–2.3 mg/l and showed wild-type VKORC1 sequence. The fourth warfarin resistant individual had consistently high ( ≥ 5.7 mg/l) serum warfarin concentrations, yet had no clinically discernible cause for warfarin resistance. VKORC1 showed a heterozygous 196G→ A transition that predicted aVal66Met substitution in the VKORC1 polypeptide. This transition was also identified in 2 asymptomatic family members who had never received warfarin.These individuals had normal vitamin-K dependent coagulation factor activities and undetectable serum PIVKAII and vitamin K 1 2,3 epoxide suggesting that their basal vitamin K epoxide reductase activity was not adversely affected by the VKORC1 Val66Met substitution.The association between a nucleotide transition in VKORC1 and pharmacodynamic warfarin resistance supports the hypothesis that VKORC1 is the site of action of warfarin and indicates that VKORC1 sequence is an important determinant of the warfarin dose response.
RNAi-induced down-regulation of FLT3 expression in AML cell lines increases sensitivity to MLN518
Authors: Walters Denise K. , Stoffregen Eric P. , Heinrich Michael C. , Deininger Michael W. , Druker Brian J. 
Published: December 2004

AbstractFMS-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase that is constitutively activated in approximately 30% of acute myelogenous leukemia (AML) patients and appears to confer an adverse prognosis. Thus, development of inhibitors and/or antibodies that specifically target FLT3 has been of substantial interest. In this regard, phase 1 and 2 trials involving FLT3 inhibitors have recently reported FLT3 inhibition and leukemic blast reduction in some patients. Despite this, issues such as specificity and resistance need to be addressed. Consequently, the development of alternative approaches for targeting FLT3 would be of great consequence. In the present report, we demonstrate that FLT3 siRNA effectively down-regulates FLT3 expression in Ba/F3 cells transfected with FLT3 containing an activating internal tandem duplication (ITD) in the juxtamembrane domain and FLT3-ITD–positive Molm-14 human leukemia cells. Treatment with the FLT3 siRNA results in growth inhibition and apoptosis of these cells. Furthermore, siRNA-induced down-regulation of FLT3 increased the sensitivity of both cell lines to treatment with the FLT3 inhibitor MLN518. This illustrates the potential benefit of combined therapeutic approaches.