bluuebunny/crossref_metadata_2025 huggingface dataset:
Disruption of
Plasmodium
Sporozoite Transmission by Depletion of Sporozoite Invasion-Associated Protein 1
Authors: Engelmann Sabine , Silvie Olivier , Matuschewski Kai
Published: January 2009

Accumulation of infectious
Plasmodium
sporozoites in
Anopheles
spp. salivary glands marks the final step of the complex development of the malaria parasite in the insect vector. Sporozoites are formed inside midgut-associated oocysts and actively egress into the mosquito hemocoel. Traversal of the salivary gland acinar cells correlates with the sporozoite's capacity to perform continuous gliding motility. Here, we characterized the cellular role of the
Plasmodium berghei
sporozoite invasion-associated protein 1 (SIAP-1). Intriguingly,
SIAP-1
orthologs are found exclusively in apicomplexan hemoprotozoa, parasites that are transmitted by arthropod vectors, e.g.,
Plasmodium
,
Babesia
, and
Theileria
species. By fluorescent tagging with mCherry, we show that SIAP-1 is expressed in oocyst-derived and salivary gland-associated sporozoites, where it accumulates at the apical tip. Targeted disruption of
SIAP-1
does not affect sporozoite formation but causes a partial defect in sporozoite egress from oocysts and abolishes sporozoite colonization of mosquito salivary glands. Parasites with the
siap-1
(−) mutation are blocked in their capacity to perform continuous gliding motility. We propose that arthropod-transmitted apicomplexan parasites specifically express secretory factors, such as SIAP-1, that mediate efficient oocyst exit and migration to the salivary glands.
Generation of Branched-Chain Fatty Acids through Lipoate-Dependent Metabolism Facilitates Intracellular Growth of
Listeria monocytogenes
Authors: Keeney Kristie , Colosi Lisa , Weber Walter , O'Riordan Mary
Published: January 2009

The gram-positive bacterial pathogen
Listeria monocytogenes
has evolved mechanisms to rapidly replicate in the host cytosol, implying efficient utilization of host-derived nutrients. However, the contribution of host nutrient scavenging versus that of bacterial biosynthesis toward rapid intracellular growth remains unclear. Nutrients that contribute to growth of
L. monocytogenes
include branched-chain fatty acids (BCFAs), amino acids, and other metabolic intermediates generated from acyl-coenzyme A, which is synthesized using lipoylated metabolic enzyme complexes. To characterize which biosynthetic pathways support replication of
L. monocytogenes
inside the host cytosol, we impaired lipoate-dependent metabolism by disrupting two lipoate ligase genes that are responsible for bacterial protein lipoylation. Interrupting lipoate-dependent metabolism modestly impaired replication in rich broth medium but strongly inhibited growth in defined medium and host cells and impaired the generation of BCFAs. Addition of short BCFAs and amino acids restored growth of the A1A2-deficient (A1A2
−
) mutant in minimal medium, implying that lipoate-dependent metabolism generates amino acids and BCFAs. BCFAs alone rescued intracellular growth and spread in L2 fibroblasts of the A1A2
−
mutant. Lipoate-dependent metabolism was also required in vivo, as a wild-type strain robustly outcompeted the lipoylation-deficient mutant in a murine model of listeriosis. The results of this study suggest that lipoate-dependent metabolism contributes to both amino acid and BCFA biosynthesis and that BCFA biosynthesis is preferentially required for intracellular growth of
L. monocytogenes
.
The Orphan Response Regulator CovR: a Globally Negative Modulator of Virulence inStreptococcus suisSerotype 2
Authors: Pan Xiuzhen , Ge Junchao , Li Ming , Wu Bo , Wang Changjun , Wang Jing , Feng Youjun , Yin Zhimin , Zheng Feng , Cheng Gong , Sun Wen , Ji Hongfeng , Hu Dan , Shi Peiju , Feng Xiaodan , Hao Xina , Dong Ruiping , Hu Fuquan , Tang Jiaqi
Published: January 2009

Streptococcus suisserotype 2 is an emerging zoonotic pathogen responsible for a wide range of life-threatening diseases in pigs and humans. However, the pathogenesis ofS. suisserotype 2 infection is not well understood. In this study, we report that an orphan response regulator, CovR, globally regulates gene expression and negatively controls the virulence ofS. suis05ZYH33, a streptococcal toxic shock syndrome (STSS)-causing strain. AcovR-defective (ΔcovR) mutant of 05ZYH33 displayed dramatic phenotypic changes, such as formation of longer chains, production of thicker capsules, and increased hemolytic activity. Adherence of the ΔcovRmutant to epithelial cells was greatly increased, and its resistance to phagocytosis and killing by neutrophils and monocytes was also significantly enhanced. More importantly, inactivation ofcovRincreased the lethality ofS. suisserotype 2 in experimental infection of piglets, and this phenotype was restored bycovRcomplementation. Colonization experiments also showed that the ΔcovRmutant exhibited an increased ability to colonize susceptible tissues of piglets. The pleiotropic phenotype of the ΔcovRmutant is in full agreement with the large number of genes controlled by CovR as revealed by transcription profile analysis: 2 genes are positively regulated, and 193 are repressed, including many that encode known or putative virulence factors. These findings suggested that CovR is a global repressor in virulence regulation of STSS-causingS. suisserotype 2.
The Putrescine Importer PuuP of
Escherichia coli
K-12
Authors: Kurihara Shin , Tsuboi Yuichi , Oda Shinpei , Kim Hyeon Guk , Kumagai Hidehiko , Suzuki Hideyuki
Published: January 2009

The Puu pathway is a putrescine utilization pathway involving gamma-glutamyl intermediates. The genes encoding the enzymes of the Puu pathway form a gene cluster, the
puu
gene cluster, and
puuP
is one of the genes in this cluster. In
Escherichia coli
, three putrescine importers, PotFGHI, PotABCD, and PotE, were discovered in the 1990s and have been studied; however, PuuP had not been discovered previously. This paper shows that PuuP is a novel putrescine importer whose kinetic parameters are equivalent to those of the polyamine importers discovered previously. A
puuP
+
strain absorbed up to 5 mM putrescine from the medium, but a Δ
puuP
strain did not.
E. coli
strain MA261 has been used in previous studies of polyamine transporters, but PuuP had not been identified previously. It was revealed that the
puuP
gene of MA261 was inactivated by a point mutation. When
E. coli
was grown on minimal medium supplemented with putrescine as the sole carbon or nitrogen source, only PuuP among the polyamine importers was required.
puuP
was expressed strongly when putrescine was added to the medium or when the
puuR
gene, which encodes a putative repressor, was deleted. When
E. coli
was grown in M9-tryptone medium, PuuP was expressed mainly in the exponential growth phase, and PotFGHI was expressed independently of the growth phase.
Creation of a Large Deletion Mutant ofCampylobacter jejuniReveals that the Lipooligosaccharide Gene Cluster Is Not Required for Viability
Authors: Marsden Gemma L. , Li Jianjun , Everest Paul H. , Lawson Andrew J. , Ketley Julian M.
Published: January 2009

Deletion of the lipooligosaccharide biosynthesis region (Cj1132c to Cj1152c) from the genome ofCampylobacter jejuniNCTC11168 shows that the core is not required for viability. The mutant was attenuated for growth and has increased sensitivity to antibiotics and detergents. Natural transformation and invasion of cultured host cells was abolished.
Two Redundant Sodium-Driven Stator Motor Proteins Are Involved in
Aeromonas hydrophila
Polar Flagellum Rotation
Authors: Wilhelms Markus , Vilches Silvia , Molero Raquel , Shaw Jonathan G. , Tomás Juan M. , Merino Susana
Published: January 2009

Motility is an essential characteristic for mesophilic
Aeromonas
strains. We identified a new polar flagellum region (region 6) in the
A. hydrophila
AH-3 (serotype O34) chromosome that contained two additional polar stator genes, named
pomA
2
and
pomB
2.
A. hydrophila
PomA
2
and PomB
2
are highly homologous to other sodium-conducting polar flagellum stator motors as well as to the previously described
A. hydrophila
AH-3 PomA and PomB.
pomAB
and
pomA
2
B
2
were present in all the mesophilic
Aeromonas
strains tested and were independent of the strains' ability to produce lateral flagella. Unlike MotX, which is a stator protein that is essential for polar flagellum rotation, here we demonstrate that PomAB and PomA
2
B
2
are redundant sets of proteins, as neither set on its own is essential for polar flagellum motility in either aqueous or high-viscosity environments. Both PomAB and PomA
2
B
2
are sodium-coupled stator complexes, although PomA
2
B
2
is more sensitive to low concentrations of sodium than PomAB. Furthermore, the level of transcription in aqueous and high-viscosity environments of
pomA
2
B
2
is reduced compared to that of
pomAB
. The
A. hydrophila
AH-3 polar flagellum is the first case described in which two redundant sodium-driven stator motor proteins (PomAB and PomA
2
B
2
) are found.
Peptide wrwycr Inhibits the Excision of Several Prophages and Traps Holliday Junctions inside Bacteria
Authors: Gunderson Carl W. , Boldt Jeffrey L. , Authement R. Nathan , Segall Anca M.
Published: January 2009

Peptide inhibitors of phage lambda site-specific recombination were previously isolated by screening synthetic combinatorial peptide libraries. These inhibitors cause the accumulation of complexes between the recombinase and the Holliday junction intermediate of several highly divergent tyrosine recombinases. Peptide WRWYCR and its
d
-amino acid derivative bind to the center of protein-free junctions and prevent their resolution either by site-specific recombinases or by junction resolvases or helicases. With lesser affinity, the peptides also bind to branched DNA molecules that mimic replication forks. The peptides are bactericidal to both gram-positive and gram-negative bacteria, presumably because they can interfere with DNA repair and with chromosome dimer resolution by the XerC and XerD tyrosine recombinases. In order to test the correspondence between their mechanism in vivo and in vitro, we have tested and shown peptide wrwycr's ability to inhibit the excision of several prophages (lambda, P22, Gifsy-1, Gifsy-2, Fels-1, Fels-2) and to trap Holliday junction intermediates of phage lambda site-specific recombination in vivo. In addition, we found that the peptide inhibits replication of the
Salmonella
prophage Fels-1 while integrated in the chromosome. These findings further support the proposed mechanistic basis for the antimicrobial activity of the peptide and its use as a tool to dissect strand exchange-dependent DNA repair within cells.
Role of Clp Proteins in Expression of Virulence Properties ofStreptococcus mutans
Authors: Kajfasz Jessica K. , Martinez Alaina R. , Rivera-Ramos Isamar , Abranches Jacqueline , Koo Hyun , Quivey Robert G. , Lemos José A.
Published: January 2009

Mutational analysis revealed that members of the Clp system, specifically the ClpL chaperone and the ClpXP proteolytic complex, modulate the expression of important virulence attributes ofStreptococcus mutans. Compared to its parent, the ΔclpLstrain displayed an enhanced capacity to form biofilms in the presence of sucrose, had reduced viability, and was more sensitive to acid killing. The ΔclpPand ΔclpXstrains displayed several phenotypes in common: slow growth, tendency to aggregate in culture, reduced autolysis, and reduced ability to grow under stress, including acidic pH. Unexpectedly, the ΔclpPand ΔclpXmutants were more resistant to acid killing and demonstrated enhanced viability in long-term survival assays. Biofilm formation by the ΔclpPand ΔclpXstrains was impaired when grown in glucose but enhanced in sucrose. In an animal study, the average number ofS. mutanscolonies recovered from the teeth of rats infected with the ΔclpPor ΔclpXstrain was slightly lower than that of the parent strain. InBacillus subtilis, the accumulation of the Spx global regulator, a substrate of ClpXP, has accounted for the ΔclpXPphenotypes. Searching theS. mutansgenome, we identified two putativespxgenes, designatedspxAandspxB. The inactivation of either of these genes bypassed phenotypes of theclpPandclpXmutants. Western blotting demonstrated that Spx accumulates in the ΔclpPand ΔclpXstrains. Our results reveal that the proteolysis of ClpL and ClpXP plays a role in the expression of key virulence traits ofS. mutansand indicates that the underlying mechanisms by which ClpXP affect virulence traits are associated with the accumulation of two Spx orthologues.
YbeY, a Heat Shock Protein Involved in Translation in
Escherichia coli
Authors: Rasouly Aviram , Schonbrun Miriam , Shenhar Yotam , Ron Eliora Z.
Published: January 2009

Here we provide evidence that YbeY, a conserved heat shock protein with unknown function, is involved in the translation process.
ybeY
deletion mutants are temperature sensitive and have a significantly reduced thermotolerance. Nonetheless, there appears to be no damage of the protein quality control of mature polypeptides, as the levels of chaperones and proteases are normal and there is no accumulation of aggregates. Rather, the mutation results in a significant reduction in the level of polysomes, and upon a shift to a restrictive temperature (42°C), there is an immediate and severe slowdown of translation. Taken together, the data indicate that YbeY is an important factor for bacterial translation even at 37°C but becomes essential at high temperatures.
Regulation of the
mazEF
Toxin-Antitoxin Module in
Staphylococcus aureus
and Its Impact on
sigB
Expression
Authors: Donegan Niles P. , Cheung Ambrose L.
Published: January 2009

In
Staphylococcus aureus
, the
sigB
operon codes for the alternative sigma factor σ
B
and its regulators that enable the bacteria to rapidly respond to environmental stresses via redirection of transcriptional priorities. However, a full model of σ
B
regulation in
S. aureus
has not yet emerged. Earlier data has suggested that
mazEF
, a toxin-antitoxin (TA) module immediately upstream of the
sigB
operon, was transcribed with the
sigB
operon. Here we demonstrate that the promoter P

mazE

upstream of
mazEF
is essential for full σ
B
activity and that instead of utilizing autorepression typical of TA systems,
sigB
downregulates this promoter, providing a negative-feedback loop for
sigB
to repress its own transcription. We have also found that the transcriptional regulator SarA binds and activates P

mazE

. In addition, P

mazE

was shown to respond to environmental and antibiotic stresses in a way that provides an additional layer of control over
sigB
expression. The antibiotic response also appears to occur in two other TA systems in
S. aureus
, indicating a shared mechanism of regulation.
A MATHEMATICAL MODEL FOR TRAINING IMPULSE AND LACTATE INFLUX AND OUTFLUX DURING EXERCISE
Authors: MOXNES JOHN F. , HAUSKEN KJELL
Published: February 2009

This paper provides a mathematical description based on the theory of differential equations, for the dynamics of lactate production and removal. Analytical and numerical results for training/exercise of endurance of athletes are presented based on the common concept of training impulse (Trimp). The relationships between activity, production rate, and removal strategies of lactate are studied. Parameters are estimated from published data. A model for optimum removal of lactate after exercise is developed. The model provides realistic predictions when compared with experimental results. We show some specific examples for the usefulness of the mathematical model by studying some recent problems discussed in the literature. (a) Is interval exercise more beneficial than steady-state exercise? (b) What is the optimum aerobic power during recovery? We discuss whether steady-state exercise gives higher Trimp than interval exercise, when imposing an upper boundary for the lactate concentration as a constraint. The model allows for testing all imaginable kinds of steady-state and interval exercises in search of the optimal exercise regime for individuals with various kinds of characteristics. In general, the dynamic model constitute a powerful tool describing the processes by which the concentration of lactate can be studied and controlled to decrease fatigue and increase endurance.
MODEL-INDEPENDENT TESTS FOR TIME REVERSAL, CP VIOLATIONS AND FOR CPT THEOREM IN Λb AND $\bar\Lambda_b$ TWO-BODY DECAYS
Authors: DI SALVO E. , AJALTOUNI Z. J.
Published: February 2009

Weak decays of beauty baryons like [Formula: see text] into [Formula: see text] and V(JP = 1-), where both decay products are polarized, offer interesting opportunities to perform tests of time reversal, CP violations and of CPT invariance. We propose a model-independent parametrization, via spin density matrix, of the angular distribution, of the polarizations and of some polarization correlations of the decay products. The transverse component of the polarization and two polarization correlations are sensitive to time reversal violations. Moreover several CP- and CPT-odd observables are singled out.
Restoration of contractility in hyperhomocysteinemia by cardiac-specific deletion of NMDA-R1
Authors: Moshal Karni S. , Kumar Munish , Tyagi Neetu , Mishra Paras K. , Metreveli Naira , Rodriguez Walter E. , Tyagi Suresh C.
Published: January 2009

Homocysteine (HCY) activated mitochondrial matrix metalloproteinase-9 and led to cardiomyocyte dysfunction, in part, by inducing mitochondrial permeability (MPT). Treatment with MK-801 [ N-methyl-d-aspartate (NMDA) receptor antagonist] ameliorated the HCY-induced decrease in myocyte contractility. However, the role of cardiomyocyte NMDA-receptor 1 (R1) activation in hyperhomocysteinemia (HHCY) leading to myocyte dysfunction was not well understood. We tested the hypothesis that the cardiac-specific deletion of NMDA-R1 mitigated the HCY-induced decrease in myocyte contraction, in part, by decreasing nitric oxide (NO). Cardiomyocyte-specific knockout of NMDA-R1 was generated using cre/lox technology. NMDA-R1 expression was detected by Western blot and confocal microscopy. MPT was determined using a spectrophotometer. Myocyte contractility and calcium transients were studied using the IonOptix video-edge detection system and fura 2-AM loading. We observed that HHCY induced NO production by agonizing NMDA-R1. HHCY induced the MPT by agonizing NMDA-R1. HHCY caused a decrease in myocyte contractile performance, maximal rate of contraction and relaxation, and prolonged the time to 90% peak shortening and 90% relaxation by agonizing NMDA-R1. HHCY decreased contraction amplitude with the increase in calcium concentration. The recovery of calcium transient was prolonged in HHCY mouse myocyte by agonizing NMDA-R1. It was suggested that HHCY increased mitochondrial NO levels and induced MPT, leading to the decline in myocyte mechanical function by agonizing NMDA-R1.
Adult progenitor cell transplantation influences contractile performance and calcium handling of recipient cardiomyocytes
Authors: Lee Joon , Stagg Mark A. , Fukushima Satsuki , Soppa Gopal K. R. , Siedlecka Urszula , Youssef Samuel J. , Suzuki Ken , Yacoub Magdi H. , Terracciano Cesare M. N.
Published: January 2009

Adult progenitor cell transplantation has been proposed for the treatment of heart failure, but the mechanisms effecting functional improvements remain unknown. The aim of this study was to test the hypothesis that, in failing hearts treated with cell transplantation, the mechanical properties and excitation-contraction coupling of recipient cardiomyocytes are altered. Adult rats underwent coronary artery ligation, leading to myocardial infarction and chronic heart failure. After 3 wk, they received intramyocardial injections of either 107 green fluorescence protein (GFP)-positive bone marrow mononuclear cells or 5 × 106 GFP-positive skeletal myoblasts. Four weeks after injection, both cell types increased ejection fraction and reduced cardiomyocyte size. The contractility of isolated GFP-negative cardiomyocytes was monitored by sarcomere shortening assessment, Ca2+ handling by indo-1 and fluo-4 fluorescence, and electrophysiology by patch-clamping techniques. Injection of either bone marrow cells or skeletal myoblasts normalized the impaired contractile performance and the prolonged time to peak of the Ca2+ transient observed in failing cardiomyocytes. The smaller and slower L-type Ca2+ current observed in heart failure normalized after skeletal myoblast, but not bone marrow cell, transplantation. Measurement of Ca2+ sparks suggested a normalization of sarcoplasmic reticulum Ca2+ leak after skeletal myoblast transplantation. The increased Ca2+ wave frequency observed in failing myocytes was reduced by either bone marrow cells or skeletal myoblasts. In conclusion, the morphology, contractile performance, and excitation-contraction coupling of individual recipient cardiomyocytes are altered in failing hearts treated with adult progenitor cell transplantation.
Impaired vascular function in mice with an active cytomegalovirus infection
Authors: Gombos R. B. , Wolan V. , McDonald K. , Hemmings D. G.
Published: January 2009

Human cytomegalovirus (CMV) is implicated in vascular complications through endothelial dysfunction. However, the effect of in vivo infections on vascular function in isolated arteries has not been examined. In pregnancy, systemic and uterine vascular adaptations accommodate increased blood volume through several mechanisms, including decreased sensitivity to vasoconstrictors and increased production of endothelial-dependent vasodilators. We hypothesized that an active in vivo CMV infection would reduce vasodilation of isolated arteries to the endothelial-dependent vasodilator methacholine and increase vasoconstriction to the α1-adrenergic receptor agonist phenylephrine and that these CMV-induced changes would be accentuated in late pregnancy. A mouse CMV infection model was used to study vascular responses in isolated mesenteric and uterine arteries from nonpregnant and late pregnant mice. In the mouse, CMV is not transmitted to the fetus. Accordingly, there was no evidence of active infection in any fetus examined, even though an active infection was found in salivary glands, uterine and mesenteric arteries, and placentas. Contrary to our hypothesis, increased endothelial-dependent vasodilation was found in mesenteric arteries from infected compared with uninfected nonpregnant and pregnant mice These data implicate active CMV infections in hypotensive disorders. Similarly, increased vasodilation was found in uterine arteries from infected vs. uninfected nonpregnant mice. However, this was completely reversed in infected compared with uninfected late pregnant mice in which vasodilation in uterine arteries was significantly reduced. Uterine arteries from infected pregnant mice also showed increased vasoconstriction to phenylephrine. Maternal infection led to decreased placental weights but had no effect on fetal weights in late pregnancy. These novel data demonstrate abnormal systemic and uterine vascular responses during an active CMV infection in both nonpregnant and late pregnant mice. Importantly, despite reduced placental weights, fetal weights were maintained, suggesting effective intrauterine compensation in the mouse model.
Inhibition of Rho-dependent kinases ROCK I/II activates VEGF-driven retinal neovascularization and sprouting angiogenesis
Authors: Kroll Jens , Epting Daniel , Kern Katrin , Dietz Christian T. , Feng Yuxi , Hammes Hans-Peter , Wieland Thomas , Augustin Hellmut G.
Published: January 2009

Vascular endothelial growth factor (VEGF) is an endothelial-specific growth factor that activates the small GTPase RhoA. While the role of RhoA for VEGF-driven endothelial migration and angiogenesis has been studied in detail, the function of its target proteins, the Rho-dependent kinases ROCK I and II, are controversially discussed. Using the mouse model of oxygen-induced proliferative retinopathy, ROCK I/II inhibition by H-1152 resulted in increased angiogenesis. This enhanced angiogenesis, however, was completely blocked by the VEGF-receptor antagonist PTK787/ZK222584. Loss-of-function experiments in endothelial cells revealed that inhibition of ROCK I/II using the pharmacological inhibitor H-1152 and ROCK I/II-specific small-interfering RNAs resulted in a rise of VEGF-driven sprouting angiogenesis. These functional data were biochemically substantiated by showing an enhanced VEGF-receptor kinase insert domain receptor phosphorylation and extracellular signal-regulated kinase 1/2 activation after inhibition of ROCK I/II. Thus our data identify that the inhibition of Rho-dependent kinases ROCK I/II activates angiogenesis both, in vitro and in vivo.
Stem cell homing and angiomyogenesis in transplanted hearts are enhanced by combined intramyocardial SDF-1α delivery and endogenous cytokine signaling
Authors: Zhao Tiemin , Zhang Dongsheng , Millard Ronald W. , Ashraf Muhammad , Wang Yigang
Published: January 2009

We used a heterotopic transplanted working heart model to probe the collaborative role of bone marrow-derived progenitor cells (BPCs) and stromal cell-derived factor (SDF)-1α in attenuating tissue remodeling in recipient and transplanted hearts. BPCs from male transgenic rats expressing green fluorescent protein (GFP+BPCs, 2 × 106cells) were injected intravenously into myeloablated female rats. One month later, heterotopic heart transplantation was performed. The left anterior descending coronary artery (LAD) of the recipient heart was occluded permanently. Mesenchymal stem cells (MSCs; 2 × 106cells) with a null gene (null group) or overexpressing SDF-1α (SDF-1α group) were injected intramyocardially in the LAD perfusion region of both recipient and transplanted hearts. Recipient and transplanted hearts ( n = 10 hearts/group) were harvested 21 days later for analysis. The survival of transplanted hearts was assessed daily by palpation in additional animals ( n = 7). Five days after LAD occlusion, subpopulations of GFP+BPCs in the circulation were significantly higher in the SDF-1α group. Y chromosome, 5-bromo-2′-deoxyuridine, Ki67-positive nuclei, newly formed vessels, and GFP+cells significantly increased in transplanted hearts of the SDF-1α group at 21 days after the injection of MSCs overexpressing SDF-1α, whereas fewer TUNEL-positive nuclei were found. The survival of transplanted hearts was also markedly increased in the SDF-1α group ( P < 0.05). Supplementation of endogenous cytokines released from the ischemic myocardium with exogenous MSCs overexpressing SDF-1α significantly increased BPC homing to acutely ischemic recipient and progressively ischemic transplanted hearts. BPC recruitment resulted in the regeneration of new cardiomyocytes and blood vessels and extended survival of the transplanted hearts.
Dietary fish oil is antihypertrophic but does not enhance postischemic myocardial function in female mice
Authors: Huggins Catherine E. , Curl Claire L. , Patel Ruchi , McLennan Peter L. , Theiss Mandy L. , Pedrazzini Thierry , Pepe Salvatore , Delbridge Lea M. D.
Published: January 2009

Clinically and experimentally, a case for omega-3 polyunsaturated fatty acid (PUFA) cardioprotection in females has not been clearly established. The goal of this study was to investigate whether dietary omega-3 PUFA supplementation could provide ischemic protection in female mice with an underlying genetic predisposition to cardiac hypertrophy. Mature female transgenic mice (TG) with cardiac-specific overexpression of angiotensinogen that develop normotensive cardiac hypertrophy and littermate wild-type (WT) mice were fed a fish oil-derived diet (FO) or PUFA-matched control diet (CTR) for 4 wk. Myocardial membrane lipids, ex vivo cardiac performance (intraventricular balloon) after global no-flow ischemia and reperfusion (15/30 min), and reperfusion arrhythmia incidence were assessed. FO diet suppressed cardiac growth by 5% and 10% in WT and TG, respectively ( P < 0.001). The extent of mechanical recovery [rate-pressure product (RPP) = beats/min × mmHg] of FO-fed WT and TG hearts was similar (50 ± 7% vs. 45 ± 12%, 30 min reperfusion), and this was not significantly different from CTR-fed WT or TG. To evaluate whether systemic estrogen was masking a protective effect of the FO diet, the responses of ovariectomized (OVX) WT and TG mice to FO dietary intervention were assessed. The extent of mechanical recovery of FO-fed OVX WT and TG (RPP, 50 ± 4% vs. 64 ± 8%) was not enhanced compared with CTR-fed mice (RPP, 60 ± 11% vs. 80 ± 8%, P = 0.335). Dietary FO did not suppress the incidence of reperfusion arrhythmias in WT or TG hearts (ovary-intact mice or OVX). Our findings indicate a lack of cardioprotective effect of dietary FO in females, determined by assessment of mechanical and arrhythmic activity postischemia in a murine ex vivo heart model.
Lipopolysaccharide-dependent interaction between PU.1 and cJun determines production of lipocalin-type prostaglandin D synthase and prostaglandin D2 in macrophages
Authors: Joo Myungsoo , Kwon Minjae , Cho Yong-Jig , Hu Ningning , Pedchenko Tetyana V. , Sadikot Ruxana T. , Blackwell Timothy S. , Christman John W.
Published: January 2009

Previously, we reported that expression of lipocalin-prostaglandin D synthase (L-PGDS) is inducible in macrophages and protects from Pseudomonas pneumonia. Here, we investigated the mechanism by which L-PGDS gene expression is induced in macrophages. A promoter analysis of the murine L-PGDS promoter located a binding site of PU.1, a transcription factor essential for macrophage development and inflammatory gene expression. A chromatin immunoprecipitation assay showed that PU.1 bound to the cognate site in the endogenous L-PGDS promoter in response to LPS. Overexpression of PU.1, but not of PU.1S148A, a mutant inert to casein kinase II (CKII) or NF-κB-inducing kinase (NIK), induced L-PGDS in RAW 264.7 cells. Conversely, siRNA silencing of PU.1 expression blunted productions of L-PGDS and prostaglandin D2 (PGD2). LPS treatment induced formation of the complex of PU.1 and cJun on the PU.1 site, but inactivation of cJun by treatment with JNK or p38 kinase inhibitor abolished the complex, and suppressed PU.1 transcriptional activity for L-PGDS gene expression. Together, these results show that PU.1, activated by CKII or NIK, cooperates with MAPK-activated cJun to maximally induce L-PGDS expression in macrophages following LPS treatment, and suggest that PU.1 participates in innate immunity through the production of L-PGDS and PGD2.
Cap-independent translation of human SP-A 5′-UTR variants: a double-loop structure andcis-element contribution
Authors: Wang Guirong , Guo Xiaoxuan , Silveyra Patricia , Kimball Scot R. , Floros Joanna
Published: January 2009

Human surfactant protein A (hSP-A), a molecule of innate immunity and surfactant-related functions, consists of two functional genes, SP-A1 and SP-A2. SP-A expression is regulated by several factors including environmental stressors. SP-A1 and SP-A2 5′-untranslated region (5′-UTR) splice variants have a differential impact on translation efficiency and mRNA stability. To study whether these variants mediate internal ribosome entry site (IRES) activity (i.e., cap-independent translation), we performed transient transfection experiments in H441 cells with constructs containing one SP-A1 (A′D′, AB′D′, or A′CD′) or SP-A2 (ABD) 5′-UTR splice variant between the Renilla and firefly luciferase genes of a bicistronic reporter vector. We found that 1) variants A′D′, ABD, and AB′D′ exhibit significantly higher IRES activities than negative control (no SP-A 5′-UTR) and A′CD′ has no activity; the order of highest IRES activity was ABD > A′D′ > AB′D; 2) IRES activity of ABD significantly increased in response to diesel particulate matter (20 μg/ml) but not in response to ozone (1 ppm for 1 h); 3) deletion mutants of ABD revealed regulatory elements associated with IRES activity; one at the end of exon A attenuated activity, whereas a region containing a short adenosine-rich motif in the second half of exon B and the start of exon D enhanced activity; 4) elimination of a predicted double-loop structure or increase in free energy significantly reduced IRES activity; 5) elimination of one or both double-loop structures in A′D′ did not affect cap-dependent translation activity. Thus several factors, including cis-elements and secondary structure type and stability, are required for hSP-A 5′-UTR variant-mediated cap-independent translation.
Retroperitoneal Extragonadal Nonseminomatous Germ Cell Tumor with Synchronous Orbital Metastasis
Authors: Atmaca Ali Fuat , Altınova Serkan , Canda Abdullah Erdem , Ozcan M. Fuat , Alıcı Suleyman , Memıs Leyla , Balbay M. Derya
Published: February 2009

A huge retroperitoneal tumor with a right orbital mass was detected and proved to be an extragonadal nonseminomatous germ cell tumor on biopsy. BEP chemotherapy caused some regression in orbital mass however no change in retroperitoneal tumor size as well as serum tumor marker levels occurred. Herein, we present a rarely seen entity of extragonadal retroperitoneal nonseminomatous germ cell tumor with synchronous orbital metastases and discuss its diagnosis and management.
In vitro and In vivo Anticancer Effects of the Novel Vitamin E Ether Analogue RRR-α-Tocopheryloxybutyl Sulfonic Acid in Prostate Cancer
Authors: Ni Jing , Mai Tiejun , Pang See-Tong , Haque Imranul , Huang Kaohsing , DiMaggio Matthew A. , Xie Shaozhen , James Nadine S. , Kasi Dhanalakshmi , Chemler Sherry R. , Yeh Shuyuan
Published: February 2009

Purpose: Among derivatives of α-vitamin E, α-vitamin E succinate (VES), has attracted much attention due to its potent anti–prostate cancer activity in vitro and in vivo. However, the in vivo antitumor activity of VES might be compromised if administrated orally due to the VES hydrolysis by esterases in the gastrointestinal tract.

Experimental Design: New nonhydrolyzable VES ether analogues were synthesized and their growth inhibition was screened by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide growth assay. Among them, RRR-α-tocopheryloxybutyl sulfonic acid (VEBSA) was further characterized by terminal deoxyribonucleotidyl transferase–mediated dUTP nick end labeling apoptosis assay, soft agar assay, and in vivo tumor formation.

Results: VEBSA has potent antitumor ability, albeit to a lesser extent than VES, in in vitro cultured prostate cancer LNCaP and PC3 cells. Like VES, VEBSA induced apoptosis, repressed androgen receptor protein expression, and enhanced vitamin D receptor expression, suggesting that VEBSA can go through mechanisms similar to those used by VES to inhibit the growth of prostate cancer cells in vitro. However, 6 weeks of oral consumption of VEBSA, but not of VES, reduced the tumor burden in the xenografted prostate tumors in nude mice. Furthermore, oral intake of VEBSA for 20 weeks inhibited prostate tumor growth and progression more efficiently compared with VES in the prostate cancer tumor model of TRAMP mice.

Conclusion: Oral consumption of VEBSA allows a greater anticancer activity compared with VES. Chemoprevention prefers the oral consumption of agents; the advantage of VEBSA over VES to be administrated orally will allow VEBSA to serve as an agent for both preventive and therapeutic purposes for prostate cancer.
Treatment of Philadelphia-Positive Chronic Myeloid Leukemia with Imatinib: Importance of a Stable Molecular Response
Authors: Palandri Francesca , Iacobucci Ilaria , Soverini Simona , Castagnetti Fausto , Poerio Angela , Testoni Nicoletta , Alimena Giuliana , Breccia Massimo , Rege-Cambrin Giovanna , Tiribelli Mario , Varaldo Riccardo , Abruzzese Elisabetta , Martino Bruno , Luciano Luigiana , Pane Fabrizio , Saglio Giuseppe , Martinelli Giovanni , Baccarani Michele , Rosti Gianantonio
Published: February 2009

Purpose: The achievement of a major molecular response (MMolR) at 12 months is a surrogate marker of progression-free survival in chronic myeloid leukemia patients treated with imatinib.

Experimental Design: We evaluated the prognostic value of the long-term evolution of the molecular response based on a retrospective analysis of 130 late chronic phase chronic myeloid leukemia patients who achieved a complete cytogenetic response (CCgR) with 400 mg/d imatinib and have now a median follow-up of 72 months (range, 48-77).

Results: In 71 (55%) patients, molecular response was consistently major (stable MMolR); in 19 (15%) patients, molecular response was occasionally less than major (unstable MMolR); in 40 (30%) patients, MMolR was never achieved (never MMolR) during all the course of CCgR. Patients with stable MMolR had a longer CCgR duration and a significantly better progression-free survival compared with patients with absent or unstable MMolR. The achievement of a MMolR, if maintained continuously, conferred a marked long-term stability to the CCgR: patients with a stable MMolR have a significantly lower risk of losing the CCgR than patients with unstable and never MMolR (4% versus 21%, P = 0.03, and 4% versus 33%, P < 0.0001, respectively). Finally, if a MMolR is not maintained consistently, the risk of losing the CCgR is higher but not significantly than if it is never achieved (33% versus 21%, P = 0.5).

Conclusions: These data confirm that achieving a MMolR is prognostically important but point out that the prognostic value of achieving a MMolR is greater if the response is confirmed and stable.
The telomeric transcriptome and SMG proteins at the crossroads
Authors: Chawla R. , Azzalin C.M.
Published: January 2009

Telomeres constitute the heterochromatic structures at the ends of linear eukaryotic chromosomes and are essential for the maintenance of genome stability. The longstanding belief that telomeres are transcriptionally silent has recently been overturned by the discovery of a telomeric transcriptome comprising telomeric repeat-containing RNA (TERRA) molecules. In mammalian cells, TERRA remains associated with telomeres after its transcription, and this association is regulated by SMG proteins, renowned for their involvement in several RNA metabolism pathways. The three SMG factors UPF1, hEST1A and SMG1, which have been associated with DNA stability networks before, also seem to be crucial to guarantee telomere integrity. Here, we review the current knowledge available of TERRA and on the role of SMG proteins in maintaining genome stability. We also propose an integrative model illustrating a putative link between telomere integrity, TERRA and SMG proteins.
Laser confocal microscopy analysis of human interphase nuclei by three-dimensional FISH reveals dynamic perinucleolar clustering of telomeres
Authors: Ramírez M.J. , Surrallés J.
Published: January 2009

Nuclear functions are strongly dependent on the three-dimensional organization of the interphase nucleus. Given the importance of telomeres in the behaviour and stability of chromosomes, we have investigated the architecture of the human nucleus from the telomere perspective by 3D-FISH and laser confocal microscopy. We observed a randomly scattered telomere distribution in all confocal sections of the interphase nuclear volume with various levels of telomere clustering in different cell types. This distribution is independent of H2AX presence or phosphorylation status. We also observed that telomeres usually cluster at the periphery of the nucleolus following its cell cycle dependent dynamic formation but are never present in the interior of the nucleolus. These perinucleolar telomeric clusters contain the telomeres of the short arms of acrocentric chromosomes, explaining the p-arm association of acrocentric chromosomes frequently found in metaphase. Thus, chromosome positioning in metaphase spreads is tightly connected to the three-dimensional architecture of the interphase nucleus.
Telomerase recruitment to telomeres
Authors: Stern J.L. , Bryan T.M.
Published: January 2009

The ability of most cancer cells to grow indefinitely relies on the presence of functional telomerase to maintain telomeres, thus circumventing normal cellular senescence. A key feature of telomerase functionality is the localization of the enzyme complex to telomeres, a process which is highly regulated. A number of recent studies have reported data with significant implications for our understanding of telomerase recruitment to telomeres. A picture is emerging that this process is governed by a number of factors including telomeric binding proteins, structural features of the enzyme complex, cell cycle regulated processes such as DNA replication, and components of the DNA damage response pathway. In this review we summarize recent findings relating to this fundamental process in eukaryotes.
Telomerase: cellular immortalization and neoplastic transformation. Multiple functions of a multifaceted complex
Authors: Belgiovine C. , Chiodi I. , Mondello C.
Published: January 2009

The telomerase complex allows telomere length maintenance, which is required for an unlimited cellular proliferation. Telomerase is virtually absent in normal human somatic cells, which are characterized by a definite proliferation potential, while it is present in the vast majority of tumors (around 90%). Restoring telomerase activity in normal somatic cells can indefinitely prolong cellular life span. However, evidence has been reported that this event can be associated with the acquisition of characteristics typical of cellular transformation. Moreover, analysis of telomerase immortalized cells, as well as of tumor cells in which telomerase is inactivated, has highlighted multiple functions of telomerase in tumorigenesis, besides telomere lengthening. In this paper, we will review telomerase immortalization of somatic cells, together with its possible consequences, and we will examine the complex role of telomerase in tumorigenesis.
Telomerase regulation at the crossroads of cell fate
Authors: Çukušić A. , Škrobot Vidaček N. , Sopta M. , Rubelj I.
Published: January 2009

Telomeres are specialized structures at the ends of eukaryotic chromosomes and are crucial for genome stability, cell growth control and carcinogenesis. Normally, they protect chromosomes from end to end fusion, degradation and recombination. Telomerase is a ribonucleoprotein essential for maintenance of telomeres and it is active in germ cells, stem cells and ∼90% of cancers but not in most normal somatic cells. Human telomerase catalytic protein subunit hTERT is crucial for telomerase activity. Although hTERT expression is sufficient to immortalize normal human cells in culture, spontaneous immortalization is extremely rare which suggests that its expression is under strong negative control. Characterization of the hTERT promoter has allowed for the analysis of potential mechanisms of hTERT expression and regulation. The hTERT promoter is very complex and contains a great number of canonical and non-canonical sequences that bind or potentially bind a variety of transcription factors. In this review we focus on the positive and negative regulators of hTERT transcription and their role in normal cell growth and immortalization.
Dissecting the non-canonical functions of telomerase
Authors: Parkinson E.K. , Fitchett C. , Cereser B.
Published: January 2009

It is now well established that the canonical function of telomerase protects the telomere repeats from erosion and the consequent induction of replicative senescence or apoptosis. In the absence of key cell cycle checkpoint proteins, the canonical function of telomerase also prevents chromosome fusions and immortalizes human cells. The canonical function of telomerase requires both the telomerase reverse transcriptase enzyme (TERT) which adds telomere (TTAGGG) repeats to the chromosome ends and the telomerase RNA component (TERC), which provides the template for TERT. However, there is growing evidence that telomerase has other (non-canonical) functions. These functions can be divided further into those that require telomerase activity but not telomere lengthening (non-canonical I or NC I) and those that require neither telomerase activity nor telomere lengthening (non-canonical II or NC II). NC I functions are associated with the induction of neoplasia in both epidermis and mammary gland, the correct response to DNA damage, and insensitivity to transforming growth factor beta. In contrast, NC II functions are not sufficient for the induction of neoplasia and are associated with the activation of the WNT and MYC signaling pathways in keratinocytes and a more general resistance to the induction of apoptosis by a variety of stimuli. The overexpression of either TERT or TERC appears to be capable of providing NC I functions but NC II functions require neither TERC nor the integrity of the TERT catalytic site. The molecular mechanisms underpinning both NC I and NC II are largely obscure but transcriptional profile changes have been reported by some groups. In this article, we will discuss the proposed mechanisms of NC I and NC II and their relevance to normal and neoplastic cell functions.
Telomere length maintenance – an ALTernative mechanism
Authors: Royle N.J. , Foxon J. , Jeyapalan J.N. , Mendez-Bermudez A. , Novo C.L. , Williams J. , Cotton V.E.
Published: January 2009

The Alternative Lengthening of Telomeres (ALT) mechanism is utilised by approximately 10% of human tumours and a higher proportion of some types of sarcomas. ALT+ cell lines and tumours show heterogeneous telomere length, extra-chromosomal circular and linear telomeric DNA, ALT associated promyelocytic bodies (APBs), a high frequency of post-replication exchanges in telomeres (designated as telomere-sister chromatid exchanges, T-SCE) and high instability at a GC-rich minisatellite, MS32 (D1S8). It is clear that there is a link between the minisatellite instability and the mechanism that underpins ALT, however currently the nature of this relationship is uncertain. Single molecule analysis of telomeric DNA from ALT+ cell lines and tumours has revealed complex telomere mutations that have not been seen in cell lines or tumours that express telomerase. These complex telomere mutations cannot be explained by T-SCE but must arise by another inter-molecular process. The break-induced replication (BIR) model that may explain the observed high frequency of T-SCE and the presence of complex telomere mutations is reviewed.
Telomeres, histone code, and DNA damage response
Authors: Misri S. , Pandita S. , Kumar R. , Pandita T.K.
Published: January 2009

Genomic stability is maintained by telomeres, the end terminal structures that protect chromosomes from fusion or degradation. Shortening or loss of telomeric repeats or altered telomere chromatin structure is correlated with telomere dysfunction such as chromosome end-to-end associations that could lead to genomic instability and gene amplification. The structure at the end of telomeres is such that its DNA differs from DNA double strand breaks (DSBs) to avoid nonhomologous end-joining (NHEJ), which is accomplished by forming a unique higher order nucleoprotein structure. Telomeres are attached to the nuclear matrix and have a unique chromatin structure. Whether this special structure is maintained by specific chromatin changes is yet to be thoroughly investigated. Chromatin modifications implicated in transcriptional regulation are thought to be the result of a code on the histone proteins (histone code). This code, involving phosphorylation, acetylation, methylation, ubiquitylation, and sumoylation of histones, is believed to regulate chromatin accessibility either by disrupting chromatin contacts or by recruiting non-histone proteins to chromatin. The histone code in which distinct histone tail-protein interactions promote engagement may be the deciding factor for choosing specific DSB repair pathways. Recent evidence suggests that such mechanisms are involved in DNA damage detection and repair. Altered telomere chromatin structure has been linked to defective DNA damage response (DDR), and eukaryotic cells have evolved DDR mechanisms utilizing proficient DNA repair and cell cycle checkpoints in order to maintain genomic stability. Recent studies suggest that chromatin modifying factors play a critical role in the maintenance of genomic stability. This review will summarize the role of DNA damage repair proteins specifically ataxia-telangiectasia mutated (ATM) and its effectors and the telomere complex in maintaining genome stability.