bluuebunny/crossref_metadata_2025_split huggingface dataset:
A dual role for integrin-linked kinase in platelets: regulating integrin function and α-granule secretion
Authors: Tucker Katherine L. , Sage Tanya , Stevens Joanne M. , Jordan Peter A. , Jones Sarah , Barrett Natasha E. , St-Arnaud Rene , Frampton Jonathan , Dedhar Shoukat , Gibbins Jonathan M. 
Published: September 2008

AbstractIntegrin-linked kinase (ILK) has been implicated in the regulation of a range of fundamental biological processes such as cell survival, growth, differentiation, and adhesion. In platelets ILK associates with β1- and β3-containing integrins, which are of paramount importance for the function of platelets. Upon stimulation of platelets this association with the integrins is increased and ILK kinase activity is up-regulated, suggesting that ILK may be important for the coordination of platelet responses. In this study a conditional knockout mouse model was developed to examine the role of ILK in platelets. The ILK-deficient mice showed an increased bleeding time and volume, and despite normal ultrastructure the function of ILK-deficient platelets was decreased significantly. This included reduced aggregation, fibrinogen binding, and thrombus formation under arterial flow conditions. Furthermore, although early collagen stimulated signaling such as PLCγ2 phosphorylation and calcium mobilization were unaffected in ILK-deficient platelets, a selective defect in α-granule, but not dense-granule, secretion was observed. These results indicate that as well as involvement in the control of integrin affinity, ILK is required for α-granule secretion and therefore may play a central role in the regulation of platelet function.
Mutation in the DC-SIGN cytoplasmic triacidic cluster motif markedly attenuates receptor activity for phagocytosis and endocytosis of mannose-containing ligands by human myeloid cells
Authors: Azad Abul K , Torrelles Jordi B , Schlesinger Larry S 
Published: September 2008

AbstractThe transmembrane C-type lectin, dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN), has three conserved cytoplasmic tail motifs: the tyrosine (Y)-based, dileucine (LL), and triacidic cluster (EEE), which are believed to regulate ligand binding, uptake, and trafficking. We mutated each of these motifs by alanine substitution and tested their roles in phagocytosis and receptor-mediated endocytosis of the highly mannosylated ligands, Mycobacterium tuberculosis mannose-capped lipoarabinomannan (ManLAM) and HIV-1 surface glycoprotein gp120, respectively, in transfected human myeloid K-562 cells. Compared with wild-type and other mutants, the EEE mutant of DC-SIGN showed a reduced cell-surface expression, near abolishment in the phagocytosis of ManLAM-coated beads (90.5±0.4%), and a marked reduction in the endocytosis of soluble gp120 (79.3±0.7%). Although, the Y mutant of DC-SIGN did not exhibit any effect on phagocytosis and intracellular trafficking to the phagolysosome, the LL mutant caused the majority of the receptor and/or ligands to remain bound to the cell surface, indicating a role for the LL motif as an internalization signal. The majority of the EEE mutant protein was found to be retained by the intracellular trans-Golgi network and not by the late endosomal/lysosomal compartment of transfected K-562 cells. Collectively, our data indicate a dual role for the EEE motif as a sorting signal in the secretory pathway and a lysosomal targeting signal in the endocytic pathway.
Protective Role of Autophagy in Palmitate-Induced INS-1 β-Cell Death
Authors: Choi Sung-E , Lee Sung-Mi , Lee Youn-Jung , Li Ling-Ji , Lee Soo-Jin , Lee Ji-Hyun , Kim Youngsoo , Jun Hee-Sook , Lee Kwan-Woo , Kang Yup 
Published: September 2008

Autophagy, a vacuolar degradative pathway, constitutes a stress adaptation that avoids cell death or elicits the alternative cell-death pathway. This study was undertaken to determine whether autophagy is activated in palmitate (PA)-treated β-cells and, if activated, what the role of autophagy is in the PA-induced β-cell death. The enhanced formation of autophagosomes and autolysosomes was observed by exposure of INS-1 β-cells to 400 μm PA in the presence of 25 mm glucose for 12 h. The formation of green fluorescent protein-LC3-labeled structures (green fluorescent protein-LC3 dots), with the conversion from LC3-I to LC3-II, was also distinct in the PA-treated cells. The phospho-mammalian target of rapamycin level, a typical signal pathway that inhibits activation of autophagy, was gradually decreased by PA treatment. Blockage of the mammalian target of rapamycin signaling pathway by treatment with rapamycin augmented the formation of autophagosomes but reduced PA-induced INS-1 cell death. In contrast, reduction of autophagosome formation by knocking down the ATG5, inhibition of fusion between autophagosome and lysosome by treatment with bafilomycin A1, or inhibition of proteolytic degradation by treatment with E64d/pepstatin A, significantly augmented PA-induced INS-1 cell death. These findings showed that the autophagy system could be activated in PA-treated INS-1 β-cells, and suggested that the induction of autophagy might play an adaptive and protective role in PA-induced cell death.
Autophagy is activated in palmitate-treated insulinoma-1 beta cells, and the induction of autophagy plays a protective role in palmitate-induced beta cell death.
Hypoxia and Leucine Deprivation Induce Human Insulin-Like Growth Factor Binding Protein-1 Hyperphosphorylation and Increase Its Biological Activity
Authors: Seferovic Maxim D. , Ali Rashad , Kamei Hiroyasu , Liu Suya , Khosravi Javad M. , Nazarian Steven , Han Victor K. M. , Duan Cunming , Gupta Madhulika B. 
Published: September 2008

Fetal growth restriction is often caused by uteroplacental insufficiency that leads to fetal hypoxia and nutrient deprivation. Elevated IGF binding protein (IGFBP)-1 expression associated with fetal growth restriction has been documented. In this study we tested the hypothesis that hypoxia and nutrient deprivation induce IGFBP-1 phosphorylation and increase its biological potency in inhibiting IGF actions. HepG2 cells were subjected to hypoxia and leucine deprivation to mimic the deprivation of metabolic substrates. The total IGFBP-1 levels measured by ELISA were approximately 2- to 2.5-fold higher in hypoxia and leucine deprivation-treated cells compared with the controls. Two-dimensional immunoblotting showed that whereas the nonphosphorylated isoform is the predominant IGFBP-1 in the controls, the highly phosphorylated isoforms were dominant in hypoxia and leucine deprivation-treated cells. Liquid chromatography-tandem mass spectrometry analysis revealed four serine phosphorylation sites: three known sites (pSer 101, pSer 119, and pSer 169); and a novel site (pSer 98). Liquid chromatography-mass spectrometry was used to estimate the changes of phosphorylation upon treatment. Biacore analysis indicated that the highly phosphorylated IGFBP-1 isoforms found in hypoxia and leucine deprivation-treated cells had greater affinity for IGF-I [dissociation constant 5.83E (times 10 to the power)−10 m and 6.40E−09 m] relative to the IGFBP-1 from the controls (dissociation constant ∼1.54E−07 m). Furthermore, the highly phosphorylated IGFBP-1 had a stronger effect in inhibiting IGF-I-stimulated cell proliferation. These findings suggest that IGFBP-1 phosphorylation may be a novel mechanism of fetal adaptive response to hypoxia and nutrient restriction.The use of HepG2 cells demonstrates that IGF binding protein-1 hyper-phosphorylation may be a novel mechanism of fetal adaptive response to hypoxia and under-nutrition.
Preclinical Characterization of a (S)-N-(4-Cyano-3-Trifluoromethyl-Phenyl)-3-(3-Fluoro, 4-Chlorophenoxy)-2-Hydroxy-2-Methyl-Propanamide: A Selective Androgen Receptor Modulator for Hormonal Male Contraception
Authors: Jones Amanda , Chen Jiyun , Hwang Dong Jin , Miller Duane D. , Dalton James T. 
Published: September 2008

The pharmacologic effects of (S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro, 4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide (S-23) were characterized in male rats as an animal model of hormonal male contraception. S-23 showed high binding affinity (inhibitory constant = 1.7 ± 0.2 nm) and was identified as a full agonist in vitro. In castrated male rats, the ED50 of S-23 in the prostate and levator ani muscle was 0.43 and 0.079 mg/d, respectively. In intact male rats treated for 14 d, S-23 alone suppressed LH levels by greater than 50% at doses greater than 0.1 mg/d, with corresponding decreases in the size of the prostate but increases in the size of levator ani muscle. In intact male rats treated for up to 10 wk with S-23 and estradiol benzoate (EB; necessary to maintain sexual behavior in rats), S-23 showed biphasic effects on androgenic tissues and spermatogenesis by suppressing serum concentrations of LH and FSH. EB alone showed no effect on spermatogenesis. In the EB + S-23 (0.1 mg/d) group, four of six animals showed no sperm in the testis and zero pregnancies (none of six) in mating trials. After termination of treatment, infertility was fully reversible, with a 100% pregnancy rate observed after 100 d of recovery. S-23 increased bone mineral density and lean mass but reduced fat mass in a dose-dependent manner. This is the first study to show that a selective androgen receptor modulator combined with EB is an effective and reversible regimen for hormonal male contraception in rats. The beneficial effects of S-23 on the muscle, tissue selectivity, and favorable pharmacokinetic properties make it a strong candidate for use in oral male contraception.An aryl-propionamide selective androgen receptor modulator (S-23) is an effective and reversible agent for hormonal male contraception in rats.
Increased Energy Expenditure and Insulin Sensitivity in the High Bone Mass ΔFosB Transgenic Mice
Authors: Rowe Glenn C. , Choi Cheol Soo , Neff Lynn , Horne William C. , Shulman Gerald I. , Baron Roland 
Published: September 2008

Obesity and osteoporosis are major health issues affecting millions of individuals. Transgenic mice overexpressing ΔFosB, an activator protein-1 transcription factor, under the control of the enolase 2 (ENO2) promoter exhibit both an increase in bone density and a decrease in adipose mass. Here we demonstrate that ΔFosB overexpression increases fatty-acid oxidation and energy expenditure, leading to a decrease in adipocyte size and adipose mass. In addition, the ENO2-ΔFosB mice exhibit increased insulin sensitivity and glucose tolerance. Targeted overexpression of ΔFosB in adipocytes using the adipocyte protein 2 promoter failed to induce changes in fat or in bone, showing that the effect on metabolic activity is not due to cell-autonomous effects of ΔFosB within adipocytes. Detailed analysis of the ENO2-ΔFosB mice demonstrated that energy expenditure was increased in muscle, independent of locomotor activity. These findings provide evidence that signaling downstream of ΔFosB is a potential target for not only osteoporosis but also obesity and diabetes.
Overexpression of ΔFosB under the control of the enolase 2 promoter increases bone mass and energy expenditure by increasing fatty-acid oxidation within muscle, reducing adiposity.
Development and Characterization of a Simian Virus 40 Immortalized Bovine Endometrial Stromal Cell Line
Authors: Krishnaswamy Narayanan , Chapdelaine Pierre , Tremblay Jacques P. , Fortier Michel A. 
Published: September 2008

In ruminants, interferon-τ (IFNτ) is the maternal recognition signal inhibiting prostaglandin (PG) F2α production by endometrial epithelial cells and stimulating interferon-stimulated genes in the stroma. Stromal cells mediate the action of progesterone on epithelial cells during pregnancy. Our working hypothesis is that IFNτ acts as a molecular switch that turns on PGE2 production in endometrial stromal cells while suppressing PGF2α production from epithelial cells. In this report we document immortalization and functional characterization of a bovine stromal cell line from the caruncular region of the endometrium [caruncular stromal cell (CSC)]. Primary stromal cells were immortalized by nucleofection with simian virus 40 large T antigen and integrase. The resulting cell line, CSC, expresses stromal cell-specific vimentin, estrogen, and progesterone receptors, and is amenable for transient transfection. Basal and stimulated production of PGE2 is higher than PGF2α and associated with cyclooxygenase (COX) 2 expression. Phorbol myristate acetate (PMA) and IFNτ up-regulate COX2 and PG production in a dose-dependent manner. When added together, low concentrations of IFNτ inhibit PMA-induced COX2 expression; whereas this inhibition is lost at high concentrations. Expression of signal transducer and activator of transcription 1 is induced by IFNτ at all concentrations studied but is not modulated by PMA. Because expression of signal transducer and activator of transcription 1 does not exhibit the biphasic response to IFNτ, we investigated the p38 MAPK pathway using the selective inhibitor SB203580. Inhibition of the p38 MAPK pathway abolishes IFNτ action on PG production. In summary, CSC appears as a good stromal cell model for investigating the molecular mechanisms related to IFNτ action and PG production in the bovine.
Interferon-t stimulates prostaglandin E2 production, and expression of cyclooxygenase 2 and signal transducer and activator of transcription 1 through two distinct signaling pathways in immortalized bovine endometrial stromal cells.
Progesterone Influence on Neurite Outgrowth Involves Microglia
Authors: Wong Angela M. , Rozovsky Irina , Arimoto Jason M. , Du Yizhou , Wei Min , Morgan Todd E. , Finch Caleb E. 
Published: September 2008

Progesterone (P4) antagonizes estradiol (E2) in synaptic remodeling in the hippocampus during the rat estrous cycle. To further understand how P4 modulates synaptic plasticity, we used entorhinal cortex lesions, which induce E2-dependent neurite sprouting in the hippocampus. In young ovariectomized rats, the E2-dependent entorhinal cortex lesion-induced sprouting was attenuated by concurrent treatment with P4 and E2. Microglial activation also showed the E2-P4 antagonism. These findings extend reports on the estrous cycle synaptic remodeling without lesions by showing the P4-E2 antagonism during simultaneous treatment with both E2 and P4. Glial mechanisms were analyzed with the wounding-in-a-dish model of cocultured glia and embryonic d-18 cortical neurons from rat. In cocultures of mixed glia (astrocytes plus 30% microglia), P4 antagonized the E2-dependent neurite outgrowth (number and length) and neuron viability in the presence of E2, as observed in vivo. However, removal of microglia (astrocyte-neuron coculture) abolished the antagonism of E2 by P4 on neuron sprouting. The P4 receptor antagonists ORG-31710 and RU-486 blocked the antagonism of P4 on E2-dependent sprouting. These findings suggest a new role for microglia in P4 antagonism of E2 in neuronal plasticity and show its dependence on progesterone receptors. These findings are also relevant to the inclusion of progestins in hormone therapy, which is controversial in relation to cognitive declines during aging and in Alzheimer’s disease.Brain glia mediate progesterone–estradiol cross-talk in neuronal sprouting after axotomy in rat models.
Structural Determinants Critical for Localization and Signaling within the Seventh Transmembrane Domain of the Type 1 Corticotropin Releasing Hormone Receptor: Lessons from the Receptor Variant R1d
Authors: Markovic Danijela , Lehnert Hendrik , Levine Michael A. , Grammatopoulos Dimitris K. 
Published: September 2008

Abstract
The type 1 CRH receptor (CRH-R1) plays a fundamental role in homeostatic adaptation to stressful stimuli. CRH-R1 gene activity is regulated through alternative splicing and generation of various CRH-R1 mRNA variants. One such variant is the CRH-R1d, which has 14 amino acids missing from the putative seventh transmembrane domain due to exon 13 deletion, a splicing event common to other members of the B1 family of G protein-coupled receptors. In this study, using overexpression of recombinant receptors in human embryonic kidney 293 and myometrial cells, we showed by confocal microscopy that in contrast to CRH-R1α, the R1d variant is primarily retained in the cytoplasm, although some cell membrane expression is also evident. Use of antibodies against the CRH-R1 C terminus in nonpermeabilized cells showed that membrane-expressed CRH-R1d contains an extracellular C terminus. Interestingly, treatment of CRH-R1d-expressing cells with CRH (100 nM) for 45–60 min elicited functional responses associated with a significant reduction of plasma membrane receptor expression, redistribution of intracellular receptors, and increased receptor degradation. Site-directed mutagenesis studies identified the cassette G356-F358 within transmembrane domain 7 as crucial for CRH-R1α stability to the plasma membrane because deletion of this cassette caused substantial intracellular localization of CRH-R1 α. Most importantly, coexpression studies between CRH-R1d and CRH-R2β demonstrated that the CRH-R2β could partially rescue CRH-R1d membrane expression, and this was associated with a significant attenuation of urocotrin II-induced cAMP production and ERK1/2 and p38MAPK activation, suggesting that CRH-R1d might specifically induce heterologous impairment of CRH-R2 signaling responses. This mechanism appears to involve accelerated CRH-R2β endocytosis.
Running on uneven ground: leg adjustment to vertical steps and self-stability
Authors: Grimmer Sten , Ernst Michael , Günther Michael , Blickhan Reinhard 
Published: September 2008

SUMMARYHuman running is characterized by comparably simple whole-body dynamics. These dynamics can be modelled with a point mass bouncing on a spring leg. Theoretical studies using such spring–mass models predict that running can be self-stable. In simulations, this self-stability allows for running on uneven ground without paying attention to the ground irregularities. Whether humans actually use this property of the mechanical system in such an irregular environment is, however, unclear. One way to approach this question is to study how the leg stiffness in stance and the leg orientation in flight are changed in response to ground perturbations. Here, for 11 human subjects we studied two consecutive contacts during running on uneven ground with a force plate of adjustable height (step of +5, +10 and +15 cm). We found that runners adjust their leg stiffness to the height of a vertical step. The adjustment is characterized by a 9% increase in leg stiffness in preparation for the perturbation and by a systematic decrease in proportion to the step height. At the highest vertical step (+15 cm), leg stiffness was reduced by about 26%. We also observed that the angle of attack decreased from 68 deg. to 62 deg. with increasing ground height. These leg adjustments are in accordance with the predictions of a stable spring–mass system. Furthermore, we could describe the identified leg forces and leg compressions with a simple spring–mass simulation for a given body mass, leg stiffness, angle of attack and initial conditions. We compared the experimental findings with the self-stabilizing properties of the spring–mass model, and discuss how humans use a combination of strategies that include purely mechanical self-stabilization and active neuromuscular control. Finally, beyond self-stability, we suggest that control may apply to smooth centre of mass kinematics.
Multisensory enhancement of electromotor responses to a single moving object
Authors: Pluta Scott R. , Kawasaki Masashi 
Published: September 2008

SUMMARY
Weakly electric fish possess three cutaneous sensory organs structured in arrays with overlapping receptive fields. Theoretically, these tuberous electrosensory, ampullary electrosensory and mechanosensory lateral line receptors receive spatiotemporally congruent stimulation in the presence of a moving object. The current study is the first to quantify the magnitude of multisensory enhancement across these mechanosensory and electrosensory systems during moving-object recognition. We used the novelty response of a pulse-type weakly electric fish to quantitatively compare multisensory responses to their component unisensory responses. Principally, we discovered that multisensory novelty responses are significantly larger than their arithmetically summed component unisensory responses. Additionally, multimodal stimulation yielded a significant increase in novelty response amplitude,probability and the rate of a high-frequency burst, known as a `scallop'. Supralinear multisensory enhancement of the novelty response may signify an augmentation of perception driven by the ecological significance of multimodal stimuli. Scalloping may function as a sensory scan aimed at rapidly facilitating the electrolocation of novel stimuli.
Caste-dependent sleep of worker honey bees
Authors: Klein Barrett A. , Olzsowy Kathryn M. , Klein Arno , Saunders Katharine M. , Seeley Thomas D. 
Published: September 2008

SUMMARYSleep is a dynamic phenomenon that changes throughout an organism's lifetime, relating to possible age- or task-associated changes in health,learning ability, vigilance and fitness. Sleep has been identified experimentally in many animals, including honey bees (Apis mellifera). As worker bees age they change castes, typically performing a sequence of different task sets (as `cell cleaners', `nurse bees', `food storers' and `foragers'). Belonging to a caste could differentially impact the duration, constitution and periodicity of a bee's sleep. We observed individually marked bees within observation hives to determine caste dependent patterns of sleep behavior. We conducted three studies to investigate the duration and periodicity of sleep when bees were outside comb cells, as well as duration of potential sleep when bees were immobile inside cells. All four worker castes we examined exhibited a sleep state. As bees aged and changed tasks, however, they spent more time and longer uninterrupted periods in a sleep state outside cells, but spent less time and shorter uninterrupted periods immobile inside cells. Although c cleaners and nurse bees exhibited no sleep:wake rhythmicity, food storers and foragers experienced a 24 h sleep:wake cycle, with more sleep and longer unbroken bouts of sleep during the night than during the day. If immobility within cells is an indicator of sleep, our study reveals that the youngest adult bees sleep the most, with all older castes sleeping the same amount. This in-cell potential sleep may compensate for what would otherwise indicate an exceptional increase of sleep in an aging animal.