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Manner Dependent (manner + dependent)
Selected AbstractsIndependent signaling pathways in ATP-evoked secretion of plasminogen and cytokines from microgliaDRUG DEVELOPMENT RESEARCH, Issue 2-3 2001*Article first published online: 28 AUG 200, Kazuhide Inoue Abstract We investigated the action of ATP on the secretion of plasminogen, TNF-,, and IL-6 from microglia. ATP (10,100 ,M) stimulated the release of plasminogen from rat cultured microglia in a concentration-dependent manner with a peak response at 5,10 min after the stimulation. The release was dependent on extracellular Ca2+ and was blocked by pretreatment with oxidized ATP, a blocker of P2X7. UTP, an agonist of P2Y2, also stimulated the release of plasminogen from a subpopulation (about 20% of total cells) of cultured microglia. The release was also dependent on extracellular Ca2+, suggesting a role of stocker-operated calcium entry (SOC). ATP potently stimulated TNF-, release from 2 h after the stimulation with TNF-, mRNA expression in primary cultures of rat brain microglia. The TNF-, release was maximally elicited by 1 mM ATP and 2,- and 3,-O-(4-benzoylbenzoyl)-adenosine 5,-triphosphate (BzATP), a P2X7 selective agonist, suggesting the involvement of P2X7. This TNF-, release was correlated with a sustained Ca2+ influx. The release was inhibited by PD98059, an inhibitor of MEK1 which activates extracellular signal-regulated protein kinase (ERK), and SB203580, an inhibitor of p38 MAP kinase. However, both ERK and p38 were rapidly activated by ATP even in the absence of extracellular Ca2+. These results indicate that extracellular ATP triggers TNF-, release in rat microglia via P2X7 in a manner dependent on the sustained Ca2+ influx and via the ERK/p38 cascade independently of Ca2+ influx. ATP caused the mRNA expression and release of IL-6 in a concentration-dependent manner in MG-5. The physiological meaning of these independent release mechanisms is also discussed. Drug Dev. Res. 53:166,171, 2001. © 2001 Wiley-Liss, Inc. [source] E2F1-mediated transcriptional inhibition of the plasminogen activator inhibitor type 1 geneFEBS JOURNAL, Issue 18 2001Magdalena Koziczak ,Gene expression of the plasminogen activation system is cell-cycle dependent. Previously, we showed that ectopic expression of E2F1 repressed the plasminogen activator inhibitor type 1 (PAI-1) promoter in a manner dependent on the presence of DNA-binding and transactivation domains of E2F1 but independent of binding to pocket-binding proteins, suggesting a novel mechanism for E2F-mediated negative gene regulation [Koziczak, M., Krek, W. & Nagamine, Y. (2000) Mol. Cell. Biol.20, 2014,2022]. However, it remains to be seen whether endogenous E2F can exert a similar effect. We report here that down-regulation of PAI-1 gene expression correlates with an increase in endogenous E2F activity. When cells were treated with a cdk2/4-specific inhibitor, which maintains E2F in an inactive state, the decline of serum-induced PAI-1 mRNA levels was suppressed. In mutant U2OS cells expressing a temperature-sensitive retinoblastoma protein (pRB), a shift to a permissive temperature induced PAI-1 mRNA expression. In U2OS cells stably expressing an E2F1-estrogen receptor chimeric protein that could be activated by tamoxifen, PAI-1 gene transcription was markedly reduced by tamoxifen even in the presence of cycloheximide. These results all indicate that endogenous E2F can directly repress the PAI-1 gene. DNase I hypersensitive-site analysis of the PAI-1 promoter suggested the involvement of conformation changes in chromatin structure of the PAI-1 promoter. 5, deletion analysis of the PAI-1 promoter showed that multiple sites were responsible for the E2F negative regulation, some of which were promoter dependent. Interestingly, one of these sites is a p53-binding element. [source] Control of tiller recruitment in bunchgrasses: uniting physiology and ecologyFUNCTIONAL ECOLOGY, Issue 4 2004K. W. TOMLINSON Summary 1Bunchgrasses are clonal plants whose dominance of moist grasslands worldwide is maintained largely through tiller recruitment. Tiller recruitment in clonal plants is a subset of the problem of lateral bud outgrowth in higher plants. This paper proposes that three currently competing hypotheses of lateral bud outgrowth , apical dominance; the nutrition hypothesis; and photosensitivity to the red : far-red light ratio , all operate in a manner dependent on environment and plant form. 2The evidence for each hypothesis is reviewed, following which an integrated model is provided that links the three hypotheses into a cohesive strategy. Consequently we assess tiller recruitment by bunchgrasses in terms of the constraints of their functional growth form and their environment. Of the mineral nutrients, only nitrogen is considered because it is the only nutrient whose relationship with tiller recruitment is well established. 3The integrated model maintains the accepted paradigm that actual bud release is hormonally controlled by the auxin : cytokinin ratio, although local nutrient concentrations may also be inhibitory. Importantly, each hormone is controlled by local signals in the shoots and roots, respectively, facilitating appropriate responses to environmental conditions. Auxin production and export from the shoots is moderated by phytochrome responses to red : far-red light ratios. Cytokinin production is mediated by root N concentration which, in turn, is a function of N absorption from the soil and seasonal reallocation of tissue N. 4The growth form of bunchgrasses and the environment in which they are found emphasize that N has a strong mediatory role over tiller production which allows the grass plant to respond appropriately to shifts in this limiting resource. This suggests that control of lateral bud outgrowth may have an evolutionary basis in resource competition for N. [source] Atg17 recruits Atg9 to organize the pre-autophagosomal structureGENES TO CELLS, Issue 5 2009Takayuki Sekito Autophagy is a degradation system of cytoplasmic proteins and organelles via formation of double-membrane vesicles called autophagosomes. In the yeast Saccharomyces cerevisiae, autophagosomes are formed via the pre-autophagosomal structure (PAS) in a manner dependent on Atg proteins. Under nutrient-rich condition, Atg9 is recruited to the PAS by binding to Atg11 for the Cvt pathway. However, because Atg9 is recruited to the PAS in atg11, cells in starved condition and autophagy is induced, autophagy-specific mechanism for the Atg9 recruitment to the PAS has been assumed. Here, we demonstrate that, in autophagy-inducing condition, Atg9 is recruited to the PAS in a manner dependent on Atg17. Atg9 physically interacts with Atg17 in the presence of rapamycin. This interaction requires Atg1, a protein kinase essential for autophagy. Consistently, the Atg17-dependent PAS localization of Atg9 requires Atg1. However, its kinase activity is dispensable for this process. It rather regulates the equilibrium of assembly and disassembly of Atg9 at the PAS. [source] ERK5 is involved in TCR-induced apoptosis through the modification of Nur77GENES TO CELLS, Issue 5 2008Yasushi Fujii Nur77 is a nuclear orphan steroid receptor that has been implicated in negative selection when immature T cells are strongly activated through interaction with self peptide-MHC complexes. The expression of Nur77 in thymocytes and T cell lines leads to apoptosis in a manner dependent on its transcriptional activity. It is well established that Nur77 function is negatively regulated by post-translational modification. Here we demonstrate that the MAPK-induced phosphorylation of Nur77 during T cell activation plays a critical role in the induction of apoptosis. Upon T cell receptor (TCR) stimulation, ERK5 (also known as big MAP kinase 1, BMK1), a member of the MAPK family, phosphorylates Nur77, leading to its transcriptional activation. In contrast, the activation of the ERK2 signaling pathway failed to activate Nur77 although ERK2 is also able to phosphorylate Nur77. Furthermore, the blockade of ERK5 signaling pathway suppressed TCR-induced cell death. These results indicate that ERK5 regulates Nur77 function through its phosphorylation. [source] Mis3 with a conserved RNA binding motif is essential for ribosome biogenesis and implicated in the start of cell growth and S phase checkpointGENES TO CELLS, Issue 7 2000Hiroshi Kondoh Background In normal somatic cell cycle, growth and cell cycle are properly coupled. Although CDK (cyclin-dependent kinase) activity is known to be essential for cell cycle control, the mechanism to ensure the coupling has been little understood. Results We here show that fission yeast Mis3, a novel evolutionarily highly conserved protein with the RNA-interacting KH motif, is essential for ribosome RNA processing, and implicated in initiating the cell growth. Growth arrest of mis3-224, a temperature sensitive mutant at the restrictive temperature, coincides with the early G2 block in the complete medium or the G1/S block in the release from nitrogen starvation, reflecting coupling of cell growth and division. Genetic interactions indicated that Mis3 shares functions with cell cycle regulators and RNA processing proteins, and is under the control of Dsk1 kinase and PP1 phosphatase. Mis3 is needed for the formation of 18S ribosome RNA, and may hence direct the level of proteins required for the coupling. One such candidate is Mik1 kinase. mis3-224 is sensitive to hydroxyurea, and the level of Mik1 protein increases during replication checkpoint in a manner dependent upon the presence of Mis3 and Cds1. Conclusions Mis3 is essential for ribosome biogenesis, supports S phase checkpoint, and is needed for the coupling between growth and cell cycle. Whether Mis3 interacts solely with ribosomal precursor RNA remains to be determined. [source] Cell cycle mechanisms of sister chromatid separation; Roles of Cut1/separin and Cut2/securinGENES TO CELLS, Issue 1 2000Mitsuhiro Yanagida The correct transmission of chromosomes from mother to daughter cells is fundamental for genetic inheritance. Separation and segregation of sister chromatids in growing cells occurs in the cell cycle stage called ,anaphase'. The basic process of sister chromatid separation is similar in all eukaryotes: many gene products required are conserved. In this review, the roles of two proteins essential for the onset of anaphase in fission yeast, Cut2/securin and Cut1/separin, are discussed with regard to cell cycle regulation, and compared with the postulated roles of homologous proteins in other organisms. Securin, like mitotic cyclins, is the target of the anaphase promoting complex (APC)/cyclosome and is polyubiquitinated before destruction in a manner dependent upon the destruction sequence. The anaphase never occurs properly in the absence of securin destruction. In human cells, securin is an oncogene. Separin is a large protein (MW ,180 kDa), the C-terminus of which is conserved, and is thought to be inhibited by association with securin at the nonconserved N-terminus. In the budding yeast, Esp1/separin is thought to be a component of proteolysis against Scc1, an essential subunit of cohesin which is thought to link duplicated sister chromatids up to the anaphase. Whether fission yeast Cut1/separin is also implicated in proteolysis of cohesin is discussed. [source] Functional genomic approach to identify novel genes involved in the regulation of oxidative stress resistance and animal lifespanAGING CELL, Issue 4 2007Yongsoon Kim Summary Genetic studies in many organisms suggest that an increased animal lifespan phenotype is often accompanied by enhanced resistance toward reactive oxygen species (ROS). In Caenorhabditis elegans, mutations in daf-2, which encode an insulin/insulin-like growth factor 1 receptor-like molecule, lead to an extended animal lifespan and increased resistance to ROS. We have optimized an assay to monitor ROS resistance in worms using the ROS-generating chemical paraquat. We have employed this assay to screen the RNAi library along chromosomes III and IV for genes that, when silenced, confer paraquat resistance. The positive RNAi clones were subsequently screened for a lifespan extension phenotype. Using this approach, we have identified 84 genes that, when inactivated by RNAi, lead to significant increases in animal lifespan. Among the 84 genes, 29 were found to act in a manner dependent on daf-16. DAF-16, a forkhead transcription factor, is known to integrate signals from multiple pathways, including the daf-2 pathway, to regulate animal lifespan. Most of the 84 genes have not been previously linked to aging, and potentially participate in important cellular processes such as signal transduction, cell,cell interaction, gene expression, protein degradation, and energy metabolism. Our screen has also identified a group of genes that potentially function in a nutrient-sensing pathway to regulate lifespan in C. elegans. Our study provides a novel approach to identify genes involved in the regulation of aging. [source] Altering the Relative Abundance of GABAA Receptor Subunits Changes GABA- and Ethanol-Responses in Xenopus OocytesALCOHOLISM, Issue 6 2009Joyce H. Hurley Background:, Variations in GABRA2 and GABRG3, genes encoding the ,2 and ,3 subunits of the pentameric GABAA receptor, are associated with the risk of developing alcoholism in adults, conduct disorder at younger ages, and with differences in electroencephalographic power in the , frequency range. The SNPs associated with alcoholism did not alter the coding of these genes, and extensive DNA sequencing of GABRA2 did not find coding changes in the high-risk haplotypes. Therefore, we hypothesize that the associations arise from differences in gene expression. Methods:, Here we report studies in Xenopus oocytes to examine the functional effects of altering the relative abundance of these 2 receptor subunits on GABA current and response to ethanol, as a model of potential effects of regulatory differences. Results:, When human ,2,2,3 subunits are co-expressed, increasing the amount of the ,2 subunit mRNA increased GABA current; in contrast, increasing the amount of the ,3 subunit decreased GABA currents. Acute ethanol treatment of oocytes injected with a 1:1:1 or 2:2:1 ratio of ,2:,2:,3 subunit mRNAs resulted in significant potentiation of GABA currents, whereas ethanol inhibited GABA currents in cells injected with a 6:2:1 ratio. Overnight treatment with ethanol significantly reduced GABA currents in a manner dependent on the ratio of subunits. Conclusions:, These studies demonstrate that changes in relative expression of GABAA receptor subunits alter the response of the resulting channels to GABA and to ethanol. [source] Mechanism of low CO2 -induced activation of the cmp bicarbonate transporter operon by a LysR family protein in the cyanobacterium Synechococcus elongatus strain PCC 7942MOLECULAR MICROBIOLOGY, Issue 1 2008Takashi Nishimura Summary The cmp operon of the cyanobacterium Synechococcus elongatus strain PCC 7942, encoding the subunits of the ABC-type bicarbonate transporter, is activated under CO2 -limited growth conditions in a manner dependent on CmpR, a LysR family transcription factor of CbbR subfamily. The 0.7 kb long regulatory region of the operon carried a single promoter, which responded to CO2 limitation. Using the luxAB reporter system, three cis -acting elements involved in the low-CO2 activation of transcription, each consisting of a pair of LysR recognition signatures overlapping at their ends, were identified in the regulatory region. CmpR was shown to bind to the regulatory region, yielding several DNA,protein complexes in gel shift assays. Addition of ribulose-1,5-bisphosphate (> 1 mM) or 2-phosphoglycolate (> 10 ,M) enhanced the binding of CmpR in a concentration-dependent manner, promoting formation of large DNA,protein complexes. Given the involvement of O2 in adaptive responses of cyanobacteria to low-CO2 conditions, our results suggest that 2-phosphoglycolate, which is produced by oxygenation by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) of ribulose-1,5-bisphosphate under CO2 -limited conditions, acts as the co-inducer in the activation of the cmp operon by CmpR. [source] Electrophysiological and Neurochemical Evidence for Voltage-Dependent Ca2+ Channel Blockade by a Novel Neuroprotective Agent NS-7,BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2001Michiko Oka In rat dorsal root ganglion neurones, NS-7 (0.3,100 ,M) inhibited the whole-cell Ba2+ currents (IBa) in a voltage-dependent manner, in which the compound more potently blocked the IBa elicited from the holding potential of ,40 mV than that induced from ,80 mV. In slices of rat cerebral cortex, KCl-evoked nitric oxide synthesis was markedly inhibited by ,-conotoxin GVIA and ,-agatoxin IVA, but only slightly attenuated by nifedipine, suggesting that the response is mediated predominantly through activation of N-type and P/Q-type Ca2+ channels. NS-7 (1,100 ,M) inhibited the KCl-stimulated nitric oxide synthesis in a manner dependent on the intensity of the depolarizing stimuli. Moreover, weak but significant inhibitory effect of NS-7 was observed even after wash-out. Similar voltage-dependent inhibition of the KCl response was observed by a limited concentration (10 ,M) of verapamil. These findings indicate that NS-7 in several concentrations blocks Ca2+ channel in a voltage-dependent manner. [source] A comparison of Ca2+ channel blocking mode between gabapentin and verapamil: implication for protection against hypoxic injury in rat cerebrocortical slicesBRITISH JOURNAL OF PHARMACOLOGY, Issue 2 2003Michiko Oka The mode of Ca2+ channel blocking by gabapentin [1-(aminomethyl)cyclohexane acetic acid] was compared to those of other Ca2+ channel blockers, and the potential role of Ca2+ channel antagonists in providing protection against hypoxic injury was subsequently investigated in rat cerebrocortical slices. mRNA for the ,2, subunits of Ca2+ channels was found in rat cerebral cortex. Nitric oxide (NO) synthesis estimated from cGMP formation was enhanced by KCl stimulation, which was mediated primarily by the activation of N- and P/Q-type Ca2+ channels. Gabapentin blocked both types of Ca2+ channels, and preferentially reversed the response to 30 mM K+ stimulation compared with 50 mM K+ stimulation. In contrast, verapamil preferentially inhibited the response to depolarization by the higher concentration (50 mM) of K+. Gabapentin inhibited KCl-induced elevation of intracellular Ca2+ in primary neuronal culture. Hypoxic injury was induced in cerebrocortical slices by oxygen deprivation in the absence (severe injury) or presence of 3 mM glucose (mild injury). Gabapentin preferentially inhibited mild injury, while verapamil suppressed only severe injury. , -Conotoxin GVIA (, -CTX) and , -agatoxin IVA (, -Aga) were effective in both models. NO synthesis was enhanced in a manner dependent on the severity of hypoxic insults. Gabapentin reversed the NO synthesis induced by mild insults, while verapamil inhibited that elicited by severe insults. , -CTX and , -Aga were effective in both the cases. Therefore, the data suggest that gabapentin and verapamil cause activity-dependent Ca2+ channel blocking by different mechanisms, which are associated with their cerebroprotective actions and are dependent on the severity of hypoxic insults. British Journal of Pharmacology (2003) 139, 435,443. doi:10.1038/sj.bjp.0705246 [source] DESENSITIZATION OF GUINEA-PIG TAENIA CAECI SMOOTH MUSCLE INDUCED BY A LOW CONCENTRATION OF CARBACHOLCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2007Shigeru Hishinuma SUMMARY 1In guinea-pig taenia caeci smooth muscle we have found that 10,4 mol/L carbachol-induced desensitization to muscarinic agonists develops within 15,30 s, followed by transient resensitization at 1 min, whereas the desensitization to depolarizing high K+ develops with maximal desensitization at 1 min followed by sustained resensitization up to 30 min. In both cases, Ca2+ -dependent processes play a crucial role in determining the development of desensitization. 2To elucidate whether these peculiar processes of desensitization/resensitization may be induced by a lower concentration of carbachol, we examined the development of desensitization induced by 10,6 mol/L carbachol, because at this concentration carbachol is known to induce biphasic changes in intracellular Ca2+ concentrations, with a smaller transient increase followed by a larger sustained increase than seen with 10,4 mol/L carbachol. 3Contractile responses to muscarinic agonists (carbachol or AHR-602) and high K+ were desensitized by pretreatment with 10,6 mol/L carbachol for 30 min in a manner dependent on the presence of extracellular Ca2+. 4The development of 10,6 mol/L carbachol-induced desensitization to these muscarinic agonists in the presence of extracellular Ca2+ showed three successive phases: fast desensitization within 30 s, followed by transient resensitization at 1 min and the subsequent development of desensitization up to 30 min. In contrast, desensitization to high K+ did not develop up to 10 min and significant desensitization occurred at 30 min, with no apparent resensitization phase. 5These results suggest that the characteristics of the Ca2+ -dependent development of desensitization to muscarinic agonists, but not to high K+, are well maintained in desensitization induced by a lower concentration of carbachol. [source] | |||||||||||||