location bias

  • 文章类型: Journal Article
    G偶联蛋白受体(GPCR)是药理学和医学的最终避难所,因为超过40%的所有市售药物直接靶向这些受体。通过细胞表面表达,它们是与外界进行蜂窝通信的最前沿。随着认识到它们是GPCRs的配体,这种通讯的传送带中的代谢物变得越来越突出。HCAR1是乳酸盐的GPCR输送机。它是与Gαi偶联的A类GPCR,可减少细胞cAMP以及下游Gβγ信号传导。它最初被发现抑制脂解,最近与不同的细胞过程有关,包括神经活动,血管生成,炎症,愿景,心血管功能,干细胞增殖,并参与促进不同条件的发病机理,比如癌症。除了来自质膜的信号,HCAR1显示了其中具有不同位置偏向活动的核定位。尽管HCAR1的不同功能正在被发现,其细胞和分子机制尚不清楚。在这里,我们提供了有关HCAR1的全面综述,其中涵盖了有关该主题的文献,并讨论其在各种生物现象中的重要性和相关性。
    G-coupled protein receptors (GPCRs) are the ultimate refuge of pharmacology and medicine as more than 40% of all marketed drugs are directly targeting these receptors. Through cell surface expression, they are at the forefront of cellular communication with the outside world. Metabolites among the conveyors of this communication are becoming more prominent with the recognition of them as ligands for GPCRs. HCAR1 is a GPCR conveyor of lactate. It is a class A GPCR coupled to Gαi which reduces cellular cAMP along with the downstream Gβγ signaling. It was first found to inhibit lipolysis, and lately has been implicated in diverse cellular processes, including neural activities, angiogenesis, inflammation, vision, cardiovascular function, stem cell proliferation, and involved in promoting pathogenesis for different conditions, such as cancer. Other than signaling from the plasma membrane, HCAR1 shows nuclear localization with different location-biased activities therein. Although different functions for HCAR1 are being discovered, its cell and molecular mechanisms are yet ill understood. Here, we provide a comprehensive review on HCAR1, which covers the literature on the subject, and discusses its importance and relevance in various biological phenomena.
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  • 文章类型: Journal Article
    G蛋白偶联受体(GPCRs)是跨膜受体的最大家族,主要通过两种主要效应蛋白发出信号:G蛋白和β-arrestin。GPCRs的许多激动剂促进“偏见”反应,其中不同的细胞信号传导途径以不同的功效被激活。偏见信号传导的潜在机制尚未完全阐明,有许多潜在的“隐藏变量”来规范这种行为。一个贡献者是“位置偏差,它指的是根据受体信号传导的细胞位置从给定的GPCR产生独特的信号传导级联。这里,我们回顾了GPCRs在不同亚细胞位置表达和转运的证据,并讨论了位置偏差如何影响GPCR激动剂的药理特性和特征.我们还评估了亚细胞环境中的差异如何调节GPCR信号传导,强调亚细胞GPCR信号的生理意义,并讨论利用GPCR定位偏差的治疗潜力。
    G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors and primarily signal through two main effector proteins: G proteins and β-arrestins. Many agonists of GPCRs promote \"biased\" responses, in which different cellular signaling pathways are activated with varying efficacies. The mechanisms underlying biased signaling have not been fully elucidated, with many potential \"hidden variables\" that regulate this behavior. One contributor is \"location bias,\" which refers to the generation of unique signaling cascades from a given GPCR depending upon the cellular location at which the receptor is signaling. Here, we review evidence that GPCRs are expressed at and traffic to various subcellular locations and discuss how location bias can impact the pharmacologic properties and characterization of GPCR agonists. We also evaluate how differences in subcellular environments can modulate GPCR signaling, highlight the physiological significance of subcellular GPCR signaling, and discuss the therapeutic potential of exploiting GPCR location bias.
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  • 文章类型: Journal Article
    通过G蛋白的G蛋白偶联受体(GPCR)信号传导的经典范例是基于下游反应相对短暂且局限于细胞表面的观点。但是近年来,随着配体-受体复合物内在化后,几种受体参与亚细胞区室的持续信号反应,这一观点得到了修正。这种现象最初是在甲状旁腺激素(PTH)1型受体(PTH1R)中发现的,一种重要的GPCR,用于维持体内正常的钙和磷酸盐水平,具有响应PTH结合而构建或分解骨骼的自相矛盾的能力。由该受体调节的多种生物过程被认为取决于其介导多种cAMP信号传导模式的能力。这些包括质膜处的瞬时信号传导和由PTH介导的早期内体内的来自内化PTH1R的持续信号传导。在这里,我们讨论最近的结构,细胞信号传导和体内研究揭示了通过cAMP的PTH1R信号传导的空间与时间维度的潜在药理学输出。值得注意的是,分子动力学(MD)模拟和基于弹性网络模型(ENM)的方法的组合揭示了如何通过肽激素结合位点和G蛋白偶联界面之间的受体内的结构编码的变构偶联来实现PTH信号应答的精确调节。目前正在探索最近发现的意义,以解决受体信号传导中的位置偏差如何有助于药理功能的关键问题。以及如何对诸如PTH1R之类的困难靶标进行药物治疗,以发现用于治疗骨骼和矿物质代谢疾病的非肽小分子候选物。
    The classical paradigm of G protein-coupled receptor (GPCR) signaling via G proteins is grounded in a view that downstream responses are relatively transient and confined to the cell surface, but this notion has been revised in recent years following the identification of several receptors that engage in sustained signaling responses from subcellular compartments following internalization of the ligand-receptor complex. This phenomenon was initially discovered for the parathyroid hormone (PTH) type 1 receptor (PTH1R), a vital GPCR for maintaining normal calcium and phosphate levels in the body with the paradoxical ability to build or break down bone in response to PTH binding. The diverse biological processes regulated by this receptor are thought to depend on its capacity to mediate diverse modes of cyclic adenosine monophosphate (cAMP) signaling. These include transient signaling at the plasma membrane and sustained signaling from internalized PTH1R within early endosomes mediated by PTH. Here we discuss recent structural, cell signaling, and in vivo studies that unveil potential pharmacological outputs of the spatial versus temporal dimension of PTH1R signaling via cAMP. Notably, the combination of molecular dynamics simulations and elastic network model-based methods revealed how precise modulation of PTH signaling responses is achieved through structure-encoded allosteric coupling within the receptor and between the peptide hormone binding site and the G protein coupling interface. The implications of recent findings are now being explored for addressing key questions on how location bias in receptor signaling contributes to pharmacological functions, and how to drug a difficult target such as the PTH1R toward discovering nonpeptidic small molecule candidates for the treatment of metabolic bone and mineral diseases.
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  • 文章类型: Journal Article
    cAMP is the indispensable second messenger regulating cell metabolism and function in response to extracellular hormones and neurotransmitters. cAMP is produced via the activation of G protein-coupled receptors located at both the cell surface and inside the cell. Recently, Tsvetanova et al. explored cAMP generation in distinct locations and the impact on respective cell functions. Using a phospho-proteomic analysis, they provide insight into the unique role of localized cAMP production in cellular phospho-responses.
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  • 文章类型: Journal Article
    荟萃分析的结果对于告知环境政策和实践决策具有潜在的价值。然而,通过仅使用广泛使用的书目平台进行搜索的主要研究的选择性抽样可能会使效应大小的估计产生偏差.这种搜索策略在环境证据审查中很常见,如果可以检测到偏差的风险,这将提供第一个经验证据,证明搜索的全面性需要提高。我们比较了使用单个和多个书目平台搜索与更全面的搜索对平均效应大小估计的影响。我们使用了137个已发表的荟萃分析,基于多个源搜索,分析9388项研究:8095项来自商业发表的文章;1293项来自灰色文献和未发表的数据。单平台和多平台搜索在100和80个荟萃分析中错过了研究,分别为:52和46项荟萃分析提供了较大的效应估计值;32和28项荟萃分析提供了较小的效应估计值;8项和4项荟萃分析提供了相反的估计方向;2项荟萃分析均因缺失所有研究而无法估计效应.Further,我们发现遗漏研究的比例与平均效应大小的偏差之间存在显著的正对数线性关系,这表明,随着错过的研究数量的增加,平均效应大小的偏差可能会扩大。我们还发现,在35%的荟萃分析中,索引研究和非索引研究之间的平均效应大小存在显著差异。这表明,当搜索被限制时,偏倚的风险很高。我们得出的结论是,受限制的搜索很可能导致研究样本没有代表性,并且对真实效果的估计有偏差。
    Results of meta-analyses are potentially valuable for informing environmental policy and practice decisions. However, selective sampling of primary studies through searches exclusively using widely used bibliographic platform(s) could bias estimates of effect sizes. Such search strategies are common in environmental evidence reviews, and if risk of bias can be detected, this would provide the first empirical evidence that comprehensiveness of searches needs to be improved. We compare the impact of using single and multiple bibliographic platform(s) searches vs more comprehensive searches on estimates of mean effect sizes. We used 137 published meta-analyses, based on multiple source searches, analyzing 9388 studies: 8095 sourced from commercially published articles; and 1293 from grey literature and unpublished data. Single-platform and multiple-platform searches missed studies in 100 and 80 of the meta-analyses, respectively: 52 and 46 meta-analyses provided larger-effect estimates; 32 and 28 meta-analyses provided smaller-effect estimates; eight and four meta-analyses provided opposite direction of estimates; and two each were unable to estimate effects due to missing all studies. Further, we found significant positive log-linear relationships between proportions of studies missed and the deviations of mean effect sizes, suggesting that as the number of studies missed increases, deviation of mean effect size is likely to expand. We also found significant differences in mean effect sizes between indexed and non-indexed studies for 35% of meta-analyses, indicating high risk of bias when the searches were restricted. We conclude that the restricted searches are likely to lead to unrepresentative samples of studies and biased estimates of true effects.
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  • 文章类型: Journal Article
    Highly expressed genes are commonly located close to the origin of replication of bacterial chromosomes (OriC). This location skew is thought to reflect selective advantages associated with gene dosage effects during the replication cycle. The expression of constitutively expressed genes can vary up to fivefold based on chromosomal location, but it is not clear what level of variation would occur in naturally regulated operons. We tested the magnitude of the chromosome location effect using EF-Tu (tufA, tufB), an abundant protein whose cellular level correlates with, and limits, the maximum growth rate. We translocated the Salmonella tufB operon to four locations across the chromosome. The distance from OriC had only a small effect on growth rate, consistent with this operon having the natural ability to upregulate expression and compensate for reduced gene dosage. In contrast, when the total EF-Tu concentration was limiting for the growth rate (tufA deleted), we observed a strong gene dosage effect when tufB was located further from OriC. However, only a short period of experimental evolution was required before the bacteria adapted to this EF-Tu starvation situation by acquiring genetic changes that increased expression levels from the translocated tufB gene, restoring growth rates. Our findings demonstrate that, at least for the tufB operon, gene dosage is probably not the dominant force selecting for a chromosomal location close to OriC. We suggest that the colocation of highly expressed genes close to OriC might instead be selected because it enhances their coregulation during various growth states, with gene dosage being a secondary benefit.IMPORTANCE A feature of bacterial chromosomes is that highly expressed essential genes are usually located close to the origin of replication. Because bacteria have overlapping cycles of replication, genes located close to the origin will often be present in multiple copies, and this is thought to be of selective benefit where high levels of expression support high growth rate. However, the magnitude of this selective effect and whether other forces could be at play are poorly understood. To study this, we translocated a highly expressed essential operon, tufB, to different locations and measured growth fitness. We found that transcriptional regulation buffered the effects of translocation and that even under conditions where growth rate was reduced, genetic changes that increased the expression of tufB were easily and rapidly selected. We conclude, at least for tufB, that forces other than gene dosage may be significant in selecting for chromosomal location.
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  • 文章类型: Journal Article
    在研究团队进行系统评价时,用英语以外的语言发表的研究往往被忽视。有关在进行评论时如何处理非英语研究的文献集中在包括此类研究的重要性上,而较少关注定位和评估相关非英语学习的实际挑战。我们调查了可能预测非英语研究纳入社会科学系统评价的因素,为了更好地理解,何时以及为什么包括/排除这些内容。
    我们评估了截至2016年7月发表的所有CampbellCollaboration系统综述(n=123),并根据其语言包容性对每个综述进行了分类。我们通过问卷从评论作者那里寻求更多信息,并收到了关于47条评论的回复。获得了17个因素的数据,我们通过统计回归模型探索了评论中非英语研究数量的相关性。此外,我们要求作者确定支持或阻碍纳入非英语研究的因素.
    123条评论中,108没有明确排除,其中,17包括非英语语言研究。一个因素与所有模型中纳入的非英语研究的数量相关:审查小组成员工作的国家数量(B值=0.56;SEB=0.24;95%CI=0.07-1.03;p=0.02)。这表明,包括非英语研究在内的评论更有可能由国际审查小组编写。我们的调查显示,来自英语国家的研究人员占主导地位(52.9%),审查团队仅由来自这些国家的团队成员组成(65.9%)。最经常提到的包括非英语学习的挑战是缺乏资源(资金和时间),其次是缺乏语言资源(例如专业翻译)。
    我们的研究结果可能表明非英语学习的有限纳入与资源缺乏之间的联系,这迫使审查团队依靠他们有限的语言技能,而不是专业翻译的支持。如果未解决,审查团队有可能忽视关键数据,并在其他高质量的审查中引入偏见。然而,如果我们要应对处理非英语学习的挑战,应该进一步评估我们发现的有效性和解释。
    Studies published in languages other than English are often neglected when research teams conduct systematic reviews. Literature on how to deal with non-English studies when conducting reviews have focused on the importance of including such studies, while less attention has been paid to the practical challenges of locating and assessing relevant non-English studies. We investigated the factors which might predict the inclusion of non-English studies in systematic reviews in the social sciences, to better understand how, when and why these are included/excluded.
    We appraised all Campbell Collaboration systematic reviews (n = 123) published to July 2016, categorising each by its language inclusiveness. We sought additional information from review authors via a questionnaire and received responses concerning 47 reviews. Data were obtained for 17 factors and we explored correlations with the number of non-English studies in the reviews via statistical regression models. Additionally, we asked authors to identify factors that support or hinder the inclusion of non-English studies.
    Of 123 reviews, 108 did not explicitly exclude, and of these, 17 included non-English language studies. One factor correlated with the number of included non-English studies across all models: the number of countries in which the members of the review team work (B-value = 0.56; SE B = 0.24; 95% CI = 0.07-1.03; p = 0.02). This indicates that reviews which included non-English studies were more likely to be produced by international review teams. Our survey showed a dominance of researchers from English-speaking countries (52.9%) and review teams consisting only of team members from these countries (65.9%). The most frequently mentioned challenge to including non-English studies was a lack of resources (funding and time) followed by a lack of language resources (e.g. professional translators).
    Our findings may indicate a connection between the limited inclusion of non-English studies and a lack of resources, which forces review teams to rely on their limited language skills rather than the support of professional translators. If unaddressed, review teams risk ignoring key data and introduce bias in otherwise high-quality reviews. However, the validity and interpretation of our findings should be further assessed if we are to tackle the challenges of dealing with non-English studies.
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  • 文章类型: Journal Article
    The objective of the present study was to determine the publication rate of cancer randomized controlled trial (RCTs) and to analyze the determinants of the publication, as well as to estimate the possible existence of a location and time lag bias. We also described the bibliometric characteristics of the publications.
    We conducted an observational study that identified publications resulting from RCTs involving cancer-related drug products. These studies were authorized and registered by the Spanish Agency of Medicines and Medical Devices between 1999 and 2003.
    We identified 168 publications of 303 RCTs, resulting in a publication rate of 55.4% after a mean follow-up of 12 years. The only factor associated to the likelihood of nonpublication was the study setting favoring only national RCTs (odds ratio 2.7; 95% confidence interval 1.5-4.8). Type of sponsor did not seem to be associated, although the largest volume of nonpublished trials is international, industry-sponsored. Positive results seemed to be associated to a publication in a higher impact factor journal and a shorter time-to-publication.
    About half of the cancer RCTs during the target period have not been published. The national setting is a factor associated to nonpublication, whereas the direction of results determines its dissemination (impact factor and timely publication).
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  • 文章类型: Journal Article
    Recent research has demonstrated that involuntary attention improves target identification accuracy for letters using non-predictive peripheral cues, helping to resolve some of the controversy over performance enhancement from involuntary attention. While various cueing studies have demonstrated that their reported cueing effects were not due to response bias to the cue, very few investigations have quantified the extent of any response bias or developed methods of removing bias from observed results in a double judgment accuracy task. We have devised a method to quantify and remove response bias to cued locations in a double judgment accuracy cueing task, revealing the true, unbiased performance enhancement from involuntary and voluntary attention. In a 7-alternative forced choice cueing task using backward masked stimuli to temporally constrain stimulus processing, non-predictive cueing increased target detection and discrimination at cued locations relative to uncued locations even after cue location bias had been corrected.
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