Gsc

GSC
  • 文章类型: Journal Article
    胶质母细胞瘤(GBM)是目前尚无有效疗法的最高级别的神经胶质瘤。尽管在诊断和治疗方面进行了广泛的研究,GBM结果没有显著改善,中位总生存期持续15-18个月。最近,胶质母细胞瘤干细胞(GSCs)已被确定为治疗抵抗和肿瘤复发的关键驱动因素,针对GSC的GBM治疗有望改善患者预后。我们使用多步骤计算机筛选策略来鉴定针对GBM中选定的治疗分子靶标的再利用候选药物,并有可能同时靶向GSC。通过分析来自基因表达综合(GEO)和癌症基因组图谱(TCGA)的多个GBM和GSC数据集来鉴定常见差异表达基因(DEGs)。为了鉴定靶基因,我们选择了对患者总生存期影响最显著的基因.还验证了TCGA对照与GBM样品中选定基因的相对mRNA和蛋白质表达,并评估了它们的癌症依赖性评分。使用ConnectivityMap(CMap)门户从LINCS数据库中鉴定了靶向这些基因及其相应蛋白质的药物,并使用来自DrugBank数据库的FDA批准的药物库通过针对每个单独靶标的计算机分子对接,分别。进一步评估由此获得的分子穿过血脑屏障(BBB)的能力和通过充当P-糖蛋白(p-Gp)底物导致药物抗性的可能性。在一组GBM细胞系上检查了这些最终入围化合物的生长抑制作用,并通过PRISM重新筛选的药物敏感性EC50值和AUC与替莫唑胺进行了比较。和IC50值从GDSC门户获得。我们鉴定了RPA3,PSMA2,PSMC2,BLVRA,和HUS1作为GBM包括GSCs的分子靶标,对患者生存有显著影响。我们的结果显示GSK-2126458/omipalisib,Linifanib,屈螺酮,eltrombopag,尼洛替尼,和PD198306作为候选药物,可以进一步评估其针对GBM的抗肿瘤潜力。通过这项工作,我们利用GSC包容性靶向方法确定了针对GBM的再利用候选疗法,具有很高的体外药效,可以前瞻性地规避耐药性。这些药物有可能被开发为单独或联合治疗以改善GBM结果。
    Glioblastoma (GBM) is the highest grade of glioma for which no effective therapy is currently available. Despite extensive research in diagnosis and therapy, there has been no significant improvement in GBM outcomes, with a median overall survival continuing at a dismal 15-18 months. In recent times, glioblastoma stem cells (GSCs) have been identified as crucial drivers of treatment resistance and tumor recurrence, and GBM therapies targeting GSCs are expected to improve patient outcomes. We used a multistep in silico screening strategy to identify repurposed candidate drugs against selected therapeutic molecular targets in GBM with potential to concomitantly target GSCs. Common differentially expressed genes (DEGs) were identified through analysis of multiple GBM and GSC datasets from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). For identification of target genes, we selected the genes with most significant effect on overall patient survival. The relative mRNA and protein expression of the selected genes in TCGA control versus GBM samples was also validated and their cancer dependency scores were assessed. Drugs targeting these genes and their corresponding proteins were identified from LINCS database using Connectivity Map (CMap) portal and by in silico molecular docking against each individual target using FDA-approved drug library from the DrugBank database, respectively. The molecules thus obtained were further evaluated for their ability to cross blood brain barrier (BBB) and their likelihood of resulting in drug resistance by acting as p-glycoprotein (p-Gp) substrates. The growth inhibitory effect of these final shortlisted compounds was examined on a panel of GBM cell lines and compared with temozolomide through the drug sensitivity EC50 values and AUC from the PRISM Repurposing Secondary Screen, and the IC50 values were obtained from GDSC portal. We identified RPA3, PSMA2, PSMC2, BLVRA, and HUS1 as molecular targets in GBM including GSCs with significant impact on patient survival. Our results show GSK-2126458/omipalisib, linifanib, drospirenone, eltrombopag, nilotinib, and PD198306 as candidate drugs which can be further evaluated for their anti-tumor potential against GBM. Through this work, we identified repurposed candidate therapeutics against GBM utilizing a GSC inclusive targeting approach, which demonstrated high in vitro efficacy and can prospectively evade drug resistance. These drugs have the potential to be developed as individual or combination therapy to improve GBM outcomes.
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  • 文章类型: Journal Article
    了解叶肉导度(gm)和气孔导度(gsc)对环境变化的短期响应仍然是植物生理学具有挑战性的核心方面。这篇综述综合了我们目前对这些短期反应的了解,支持二氧化碳在叶片内的扩散。使用在线同位素区分和叶绿素荧光测量gm的最新方法学进展提高了我们检测短期gm响应的信心,但是结果需要仔细评估。环境因素,如蒸气压不足和CO2浓度通过gsc变化间接影响gm,突出两个参数之间的一些复杂的相互作用。有证据表明,转基因的短期反应不是,或者至少不是完全的,在机械上与gsc的变化联系在一起,告诫不要使用gsc作为通用汽车的可靠代理。首要挑战在于解开短期转基因反应的机制基础,这将有助于开发准确的模型,将实验室的见解与更广泛的生态影响联系起来。解决这些理解上的差距对于在不断变化的环境条件下完善转基因行为的预测至关重要。
    Understanding the short-term responses of mesophyll conductance (gm) and stomatal conductance (gsc) to environmental changes remains a challenging yet central aspect of plant physiology. This review synthesises our current knowledge of these short-term responses, which underpin CO2 diffusion within leaves. Recent methodological advances in measuring gm using online isotopic discrimination and chlorophyll fluorescence have improved our confidence in detecting short-term gm responses, but results need to be carefully evaluated. Environmental factors like vapour pressure deficit and CO2 concentration indirectly impact gm through gsc changes, highlighting some of the complex interactions between the two parameters. Evidence suggests that short-term responses of gm are not, or at least not fully, mechanistically linked to changes in gsc, cautioning against using gsc as a reliable proxy for gm. The overarching challenge lies in unravelling the mechanistic basis of short-term gm responses, which will contribute to the development of accurate models bridging laboratory insights with broader ecological implications. Addressing these gaps in understanding is crucial for refining predictions of gm behaviour under changing environmental conditions.
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  • 文章类型: Journal Article
    引导自我改变(GSC)是一个基于动机访谈(MI)的早期干预计划,注入认知行为疗法(CBT),对于有物质使用问题的个人。在这项研究中,我们实施了一个4期GSC计划,在少数族裔服务机构中创新地增加了基于正念的技术,以减少自我推荐的大学生的物质使用和负面后果.我们调查了可能与行为改变相关的过程,包括报告其主要选择物质为大麻(n=18)或酒精(n=18)的大学生的使用风险和自我效能评分.36名参与者的样本(Mage=24.4,SDage=5,范围18-37)大多被确定为女性(58.3%),然后是男性(41.7%);52.8%被确定为西班牙裔/拉丁裔,22.2%是黑人或非裔美国人,19.5%是性少数群体。在使用大麻的学生中,结果表明,每周使用大麻的感知风险,改变的信心,和准备变化显示从评估前到评估后有统计学显著的增加。在主要使用酒精的学生中,从评估前到评估后,对变化的信心和对变化的准备程度均有统计学意义的增加.所有结果都产生了很大的效果,由于样本量小,可能会膨胀。调查结果表明,在参加简报的过程中,4-sessiontargetedGSCprogram,主要使用大麻或主要饮酒的少数民族大学生的感知风险和自我效能感显著增加.
    Guided Self-Change (GSC) is a Motivational Interviewing (MI)-based early intervention program, infused with Cognitive Behavioral Therapy (CBT), for individuals with substance use problems. In this study, we implemented a 4-session GSC program with the innovative addition of mindfulness-based techniques at a minority-serving institution to reduce substance use and negative consequences among self-referred university students. We investigated processes that may be associated with behavior change, including perceived risk of use and self-efficacy ratings among university students who reported their primary substance of choice was cannabis (n = 18) or alcohol (n = 18). The sample of 36 participants (Mage = 24.4, SDage = 5, range 18-37) mostly identified as female (58.3%), then male (41.7%); 52.8% identified as Hispanic/Latine, 22.2% as Black or African American, and 19.5% as a sexual minority. Among cannabis primary using students, results indicated that the perceived risk of weekly cannabis use, confidence to change, and readiness to change showed statistically significant increases from pre- to post-assessment. Among alcohol primary using students, confidence to change and readiness to change showed statistically significant increases from pre- to post-assessments. All results yielded large effect sizes, which may be inflated due to the small sample size. Findings suggest that over the course of participation in a brief, 4-session targeted GSC program, there were significant increases in perceived risk and self-efficacy among minority university students who engage in primary cannabis or primary alcohol use.
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  • 文章类型: Journal Article
    背景:弥漫性中线神经胶质瘤(DMG)是儿科肿瘤,诊断后的2年生存率可忽略不计,其特征在于其渗入中枢神经系统的能力。希望控制局部生长并减缓疾病,所有患者都接受放射治疗。然而,在DMG患者中经常发生远处进展。目前的线索是什么导致肿瘤浸润圈主要围绕肿瘤微环境,但是目前没有已知的决定因素来预测侵袭程度。
    方法:在这项研究中,我们使用患者来源的神经胶质瘤干细胞(GSCs)来创建患者特异性3D化身,以模拟个体间的侵袭并阐明细胞支持机制。
    结果:我们显示GSC模型在3D中反映了亲本肿瘤的侵袭行为,因此证明了DMG浸润的能力是肿瘤细胞的自主特征。此外,我们区分了两种迁移模式,间充质和变形虫样,并将变形虫样形态与来自最具侵袭性肿瘤的GSC相关联。使用类器官和原发性肿瘤的转录组学,我们进一步将侵袭性变形虫样肿瘤描述为少突胶质细胞祖细胞样,具有高度收缩的细胞骨架和由BMP7的关键过度表达驱动的粘附能力降低。最后,我们破译了MEK,ERK和Rho/ROCK激酶在BMP7刺激的下游激活,作为控制肿瘤细胞运动的可操作靶标。
    结论:我们的发现确定了两种新的治疗途径。首先,患者来源的GSCs代表了患者分层的预测工具,以适应辐射策略.第二,自分泌和短程BMP7相关信号成为预防DMG扩散和转移的药物靶标。
    Diffuse midline gliomas (DMG) are pediatric tumors with negligible 2-year survival after diagnosis characterized by their ability to infiltrate the central nervous system. In the hope of controlling the local growth and slowing the disease, all patients receive radiotherapy. However, distant progression occurs frequently in DMG patients. Current clues as to what causes tumor infiltration circle mainly around the tumor microenvironment, but there are currently no known determinants to predict the degree of invasiveness.
    In this study, we use patient-derived glioma stem cells (GSCs) to create patient-specific 3D avatars to model interindividual invasion and elucidate the cellular supporting mechanisms.
    We show that GSC models in 3D mirror the invasive behavior of the parental tumors, thus proving the ability of DMG to infiltrate as an autonomous characteristic of tumor cells. Furthermore, we distinguished 2 modes of migration, mesenchymal and ameboid-like, and associated the ameboid-like modality with GSCs derived from the most invasive tumors. Using transcriptomics of both organoids and primary tumors, we further characterized the invasive ameboid-like tumors as oligodendrocyte progenitor-like, with highly contractile cytoskeleton and reduced adhesion ability driven by crucial over-expression of bone morphogenetic pathway 7 (BMP7). Finally, we deciphered MEK, ERK, and Rho/ROCK kinases activated downstream of the BMP7 stimulation as actionable targets controlling tumor cell motility.
    Our findings identify 2 new therapeutic avenues. First, patient-derived GSCs represent a predictive tool for patient stratification in order to adapt irradiation strategies. Second, autocrine and short-range BMP7-related signaling becomes a druggable target to prevent DMG spread and metastasis.
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  • 文章类型: Journal Article
    胶质母细胞瘤(GBM)是成人脑癌中最常见和最严重的形式。它的侵略性很大程度上归因于其复杂和异质的生物学,尽管最大的手术和多模式放化疗治疗,不可避免地复发。传统的大规模分析方法对了解GBM中患者与患者之间的肿瘤间差异做出了重大贡献。然而,现在很清楚,个体内的生物学差异(肿瘤内异质性)也是GBM治疗耐药和复发的一个重要因素,很可能需要整合来自多个最近开发的组学平台的数据才能完全解开.在这里,我们剖析了不断增长的GBM地理空间模型,在GBM干细胞(GSC)前体上分层肿瘤内异质性,单细胞,和空间水平。我们讨论了模型的潜在独特和相互依赖的方面,包括GBM中观察到的基因型和表型之间的潜在不一致。
    Glioblastoma (GBM) is the most common and severe form of brain cancer among adults. Its aggressiveness is largely attributed to its complex and heterogeneous biology that despite maximal surgery and multimodal chemoradiation treatment, inevitably recurs. Traditional large-scale profiling approaches have contributed substantially to the understanding of patient-to-patient inter-tumoral differences in GBM. However, it is now clear that biological differences within an individual (intra-tumoral heterogeneity) are also a prominent factor in treatment resistance and recurrence of GBM and will likely require integration of data from multiple recently developed omics platforms to fully unravel. Here we dissect the growing geospatial model of GBM, which layers intra-tumoral heterogeneity on a GBM stem cell (GSC) precursor, single cell, and spatial level. We discuss potential unique and inter-dependant aspects of the model including potential discordances between observed genotypes and phenotypes in GBM.
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  • 文章类型: Journal Article
    一个早老素基因(PSEN)在海胆胚胎中表达,在胃的植物极中,然后主要在位于羽绒消化系统周围的纤毛细胞中,正如我们最近报道的那样。PSEN表达必须被准确地调节以正确执行这两个发展步骤。通过研究用LiCl扩增内胚层或用Zn扩增外胚层后胚胎中PSEN表达的变化,我们通过全坐法原位杂交(WISH)和定量PCR(qPCR)测量了PSEN天然反义转录。然后我们发现Endo16和Wnt5,内胚层的标记,以及Hnf6和Gsc,外胚层的标记,也有义和反义转录。我们讨论了一般基因表达可能取决于有义和反义转录。这个机制,连同PSEN基因,应包含在基因调控网络(GRN)中,该网络对该物种的多种过程进行理论化。我们建议在阿尔茨海默病(AD)领域研究PSEN天然反义转录也是相关的,其中人类PSEN1和PSEN2的作用是众所周知的。
    One presenilin gene (PSEN) is expressed in the sea urchin embryo, in the vegetal pole of the gastrula and then mainly in cilia cells located around the digestive system of the pluteus, as we recently have reported. PSEN expression must be accurately regulated for correct execution of these two steps of development. While investigating PSEN expression changes in embryos after expansion of endoderm with LiCl or of ectoderm with Zn2+ by whole-mount in situ hybridization (WISH) and quantitative PCR (qPCR), we detected natural antisense transcription of PSEN. We then found that Endo16 and Wnt5, markers of endo-mesoderm, and of Hnf6 and Gsc, markers of ectoderm, are also sense and antisense transcribed. We discuss that general gene expression could depend on both sense and antisense transcription. This mechanism, together with the PSEN gene, should be included in gene regulatory networks (GRNs) that theorize diverse processes in this species. We suggest that it would also be relevant to investigate natural antisense transcription of PSEN in the field of Alzheimer\'s disease (AD) where the role of human PSEN1 and PSEN2 is well known.
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  • 文章类型: Journal Article
    胶质母细胞瘤(GBM)是最致命的癌症之一,使用标准治疗(手术,辐射,和化疗),几十年来没有显著延长。GBM表现出显著的细胞异质性,先端有胶质母细胞瘤干细胞样细胞(GSC)。GSC是具有自我更新能力的GBM细胞亚群,区分,启动肿瘤形成,并操纵肿瘤微环境(TME)。GSC不再被认为是具有特异性标志物的静态细胞群,但在表型上和驱动肿瘤异质性和治疗抗性方面是相当灵活的。鉴于这些特点,它们是GBM治疗成功的关键目标。溶瘤病毒,特别是溶瘤单纯疱疹病毒(oHSV),具有许多治疗属性,并且是靶向GSC的有前途的药物。oHSV经过基因工程改造,可以选择性地在癌细胞中复制并杀死癌细胞,包括GSC,但不是正常细胞。此外,oHSV可以诱导抗肿瘤免疫反应,并与其他疗法协同作用,比如化疗,DNA修复抑制剂,免疫检查点抑制剂,以增强治疗效果并减少部分负责化学和放射性抗性的GSC群体。在这里,我们概述了GSC,不同OHSV的活动,临床试验结果,以及提高疗效的组合策略,包括OHSV的治疗武装。在整个过程中,治疗重点将放在GSCs和专门针对这些细胞的研究上.最近的临床试验和oHSVG47Δ在日本对复发性神经胶质瘤患者的批准证明了oHSV治疗的有效性和前景。
    Glioblastoma (GBM) is one of the most lethal cancers, having a poor prognosis and a median survival of only about 15 months with standard treatment (surgery, radiation, and chemotherapy), which has not been significantly extended in decades. GBM demonstrates remarkable cellular heterogeneity, with glioblastoma stem-like cells (GSCs) at the apex. GSCs are a subpopulation of GBM cells that possess the ability to self-renew, differentiate, initiate tumor formation, and manipulate the tumor microenvironment (TME). GSCs are no longer considered a static population of cells with specific markers but are quite flexible phenotypically and in driving tumor heterogeneity and therapeutic resistance. In light of these features, they are a critical target for successful GBM therapy. Oncolytic viruses, in particular oncolytic herpes simplex viruses (oHSVs), have many attributes for therapy and are promising agents to target GSCs. oHSVs are genetically-engineered to selectively replicate in and kill cancer cells, including GSCs, but not normal cells. Moreover, oHSV can induce anti-tumor immune responses and synergize with other therapies, such as chemotherapy, DNA repair inhibitors, and immune checkpoint inhibitors, to potentiate treatment effects and reduce GSC populations that are partly responsible for chemo- and radio-resistance. Herein, we present an overview of GSCs, activity of different oHSVs, clinical trial results, and combination strategies to enhance efficacy, including therapeutic arming of oHSV. Throughout, the therapeutic focus will be on GSCs and studies specifically targeting these cells. Recent clinical trials and approval of oHSV G47Δ in Japan for patients with recurrent glioma demonstrate the efficacy and promise of oHSV therapy.
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  • 文章类型: Journal Article
    胶质母细胞瘤(GBM)是成年人中最常见的原发性脑恶性肿瘤,预后不良。尽管基因组分析和外科技术的进步以及靶向治疗的发展,大多数治疗方案无效,且主要是姑息治疗.自噬是细胞自我消化的一种形式,目的是回收细胞内成分以维持细胞代谢。这里,我们描述了一些最近的发现,这些发现表明GBM肿瘤对导致自噬依赖性细胞死亡的自噬过度激活更敏感。GBM肿瘤干细胞(GSCs)是GBM肿瘤群体的一个子集,在肿瘤形成和进展中发挥关键作用。转移,和复发,它们对大多数治疗策略具有内在的抵抗力。证据表明GSCs能够适应缺氧的肿瘤微环境,酸中毒,缺乏营养.这些发现表明,自噬可能促进和维持GSCs的干细胞样状态以及它们对癌症治疗的抗性。然而,自噬是一把双刃剑,在一定条件下可能具有抗肿瘤特性。还描述了STAT3转录因子在自噬中的作用。这些发现为未来的研究提供了基础,旨在靶向自噬依赖性途径以克服GBM的固有治疗抗性,并通过自噬调节特异性靶向高度治疗抗性的GSC群体。
    Glioblastoma (GBM) is the most common primary brain malignancy in adults with a dismal prognosis. Despite advances in genomic analysis and surgical technique and the development of targeted therapeutics, most treatment options are ineffective and mainly palliative. Autophagy is a form of cellular self-digestion with the goal of recycling intracellular components to maintain cell metabolism. Here, we describe some recent findings that suggest GBM tumors are more sensitive to the excessive overactivation of autophagy leading to autophagy-dependent cell death. GBM cancer stem cells (GSCs) are a subset of the GBM tumor population that play critical roles in tumor formation and progression, metastasis, and relapse, and they are inherently resistant to most therapeutic strategies. Evidence suggests that GSCs are able to adapt to a tumor microenvironment of hypoxia, acidosis, and lack of nutrients. These findings have suggested that autophagy may promote and maintain the stem-like state of GSCs as well as their resistance to cancer treatment. However, autophagy is a double-edged sword and may have anti-tumor properties under certain conditions. The role of the STAT3 transcription factor in autophagy is also described. These findings provide the basis for future research aimed at targeting the autophagy-dependent pathway to overcome the inherent therapeutic resistance of GBM in general and to specifically target the highly therapy-resistant GSC population through autophagy regulation.
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  • 文章类型: Journal Article
    胶质母细胞瘤(GBM)仍然是最具破坏性的原发性脑恶性肿瘤。尽管在理解基础GBM生物学方面取得了重大进展,并且在开发新的治疗方法方面付出了巨大的努力,大多数GBM患者的预后仍然较差,中位生存时间为15个月.最近,SOX(SRY相关HMG-box)基因和lncRNAs(长链非编码RNAs)之间的相互作用已成为GBM研究的焦点。这两类分子在GBM中都有异常表达,并在肿瘤的发生中起着重要作用。programming,治疗抵抗,和复发。在GBM中,SOX和lncRNAs通过许多功能轴串扰,其中一些是复杂的转录和表观遗传调控机制的一部分。这篇综述提供了关于SOX基因和lncRNAs之间复杂相互作用的现有文献数据的系统总结,并代表了强调SOX/lncRNA串扰对GBM细胞恶性特性的影响的努力。此外,我们强调了这种串扰在寻找GBM治疗中的新生物标志物和治疗方法方面的重要性。
    Glioblastoma (GBM) continues to be the most devastating primary brain malignancy. Despite significant advancements in understanding basic GBM biology and enormous efforts in developing new therapeutic approaches, the prognosis for most GBM patients remains poor with a median survival time of 15 months. Recently, the interplay between the SOX (SRY-related HMG-box) genes and lncRNAs (long non-coding RNAs) has become the focus of GBM research. Both classes of molecules have an aberrant expression in GBM and play essential roles in tumor initiation, progression, therapy resistance, and recurrence. In GBM, SOX and lncRNAs crosstalk through numerous functional axes, some of which are part of the complex transcriptional and epigenetic regulatory mechanisms. This review provides a systematic summary of current literature data on the complex interplay between SOX genes and lncRNAs and represents an effort to underscore the effects of SOX/lncRNA crosstalk on the malignant properties of GBM cells. Furthermore, we highlight the significance of this crosstalk in searching for new biomarkers and therapeutic approaches in GBM treatment.
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  • 文章类型: Journal Article
    两个信号中心之间的相互抑制,Spemann组织者(背侧中胚层)和腹侧区域(中胚层和外胚层),共同调节脊椎动物胚胎的整体发育。每个中心表达直接控制靶基因转录的关键同源盒转录因子(TF)。Goosecoid(Gsc)是一种组织者(背侧中胚层)特异性TF,已知可诱导背侧命运并抑制腹侧/外胚层规格。Ventx1.1(Bmp信号的下游)诱导表皮谱系并抑制腹侧区域的背侧组织者特异性基因。Chordin(Chrd)是一种组织者特异性分泌的Bmp拮抗剂,其表达主要由Gsc激活。或者,在腹侧/表皮区域中,Bmp/Ventx1.1抑制了chrd表达。然而,Gsc和Ventx1.1介导的转录调控机制仍然难以捉摸。这里,我们发现,chrd启动子含有两个顺式作用反应元件,对Ventx1.1负反应,对Gsc正反应。在腹侧/外胚层区域,Ventx1.1直接与Ventx1.1反应元件(VRE)结合并抑制chrd转录。在组织者区域中,Gsc与Gsc反应元件(GRE)结合以激活chrd转录。Gsc介导的对chrd启动子的阳性反应完全依赖于另一个相邻的Wnt反应顺式作用元件(WRE),即TCF7(也称为Tcf1)结合元件。VRE的定点诱变,GRE,或WRE完全废除了Ventx1.1和GSC的抑制或激活活性,分别。ChIP-PCR结果证实了Ventx1.1和Gsc/Tcf7与VRE和GRE/WRE的直接结合,分别。这些结果表明,chrd表达被同源异型盒TFs相反地调节,非洲爪狼胚胎形成过程中的Ventx1.1和Gsc/Tcf7。
    The reciprocal inhibition between two signaling centers, the Spemann organizer (dorsal mesoderm) and ventral region (mesoderm and ectoderm), collectively regulate the overall development of vertebrate embryos. Each center expresses key homeobox transcription factors (TFs) that directly control target gene transcription. Goosecoid (Gsc) is an organizer (dorsal mesoderm)-specific TF known to induce dorsal fate and inhibit ventral/ectodermal specification. Ventx1.1 (downstream of Bmp signaling) induces the epidermal lineage and inhibits dorsal organizer-specific genes from the ventral region. Chordin (Chrd) is an organizer-specific secreted Bmp antagonist whose expression is primarily activated by Gsc. Alternatively, chrd expression is repressed by Bmp/Ventx1.1 in the ventral/epidermal region. However, the regulatory mechanisms underlying the transcription mediated by Gsc and Ventx1.1 remain elusive. Here, we found that the chrd promoter contained two cis-acting response elements that responded negatively to Ventx1.1 and positively to Gsc. In the ventral/ectodermal region, Ventx1.1 was directly bound to the Ventx1.1 response element (VRE) and inhibited chrd transcription. In the organizer region, Gsc was bound to the Gsc response elements (GRE) to activate chrd transcription. The Gsc-mediated positive response on the chrd promoter completely depended on another adjacent Wnt response cis-acting element (WRE), which was the TCF7 (also known as Tcf1) binding element. Site-directed mutagenesis of VRE, GRE, or WRE completely abolished the repressive or activator activity of Ventx1.1 and Gsc, respectively. The ChIP-PCR results confirmed the direct binding of Ventx1.1 and Gsc/Tcf7 to VRE and GRE/WRE, respectively. These results demonstrated that chrd expression is oppositely modulated by homeobox TFs, Ventx1.1, and Gsc/Tcf7 during the embryonic patterning of Xenopus gastrula.
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