| SMART (Single Molecule Analysis of Resection Tracks) Technique for Assessing DNA end-Resection in Response to DNA Damage
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Author:
Date:
2020-08-05
[Abstract] DNA double strand breaks (DSBs) are among the most toxic lesions affecting genome integrity. DSBs are mainly repaired through non-homologous end joining (NHEJ) and homologous recombination (HR). A crucial step of the HR process is the generation, through DNA end-resection, of a long 3′ single-strand DNA stretch, necessary to prime DNA synthesis using a homologous region as a template, following DNA strand invasion. DNA end resection inhibits NHEJ and triggers homology-directed DSB repair, ultimately guaranteeing a faithful DNA repair. Established methods to evaluate the DNA end-resection process are the immunofluorescence analysis of the phospho-S4/8 RPA32 protein foci, a marker of DNA end-resection, or of the phospho-S4/8 RPA32 protein levels by Western blot. Recently, the Single ...
[摘要] [摘要] DNA双链断裂（dsb）是影响基因组完整性的最具毒性的损伤之一。dsb主要通过非同源末端连接（NHEJ）和同源重组（HR）进行修复。HR过程的一个关键步骤是通过DNA末端切除，产生一个长的3′单链DNA链，这是在DNA链入侵后，以同源区域为模板进行DNA合成所必需的。DNA末端切除抑制NHEJ并触发同源定向的DSB修复，最终保证DNA的可靠修复。已建立的评价DNA末端切除过程的方法是免疫荧光法分析磷酸化S4/8rpa32蛋白病灶（DNA末端切除的标志物）或磷酸化S4/8rpa32蛋白水平。近年来，切除轨迹单分子分析（SMART）被认为是一种可靠的方法，可以通过免疫荧光法观察S期特异性DNA损伤剂（如喜树碱）处理细胞后产生的长3′单链DNA尾。然后，通过图像分析软件（如Photoshop）测量DNA束长度，评价DNA末端切除机的处理能力。DNA纤维的制备是在非变性条件下进行的，因此免疫荧光只检测DSB处理产生的特定的3′单链DNA尾。
[背景] ...
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| DNA Fiber Assay upon Treatment with Ultraviolet Radiations
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Author:
Date:
2017-06-05
[Abstract] Genome stability is continuously challenged by a wide range of DNA damaging factors. To promote a correct DNA repair and cell survival, cells orchestrate a coordinated and finely tuned cascade of events collectively known as the DNA Damage Response (DDR). Ultra Violet (UV) rays are among the main environmental sources of DNA damage and a well recognized cancer risk factor. UV rays induce the formation of toxic cyclobutane-type pyrimidine dimers (CPD) and [6-4]pyrimidine-pyrimidone (6-4PP) photoproducts which trigger the activation of the intra-S phase cell cycle checkpoint (Kaufmann, 2010) aimed at preventing replication fork collapse, late origin firing, and stabilizing fragile sites (Branzei and Foiani, 2009). To monitor the activation of the intra-S phase checkpoint in response to UV ...
[摘要] 基因组稳定性不断受到DNA损伤因素的广泛影响。为了促进正确的DNA修复和细胞存活，细胞协调统一称为DNA损伤反应（DDR）的协调和精细调整的事件级联。超紫外线（UV）是DNA损伤的主要环境来源之一，也是公认的癌症危险因素。紫外线诱导形成毒性环丁烷型嘧啶二聚体（CPD）和[6-4]嘧啶嘧啶酮（6-4PP）光产物，其触发S期细胞周期检查点的活化（Kaufmann，2010），目的在于防止复制叉崩溃，晚期起火和稳定脆弱场所（Branzei和Foiani，2009）。为了监测响应于UV型C（UVC）暴露的S-S相检查点的激活，DNA纤维测定可用于分析新的起始点和DNA合成速率（Jackson等， ，1998; Merrick等人，2004; Alfano等人，2016）。 DNA纤维测定技术在90年代被设想，然后通过使用并入新生DNA链中的胸苷类似物（如CldU和IdU）进一步开发。通过用这些类似物以连续模式处理细胞，可以通过携带不同荧光团的特异性抗体来观察细胞，可以监测复制叉活性并评估其如何受到紫外辐射或其他试剂的影响。
背景 ...
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| Identification of Factors in Regulating a Protein Ubiquitination by Immunoprecipitation: a Case Study of TRF2 on Human REST4 Ubiquitination
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Author:
Date:
2015-07-05
[Abstract] Ubiquitination is the first step of the ubiquitin-proteasome pathway that regulates cells for their homeostatic functions and is an enzymatic, protein post-translational modification process in which ubiquitin is transferred to a target protein substrate by a set of three ubiquitin enzymes (Weissman et al., 2011; Bhattacharyya et al., 2014; Ristic et al., 2014). Given the importance of this process, it is plausible that ubiquitination is under strict control by many factors and that the regulatory machineries are protein-specific. An assay for the detection of a specific protein ubiquitination will enable us to examine whether a factor has a function to regulate the ubiquitination of this protein. Here we describe a protocol that detects the ubiquitination ...
[摘要] 泛素化是泛素 - 蛋白酶体通路的第一步，其调节细胞的内环境稳定功能，并且是酶，蛋白质翻译后修饰过程，其中通过一组三种泛素酶将泛素转移到靶蛋白质底物（Weissman et al。，2011; Bhattacharyya et al。，2014; Ristic 等人，2014）。考虑到这一过程的重要性，似乎可能的是，泛素化受到许多因素的严格控制，并且调节机制是蛋白质特异性的。用于检测特异性蛋白泛素化的测定将使我们能够检查因子是否具有调节该蛋白的泛素化的功能。在这里我们描述一个协议，检测人类REST4蛋白在培养细胞中的神经选择性剪接异构体（RE-1沉默转录因子），拮抗REST对神经分化和神经元形成的镇压功能的泛素化状态。使用这个协议，我们显示端粒结合蛋白TRF2通过抑制其泛素化稳定人类REST4的表达。这表明TRF2在神经分化中发挥阳性作用（Ovando-Roche等人，2014）。该方案还可用于检测其他感兴趣的蛋白质的泛素化。
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