| Lipid Mixing Assay for Murine Myoblast Fusion and Other Slow Cell-cell Fusion Processes
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Author:
Date:
2020-03-05
[Abstract] Lipid mixing (redistribution of lipid probes between fusing membranes) has been widely used to study early stages of relatively fast viral and intracellular fusion processes that take seconds to minutes. Lipid mixing assays are especially important for identification of hemifusion intermediates operationally defined as lipid mixing without content mixing. Due to unsynchronized character and the slow rate of the differentiation processes that prime the cells for cell-cell fusion processes in myogenesis, osteoclastogenesis and placentogenesis, these fusions take days. Application of lipid mixing assays to detect early fusion intermediates in these very slow fusion processes must consider the continuous turnover of plasma membrane components and potential fusion-unrelated exchange of the ...
[摘要]
[摘要 ] 脂质混合（脂质探针在融合膜之间的分布）已广泛用于研究相对快速的病毒和细胞内融合过程的各个阶段，这些过程耗时数秒至数分钟。脂质混合测定对于鉴定在操作上定义为没有内容混合的脂质混合的半融合中间体特别重要。由于不同步的特性以及分化过程的缓慢速度，这些分化过程使细胞在成肌，破骨细胞生成和胎盘生成中引发细胞间的融合过程，因此这些融合需要几天的时间。在这些非常缓慢的融合过程中应用脂质混合测定法检测早期融合中间体时，必须考虑质膜成分的连续转换以及脂质探针在膜之间的潜在融合无关交换。在这里，我们描述了脂质混合分析在骨骼肌细胞发育和再生中成肌融合阶段的工作中的应用。我们的方法利用了基于鼠C2C12细胞的成肌分化和融合的常规体外模型。当我们观察到第一个多核细胞的外观时，我们将细胞提起并用荧光脂质DiI 作为膜探针或CellTracker TM Green 作为含量探针标记它们。通过荧光显微镜对探针在细胞之间的重新分布进行评分。半融合细胞被鉴定为用内含物和膜探针标记的单核细胞。解释必须由具有融合能力不足细胞的阴性对照系统支持，以说明脂质探针的与融合无关的交换，并将其贡献降到最低。这种方法进行了较小的修改已用于调查原代鼠成肌细胞，破骨细胞前体的融合以及由配子融合原HAP2 介导的融合，并且很可能可以用于其他缓慢的细胞-细胞融合过程。
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| Isolation, Culturing, and Differentiation of Primary Myoblasts from Skeletal Muscle of Adult Mice
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Author:
Date:
2017-05-05
[Abstract] Myogenesis is a multi-step process that leads to the formation of skeletal muscle during embryonic development and repair of injured myofibers. In this process, myoblasts are the main effector cell type which fuse with each other or to injured myofibers leading to the formation of new myofibers or regeneration of skeletal muscle in adults. Many steps of myogenesis can be recapitulated through in vitro differentiation of myoblasts into myotubes. Most laboratories use immortalized myogenic cells lines that also differentiate into myotubes. Although these cell lines have been found quite useful to delineating the regulatory mechanisms of myogenesis, they often show a great degree of variability depending on the origin of the cells and culture conditions. Primary myoblasts have been ...
[摘要] 造血是一种多步骤过程，导致在损伤的肌纤维的胚胎发育和修复期间骨骼肌的形成。在这个过程中，成肌细胞是主要的效应细胞类型，彼此融合或损伤肌纤维，导致新成肌纤维的形成或成年人骨骼肌的再生。通过体外成骨细胞分化成肌管可以概括出许多发生肌肉发育的步骤。大多数实验室使用也分化成肌管的永生化肌原细胞系。虽然已经发现这些细胞系对于描绘造血的调节机制非常有用，但是它们通常依赖于细胞的来源和培养条件而显示出很大的变异性。原代成肌细胞被认为是体外研究肌生成的最生理学相关模型。然而，由于成体骨骼肌的丰度低，原代成肌细胞的分离在技术上是有挑战性的。在本文中，我们描述了一种用于从小鼠的成年骨骼肌分离原代成肌细胞的改进方案。我们还描述了其培养和分化成肌管的方法。
背景 造血是一个复杂而高度协调的过程，其涉及多潜能中胚层细胞的测定，以产生成肌细胞，成肌细胞从细胞周期中排出，以及它们最终分化为骨骼肌纤维。 Myogen-5，MyoD，myogenin和MRF4的基因螺旋 - 环 - 螺旋转录因子的一组基因调控因子（MRFs）的顺序表达调控。 Myf-5和MyoD是成肌细胞形成，增殖和存活所需的主要MRFs，而其他MRF（如肌细胞生成素和MRF-4）在肌发生过程中起作用迟发，激活收缩蛋白和其他结构和代谢蛋白的基因表达（白金汉，2003; ...
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| Heterochronic Pellet Assay to Test Cell-cell Communication in the Mouse Retina
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Author:
Date:
2017-02-05
[Abstract] All seven retinal cell types that make up the mature retina are generated from a common, multipotent pool of retinal progenitor cells (RPCs) (Wallace, 2011). One way that RPCs know when sufficient numbers of particular cell-types have been generated is through negative feedback signals, which are emitted by differentiated cells and must reach threshold levels to block additional differentiation of that cell type. A key assay to assess whether negative feedback signals are emitted by differentiated cells is a heterochronic pellet assay in which early stage RPCs are dissociated and labeled with BrdU, then mixed with a 20-fold excess of dissociated differentiated cells. The combined cells are then re-aggregated and cultured as a pellet on a membrane for 7-10 days in vitro. During ...
[摘要] 构成成熟视网膜的所有七种视网膜细胞类型都是由普通的多能视网膜祖细胞池（RPC）产生的（Wallace，2011）。已经产生足够数量的特定细胞类型的RPC知道的一种方式是通过负反馈信号，其由分化细胞发射并且必须达到阈值水平以阻止该细胞类型的额外分化。评估负反馈信号是否由分化细胞发出的关键测定是异源沉淀测定，其中早期RPC被解离并用BrdU标记，然后与20倍过量的解离的分化细胞混合。然后将组合的细胞再次聚集并在细胞膜上培养7-10天。在这段时间内，RPC将会分化，BrdU + RPC的命运可以使用细胞类型特异性标记进行评估。开发这种沉淀测定的研究人员最初表明，当两种细胞类型混合在一起时，新生儿RPC与胚胎RPC相比，在加速进度条件下产生杆（Watanabe和Raff，1990; Watanabe等，1997）。我们已经使用这种测定来证明我们发现作为视网膜神经节细胞（RGC）分化的负调节物的声刺猬（Shh）促进RPC增殖（Jensen和Wallace，1997; Ringuette等，2014）。最近我们修改了异质性沉淀测定法，以评估视网膜无长突细胞的反馈信号的作用，将转化生长因子β2（Tgfβ2）鉴定为负反馈信号，并将Pten作为Tgfβ2应答的调节剂（Ma et al。，2007 ; ...
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