从发展胚胎小鼠心脏瓣膜区蛋白分离
Summary
The analysis of protein expression in young embryonic mouse valves has been hampered by the limited tissue available. This manuscript provides a protocol for preparing protein from developing embryonic mouse valve regions for western blot analysis.
Abstract
Western blot analysis is a commonly employed technique for detecting and quantifying protein levels. However, for small tissue samples, this analysis method may not be sufficiently sensitive to detect a protein of interest. To overcome these difficulties, we examined protocols for obtaining protein from adult human cardiac valves and modified these protocols for the developing early embryonic mouse counterparts. In brief, the mouse embryonic aortic valve regions, including the aortic valve and surrounding aortic wall, are collected in the minimal possible volume of a Tris-based lysis buffer with protease inhibitors. If required based on the breeding strategy, embryos are genotyped prior to pooling four embryonic aortic valve regions for homogenization. After homogenization, an SDS-based sample buffer is used to denature the sample for running on an SDS-PAGE gel and subsequent western blot analysis. Although the protein concentration remains too low to quantify using spectrophotometric protein quantification assays and have sample remaining for subsequent analyses, this technique can be used to successfully detect and semi-quantify phosphorylated proteins via western blot from pooled samples of four embryonic day 13.5 mouse aortic valve regions, each of which yields approximately 1 μg of protein. This technique will be of benefit for studying cell signaling pathway activation and protein expression levels during early embryonic mouse valve development.
Introduction
能够识别并量化蛋白表达水平是一个标准技术，动物 – 和基于细胞的实验。然而，尽管一个长期的兴趣在早期胚胎心脏瓣膜的开发，在开发过程中评估蛋白表达在这个特定的组织目前仅限于免疫组化在两个小鸡和鼠标1,2。在大多数模型生物体（ 如小鸡和小鼠）的显影阀定量蛋白表达的难度的部分是阀，从而限制了蛋白质，可以得到的数量的小尺寸。因此，为了定量分析，研究人员通常依靠RNA提取和扩增用于随后定量PCR或微阵列分析2-5。然而，RNA和蛋白的表达水平是不完全相关6，所以着眼于RNA的表达不能提供一个严格的帐户中发生的任何给定的信号的许多改变在发展途径，在不同的时间。基于此限制，在目前可用的方法，该方法的目标是开发一种协议，用于可靠地获得足够量的蛋白质从显影小鼠胚胎心脏瓣膜的区域为所发生的各种信号通路是在重要的变化的定量分析这个组织的成熟。
胚胎瓣膜已普遍从老鼠RNA分离和后续基因表达分析2-5解剖。然而，这些研究已不限于使用基因表达作为一个读出信号通路的激活，它不允许检测翻译后蛋白修饰，其可能会影响下游信号的检测。利用RNA分离技术为出发点，我们开始与解剖感兴趣的区域。因为我们关心的是检测磷酸化蛋白质，都说明信号拍拍在主动脉瓣发展（E13.5-14.5）的一个特定时期hway活性，我们进行的所有解剖在无磷酸盐的Tris缓冲液和收集的阀门与磷酸酶和蛋白酶抑制剂的Tris-基的裂解缓冲液。在我们的具体情况下，仅收集主动脉瓣区域，但肺动脉瓣区域可以很容易地在相同的时间来获得。该阀的区域分别然后均质化并结合当前用于研究在成年心脏瓣膜7蛋白表达的样品缓冲液。通过使用小样品体积（ 例如 ，2微升），并从胚胎中具有相同的基因型汇集阀的区域，我们能够检测磷酸化和未磷酸化的蛋白质在13.5 8天胚胎。因为阀的区域可以被冻结并存储在裂解缓冲液中，胚胎可以在需要集中之前进行基因分型。
这种技术拓宽了一套工具，可用于评估细胞signalin在开发过程中克途径，并提供了定量的恭维免疫组化，专门为开发心脏瓣膜。这种技术应该是有益的，不仅要发展心脏病，也给所有谁与早期胚胎的工作有兴趣，包含有限的组织区域发育生物学家。
Protocol
Representative Results
Discussion
量化蛋白质水平在早期胚胎小鼠和鸡胚心脏瓣膜区域的能力提供了理解的关键细胞信号传递活动阀发展的额外工具。我们这里所描述的协议不从标准蛋白分离方法有很大的不同。然而，通过修改某些关键步骤，我们已经成功地从非常小的样品尺寸相加得到的磷酸化蛋白。为实现这一结果，下面的步骤是特别重要的。以确保得到的优质蛋白，关键的是要保持样品冷却，不论在冰上或用冰冷却的缓冲?…
Divulgations
The authors have nothing to disclose.
Acknowledgements
We would like to thank Andrea Portbury and Davin Townley-Tilson for critical reading of the manuscript and the NIH (grant # R01HL061656) for funding support.
Materials
| Name of Reagent/ Equipment | Company | Catalog Number | Comments/Description |
| Timed-pregnant mouse | To be dissected at the embryonic stage of interest | ||
| Stereoscopic microscope | Nikon | SMZ645 | |
| 0.1 M Tris, pH 7.6 | |||
| Microscissors | Fine Science Tools | 15003-08 | |
| Fine forceps, #5 | Fine Science Tools | 11251-30 | |
| Dissecting needle holders | Ted Pella Inc. | 13560 | |
| Dissecting needles | Ted Pella Inc. | 13561-10 | |
| Micropipette, 20 μl, with tips | |||
| Lysis buffer | 50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 5 mM EDTA, 1% Triton | ||
| PhosSTOP | Roche | 4906845001 | Add 1 tablet to 10 ml lysis buffer |
| TissueLyser LT | Qiagen | 85600 | |
| Stainless steel beads | Qiagen | 69989 | |
| Microcentrifuge |
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