Whole Genome Epigenetics

摘要

An understanding of the cancer cell begins with knowledge of the genetic alterations that lead to neoplastic transformation. Much progress has been made in identifying areas of deletion, amplification and mutation in tumors. However, this is only part of the picture. Increasingly, we are learning that epigenetic changes, that is, changes in chromatin structure, are critically important in regulating cellular gene expression. Recently, several labs have published manuscripts identifying RNA interference as being crucial for the establishment of such epigenetic changes in species as diverse as Drosophila, plants, and the fission yeast S. pombe. This knowledge presented a fantastic opportunity not only to study epigenetic changes, but to potentially create epigenetic changes by creating germline transgenic mice in which a target gene has been silenced by RNAi. After the demonstration that RNAi mammalian cells can be mediated by vectors encoding short, hairpin RNAs (shRNAs), we sought to develop a system by which to create transgenic mice using this technology. We demonstrate that a stable, heritable RNAi trigger in the form of a short hairpin was successfully passed through the mouse germline. As well as demonstrating a technique that can be applied to any gene of interest, we have created gene knock-down mouse models for the Neil-1 DNA glycosylase involved in DNA repair pathways, and for p53. These observations open the way to the use of RNAi as a complement to standard knockout methodologies and provides a means to rapidly assess the consequences of suppressing a gene of interest in a living animal. The vision driving the creation of this technology was one of eventual RNAi-based therapeutics. One could particularly imagine silencing oncogenes in cancer cells to attenuate their tumorigenic tendencies.