Crystal Structure of Cas9 bound to DNAWIKIMEDIA, CAS9 WIKI PROJECTWhile several groups are working to apply the CRISPR/Cas9 system for clinical purposes, some are using the tool to address fundamental questions about biology. Reuven Agami, a professor of genetics at the Netherlands Cancer Institute in Amsterdam, and his colleagues recently applied CRISPR to search for regulatory enhancer elements throughout the genome. They targeted the Cas9 nuclease to previously identified enhancer elements—transcription factor-binding DNA sequences that distally regulate gene expression—of two transcription factors: p53, and estrogen receptor alpha (ERα), which are both frequently mutated and deregulated in cancer. The team’s findings, published today (January 11) in Nature Biotechnology, highlight key enhancer sequences of these two proteins, and demonstrate the utility of CRISPR for the systematic study of noncoding DNA sequences.
Two other groups had previously used CRISPR to create knockout libraries of protein-coding genes in human cells for functional genetic screens. But the current work is the first genetic screen of regulatory elements using the CRISPR/Cas9 system, said Cecilia Moens of the Fred Hutchinson Cancer Research Center in Seattle who was not involved in the work. “This is a proof-of-concept study,” she said.
“This [CRISPR-based approach] is really necessary because it is quite difficult to assess the function of regulatory elements in endogenous situations, without using reporter assays,” said Ramin Shiekhattar, who studies the human epigenome and the molecular bases of cancer at the University of Miami Miller School of Medicine but was not part of the current work.
Many mutations in protein-coding genes are ...
