TALEN/CRISPR-mediated eGFP knock-in add-on at the OCT4 locus does not impact differentiation of human embryonic stem cells towards endoderm

PLoS One. 2014 Dec 4;9(12):e114275. doi: 10.1371/journal.pone.0114275. eCollection 2014.

Abstract

Human embryonic stem cells (hESCs) have great promise as a source of unlimited transplantable cells for regenerative medicine. However, current progress on producing the desired cell type for disease treatment has been limited due to an insufficient understanding of the developmental processes that govern their differentiation, as well as a paucity of tools to systematically study differentiation in the lab. In order to overcome these limitations, cell-type reporter hESC lines will be required. Here we outline two strategies using Transcription Activator Like Effector Nucleases (TALENs) and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR-Associated protein (Cas) to create OCT4-eGFP knock-in add-on hESC lines. Thirty-one and forty-seven percent of clones were correctly modified using the TALEN and CRISPR-Cas9 systems, respectively. Further analysis of three correctly targeted clones demonstrated that the insertion of eGFP in-frame with OCT4 neither significantly impacted expression from the wild type allele nor did the fusion protein have a dramatically different biological stability. Importantly, the OCT4-eGFP fusion was easily detected using microscopy, flow cytometry and western blotting. The OCT4 reporter lines remained equally competent at producing CXCR4+ definitive endoderm that expressed a panel of endodermal genes. Moreover, the genomic modification did not impact the formation of NKX6.1+/SOX9+ pancreatic progenitor cells following directed differentiation. In conclusion, these findings demonstrate for the first time that CRISPR-Cas9 can be used to modify OCT4 and highlight the feasibility of creating cell-type specific reporter hESC lines utilizing genome-editing tools that facilitate homologous recombination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CRISPR-Cas Systems
  • Cell Differentiation / genetics*
  • Cell Line
  • Endoderm / cytology*
  • Endoderm / growth & development
  • Gene Expression Regulation, Developmental
  • Gene Knock-In Techniques
  • Genome, Human
  • Homologous Recombination / genetics
  • Human Embryonic Stem Cells / cytology*
  • Humans
  • Octamer Transcription Factor-3 / biosynthesis
  • Octamer Transcription Factor-3 / genetics*

Substances

  • Octamer Transcription Factor-3
  • POU5F1 protein, human

Grants and funding

FCL salary support provided by the Michael Smith Foundation for Health Research, the Canadian Diabetes Association, and the Child and Family Research Institute. NAJK is a recipient of the Canadian Institute of Health Research-BC Transplantation Trainee Fellowship, Child and Family Research Institute Sue Carruthers Graduate Studentship, and University of British Columbia Four Year Fellowship. FCL received the following grants in support of this work: Juvenile Diabetes Research Foundation 2-2011-91; Canadian Institutes of Health Research RMF-111626; Child and Family Research Institute Canucks for Kids Fund 2014. The funders had no role in study design, data collection or analysis, decision to publish or preparation of the manuscript.