Journal: PLOS ONE
Article Title: A suboptimal OCT4-SOX2 binding site facilitates the naïve-state specific function of a Klf4 enhancer
doi: 10.1371/journal.pone.0311120
Figure Lengend Snippet: (A) Mutant mESC lines were generated by recombinase-mediated cassette exchange (RMCE). Heterotypic Flp recognition target (FRT) sites and an mCherry expression reporter were inserted around Klf4 enhancer E2 in mESCs. In the presence of an exchange plasmid, which contains the enhancer E2 flanked by the heterotypic FRT sites, Flp recombinase facilitates integration of the desired enhancer E2 sequence. Single cells were selected after RMCE, isolated for clonal outgrowth, and confirmed by PCR and sequencing. (B-F) Analysis of gene expression in the mutant mESC lines. For each enhancer E2 sequence, multiple clonal populations were grown under naïve-state conditions, and total mRNA was harvested from each and reverse transcribed into cDNA. Quantitative PCR was performed on the cDNA to measure levels of Klf4 (B), Rad23b (C), Pou5f1 (D), Sox2 (E), Nanog (F), Esrrb (G), Tbx3 (H), Klf2 (I), and Klf5 (J). Data was analyzed using the ΔΔCT method. Each data point represents the average from 2–3 technical replicates for each isolated clone, and error bars represent mean of clones ± 95% confidence interval. Asterisks represent statistically significant differences between averages (*p<0.05; **p<0.01, unpaired t-test), with brackets to indicate samples compared. If not shown, averages were not statistically different. Outliers, as determined by the Grubb’s test, are denoted by unfilled shapes and were not utilized in statistical tests.
Article Snippet: The PGK promoter was inserted at the KpnI/XhoI cut sites; the optimized Flp recombinase expression cassette was amplified from pDIRE (Addgene #26745) and inserted at EcoRI/NotI; and a cassette with an internal ribosome entry sequence (IRES) sequence followed by the puromycin resistance gene was inserted at NotI/SacI.
Techniques: Mutagenesis, Generated, Expressing, Plasmid Preparation, Sequencing, Isolation, Gene Expression, Reverse Transcription, Real-time Polymerase Chain Reaction, Clone Assay