Journal: International Journal of Molecular Sciences
Article Title: Reversible Regulation of Polyubiquitin Gene UBC via Modified Inducible CRISPR/Cas9 System
doi: 10.3390/ijms20133168
Figure Lengend Snippet: Application of an MS2 RNA aptamer and additional activators for UBC upregulation, based on the idCas9–VP64 system. ( A ) Schematic diagram of the working model of the MS2 aptamer and additional activators for the CRISPR activation system. MS2 protein conjugated to C-terminal activator domains, composed of the mouse NF-κB subunit (p65) and human heat shock factor 1 (HSF1), binds to the MS2 RNA stem-loop structure of sgRNA ver. 2. These sgRNA ver. 2 and MS2-p65-HSF1 complexes cooperate with idCas9–VP64 for the upregulation of target genes. ( B ) HEK293T cells were transiently transfected with idCas9–VP64, MS2-p65-HSF1, and scrambled sgRNA ver. 2 (indicated as -) or sg UBC #1~#4 ver. 2 (alone or in combination), and then treated with 10 μg/mL Dox for 2 days. UBC mRNA levels were determined by qRT-PCR ( n = 3 each), normalized to GAPDH , and expressed as the fold change relative to the control (-Dox, scrambled sgRNA ver. 2). ( C ) Transient transfection of HEK293T cells and Dox treatment were performed as described in ( B ). Ub conjugates (Ub n ) and free Ub were detected by immunoblot analysis using an anti-Ub antibody. α-Tubulin was used as a loading control. ( D , F ) HEK293T cells were transiently transfected with idCas9–VP64, MS2-p65-HSF1, and scrambled sgRNA (sgScramble) ver. 2 or sg UBC #3 ver. 2, and then treated with 10 μg/mL Dox for up to 4 days. To washout Dox, cells were treated with 10 μg/mL Dox for 2 days and it was then removed from the media for 2 days (2/-2). UBC and UBB mRNA levels were determined by qRT-PCR ( n = 3 each), normalized to GAPDH , and expressed as the fold change relative to the control (0 days of Dox treatment, scrambled sgRNA ver. 2). ( E ) HEK293T cells were transiently transfected with idCas9–VP64, MS2-p65-HSF1, and sg UBC #3 ver. 2, and then treated with 10 μg/mL Dox for up to 4 days. Dox washout (2/-2) was performed as described above. dCas9 mRNA levels were determined by qRT-PCR ( n = 3 each), normalized to GAPDH , and expressed as the fold change relative to the control (0 days of Dox treatment, scrambled sgRNA ver. 2). Representative immunoblots are shown from three independent experiments ( C ). All data are presented as means ± SEM from the indicated number of samples. * p < 0.05; ** p < 0.01; *** p < 0.001 vs. control (0 days of Dox treatment or -Dox) or between two groups as indicated by horizontal bars. NS: Not significant.
Article Snippet: Using the catalytically inactive Cas9 (dCas9)-VP64 expression vector (pMSCV-LTR-dCas9–VP64, #46912, Addgene) and pCW-Cas9-Blast, we generated a Dox-inducible dCas9–VP64 expression vector (pCW-dCas9–VP64-Blast) through Gibson assembly.
Techniques: CRISPR, Activation Assay, Transfection, Quantitative RT-PCR, Western Blot