CRISPRi lentiviral sgRNA is well suited for long term repression

U2OS and A549 cells stably expressing integrated dCas9-KRAB or dCas9-SALL1-SDS3 were plated at 50,000 cells/well in 24 well plates and transduced with CRISPRi sgRNA lentiviral particles targeting PPIB, SEL1L, BRCA1 or CANX at a MOI of 0.3 to obtain cells with a single integrant. Cells were selected with 2 µg/mL puromycin for 5 days, split into two populations, and allowed to recover for an additional day. At 7 days post-transduction one population was harvested for RT-qPCR analysis. The replicate populations of cells were cultured for 7 additional days before harvest. Total RNA was isolated from harvested plates and relative gene expression was calculated with the Cq method using GAPDH as the housekeeping gene and normalized to a non-targeting control.