Stable dCas9-KRAB and Cas9 Expression Cell Lines

In a screen, most of the variance comes from the effector line rather than the guides:

• • Expression level determines knockdown efficiency and toxicity.
• • Integration number determines whether effector level drifts at high MOI.
• • Inducibility determines whether essential genes are tractable.
• • Per-cell consistency determines how noisy the readout is.

A line that was not characterised on these four axes produces screens that either work spectacularly or not at all, with no diagnostic in between.

Each line is delivered with the parental background documented, so results are attributable.

The fourth item is the one that distinguishes a validated line from a transduced pool: a control guide with a known, large effect proves the background works before your library is spent on it.

Very high dCas9–KRAB expression produces global repression and growth defects; very low expression produces partial knockdowns that differ between clones. The useful range is narrow, and it is cell-type-specific.

We therefore deliver clones at a moderate, characterised level rather than the highest-expressing clone — and report the level so that a screen's performance can be interpreted against it.

• • Inducible systems leak. Report baseline repression in the uninduced state; small leaks matter for essential genes.
• • Effector performance is cell-type specific. A line validated in HEK293 may underperform in iPSC-derived cells; pilot in the target background.
• • Stable Cas9 lines accumulate edits over time. Bank early passages; do not culture indefinitely.

Constitutive or inducible?Constitutive for screens and routine knockdown; inducible when the target is essential or when a titration series is needed. Inducible lines are slower to build and should be chosen for a reason.

How many clones do you provide?Two, at a characterized expression level, with the parental background as control.

Can you put the effector into our line?Yes, with a receipt QC first. If the line proves refractory to transduction or selection, we report that rather than delivering a poorly expressing pool.

Tell us the cell type, the readout, and whether you need inducibility. We will confirm which line type fits and what pilot data we can share before you order.

Contact EDITGENE to request a project consultation or quote.

Effector performance varies by cell type, promoter, and integration site; the QC package describes what we measure, not a guarantee of knockdown efficiency in every background.

Inducible systems should be characterized for leakiness and induction kinetics in the target cells.

• • Gilbert LA, et al. CRISPR-mediated modular RNA-guided regulation of transcription in eukaryotes. Cell. 2013;154:442–451.
• • Gilbert LA, et al. Genome-scale CRISPR-mediated control of gene repression and activation. Cell. 2014;159:647–661.
• • Konermann S, et al. Genome-scale transcriptional activation by an engineered CRISPR-Cas9 complex. Nature. 2015;517:583–588.