CRISPR interference (CRISPRi) allows researchers to down-regulate specific gene function by blocking transcription, without editing the DNA. Visit our CRISPRi applications page to learn more.

The Horizon CRISPRmod CRISPRi system requires two components to operate: a gene-specific CRISPRi guide RNA and a catalytically deactivated Cas9 (dCas9) fused to transcriptional repressor domains (SALL1 and SDS3). Our CRISPRi reagents provide a straightforward, efficient set of tools to study a gene’s function via transcriptional repression. 


Algorithm-designed lentiviral and synthetic single guide RNA (sgRNA) specifically target immediately downstream of the gene's transcriptional start site (TSS).

  • CRISPRi synthetic sgRNA

    The most rapid CRISPRi system, with repression within 24 hours post-transfection. Synthetic RNAs are modified for nuclease resistance and available as pooled or individual reagents.

  • CRISPRi lentiviral sgRNA

    An ideal delivery method for CRISPRi in difficult-to-transfect cells, or when longer term repression is desired.


Nuclease-deactivated Cas9, fused to our proprietary transcriptional repressor domains SALL1 and SDS3.

CRISPRi assay considerations for reagent selection

There are many options and considerations for CRISPRi experimental conditions. Generally, users achieve the most robust knockdown when working with a stable population of dCas9-SALL1-SDS3 expressing cells. For extended timepoint assays (more than 120 hours), many choose lentiviral sgRNA. For short-term assays (less than 120 hours), synthetic sgRNA gives more robust gene repression than expressed guide RNAs. 

CRISPRi dCas9-SALL1-SDS3 source Guide RNA format Delivery method Benefits & Recommended uses

CRISPRi dCas9-SALL1-SDS3 lentiviral particles

transduction & selection for CRISPRi dCas9 stable cells

CRISPRi synthetic sgRNA Transfection or electroporation
  • Short term assays
  • Pool guide RNAs for increased repression of target gene function
  • Multiplex targets for simultaneous knockdown within gene pathways or networks
  • Arrayed screening
CRISPRi lentiviral sgRNA particles Transduction
  • Stable expression for extended timepoint assays
  • Low MOI - single integration for stable and even repression
CRISPRi dCas9-SALL1-SDS3 mRNA CRISPRi synthetic sgRNA Co-transfection or electroporation
  • Short timepoint assays - Results within hours
  • Lentiviral free workflow
  • EGFP and puromycin resistance options for enrichment of cells expressing dCas9-SALL1-SDS3 machinery
  • Pool guide RNAs for increased target gene repression
  • Multiplex targets for simultaneous knockdown within gene pathways or networks
  • Ideal for working in primary cells