CBX4 CRISPR Activation Plasmid (h): sc-403903-ACT

CBX4 (chromobox 4) is a Polycomb group protein that functions as an epigenetic reader of repressive histone marks and contributes to stable transcriptional silencing. As a component associated with Polycomb repressive complex activity, CBX4 helps regulate chromatin compaction, cell cycle control, differentiation programs, and maintenance of cellular identity through long-term gene repression. CBX4 also has SUMO E3 ligase activity that can modulate transcription factor function and DNA damage-associated chromatin responses. Dysregulated CBX4 expression or activity has been linked to altered proliferation and aberrant epigenetic states observed in cancer biology and other disorders involving transcriptional misregulation.

CBX4 CRISPR Activation Plasmid (h) provides a targeted, non-destructive approach to upregulating endogenous CBX4 expression without altering the underlying DNA sequence.

CBX4 CRISPR Activation Plasmid (h) is a three-plasmid synergistic activation mediator (SAM) system engineered for highly efficient, site-specific transcriptional upregulation of the CBX4 locus in human cell lines. The system is built around a catalytically inactive Cas9 (dCas9) carrying two inactivating mutations (D10A and N863A) that eliminate nuclease activity while preserving DNA binding. This dCas9 is fused to VP64, a potent transcriptional activator, and is co-expressed with a blasticidin resistance gene for selection. The second plasmid encodes the MS2-p65-HSF1 fusion protein, a secondary activator complex that works in concert with dCas9-VP64, alongside a hygromycin resistance gene. The third plasmid encodes a target-specific 20 nt sgRNA fused to two MS2 RNA aptamers that recruit the MS2-p65-HSF1 complex to the activation site, accompanied by a puromycin resistance gene. The three plasmids are delivered at a 1:1:1 mass ratio for balanced expression of all system components.

Once assembled at the target locus, the SAM complex binds within approximately 200 bp upstream of the CBX4 transcriptional start site, where VP64, p65, and HSF1 act in concert to recruit transcriptional machinery and drive upregulation of endogenous CBX4 expression. Unlike nuclease-active Cas9, dCas9 does not introduce double-strand breaks or modify the genomic sequence, preserving the native CBX4 locus and enabling the study of CBX4-dependent transcriptional responses at the endogenous locus, making it a valuable tool for functional studies, target gene identification, and the modeling of CBX4 pathway restoration in tumor cells with silenced or reduced CBX4 expression.

For Research Use Only. Not Intended for Diagnostic or Therapeutic Use.