MSH3 CRISPR Activation Plasmid (h): sc-403422-ACT

Human MSH3 encodes a core component of the DNA mismatch repair machinery that forms the MutSβ complex with MSH2 to recognize insertion–deletion loops and other replication-associated DNA distortions. By coordinating lesion recognition with downstream repair and damage signaling, MSH3 supports genome stability during S phase and influences microsatellite maintenance. Altered MSH3 activity is linked to elevated mutation burden, microsatellite instability, and impaired resolution of replication errors, which are recurrent features in multiple cancer types and other disorders of genomic maintenance. MSH3 function is also studied in the context of DNA repair pathway choice, replication stress responses, and mutational signatures.

MSH3 CRISPR Activation Plasmid (h) provides a targeted, non-destructive approach to upregulating endogenous MSH3 expression without altering the underlying DNA sequence.

MSH3 CRISPR Activation Plasmid (h) is a three-plasmid synergistic activation mediator (SAM) system engineered for highly efficient, site-specific transcriptional upregulation of the MSH3 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 MSH3 transcriptional start site, where VP64, p65, and HSF1 act in concert to recruit transcriptional machinery and drive upregulation of endogenous MSH3 expression. Unlike nuclease-active Cas9, dCas9 does not introduce double-strand breaks or modify the genomic sequence, preserving the native MSH3 locus and enabling the study of MSH3-dependent transcriptional responses at the endogenous locus, making it a valuable tool for functional studies, target gene identification, and the modeling of MSH3 pathway restoration in tumor cells with silenced or reduced MSH3 expression.

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