HSF4 CRISPR Activation Plasmid (h): sc-403850-ACT

Human HSF4 (heat shock transcription factor 4) is a DNA-binding transcription factor that regulates stress-responsive gene expression programs, including molecular chaperones and proteostasis components that safeguard protein folding and cellular homeostasis. Distinct from classic heat-inducible HSFs, HSF4 contributes to developmental and differentiation-associated transcriptional control, with prominent roles in ocular lens biology and maintenance of transparency. Through modulation of heat shock element (HSE)-containing promoters, HSF4 intersects with proteotoxic stress responses, protein quality control, and cell-state transitions. Dysregulated HSF4 activity and variants have been linked to lens abnormalities and cataract-associated phenotypes, making it relevant for studies of protein aggregation, epithelial differentiation, and tissue-specific transcriptional networks.

HSF4 CRISPR Activation Plasmid (h) provides a targeted, non-destructive approach to upregulating endogenous HSF4 expression without altering the underlying DNA sequence.

HSF4 CRISPR Activation Plasmid (h) is a three-plasmid synergistic activation mediator (SAM) system engineered for highly efficient, site-specific transcriptional upregulation of the HSF4 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 HSF4 transcriptional start site, where VP64, p65, and HSF1 act in concert to recruit transcriptional machinery and drive upregulation of endogenous HSF4 expression. Unlike nuclease-active Cas9, dCas9 does not introduce double-strand breaks or modify the genomic sequence, preserving the native HSF4 locus and enabling the study of HSF4-dependent transcriptional responses at the endogenous locus, making it a valuable tool for functional studies, target gene identification, and the modeling of HSF4 pathway restoration in tumor cells with silenced or reduced HSF4 expression.

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