C4a CRISPR Activation Plasmid (h): sc-402428-ACT

Human C4A encodes complement component C4, a central effector of the classical and lectin complement pathways that amplifies immune surveillance through opsonization and propagation of inflammatory signaling. Proteolytic processing of C4 contributes to generation of activation fragments that coordinate interactions with complement receptors and other innate immune mediators, influencing clearance of immune complexes and cellular debris. Variation in C4A dosage or expression has been linked to altered complement activity and is associated with immune dysregulation, including susceptibility to autoimmune phenotypes and neuroinflammatory processes. As a functional node within the complement cascade, C4A is widely studied in models of host defense, tissue inflammation, and synaptic or myelin-associated remodeling.

C4a CRISPR Activation Plasmid (h) provides a targeted, non-destructive approach to upregulating endogenous C4A expression without altering the underlying DNA sequence.

C4a CRISPR Activation Plasmid (h) is a three-plasmid synergistic activation mediator (SAM) system engineered for highly efficient, site-specific transcriptional upregulation of the C4A 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 C4A transcriptional start site, where VP64, p65, and HSF1 act in concert to recruit transcriptional machinery and drive upregulation of endogenous C4a expression. Unlike nuclease-active Cas9, dCas9 does not introduce double-strand breaks or modify the genomic sequence, preserving the native C4A locus and enabling the study of C4a-dependent transcriptional responses at the endogenous locus, making it a valuable tool for functional studies, target gene identification, and the modeling of C4a pathway restoration in tumor cells with silenced or reduced C4A expression.

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