FBL3B CRISPR Activation Plasmid (h): sc-405317-ACT

FBXL21 encodes an F-box and leucine-rich repeat protein that functions as the substrate recognition component of an SCF (SKP1–CUL1–F-box) E3 ubiquitin ligase complex, directing specific targets for ubiquitination and proteasomal turnover. Through regulated protein degradation, FBXL21 contributes to control of cellular timing, stress responses, and proteostasis, with particular relevance to circadian and transcriptional regulatory networks. By shaping the stability of pathway effectors, FBXL21 can influence signaling dynamics, cell-cycle coordination, and adaptation to environmental cues. Dysregulation of ubiquitin–proteasome system components, including F-box proteins, is broadly associated with oncogenic signaling, neurobiology, and inflammatory phenotypes, making FBXL21/FBL3B a useful node for mechanistic investigation.

FBL3B CRISPR Activation Plasmid (h) provides a targeted, non-destructive approach to upregulating endogenous FBXL21 expression without altering the underlying DNA sequence.

FBL3B CRISPR Activation Plasmid (h) is a three-plasmid synergistic activation mediator (SAM) system engineered for highly efficient, site-specific transcriptional upregulation of the FBXL21 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 FBXL21 transcriptional start site, where VP64, p65, and HSF1 act in concert to recruit transcriptional machinery and drive upregulation of endogenous FBL3B expression. Unlike nuclease-active Cas9, dCas9 does not introduce double-strand breaks or modify the genomic sequence, preserving the native FBXL21 locus and enabling the study of FBL3B-dependent transcriptional responses at the endogenous locus, making it a valuable tool for functional studies, target gene identification, and the modeling of FBL3B pathway restoration in tumor cells with silenced or reduced FBXL21 expression.

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