FBXL15 Knockout Raji Polyclonal Cells comprise a CRISPR/Cas9-edited polyclonal knockout cell population generated from the Raji B lymphocyte line, designed for loss-of-function studies of the F-box protein FBXL15. This polyclonal format provides a heterogeneous population of gene-disrupted cells, enabling robust functional analyses without the constraints of clonal selection. The knockout model serves as a versatile tool for dissecting the role of FBXL15 in ubiquitin-dependent signaling and its implications in B-cell malignancies.
The parental Raji cell line is a well-established human lymphoblastoid model derived from a Burkitt lymphoma patient and is latently infected with Epstein-Barr virus (EBV). These EBV-positive mature B lymphocytes exhibit characteristics of antibody-producing immune cells and are widely employed in studies of humoral immunity, lymphomagenesis, and B-cell receptor signaling. The Raji background provides a clinically relevant context for exploring how the ubiquitin-proteasome system contributes to malignant B-cell phenotypes.
FBXL15 functions as the substrate-recognition subunit of the Skp1-Cul1-F-box (SCF) E3 ubiquitin ligase complex, assembled with SKP1, CUL1, and RBX1. Within the BMP/TGF-beta signaling axis, FBXL15 specifically binds to and ubiquitinates SMAD4, targeting it for proteasomal degradation. This negative feedback mechanism is activated downstream of BMP ligands (BMP2/4/7) and their receptors (BMPR1A/BMPR2), which phosphorylate the receptor-regulated SMADs (SMAD1/5/8) and promote complex formation with SMAD4. By mediating SMAD4 turnover, FBXL15 attenuates signal transduction and modulates transcriptional responses to TGF-beta superfamily ligands. Additionally, FBXL15 interacts with DVL2, connecting it to the modulation of Wnt signaling and highlighting its broader role in coordinating key developmental and oncogenic pathways.
In the Raji EBV-positive B-cell lymphoma model, FBXL15 knockout allows researchers to directly assess its impact on TGF-beta/BMP pathway activity and its contribution to lymphomagenesis. Loss of FBXL15-mediated SMAD4 degradation may stabilize SMAD4 and enhance BMP/TGF-beta signaling, potentially altering cell proliferation, apoptosis, and immune function. This polyclonal knockout population is particularly advantageous for studying the interplay between ubiquitin-dependent proteolysis and oncogenic signaling in a B-cell context, offering insights into how dysregulation of these pathways drives Burkitt lymphoma and other B-cell malignancies.
Typical research applications include Western blot analysis of FBXL15 and SMAD4 protein levels, phosphorylation status of SMAD1/5/8, and SMAD-responsive luciferase reporter assays to quantify pathway activation. Cycloheximide chase experiments can be performed to determine SMAD4 half-life, while flow cytometry-based apoptosis and cell cycle assays, along with proliferation assays (e.g., MTT), enable detailed phenotypic characterization. The model is also suitable for drug sensitivity screening in B-cell malignancies and for identifying novel substrates of the FBXL15-SCF ligase complex. For further technical assistance or additional product information, please contact Ascent Research.
