The CUL5 Knockout Raji Polyclonal Cells represent a CRISPR/Cas9-edited polyclonal knockout population derived from the Raji B lymphocyte cell line, with targeted disruption of the Cullin-5 (CUL5) gene. This polyclonal format, generated without single-cell cloning, yields a heterogeneous pool of gene-edited cells that retains the intrinsic diversity of the editing outcomes, making it well-suited for pooled functional screens and bulk biochemical analyses. The product serves as a loss-of-function model for studying CUL5-dependent ubiquitination and protein turnover in a human B-cell lymphoma background.
The Raji host cell line is an Epstein-Barr virus (EBV)-positive Burkitt??s lymphoma line originally established in 1963 from a Nigerian patient, and it is widely used as a suspension culture model in immunology and cancer research. As a B lymphocyte-derived line, Raji cells endogenously express key components of B-cell receptor signaling and survival pathways, providing a physiologically relevant environment for interrogating the ubiquitin-proteasome system and its role in lymphomagenesis. Their robust growth in suspension facilitates high-throughput and scalable experimental protocols.
CUL5 functions as the scaffold subunit of the Elongin BC-CUL5-SOCS (ECS) E3 ubiquitin ligase complex, which directs the ubiquitination and subsequent proteasomal degradation of specific substrates. Activation of this complex is tightly regulated by NEDD8 modification via the NEDD8-activating enzyme (NAE) and the COP9 signalosome, and requires assembly with Elongin B (TCEB1), Elongin C (TCEB2), Rbx2 (RNF7), and SOCS family adaptor proteins. Within signaling networks, the ECS complex targets multiple effectors, including JAK kinases, STAT proteins, PD-L1, DEPTOR, and p53, thereby exerting regulatory control over the JAK-STAT, NF-??B, Hippo, and TGF-?? pathways. Cytokine stimulation, notably by IL-6 and IFN-??, further modulates CUL5-mediated substrate degradation.
In the context of Raji B lymphocytes, disruption of CUL5 is predicted to impair ECS ligase function, leading to stabilization of key oncogenic substrates and immune checkpoint molecules such as PD-L1. This perturbation may alter cell proliferation, survival, and apoptotic balance, mirroring aspects of B-cell lymphoma pathogenesis and providing a platform to dissect CUL5??s role in lymphomagenesis. The model is especially relevant for investigating how viral proteins, such as HIV Vif, exploit the ubiquitin machinery via CUL5 to degrade host restriction factors like APOBEC3G.
Researchers can employ these polyclonal knockout cells in a wide array of assays, including Western blotting to monitor CUL5 protein levels and substrate accumulation, ubiquitination assays to measure E3 ligase activity, proteasome inhibition studies, and flow cytometry to assess cell cycle distribution, apoptosis, and phospho-STAT5 status. The cells are also compatible with RT-qPCR for gene expression analysis, co-immunoprecipitation to probe ECS complex integrity, and suspension culture growth assays under varying cytokine or drug treatments. These applications support functional annotation of the ubiquitin-proteasome system, validation of CUL5 as a therapeutic target in lymphoma, and screening for novel ECS substrates. For additional information or to inquire about custom products, contact Ascent Research.
