MIB1 Knockout Raji Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the Raji B-lymphocyte line, engineered for loss-of-function studies of the MIB1 gene. This product provides a heterogeneous pool of cells carrying diverse CRISPR/Cas9-mediated gene disruptions at the MIB1 locus, enabling robust modeling of MIB1 deficiency in a lymphoid context without clonal selection artifacts. The polyclonal format preserves population-level responses and is well suited for experiments where pooled knockout phenotypes are interrogated, such as bulk signaling analyses, drug response profiling, and functional genomic screens. As a non-monoclonal knockout reagent, it captures the average effect of MIB1 loss across a genetically varied cell population, making it particularly valuable for studying signaling pathways where clonal variability may mask true biological outcomes.
Raji cells are an Epstein-Barr virus (EBV)-positive human Burkitt’s lymphoma B-cell line that stably expresses characteristic B-cell surface markers, including CD19, CD20, and CD22, and retains many features of germinal center B cells. This cell line is widely used in immunology and cancer research due to its robust proliferative capacity, well-defined B-cell receptor signaling, and constitutive activation of NF-??B. The EBV-driven latency III program in Raji cells contributes to high-level expression of viral oncoproteins, creating a permissive background for studying oncogenic cooperation and tumor cell survival mechanisms. As a suspension-adapted line, Raji cells are amenable to high-throughput assays, co-culture experiments, and pharmacological interventions, making them an ideal host for investigating the role of ubiquitin ligases in lymphoma biology.
The MIB1 gene encodes an E3 ubiquitin ligase that functions as a critical positive regulator of Notch signaling by catalyzing the ubiquitination of Notch ligands DLL1, DLL4, JAG1, and JAG2. This post-translational modification promotes ligand endocytosis, a process dependent on interactions with EPS15, EPN1, and the clathrin adaptor AP-2 complex, ultimately triggering mechano-activation and cleavage of Notch receptors NOTCH1 through NOTCH4. Activated Notch intracellular domain translocates to the nucleus, forming a complex with RBPJ/CSL and Mastermind-like coactivators to induce transcription of target genes such as HES1 and HEY1. MIB1 activity is regulated by upstream signals including NF-??B, TP53, and HIF1A, and MIB1 additionally intersects with NF-??B and Wnt pathways, as well as autophagy and apoptosis regulation, positioning it at the nexus of multiple signaling cascades that govern cell fate and survival.
In the Raji B-cell lymphoma context, MIB1 knockout disrupts Notch ligand ubiquitination, impairing ligand endocytosis and thereby attenuating Notch receptor activation. This perturbation is expected to blunt Notch-dependent proliferation and survival signals, offering a model to dissect Notch addiction in B-cell malignancies. Given that Raji cells exhibit constitutive NF-??B activity, MIB1 loss may alter the balance between Notch and NF-??B signaling, providing insight into pathway cross-talk relevant to lymphomagenesis and therapeutic resistance. The knockout model is particularly suited for investigating how MIB1-mediated ubiquitination influences B-cell apoptosis and autophagy, processes frequently dysregulated in lymphoma. By eliminating MIB1 function, researchers can study the dependency of Burkitt’s lymphoma cells on Notch signaling and identify synthetic lethal interactions that may be exploited therapeutically.
This MIB1 knockout polyclonal population is designed for a range of applications in signal transduction and oncology research. It can be employed in Western blotting experiments to measure Notch1 intracellular domain (NICD) levels, RT-qPCR assays to quantify HES1 and HEY1 transcript abundance, and flow cytometry to assess surface Notch ligand expression and CD20 status. Co-immunoprecipitation studies enable detection of MIB1-ubiquitinylated substrate interactions, while luciferase reporter assays using RBPJ-responsive elements measure Notch transcriptional output. Additionally, annexin V apoptosis assays and drug sensitivity tests with gamma-secretase inhibitors or other Notch modulators support functional studies of cell death and therapeutic response. These cells are also suitable for genetic screens and drug library profiling aimed at dissecting MIB1-related pathways in B-cell lymphoma. For further information, please contact Ascent Research.
