The MLLT3 Knockout Raji Polyclonal Cells represent a CRISPR/Cas9-edited polyclonal knockout cell population derived from the human Raji B lymphocyte line. This product consists of a heterogeneous pool of cells harboring targeted disruption of the MLLT3 gene, offering a versatile loss-of-function model for high-throughput and bulk functional studies. The polyclonal format circumvents the limitations of single-cell cloning, preserving the stochastic indel spectrum typical of CRISPR/Cas9 editing while ensuring that the population reflects the diversity of edited alleles. These cells are ideal for applications requiring large numbers of functionally characterized knockout cells, such as drug screening and epistasis analysis.
The Raji cell line is an Epstein-Barr virus (EBV)-positive lymphoblastoid line originally established from a patient with Burkitt lymphoma. As a B lymphocyte model, Raji cells exhibit rapid proliferation in suspension culture and retain key features of B-cell biology, including surface immunoglobulin expression and susceptibility to EBV-mediated transformation. Their transformed phenotype and well-characterized genetic background make Raji cells a widely used system for investigating oncogenic mechanisms in B-cell malignancies, particularly those involving transcriptional deregulation.
MLLT3 (AF9) is a transcriptional coactivator and core component of the super elongation complex (SEC), which governs productive transcription elongation by RNA polymerase II. Within the SEC, MLLT3 bridges interactions with MLL (KMT2A), DOT1L, AF4, ENL, ELL, and P-TEFb (CDK9/Cyclin T), facilitating the release of paused Pol II at target genes such as HOXA cluster members, MEIS1, and MYC. In MLL-rearranged leukemias, the MLL-AF9 fusion protein aberrantly recruits DOT1L, leading to H3K79 hypermethylation and sustained activation of leukemogenic programs driven by HOXA9 and MEIS1. Thus, MLLT3 integrates physiologic transcription elongation with oncogenic gene activation.
In Raji B cells, MLLT3 knockout permits dissection of SEC functions in lymphoid biology. Although primarily studied in myeloid leukemias, MLLT3 is expressed in B lymphocytes, implying roles in B-cell transcription. The EBV-positive Raji background adds complexity, as viral factors may interact with SEC-mediated regulation. Knocking out MLLT3 enables investigation of SEC contribution to Burkitt lymphoma phenotype and B-cell cancer dependency on wild-type MLLT3, independent of fusion proteins.
This knockout product enables a broad range of experiments. Western blotting and RT-qPCR can confirm MLLT3 loss and quantify downstream targets like HOXA9, MEIS1, and MYC. Functional assays??cell proliferation, colony formation, and DOT1L inhibitor sensitivity testing (e.g., pinometostat)??assess therapeutic liabilities. ChIP-qPCR measures H3K79me2 at target promoters, and flow cytometry analyzes apoptosis and differentiation. These cells suit pooled screens and tumor microenvironment co-cultures. For further details, contact Ascent Research.
