The LMBRD1 Knockout Raji Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population designed for investigating the roles of the LMBRD1 gene in lysosomal cobalamin transport and associated metabolic pathways. These polyclonal cells, derived from the Raji B lymphocyte cell line, carry a targeted disruption of LMBRD1 achieved via CRISPR/Cas9-mediated genome editing, resulting in a loss-of-function model. This product provides a heterogeneous pool of edited cells, each with distinct indel mutations, ideal for studying gene function without the bottleneck of clonal selection.
The Raji cell line is an immortalized B lymphocyte line originally derived from a Burkitt lymphoma patient and is widely used in immunology, cancer biology, and virology research. As an EBV-positive B lymphocyte line, Raji cells retain key characteristics of B-cell signaling and endocytic trafficking, making them a suitable host for examining lysosomal transporter functions. Their robust growth in suspension culture and established use in functional assays facilitate straightforward integration into experimental workflows for studying cobalamin metabolism and lysosomal biology.
LMBRD1 encodes LMBD1, a lysosomal transporter that partners with ABCD4 to release cobalamin into the cytoplasm, a process essential for MTR-dependent methionine synthesis and MUT-mediated methylmalonyl-CoA metabolism. LMBD1 activity is transcriptionally regulated by TFEB and cellular cobalamin levels, linking nutrient sensing to lysosomal function. The LMBD1-ABCD4 complex interacts with MMACHC and MMADHC, which process cobalamin prior to export. Disruption of LMBRD1 therefore impairs cobalamin efflux, leading to deficiencies in MTR and MUT activity and lysosomal cobalamin accumulation.
In the Raji B lymphocyte background, LMBRD1 knockout models the cellular defects observed in methylmalonic aciduria and homocystinuria type cblF, a rare inborn error of cobalamin metabolism. The loss of LMBD1 function in these proliferative B cells recapitulates the metabolic block underlying cblF, characterized by defective conversion of homocysteine to methionine and accumulation of methylmalonic acid. Because B lymphocytes rely on one-carbon metabolism for proliferation and antibody production, this knockout system provides a physiologically relevant platform to dissect how cobalamin trafficking defects affect immune cell function and cancer cell metabolism. Moreover, the EBV-positive nature of Raji cells allows investigation of viral interactions with host lysosomal pathways.
This polyclonal knockout model is suitable for cobalamin uptake and trafficking assays, cblF disease modeling, lysosomal transporter studies, and drug screening for vitamin B12 metabolism disorders. Researchers can employ Western blotting, co-immunoprecipitation, immunofluorescence, and RT-qPCR to confirm LMBD1 loss, probe ABCD4 complexes, visualize lysosomal cobalamin accumulation, and analyze transcriptional responses. Functional assays may include cobalamin uptake measurement, methionine/methylmalonic acid quantification, and MTR/MUT activity assays. These cells are also amenable to high-content screens identifying small molecules that restore cobalamin export. For technical specifications and ordering information, please contact Ascent Research.
