The MTM1 Knockout Raji Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the human Burkitt’s lymphoma B lymphocyte cell line Raji. This product features targeted disruption of the MTM1 gene, which encodes the lipid phosphatase myotubularin, via CRISPR/Cas9-mediated gene editing. The resulting polyclonal pool provides a heterogeneous loss-of-function model for investigating MTM1-dependent signaling without selection of a single clonal genotype. Researchers can employ these cells to dissect the functional consequences of MTM1 depletion in a lymphoma background, facilitating studies of endosomal trafficking, autophagy, and phosphoinositide metabolism. The polyclonal format preserves genetic diversity and avoids clonal artifacts, making it suitable for population-level analyses.
The parental Raji cell line is an Epstein-Barr virus (EBV)-positive B lymphocyte model established from a Burkitt’s lymphoma patient. Raji cells maintain key B-cell characteristics, including surface immunoglobulin expression, antigen-presentation capacity, and active endocytic machinery. Widely employed in immunological research, Raji cells serve as a robust platform for examining B-cell receptor signaling, EBV latency, and lymphoma biology. Their transformed phenotype and rapid proliferation support scalable cell-based assays and genetic manipulation. The use of Raji as the host cell line for MTM1 knockout thus allows exploration of myotubularin function in a malignant B-cell context, where endolysosomal and autophagic pathways influence immune cell activation, survival, and viral pathogenesis.
MTM1 encodes myotubularin, a phosphoinositide 3-phosphatase that specifically dephosphorylates phosphatidylinositol 3-phosphate (PI3P) to phosphatidylinositol, thereby serving as a critical negative regulator of endosomal PI3P pools. MTM1 activity is regulated upstream by class III PI3K (PIK3C3/VPS34), which generates PI3P, and growth factor receptor stimulation, which can modulate its localization or interacting partners. The protein interacts directly with MTMR12 (3-PAP) and BIN1 to form multimeric complexes on endosomal membranes. Downstream, MTM1-mediated PI3P turnover impairs the recruitment of PI3P-binding effectors such as EEA1 and Hrs, thereby delaying early-to-late endosome maturation and attenuating autophagosome biogenesis. Consequently, MTM1 inactivation leads to elevated PI3P levels, sustained recruitment of WIPI proteins, and altered flux through the endosomal-lysosomal system and autophagy. Representative pathway components include PIK3C3, PI3P, MTM1, EEA1, Hrs, WIPI1, and the autophagy marker LC3-II.
In B lymphocytes, MTM1-regulated PI3P metabolism intersects with processes essential for immune function. The endosomal-lysosomal pathway in B cells governs antigen internalization, processing, and presentation on MHC class II molecules; proper endosomal maturation, driven in part by PI3P gradients, is necessary for efficient antigen presentation. Autophagy, also controlled by MTM1, contributes to B-cell homeostasis, plasma cell differentiation, and the clearance of intracellular pathogens. Because Raji cells are latently infected with EBV, endocytic trafficking is further relevant to viral entry and intracellular trafficking during lytic reactivation. Disruption of MTM1 in Raji cells may therefore provide insights into how aberrant PI3P signaling influences B-cell endocytic activity, autophagy-dependent survival, and EBV?Chost interactions, with potential implications for understanding lymphomagenesis and immune dysregulation.
This polyclonal knockout model is suited for a range of research applications. Scientists can examine the impact of MTM1 loss on endosomal trafficking and autophagy in B lymphocytes using immunofluorescence staining for EEA1, LAMP1, and PI3P probes, as well as Western blotting for LC3-II and p62 to assess autophagic flux. Flow cytometry-based endocytosis assays enable quantification of antigen uptake, while co-immunoprecipitation studies can probe altered MTM1?CMTMR12 or BIN1 complex formation. The cells are amenable to lipid phosphatase activity assays and RNA-seq transcriptional profiling to map downstream signaling networks. Additionally, this model supports drug screening efforts for X-linked myotubular myopathy and evaluation of autophagy-modulating agents in lymphoma. For further technical details, please contact Ascent Research.
