The OSTM1 Knockout Raji Polyclonal Cells constitute a CRISPR/Cas9-mediated gene-disrupted polyclonal population derived from the Raji B lymphocyte cell line, engineered to abolish expression of the osteopetrosis-associated transmembrane protein OSTM1. This pool of edited cells provides a robust loss-of-function model for investigating lysosomal biology in a human Burkitt lymphoma background, without selection for single-cell clones. The polyclonal format preserves the heterogeneity of knockout events across the population, which can be advantageous for screening applications that require representation of diverse genetic alterations while maintaining the critical loss of OSTM1 function.
The Raji cell line is an Epstein-Barr virus (EBV)-transformed lymphoblastoid line originally established from a Burkitt lymphoma patient. Cultivated in suspension, these cells exhibit characteristics of mature B lymphocytes and are extensively used in immunology, cancer biology, and virology research. The EBV-transformed status imparts continuous proliferation and stable antigen-presenting machinery, making Raji cells a suitable host for dissecting lysosomal contributions to immune processes such as antigen processing and MHC class II presentation, as well as for studying oncogenic signaling pathways inherent to Burkitt lymphoma.
OSTM1 encodes a transmembrane chaperone essential for the stability and lysosomal localization of the chloride/proton antiporter CLCN7. By ensuring proper CLCN7 function, OSTM1 maintains lysosomal acidification, which is pivotal for the activity of acid hydrolases like cathepsin K and for autophagy flux. The OSTM1-CLCN7 complex operates downstream of the mTORC1-TFEB signaling axis; under nutrient-rich conditions, mTORC1 phosphorylates and retains TFEB in the cytoplasm, whereas lysosomal stress or mTORC1 inhibition promotes TFEB nuclear translocation and induction of lysosomal genes. In osteoclasts, OSTM1 is further regulated by RANKL and M-CSF signaling, which drive osteoclast differentiation via NFATC1, connecting lysosomal activity to bone resorption. Interacting partners include V-ATPase subunits, LAMP1, and SNX10, which collectively orchestrate endosomal trafficking and lysosomal pH homeostasis. Consequently, OSTM1 disruption uncouples CLCN7-dependent anion transport, elevates lysosomal pH, and impairs degradative capacity.
In Raji B lymphocytes, OSTM1 knockout provides a targeted system to explore the intersection of lysosomal dysfunction and B cell biology. Although OSTM1 is classically associated with osteoclast-mediated bone resorption, its role in lysosomal acidification is universal. Loss of OSTM1 in B cells may compromise lysosome-dependent processes including autophagy, antigen proteolysis, and the turnover of signaling molecules, potentially affecting cell growth, survival, or immune functions. The EBV-driven background further offers a setting to examine how lysosomal impairment influences viral latency, oncogenic programs, and the unfolded protein response. This model thus enables dissection of OSTM1-dependent pathways in a hematopoietic context devoid of osteoclast-specific confounding factors.
Researchers can utilize these polyclonal knockout cells in a variety of assays to interrogate lysosomal biology. Lysosomal pH can be measured using LysoTracker or ratiometric dyes, while CLCN7 and OSTM1 protein levels are assessed by western blotting and immunofluorescence for lysosomal markers. Autophagy flux can be monitored through LC3 turnover or p62 accumulation, and antigen presentation capacity evaluated via flow cytometry for surface MHC class II molecules. Additionally, RT-qPCR profiling of lysosomal genes (such as TFEB targets) and cathepsin activity assays provide functional readouts. The polyclonal population is particularly suited for high-throughput screens seeking modulators of lysosomal function, as the diverse knockout alleles reduce the risk of clonal artifacts. For further information or to request a quote, please contact Ascent Research.
