The DNAJB9 Knockout Raji Polyclonal Cells represent a CRISPR/Cas9-edited polyclonal knockout cell population derived from the human Raji B-lymphocyte line, with targeted disruption of the DNAJB9 gene. This product provides a loss-of-function model for studying the ER co-chaperone DNAJB9 (ERdj4), a critical regulator of endoplasmic reticulum-associated degradation (ERAD) and proteostasis. The polyclonal format comprises a heterogeneous pool of cells carrying diverse CRISPR/Cas9-mediated gene disruptions, avoiding clonal artifacts and enabling functional analysis in a population context ideal for screening and pathway dissection.
The Raji host cell line is an EBV-immortalized B-lymphoblastoid cell line isolated from a Burkitt’s lymphoma patient. These suspension-adapted cells display hallmark features of mature B lymphocytes, including antigen presentation and antibody secretion, while retaining oncogenic characteristics such as constitutive NF-??B activation. Their high secretory demand places exceptional reliance on ER quality control mechanisms, making them exquisitely sensitive to perturbations in protein folding and degradation pathways.
DNAJB9 functions as an ER luminal co-chaperone that directly interacts with the HSPA5/BiP ATPase to recognize misfolded proteins and shuttle them to the ERAD machinery, involving the SEL1L-HRD1 ubiquitin ligase complex, the SEC61 retrotranslocon, and the proteasome. It operates downstream of all three unfolded protein response (UPR) sensors??IRE1??, PERK, and ATF6??and is transcriptionally induced by the spliced XBP1s transcription factor and ATF4. Disruption of DNAJB9 uncouples BiP from ERAD substrate delivery, leading to accumulation of misfolded proteins, unresolved ER stress, and hyperactivation of the IRE1??-XBP1s and PERK-eIF2??-ATF4-CHOP signaling axes. Additional interacting partners include HSPA4 and the DERL1 adaptor, placing DNAJB9 at a central node coordinating proteasomal clearance.
In the Raji lymphoma context, DNAJB9 knockout imposes severe proteotoxic stress due to the cell line’s inherent immunoglobulin synthesis. Loss of this co-chaperone is predicted to sensitize cells to apoptosis under basal conditions and amplify UPR-mediated cell death upon exogenous ER stress, mirroring vulnerabilities in high-secretory B-cell malignancies. This model recapitulates ER stress-driven pathologies relevant to Burkitt’s lymphoma and other lymphoproliferative disorders, offering a platform to evaluate DNAJB9 as a therapeutic target and to dissect adaptive responses that sustain malignant growth.
Researchers can leverage these polyclonal knockout cells to quantify UPR activation via Western blotting for HSPA5/BiP, CHOP, and ATF4, or to monitor XBP1 splicing by RT-qPCR. Functional characterization includes flow cytometric assessment of apoptosis (Annexin V/PI), proteasome activity assays, and co-immunoprecipitation to verify loss of DNAJB9-HSPA5 complexes. Drug screening studies with thapsigargin or tunicamycin enable identification of ER stress modulators, while immunofluorescence reveals alterations in ER morphology. This cell population serves as a robust tool for advancing our understanding of ERAD in lymphomagenesis and for preclinical testing of strategies that exploit proteostatic vulnerabilities. For additional technical information or custom cell product inquiries, please contact Ascent Research.
