The BAG3 Knockout 143B Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the 143B human osteosarcoma cell line (Homo sapiens), in which the gene encoding BAG3 (Bcl-2-associated athanogene 3) has been disrupted. This product provides a heterogeneous pool of cells carrying diverse gene-editing events at the BAG3 locus, resulting in loss of functional BAG3 protein expression. The polyclonal format offers a physiologically relevant model system to study the collective consequences of BAG3 inactivation without clonal selection biases, closely mimicking the genetic variability encountered in tumor cell populations.
The 143B host cell line is a well-characterized subclone of the HOS (Human Osteogenic Sarcoma) cell line, widely employed as a model for bone cancer biology. Originally isolated from a human osteosarcoma, 143B cells exhibit transformed properties including robust proliferation and the capacity to form tumors in xenograft models. This cellular background is particularly suited for dissecting oncogenic signaling cascades, drug response mechanisms, and the role of cellular quality control pathways in tumor maintenance, providing a clinically relevant context for cancer research.
BAG3 functions as a stress-inducible co-chaperone that orchestrates chaperone-mediated autophagy by bridging the HSP70 (HSPA1A) chaperone complex to the autophagic machinery. It interacts directly with HSP70, the small heat shock protein HSPB8, and the ubiquitin ligase CHIP (STUB1), facilitating the recognition and targeting of ubiquitinated misfolded proteins to autophagosomes. BAG3 also associates with 14-3-3 proteins and Bcl-2 family members, linking proteostasis to apoptosis regulation. Under proteotoxic stress, BAG3 expression is upregulated by the transcription factor HSF1, promoting the formation of the BAG3?CHSP70?CHSPB8 complex. This complex engages cargo receptors such as p62 (SQSTM1) and the autophagosome marker LC3 (MAP1LC3B), delivering aggregated substrates for lysosomal degradation. Consequently, BAG3 is a critical node in the proteostasis network, preventing accumulation of damaged proteins and inhibiting intrinsic apoptotic signaling through its interactions with Bcl-2 and other apoptotic regulators.
In 143B osteosarcoma cells, disruption of BAG3 profoundly compromises the chaperone-assisted selective autophagy pathway, leading to impaired clearance of polyubiquitinated protein aggregates and heightened sensitivity to proteotoxic and chemotherapeutic stressors. The BAG3 knockout model reveals the dependency of these cancer cells on BAG3-mediated proteostasis for survival under adverse conditions, such as nutrient deprivation or drug treatment. This vulnerability makes the BAG3 knockout 143B cells a powerful tool for investigating the mechanisms by which aggressive bone cancer cells cope with proteotoxic stress and evade apoptosis, potentially uncovering synthetic lethal interactions or therapeutic targets.
This polyclonal knockout cell product is suitable for a broad range of advanced research applications, including autophagy flux analyses using tandem fluorescent LC3 reporters or LC3 turnover assays, quantification of autophagic substrates via western blotting for p62 and LC3-II, and assessment of apoptosis by caspase-3/7 activation and annexin V staining. Furthermore, it enables co-immunoprecipitation studies to confirm disrupted BAG3?CHSP70 or BAG3?CHSPB8 complexes, and immunofluorescence microscopy to visualize autophagosome accumulation. The model is also well suited for viability assays under stress conditions, drug resistance profiling, and mechanistic studies of HSF1?CBAG3?Cautophagy signaling in cancer. For further information, please contact Ascent Research.
