Hmgb1 Knockout iBMDM Cell Line

The Hmgb1 Knockout iBMDM Cell Line is a CRISPR/Cas9-edited knockout cell line derived from immortalized C57BL/6 mouse bone marrow-derived macrophages (iBMDMs) carrying a targeted disruption of the Hmgb1 gene. This loss-of-function model enables precise investigation of HMGB1-dependent signaling in a well-characterized macrophage background.

The parental iBMDM cell line originates from C57BL/6 mouse bone marrow-derived macrophages that have been immortalized, retaining key macrophage functions including phagocytosis, antigen presentation, and cytokine secretion. This homogeneous and genetically tractable host system provides a robust platform for dissecting macrophage-specific gene functions and signaling pathways.

HMGB1 is a highly conserved DNA-binding protein that functions as a damage-associated molecular pattern (DAMP) when released into the extracellular milieu during cellular stress or necrotic cell death. Extracellular HMGB1 engages receptors TLR4 and RAGE, triggering MyD88-dependent signal transduction that culminates in the activation of NF-??B and MAP kinase cascades, including ERK1/2 and p38. This signaling axis drives the transcriptional upregulation of pro-inflammatory mediators such as IL-6 and TNF-??. Release of HMGB1 is stimulated by upstream signals including TNF-??, IL-1??, lipopolysaccharide (LPS), and oxidative stress, and it interacts directly with p53 and the NF-??B p65 (RELA) subunit within the nucleus, linking inflammation to transcriptional and cell fate decisions.

Ablation of Hmgb1 in iBMDM cells abrogates the major alarmin-driven feedforward loop that amplifies macrophage inflammatory responses. In the knockout cells, stimulation with LPS, TNF-??, or other danger signals fails to fully activate TLR4/RAGE-dependent NF-??B and MAPK pathways, resulting in attenuated secretion of IL-6, TNF-??, and other effector cytokines. Consequently, key macrophage functional outputs??including phagocytic capacity, antigen presentation, and chemotactic migration??are altered, making this cell line a definitive tool for distinguishing HMGB1-dependent from HMGB1-independent mechanisms in macrophage biology.

Researchers employ this knockout cell line in a variety of experimental settings to probe innate immune regulation. It is suitable for DAMP signaling analysis, where the absence of HMGB1 clarifies its contribution to TLR4/RAGE-mediated inflammatory cascades; for sepsis and acute lung injury models, where HMGB1 acts as a late mediator; and for rheumatoid arthritis and ischemia-reperfusion injury studies, where extracellular HMGB1 exacerbates tissue damage. The line is also used in macrophage polarization experiments to determine how HMGB1 influences M1/M2 balance, and in high-throughput screening campaigns aimed at identifying small-molecule HMGB1 inhibitors. Representative assay readouts include HMGB1 western blotting and ELISA to confirm knockout, NF-??B luciferase reporters for pathway activity, RT-qPCR for cytokine transcripts, immunofluorescence for subcellular localization, and functional assays such as phagocytosis and transwell migration. For further technical details, please contact Ascent Research.