What effect does TNFα have on NF-κB occupancy of the Cxcl2 promoter?

• A. Decreases NF-κB occupancy
• B. Increases NF-κB occupancy
• C. Has no effect on NF-κB occupancy
• D. Eliminates NF-κB occupancy

Answer: (B)

TNFα, or Tumor Necrosis Factor-alpha, is a pro-inflammatory cytokine that plays a significant role in regulating immune responses and is known to activate multiple intracellular signaling pathways. One of the major pathways it activates is the NF-κB (Nuclear Factor kappa-light-chain-enhancer of activated B cells) signaling pathway.

When TNFα binds to its receptor, it initiates a cascade of events that results in the activation of the IKK (IκB kinase) complex. This activation leads to the phosphorylation and degradation of IκB proteins, which normally sequester NF-κB dimers in the cytoplasm and prevent their translocation to the nucleus. Once IκB is degraded, NF-κB is released and can translocate to the nucleus, where it binds to specific promoter regions of target genes, such as the Cxcl2 gene.

The Cxcl2 promoter contains responsive elements for NF-κB. Therefore, upon stimulation with TNFα, NF-κB occupancy at the Cxcl2 promoter increases, leading to enhanced expression of Cxcl2. This is an important aspect of the inflammatory response, as Cxcl2 is a chemokine