Real-time imaging of ligand-induced IKK activation in intact cells and in living mice

Nat Methods. 2005 Aug;2(8):607-14. doi: 10.1038/nmeth779.


The transcription factor NF-kappaB is a key regulator of cellular activation, proliferation and apoptosis. Defects in the NF-kappaB pathway contribute to a broad array of malignant, neurodegenerative and chronic inflammatory diseases. IKK-dependent IkappaB alpha degradation by the 26S proteasome is a critical NF-kappaB regulatory control point, which is emerging as an important target for drug development. To directly monitor regulation of IKK activation in intact organisms, we engineered an IkappaB alpha-firefly luciferase (IkappaB alpha-FLuc) fusion reporter. In cultured cells and living animals, the reporter provided a continuous, noninvasive readout of the kinetics of ligand-induced IKK activation and the pharmacodynamics of selective inhibitors of both IKK and the 26S proteasome. This IkappaB alpha-FLuc reporter now permits continuous readout of IKK activation in vivo, facilitates development and validation of target-specific therapeutics, and complements conventional NF-kappaB transcriptional reporters for more complete temporal and regional investigations of the NF-kappaB signaling pathway in health and disease.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Computer Systems
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / physiology
  • HeLa Cells
  • Humans
  • I-kappa B Proteins / genetics
  • I-kappa B Proteins / metabolism*
  • Intracellular Signaling Peptides and Proteins
  • Ligands
  • Luciferases, Firefly
  • Mice
  • Microscopy, Fluorescence / methods*
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • Spectrometry, Fluorescence / methods*
  • Tissue Distribution
  • Transcriptional Elongation Factors
  • Tumor Necrosis Factor-alpha / pharmacology


  • Carrier Proteins
  • Elp1 protein, human
  • I-kappa B Proteins
  • Ikbkap protein, mouse
  • Intracellular Signaling Peptides and Proteins
  • Ligands
  • NF-kappa B
  • NFKBIA protein, human
  • Nfkbia protein, mouse
  • Recombinant Fusion Proteins
  • Transcriptional Elongation Factors
  • Tumor Necrosis Factor-alpha
  • NF-KappaB Inhibitor alpha
  • Luciferases, Firefly