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CK2 Is a C-Terminal IkappaB Kinase Responsible for NF-kappaB Activation during the UV Response

Tomohisa Kato1, Mireille Delhase, Alexander Hoffmann

  • 1Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.

Molecular Cell
|October 29, 2003
PubMed

Insights

Ultraviolet (UV) radiation activates NF-kappaB through a novel pathway involving p38 MAP kinase and CK2, independent of the typical IKK complex. This discovery clarifies UV-induced cellular responses and NF-kappaB activation mechanisms.

Area of Science:

  • Molecular Biology
  • Cellular Signaling
  • UV Radiation Biology

Background:

  • NF-kappaB is a key transcription factor activated by various stressors, including inflammation and infection.
  • Activation typically involves the IkappaB kinase (IKK) complex, phosphorylating IkappaBs at N-terminal sites.
  • The precise mechanism of NF-kappaB activation by ultraviolet (UV) radiation remained unclear, as it bypasses the IKK pathway.

Purpose of the Study:

  • To elucidate the mechanism of NF-kappaB activation induced by UV radiation.
  • To identify the specific molecular players involved in UV-mediated NF-kappaB signaling.
  • To understand the role of this pathway in cellular response to UV damage.

Main Methods:

  • Investigated UV-induced NF-kappaB activation in mammalian cells.
  • Utilized biochemical assays to study protein phosphorylation, including IkappaBalpha.
  • Employed kinase inhibitors to probe the roles of CK2 and p38 MAP kinase.
  • Assessed the impact of pathway inhibition on IkappaBalpha degradation and cell viability.

Main Results:

  • UV-induced NF-kappaB activation is independent of the IKK complex.
  • Demonstrated that UV radiation triggers phosphorylation of IkappaBalpha at C-terminal sites by CK2.
  • Showed that CK2 activity is UV-inducible via p38 MAP kinase activation.
  • Inhibition of the p38-CK2 pathway blocked UV-induced IkappaBalpha degradation and enhanced UV-induced cell death.

Conclusions:

  • The p38 MAP kinase-CK2-NF-kappaB signaling axis is critical for the mammalian cellular response to UV radiation.
  • This pathway represents a distinct mechanism of NF-kappaB activation compared to canonical inflammatory stimuli.
  • Understanding this axis offers insights into UV-induced DNA damage response and potential therapeutic targets.

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