Mutant cells that do not respond to interleukin-1 (IL-1) reveal a novel role for IL-1 receptor-associated kinase

Mol Cell Biol. 1999 Jul;19(7):4643-52. doi: 10.1128/MCB.19.7.4643.

Abstract

Mutagenized human 293 cells containing an interleukin-1 (IL-1)-regulated herpes thymidine kinase gene, selected in IL-1 and gancyclovir, have yielded many independent clones that are unresponsive to IL-1. The four clones analyzed here carry recessive mutations and represent three complementation groups. Mutant A in complementation group I1 lacks IL-1 receptor-associated kinase (IRAK), while the mutants in the other two groups are defective in unknown components that function upstream of IRAK. Expression of exogenous IRAK in I1A cells (I1A-IRAK) restores their responsiveness to IL-1. Neither NFkappaB nor Jun kinase is activated in IL-1-treated I1A cells, but these responses are restored in I1A-IRAK cells, indicating that IRAK is required for both. To address the role of the kinase activity of IRAK in IL-1 signaling, its ATP binding site was mutated (K239A), completely abolishing kinase activity. In transfected I1A cells, IRAK-K239A was still phosphorylated upon IL-1 stimulation and, surprisingly, still complemented all the defects in the mutant cells. Therefore, IRAK must be phosphorylated by a different kinase, and phospho-IRAK must play a role in IL-1-mediated signaling that does not require its kinase activity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cell Line, Transformed
  • Genetic Complementation Test
  • Humans
  • Interleukin-1 / metabolism*
  • Interleukin-1 / pharmacology
  • Interleukin-1 Receptor-Associated Kinases
  • Mutagenesis
  • Phenotype
  • Phosphorylation
  • Protein Kinases / metabolism*
  • Protein Kinases / physiology
  • Receptors, Interleukin-1 / metabolism*
  • Signal Transduction*
  • Simplexvirus / enzymology
  • Simplexvirus / genetics
  • Thymidine Kinase / genetics

Substances

  • Interleukin-1
  • Receptors, Interleukin-1
  • Protein Kinases
  • Thymidine Kinase
  • Interleukin-1 Receptor-Associated Kinases