IL-15/IL-15Ralpha intracellular trafficking in human melanoma cells and signal transduction through the IL-15Ralpha

Oncogene. 2000 Oct 26;19(45):5153-62. doi: 10.1038/sj.onc.1203873.


There are two IL-15 isoforms and eight isoforms for the IL-15Ralpha chain whose biological role is poorly understood. Here, we have analysed the intracellular trafficking of IL-15 and IL-15Ralpha and tried to shed some light on their function(s). In IL-15/GFP CHO transfectants both IL-15 isoforms show nuclear localization. Two melanoma cell lines (MELP and MELREO) spontaneously expressing the IL-15 isoforms, display different intracellular trafficking of the IL-15/IL-15Ralpha complex. In MELP cells only IL-15Ralpha is detected inside the nucleus, whereas IL-15 and IL-15Ralpha assemble at the cell surface and are internalized. Moreover, the transducing molecule TRAF2 co-immunoprecipitates with IL-15Ralpha and may be deflected to TNFRI using anti-IL-15 blocking mAbs and TNF-alpha. By contrast, MELREO cells display IL-15Ralpha and IL-15 nuclear localization but only a partial co-localization of these molecules on the cell surface. In these cells, TRAF2 is strongly associated with IL-15Ralpha and cannot be deflected by any treatment. Since TRAF2 activates the transcription factor NF-kappaB, IL-15 through IL-15Ralpha, could have a role in the control of this pathway. Indeed, anti-IL-15 MaB inhibit the constitutive nuclear localization of NFkappaB and the phosphorylation of its inhibitor Ikappa-Balpha. Thus, IL-15Ralpha controls NF-kappaB activation, however differences in the intracellular trafficking of the IL-15 and/or IL-15Ralpha suggest a different biological role for this complex in MELP versus MELREO cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Cell Compartmentation
  • Cell Nucleus
  • Cricetinae
  • Green Fluorescent Proteins
  • Humans
  • Interleukin-15 / genetics
  • Interleukin-15 / isolation & purification
  • Interleukin-15 / metabolism*
  • Luminescent Proteins / genetics
  • Luminescent Proteins / isolation & purification
  • Melanoma / metabolism*
  • Microscopy, Confocal
  • NF-kappa B / metabolism
  • Protein Binding
  • Protein Sorting Signals
  • Protein Subunits
  • Protein Transport
  • Proteins / isolation & purification
  • Receptors, Interleukin-15
  • Receptors, Interleukin-2 / genetics
  • Receptors, Interleukin-2 / isolation & purification
  • Receptors, Interleukin-2 / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction
  • TNF Receptor-Associated Factor 2


  • IL15RA protein, human
  • Interleukin-15
  • Luminescent Proteins
  • NF-kappa B
  • Protein Sorting Signals
  • Protein Subunits
  • Proteins
  • Receptors, Interleukin-15
  • Receptors, Interleukin-2
  • Recombinant Fusion Proteins
  • TNF Receptor-Associated Factor 2
  • Green Fluorescent Proteins