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Internalization of factor J and cellular signalization after factor J-cell interaction

S Larrucea1, R Cambronero, C González-Rubio

  • 1Unidad de Inmunología, Hospital La Paz, Madrid, 28046, Spain.

Biochemical and Biophysical Research Communications
|December 3, 1999
PubMed

Insights

Factor J (FJ) binds to cells, is internalized, and triggers intracellular signaling. This suggests FJ

Area of Science:

  • Immunology and Cell Biology
  • Complement System and Signal Transduction

Background:

  • Factor J (FJ) is a glycoprotein inhibiting complement activation.
  • FJ mediates cell adhesion via the nucleolin receptor.

Purpose of the Study:

  • Investigate cellular events following Factor J binding.
  • Elucidate the role of FJ in intracellular signal transduction.

Main Methods:

  • Cell incubation with Factor J (FJ) in K562 and Jurkat cell lines.
  • Analysis of FJ internalization and localization (cytoplasm, nucleus).
  • Assessment of tyrosine phosphorylation induced by FJ adhesion, compared to fibronectin (FN).

Main Results:

  • Factor J was actively internalized and localized intracellularly.
  • Cell adhesion to FJ induced tyrosine phosphorylation of proteins.
  • This phosphorylation pattern mimicked fibronectin effects and was inhibited by anti-FJ monoclonal antibody (mAb).

Conclusions:

  • Cellular binding of Factor J initiates intracellular biochemical signaling.
  • FJ may play a crucial role in signal transduction across the plasma membrane.

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