Tyrosine phosphorylation and activation of Janus kinase 1 and STAT3 by sublytic C5b-9 complement complex in aortic endothelial cells

Immunopharmacology. 1999 May;42(1-3):187-93. doi: 10.1016/s0162-3109(99)00014-4.


The pathway involving Janus kinase (JAK) and signal transducers and activators of transcription (STATs) plays an important role in differentiation and proliferation of cells initiated by receptor activation. In the present study we identified the JAK and STAT proteins activated by C5b-9 in human aortic endothelial cells (AEC). JAK1 but not JAK2 was tyrosine phosphorylated in response to sublytic C5b-9. STAT3 was rapidly tyrosine phosphorylated also by C5b-9. Pertussis toxin inhibited the C5b-9 induced JAK1 activation. However, phosphorylation of STAT3 was not inhibited by Pertussis toxin, although C5b-9 induced a time-dependent nuclear translocation of STAT3. These observations indicated that JAK1 is phosphorylated by C5b-9 through activation of trimeric G proteins of the Gi/Go family. Raf-1 and ERK1 were also activated by C5b-9 in human AEC in a G protein dependent manner. Therefore, JAK1 activity may be involved in activation of Raf-1 and ERK1 via G proteins activated by C5b-9. This study demonstrates the ability of membrane-inserted C5b-9 to activate JAK1 and STAT3 proteins, thus defining new signalling pathway by which C5b-9 may regulate gene activation.

Publication types

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

MeSH terms

  • Adult
  • Aorta / enzymology
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Cell Nucleus / metabolism
  • Cells, Cultured
  • Complement Membrane Attack Complex / pharmacology*
  • DNA-Binding Proteins / metabolism*
  • DNA-Binding Proteins / physiology
  • Endothelium, Vascular / enzymology*
  • Endothelium, Vascular / immunology
  • Endothelium, Vascular / metabolism
  • Enzyme Activation / immunology
  • Humans
  • Janus Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases*
  • Pertussis Toxin
  • Phosphorylation
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / metabolism*
  • Protein-Tyrosine Kinases / physiology
  • Proto-Oncogene Proteins c-raf / antagonists & inhibitors
  • Proto-Oncogene Proteins c-raf / metabolism
  • STAT3 Transcription Factor
  • STAT4 Transcription Factor
  • Signal Transduction / immunology
  • Trans-Activators / metabolism*
  • Trans-Activators / physiology
  • Tyrosine / metabolism*
  • Virulence Factors, Bordetella / pharmacology


  • Complement Membrane Attack Complex
  • DNA-Binding Proteins
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • STAT4 Transcription Factor
  • STAT4 protein, human
  • Trans-Activators
  • Virulence Factors, Bordetella
  • Tyrosine
  • Pertussis Toxin
  • Protein-Tyrosine Kinases
  • JAK1 protein, human
  • Janus Kinase 1
  • Proto-Oncogene Proteins c-raf
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases