Physical and functional interaction between Hck tyrosine kinase and guanine nucleotide exchange factor C3G results in apoptosis, which is independent of C3G catalytic domain

J Biol Chem. 2003 Dec 26;278(52):52188-94. doi: 10.1074/jbc.M310656200. Epub 2003 Oct 9.


The hematopoietic cell kinase Hck is a Src family tyrosine kinase expressed in cells of myelomonocytic lineage, B lymphocytes, and embryonic stem cells. To study its role in signaling pathways we used the Hck-SH3 domain in protein interaction cloning and identified C3G, the guanine nucleotide exchange factor for Rap1 and R-Ras, as a protein that associated with Hck. This interaction was direct and was mediated partly through the proline-rich region of C3G. C3G could be co-immunoprecipitated with Hck from Cos-1 cells transfected with Hck and C3G. C3G was phosphorylated on tyrosine 504 in cells when coexpressed with Hck but not with a catalytically inactive mutant of Hck. Phosphorylation of endogenous C3G at Tyr-504 was increased by treatment of human myelomonocytic THP-1 cells with mercuric chloride, which is known to activate Hck tyrosine kinase specifically. Coexpression of Hck with C3G induced a high level of apoptosis in many cell lines by 30-42 h of transfection. Induction of apoptosis was not dependent on Tyr-504 phosphorylation or the catalytic domain of C3G but required the catalytic activity of Hck. Using dominant negative constructs of caspases we found that caspase-1, -8, and -9 are involved in this apoptotic pathway. These results suggest that C3G and Hck interact physically and functionally in vivo to activate kinase-dependent and caspase-mediated apoptosis, which is independent of catalytic domain of C3G.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Blotting, Western
  • COS Cells
  • Caspase 1 / metabolism
  • Caspase 8
  • Caspase 9
  • Caspases / metabolism
  • Catalysis
  • Catalytic Domain
  • Cell Line
  • Cell Line, Tumor
  • Electrophoresis, Polyacrylamide Gel
  • Genes, Dominant
  • Genetic Vectors
  • Glutathione Transferase / metabolism
  • Guanine Nucleotide-Releasing Factor 2 / chemistry
  • Guanine Nucleotide-Releasing Factor 2 / metabolism*
  • HeLa Cells
  • Humans
  • Mercuric Chloride / pharmacology
  • Microscopy, Fluorescence
  • Phosphorylation
  • Precipitin Tests
  • Protein Binding
  • Protein-Tyrosine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-hck
  • Signal Transduction
  • Time Factors
  • Transfection
  • Tyrosine / metabolism
  • rap1 GTP-Binding Proteins / metabolism
  • src Homology Domains


  • Guanine Nucleotide-Releasing Factor 2
  • Proto-Oncogene Proteins
  • Tyrosine
  • Mercuric Chloride
  • Glutathione Transferase
  • Protein-Tyrosine Kinases
  • HCK protein, human
  • Proto-Oncogene Proteins c-hck
  • CASP8 protein, human
  • CASP9 protein, human
  • Caspase 8
  • Caspase 9
  • Caspases
  • Caspase 1
  • rap1 GTP-Binding Proteins