Activation of src family kinases in human pre-B cells by IL-7

J Immunol. 1994 Jul 1;153(1):97-109.

Abstract

IL-7 was identified originally as a specific pre-B cell growth factor. We have investigated its signal transduction mechanism by using the human pre-B cell line Nalm-6, and have found that it stimulates tyrosine phosphorylation of various proteins: pp27, pp43, pp54, pp64, pp78, pp90, pp105, and pp120. Antiphosphotyrosine immunoprecipitates from IL-7-stimulated Nalm-6 showed two major proteins of M(r) = 60,000 and 55,000, capable of autophosphorylation. Autophosphorylation was maximal 10 min after the cells were challenged with the cytokine. Antiphosphotyrosine immunoprecipitates from IL-7-stimulated cells also increased tyrosine phosphorylation of the exogenously added substrate histone H2B. Furthermore, by using a polyclonal anti-IL-7 receptor (IL-7R) Ab in Western blotting analysis, we observed that antiphosphotyrosine immunoprecipitates were associated with the IL-7R in a transient manner. These data indicate that the IL-7R associates with tyrosine-phosphorylated proteins as its amino acid sequence is devoid of a putative site of tyrosine phosphorylation. These results were confirmed as several 32P-labeled proteins were visualized after immunoprecipitation by using anti-IL-7R Ab. Anti-IL-7R immunoprecipitates from IL-7-stimulated cells revealed a unique band of M(r) = 60,000 associated with the receptor able to autophosphorylate in the presence of ATP and Mn2+. Hence, we identified p59fyn and p53/56lyn to be stimulated by IL-7. In contrast to p53/56lyn, p59fyn was found to be associated constitutively with the cloned IL-7R. These data emphasize the role of the src family in hematopoiesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • B-Lymphocytes / cytology
  • B-Lymphocytes / enzymology*
  • Cell Differentiation
  • Enzyme Activation
  • Hematopoiesis
  • Humans
  • Interleukin-7 / pharmacology*
  • Molecular Sequence Data
  • Peptides / chemistry
  • Phosphoproteins / metabolism
  • Phosphotyrosine
  • Protein-Tyrosine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-fyn
  • Receptors, Interleukin / chemistry
  • Receptors, Interleukin / metabolism*
  • Receptors, Interleukin-7
  • Signal Transduction
  • Tyrosine / analogs & derivatives
  • Tyrosine / metabolism
  • src-Family Kinases*

Substances

  • Interleukin-7
  • Peptides
  • Phosphoproteins
  • Proto-Oncogene Proteins
  • Receptors, Interleukin
  • Receptors, Interleukin-7
  • Phosphotyrosine
  • Tyrosine
  • Protein-Tyrosine Kinases
  • FYN protein, human
  • Proto-Oncogene Proteins c-fyn
  • lyn protein-tyrosine kinase
  • src-Family Kinases