Differential expression of spleen tyrosine kinase Syk isoforms in tissues: Effects of the microbial flora

Histochem Cell Biol. 2006 Oct;126(4):495-505. doi: 10.1007/s00418-006-0188-z. Epub 2006 May 18.


Spleen tyrosine kinase (Syk) is expressed widely in hematopoietic and non-hematopoietic cells. The widespread distribution of Syk and its involvement in host defense and allergic reactions, prompted us analyze the influence of microbial exposure on Syk expression. We compared the distribution of Syk in various tissues of germ-free and conventional mice using immunohistochemistry, Western blot analysis and real time RT-PCR. Total Syk expression was similar between germ-free and conventional mice. Since it has been claimed that Syk isoforms are differentially expressed, we studied the distribution and abundance of Syk (L) and Syk (S) isoforms in tissues from these mice. In contrast to previous reports, we found broad tissue expression of Syk (S). Interestingly, in germ-free mice the amount of Syk (S) but not Syk L protein was selectively increased in lung and spleen. In summary, our study reveals new and broad tissue expression of both Syk isoforms and demonstrates that lack of microbial flora results in selectively increased expression of Syk (S) isoform in lung and spleen.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Cells, Cultured
  • Germ-Free Life*
  • Humans
  • Immunohistochemistry
  • Intracellular Signaling Peptides and Proteins / analysis
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Lung / enzymology*
  • Mice
  • Mice, Inbred C57BL
  • Protein Isoforms / analysis
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein-Tyrosine Kinases / analysis
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism*
  • RNA, Messenger / analysis
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spleen / enzymology*
  • Syk Kinase
  • Tissue Distribution
  • Transfection
  • Up-Regulation


  • Intracellular Signaling Peptides and Proteins
  • Protein Isoforms
  • RNA, Messenger
  • Protein-Tyrosine Kinases
  • SYK protein, human
  • Syk Kinase
  • Syk protein, mouse