Proteomic Approach to FcepsilonRI aggregation-initiated signal transduction cascade in human mast cells.

Background: Mast cells (MCs) play a central role in allergic reactions through high-affinity IgE receptor (FcepsilonRI)-mediated responses. Many attempts have been performed to investigate MC functions, though molecular bases of the intracellular signaling cascade through FcepsilonRI, especially in human MCs, remain scant and unexplored.

Methods: Human MCs were differentiated from CD34+ cells by culture with stem cell factor, IL-6 and IL-3. The differential phosphorylation profiles of protein tyrosine residues in the resulting MCs with or without FcepsilonRI aggregation were examined by two-dimensional gel electrophoresis. The candidate phosphoproteins of interest were picked, in-gel digested and mass spectrometry fingerprinted.

Results: Approximately 40 proteins in MCs were phosphorylated on their tyrosine residues in response to activation and some of them were identified. Particularly IL-31 receptor alpha, solute carrier family 39, syntaxin 5 and heterogeneous nuclear ribonucleoprotein are newly identified as phosphoproteins that are potentially involved in the MC signaling cascade through FcepsilonRI.

Conclusion: Our present phosphoproteome data may provide the clue to understand the molecular mechanisms for the activation of human MCs.