Roles of the transmembrane domain and the cytoplasmic domain of Fc epsilon RI alpha in immunoglobulin E-mediated up-regulation of surface Fc epsilon RI expression.
BACKGROUND
Human mast cells express both Fc epsilon RI alpha and Fc gamma RI alpha. IgE up-regulates Fc epsilon RI alpha expression, but IgG1 does not up-regulate Fc gamma RI alpha expression. The transmembrane domain (TM) of Fc gamma RI alpha determines the stability of cell surface expression of this receptor.


OBJECTIVE
The aim of this study was to clarify the roles of the TM and cytoplasmic domain (CY) of Fc epsilon RI alpha in IgE-mediated Fc epsilon RI up-regulation.


METHODS
Chimeric receptors created by domain shuffling between Fc epsilon RI alpha and Fc gamma RI alpha were transduced into human mast cell line HMC-1. Cell surface expression of the chimeric receptors and the effect of IgE or IgG1 on chimeric receptor expression were examined by FACS. The association of the chimeric receptors with FcR gamma was investigated by immunoprecipitation.


RESULTS
The results showed that the TM and CY of Fc epsilon RI alpha are not essential for IgE-mediated up-regulation of surface Fc epsilon RI.


CONCLUSIONS
The extracellular domain of each Fc receptor determines the diversity of Ig-regulated Fc receptor expression.
Okayama
Y
Y
Research Unit for Allergy Transcriptome, Research Center for Allergy and Immunology, RIKEN Yokohama Institute, Yokohama, Japan. yokayama@rcai.riken.go.jp
Kagaya
S
S
Yuki
K
K
Arai
T
T
Saito
H
H
D002460:Cell Line; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000276:immunology*; D008407:Mast Cells / Q000276:immunology*; D012313:RNA / Q000378:metabolism; D017455:Receptors, IgE / Q000378:metabolism*; D017452:Receptors, IgG / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D017455:Receptors, IgE; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D007073:Immunoglobulin E; D012313:RNA