Regulation of FcepsilonRI-mediated degranulation by an adaptor protein 3BP2 in rat basophilic leukemia RBL-2H3 cells.
Aggregation of high-affinity IgE receptor FcepsilonRI induces sequential activation of nonreceptor-type protein-tyrosine kinases and subsequent tyrosine phosphorylation of cellular proteins, leading to degranulation in mast cells. A hematopoietic cell-specific adaptor protein, 3BP2, that was originally identified as an Abl SH3-binding protein was rapidly tyrosine phosphorylated by the aggregation of FcepsilonRI on rat basophilic leukemia RBL-2H3 cells. Tyrosine phosphorylation of 3BP2 did not depend on calcium influx from external sources. To examine the role of 3BP2 in mast cells, we overexpressed the SH2 domain of 3BP2 in the RBL-2H3 cells. Overexpression of 3BP2-SH2 domain resulted in a suppression of antigen-induced degranulation as assessed by beta-hexosaminidase release. Even though overall tyrosine phosphorylation of cellular protein was not altered, antigen-mediated tyrosine phosphorylation of phospholipase C-gamma (PLC-gamma) and calcium mobilization were significantly suppressed in the cells overexpressing the 3BP2-SH2 domain. Furthermore, antigen stimulation induced the association of 3BP2-SH2 domain with LAT and other signaling molecule complexes in the RBL-2H3 cells. FcepsilonRI-mediated phosphorylation of JNK and ERK was not affected by the overexpression of 3BP2-SH2 domain. These data indicate that 3BP2 functions to positively regulate the FcepsilonRI-mediated tyrosine phosphorylation of PLC-gamma and thereby the signals leading to degranulation.
Division of Proteomics, Department of Genome Sciences, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan. ksada@med.kobe-u.ac.jp
Kiyonao
K
Sada
S M Shahjahan
SM
Miah
Koichiro
K
Maeno
Shinkou
S
Kyo
Xiujuan
X
Qu
Hirohei
H
Yamamura
D000818:Animals; D015703:Antigens, CD / Q000187:drug effects* / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D015550:Cell Degranulation / Q000187:drug effects*; D007527:Isoenzymes / Q000378:metabolism; D015471:Leukemia, Basophilic, Acute / Q000473:pathology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D051966:Phospholipase C gamma; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D011961:Receptors, Fc / Q000187:drug effects* / Q000502:physiology; D017455:Receptors, IgE / Q000187:drug effects* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains / Q000502:physiology
D015703:Antigens, CD; D002352:Carrier Proteins; C036832:Fc(alpha) receptor; D007527:Isoenzymes; D008565:Membrane Proteins; D011961:Receptors, Fc; D017455:Receptors, IgE; D014443:Tyrosine; D010738:Type C Phospholipases; D051966:Phospholipase C gamma