Activation of Fc epsilon RI inhibits the pyruvate kinase through direct interaction with the gamma-chain.
The downstream signaling components of high-affinity IgE receptor (FcepsilonRI) were studied using yeast two-hybrid screening of the cDNA library constructed from RBL-2H3 cells. The cytoplasmic part of the gamma-chain but not that of the beta-chain was found to interact with pyruvate kinase in the yeast. The in-vitro-translated pyruvate kinase also specifically interacted with the bacterially expressed glutathione-S transferase fusion protein of the cytoplasmic part of the gamma-chain. When RBL-2H3 cells were challenged with antigen, the activity of pyruvate kinase gradually decreased, reaching the minimum activity around 5 min after the activation, and then slowly returned to the normal level. The dose-response curve (antigen vs. pyruvate kinase activity) plotted at 5 min after stimulation showed that the pyruvate kinase was dose-dependently inhibited and the maximum inhibition was reached at the concentration of 0.1 microgram/ml of antigen. Direct interaction between FcepsilonRI and pyruvate kinase was also demonstrated by co-immunoprecipitation in RBL-2H3 cells. These data suggest that pyruvate kinase is functionally linked with FcepsilonRI and might exert an important role in controlling cellular functions following the activation of FcepsilonRI.
Pharmacology Laboratory, College of Pharmacy, Chonnam National University, Kwang-Ju, Korea.
M H
MH
Oak
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H
Cheong
K M
KM
Kim
D000818:Animals; D015550:Cell Degranulation; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005189:False Positive Reactions; D006801:Humans; D007142:Immunoglobulin gamma-Chains / Q000502:physiology*; D008407:Mast Cells / Q000166:cytology; D011770:Pyruvate Kinase / Q000037:antagonists & inhibitors*; D017455:Receptors, IgE / Q000737:chemistry / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors; D014407:Tumor Cells, Cultured
D007142:Immunoglobulin gamma-Chains; D017455:Receptors, IgE; D011770:Pyruvate Kinase