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.
Oak
M H
MH
Pharmacology Laboratory, College of Pharmacy, Chonnam National University, Kwang-Ju, Korea.
Cheong
H
H
Kim
K M
KM
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