Fc epsilon RI-mediated expression of mRNA for c-fos in rat basophilic leukemia cells does not require ongoing aggregation of the receptor.
Cross-linkage of the high-affinity receptor for IgE (Fc epsilon RI) by a polyvalent ligand, leads to activation of mast cells and basophils. We have studied Fc epsilon RI-mediated expression of RNA coding for the protooncogene, c-fos, in rat basophilic leukemia (RBL) cells and specifically have examined the requirements for ongoing receptor aggregation in the generation of this signal. RBL cells were sensitized with IgE specific for 2,4-dinitrophenyl (DNP) and incubated at 37 degrees C in the presence of DNP24BSA or BSA alone. Following activation for 0 to 30 min, the reaction was terminated. RNA was isolated and separated on denaturing gels, blotted to nylon membranes and hybridized with a 32P-labelled cDNA probe for c-fos. Messenger RNA for c-fos is detectable as early as 5-10 min following the addition of antigen and increases in a time-dependent fashion over 30 min. Unexpectedly, the addition of the hapten, 10(-4) M DNP-lysine, 5 min after the addition of antigen (which causes immediate cessation of exocytosis) does not dramatically alter the amount of message detected at 30 min. This effect is present as early as 2 min after cross-linking of the receptor and occurs at various doses of the aggregating stimulus. Thus, in contrast to the case with exocytosis and other well-described intracellular events, Fc epsilon RI-mediated increases in the level of mRNA for c-fos does not require ongoing aggregation of Fc epsilon RI.
Dogar
J H
JH
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262.
Nemeth
G G
GG
Durdik
J M
JM
Dreskin
S C
SC
D000818:Animals; D004136:Dinitrobenzenes / Q000276:immunology; D005089:Exocytosis; D016762:Genes, fos; D006241:Haptens; D015471:Leukemia, Basophilic, Acute / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011940:Receptor Aggregation; D017455:Receptors, IgE / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured / Q000276:immunology / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
D004136:Dinitrobenzenes; D006241:Haptens; D012333:RNA, Messenger; D017455:Receptors, IgE; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010738:Type C Phospholipases