Rapid induction of thymosin beta 4 in concanavalin A-stimulated thymocytes by translational control.
The expression of thymosin beta 4, an ubiquitous peptide of high cellular content, was studied in concanavalin A-stimulated rat thymocytes within the first 3 h after activation of the cells. An early 6.3-fold increase of the peptide occurred after 1 h of stimulation amounting to 0.4% of the total cellular protein. This increase coincided with that of thymosin beta 4 biosynthesis measured by [35S]methionine incorporation. The share of thymosin beta 4 synthesis in total protein synthesis 1 h after addition of concanavalin A amounts to 1% but no elevation of the corresponding mRNA was observed. These data suggest that a translational control mechanism is involved in this rapid induction. Consequently, actinomycin D did not inhibit thymosin beta 4 induction in contrast to cycloheximide. The peaks of maximal thymosin beta 4 levels and biosynthesis were followed by rapid decreases of these parameters suggesting a function of thymosin beta 4 in the early phase of T cell activation.
Institute of Biochemistry, Medical Faculty, University of Erlangen-Nuremberg, Federal Republic of Germany.
B
B
Schöbitz
R
R
Netzker
E
E
Hannappel
K
K
Brand
D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003208:Concanavalin A / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005260:Female; D007700:Kinetics; D014176:Protein Biosynthesis / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D013947:Thymosin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D013950:Thymus Gland / Q000378:metabolism; D000099201:Thymosin beta(4)
D003208:Concanavalin A; D003513:Cycloheximide; D003609:Dactinomycin; D013947:Thymosin; D000099201:Thymosin beta(4)