Cell-cycle-regulated expression of thymosin beta 4 in thymocytes.
Thymosin beta 4 belongs to a family of ubiquitous peptides present at a high cellular content but still with an unknown intracellular function. The expression of this peptide was studied in concanavalin-A-stimulated, proliferating rat thymocytes during cell cycle progression. An early, transient 10-fold increase of the peptide occurred 1 h after stimulation without elevation of the corresponding mRNA level. This increase coincided with that of thymosin beta 4 biosynthesis. The sharp decline of the thymosin beta 4 content was not due to a secretion of the peptide into the medium. During S phase and mitosis, the biosynthetic rates as well as mRNA content, but not the cellular thymosin beta 4 concentration, increased again. After 96 h of culture the values returned to those of quiescent cells.
Schöbitz
B
B
Institute of Biochemistry, Medical Faculty, University of Erlangen-Nürnberg, Federal Republic of Germany.
Netzker
R
R
Hannappel
E
E
Brand
K
K
D000818:Animals; D002453:Cell Cycle; D002478:Cells, Cultured; D003208:Concanavalin A; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication; D005260:Female; D007700:Kinetics; D008213:Lymphocyte Activation; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013947:Thymosin / Q000031:analogs & derivatives* / Q000096:biosynthesis; D000099201:Thymosin beta(4)
D003208:Concanavalin A; D004247:DNA; D012313:RNA; D013947:Thymosin; D000099201:Thymosin beta(4)