Cell‐cycle‐regulated expression of thymosin β₄ in thymocytes

Abstract

Thymosin p4 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 p4 biosynthesis. The sharp decline of the thymosin p4 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 p4 concentration, increased again.

Glucose regulates the promoter activity of aldolase A and pyruvate kinase M2 via dephosphorylation of Sp1

“…This phenomenon has been demonstrated also in proliferating thymocytes [6]. Mitogen‐stimulated rat thymocytes cultured in a conventional medium containing glucose induce their glycolytic enzymes 8–10‐fold in the S‐phase of the cell cycle and divide within a culture period of 72 h [7–9]. Deprivation of glucose from the medium prevents glycolytic enzyme induction and proliferation of thymocytes [4].…”

Differences in DNA‐binding efficiency of Sp1 to aldolase and pyruvate kinase promoter correlate with altered redox states in resting and proliferating rat thymocytes

“…A complete cell cycle of mitogen-activated thymocytes has been obtained [1,3,4]. Cell division is completed after 72 h of culture with the S-phase peaking between 44 h and 48 h. Induction of glycolytic enzymes has been shown to be well correlated with controlled proliferation [2].…”

Redox‐regulated expression of glycolytic enzymes in resting and proliferating rat thymocytes

“…Thymocytes were harvested after 42-48 h of culture, which corresponds to the maximum of the S phase of the cell cycle [1,7]. Cell extracts were obtained by ultrasonication of the cells in KSP for five separate periods of 6 s at 70 W with a Branson sonifier.…”