Open AccessRegulation of Prothymosin α During the Cell Cycle
Author(s) -
Vareli Katerina,
Tsolas Orestes,
FrangouLazaridis Maria
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0799w.x
Subject(s) - cell cycle , cell growth , e2f , biology , cyclin , microbiology and biotechnology , messenger rna , cell cycle protein , nuclear protein , cell division , cyclin a , proliferating cell nuclear antigen , transfection , transcription factor , cell , gene , biochemistry
A number of studies have indicated that the small nuclear acidic protein prothymosin α is associated with cellular‐proliferation events. For example, c‐myc causes immediate transcriptional activation of prothymosin α, and prothymosin α antisense oligonucleotides inhibit myeloma cell division. To investigate the regulation of prothymosin α, we examined its mRNA and protein levels during the cell cycle of mononuclear cells and fibroblastic cells. We isolated immunoreactive material from cellular extracts and immunolocalized the protein to the nucleus during the cell cycle. We report here that the material present in the cells is prothymosin α rather than the amino‐terminal peptide thymosin α1. [ 3 H]Thymidine‐incorporation studies associate maximum accumulation of mRNA and protein with the S/G2 phase of the cell cycle. This induction of prothymosin α mRNA seems to resemble cyclin B expression and is more pronounced in fibroblasts. Moreover, transient‐transfection experiments indicate that transcription factor E2F is a strong positive regulator of the prothymosin α gene. Our results are consistent with the hypothesis that prothymosin α is involved in proliferation checkpoints of the cell cycle.