Portal de Periódicos da CAPES

Regulation of Prothymosin α During the Cell Cycle

1996; Wiley; Volume: 238; Issue: 3 Linguagem: Inglês

10.1111/j.1432-1033.1996.0799w.x

1432-1033

Katerina Vareli, Orestes Tsolas, Maria Frangou‐Lazaridis,

Plant Disease Resistance and Genetics

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.