Cell cycle activity and expression of prohibitin mRNA

Abstract

Prohibitin, a novel intracellular antiproliferative protein, blocks entry into the S phase of the cell division cycle when its mRNA is microinjected into normal fibroblasts or HeLa cells. To learn more about the interaction between prohibitin and the cell cycle, we studied the effect of microinjecting prohibitin mRNA at different points during the transition from G₀ to S phase and analyzed prohibitin mRNA and protein levels in different parts of the cell cycle. The antiproliferative activity of microinjected prohibitin mRNA is high in G₀/G₁ and falls as cells approach S phase. Prohibitin mRNA and protein levels are high in G₁, fall with S phase, rise again in G₂, and fall in M. Together, these findings suggest that endogenous prohibitin contributes to the control of the G₁ to S transition in cycling cells in a complex manner, which involves both a transcriptional and posttranslational mechanism.