CELL-CYCLE ACTIVITY AND EXPRESSION OF PROHIBITION MESSENGER-RNA

Prohibitin, a novel intracellular antiproliferative protein, blocks en try into the S phase of the cell division cycle when its mRNA is micro injected into normal fibroblasts or HeLa cells. To learn more about th e interaction between prohibitin and the cell cycle, we studied the ef fect 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 ac tivity 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, the se findings suggest that endogenous prohibitin contributes to the cont rol of the G, to S transition in cycling cells in a complex manner, wh ich involves both a transcriptional and posttranslational mechanism. ( C) 1993 Wiley-Liss, Inc.