Journal article

RNA polymerase I transcription in confluent cells: Rb downregulates rDNA transcription during confluence-induced cell cycle arrest

KM Hannan, BK Kennedy, AH Cavanaugh, RD Hannan, I Hirschler-Laszkiewicz, LS Jefferson, LI Rothblum

Oncogene | NATURE PUBLISHING GROUP | Published : 2000

Abstract

When 3T6 cells are confluent, they withdraw from the cell cycle. Concomitant with cell cycle arrest a significant reduction in RNA polymerase I transcription (80% decrease at 100% confluence) is observed. In the present study, we examined mechanism(s) through which transcription of the ribosomal genes is coupled to cell cycle arrest induced by cell density. Interestingly with an increase in cell density (from 3 - 43% confluence), a significant accumulation in the cellular content of hyperphosphorylated Rb was observed. As cell density increased further, the hypophosphorylated form of Rb became predominant and accumulated in the nucleoli. Co-immunoprecipitation experiments demonstrated there ..

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