Article abstract
Nature Cell Biology 4, 358 - 366 (2002)
Published online: 22 April 2002 | doi:10.1038/ncb785
E2F-dependent accumulation of hEmi1 regulates S phase entry by inhibiting APCCdh1
Jerry Y. Hsu1,2, Julie D.R. Reimann1, Claus S. Sørensen3, Jiri Lukas3 & Peter K. Jackson1,2
Abstract
Emi1 promotes mitotic entry in Xenopus laevis embryos by inhibiting the APCCdc20 ubiquitination complex to allow accumulation of cyclin B. We show here that human Emi1 (hEmi1) functions to promote cyclin A accumulation and S phase entry in somatic cells by inhibiting the APCCdh1 complex. At the G1–S transition, hEmi1 is transcriptionally induced by the E2F transcription factor, much like cyclin A. hEmi1 overexpression accelerates S phase entry and can override a G1 block caused by overexpression of Cdh1 or the E2F-inhibitor p105 retinoblastoma protein (pRb). Depleting cells of hEmi1 through RNA interference prevents accumulation of cyclin A and inhibits S phase entry. These data suggest that E2F can activate both transcription of cyclin A and the hEmi1-dependent stabilization of APCCdh1 targets, such as cyclin A, to promote S phase entry.
- Departments of Pathology, Microbiology & Immunology, and Program in Biophysics, Stanford, CA 94305, USA
- Program in Cancer Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Institute of Cancer Biology, Danish Cancer Society, DK-2100 Copenhagen, Denmark
Correspondence to: Peter K. Jackson1,2 e-mail: pjackson@stanford.edu
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