Human geminin promotes pre-RC formation and DNA replication by stabilizing CDT1 in mitosis

Andrea Ballabeni, Marina Melixetian, Raffaella Zamponi, Laura Masiero, Federica Marinoni, Kristian Helin

Research output: Contribution to journalArticlepeer-review


Geminin is an unstable inhibitor of DNA replication that negatively regulates the licensing factor CDT1 and inhibits pre-replicative complex (pre-RC) formation in Xenopus egg extracts. Here we describe a novel function of Geminin. We demonstrate that human Geminin protects CDT1 from proteasome-mediated degradation by inhibiting its ubiquitination. In particular, Geminin ensures basal levels of CDT1 during S phase and its accumulation during mitosis. Consistently, inhibition of Geminin synthesis during M phase leads to impairment of pre-RC formation and DNA replication during the following cell cycle. Moreover, we show that inhibition of CDK1 during mitosis, and not Geminin depletion, is sufficient for premature formation of pre-RCs, indicating that CDK activity is the major mitotic inhibitor of licensing in human cells. Taken together with recent data from our laboratory, our results demonstrate that Geminin is both a negative and positive regulator of pre-RC formation in human cells, playing a positive role in allowing CDT1 accumulation in G2-M, and preventing relicensing of origins in S-G2.

Original languageEnglish
Pages (from-to)3122-3132
Number of pages11
JournalEMBO Journal
Issue number15
Publication statusPublished - Aug 4 2004


  • CDT1
  • Cell cycle
  • DNA replication
  • Geminin
  • Licensing

ASJC Scopus subject areas

  • Genetics
  • Cell Biology


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