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

TY - JOUR

T1 - Human geminin promotes pre-RC formation and DNA replication by stabilizing CDT1 in mitosis.

AU - Ballabeni, Andrea

AU - Melixetian, Marina

AU - Zamponi, Raffaella

AU - Masiero, Laura

AU - Marinoni, Federica

AU - Helin, Kristian

N1 - Keywords: Animals; Cell Cycle Proteins; Cell Line, Tumor; Cercopithecus aethiops; Cyclin-Dependent Kinases; DNA; DNA Replication; Enzyme Activation; G1 Phase; Gene Deletion; Gene Expression Regulation; Humans; Mitosis; Proteasome Endopeptidase Complex; Protein Binding; Ubiquitins

PY - 2004

Y1 - 2004

N2 - 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.

AB - 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.

U2 - 10.1038/sj.emboj.7600314

DO - 10.1038/sj.emboj.7600314

M3 - Journal article

C2 - 15257290

SN - 0261-4189

VL - 23

SP - 3122

EP - 3132

JO - E M B O Journal

JF - E M B O Journal

IS - 15

ER -