Geminin is bound to chromatin in G2/M phase to promote proper cytokinesis

Nakuci, Enkeleda; Xu, Mai; Pujana, Miguel Ángel; Valls, Joan; ElShamy, Wael M.

doi:10.1016/j.biocel.2005.12.017

Cited by 15 publications

(62 citation statements)

References 43 publications

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“…The oncosuppressor, retinoblastoma protein, also shows multiple bands on western blots [21], and this is due to the phosphorylation of serine/threonine sites by cdc2 kinase. Geminin is thought to be phosphorylated at both serine/threonine and tyrosine residues by cell cycledependent kinases [22,23] and it is therefore possible that the 28-kDa geminin band could have resulted from hyperphosphorylation.…”

Section: Discussionmentioning

confidence: 99%

Geminin, Ki67, and minichromosome maintenance 2 in gastric hyperplastic polyps, adenomas, and intestinal-type carcinomas: pathobiological significance

et al. 2010

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Section: Discussionmentioning

confidence: 99%

Geminin, Ki67, and minichromosome maintenance 2 in gastric hyperplastic polyps, adenomas, and intestinal-type carcinomas: pathobiological significance

et al. 2010

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“…Since then, however, roles for geminin during mitosis have been described [12-20], arguing against its mitotic degradation, at least in mammalian cells. More precisely, geminin silencing in human mammary epithelial (HME) cells [12] or mouse embryos [14], while showing minimal effect on S-phase progression, completely blocked the progress through mitosis [12]. The HME mitosis-arrested cells (due to geminin silencing) showed increased expression and activity of cyclin B1, checkpoint protein 1 (Chk1), and Cdc7 [12].…”

Section: Introductionmentioning

confidence: 99%

“…More precisely, geminin silencing in human mammary epithelial (HME) cells [12] or mouse embryos [14], while showing minimal effect on S-phase progression, completely blocked the progress through mitosis [12]. The HME mitosis-arrested cells (due to geminin silencing) showed increased expression and activity of cyclin B1, checkpoint protein 1 (Chk1), and Cdc7 [12]. Surprisingly, only Cdc7 cosilencing triggered apoptosis in geminin-silenced cells [12], implying that Cdc7 is the kinase that maintains the cytokinetic checkpoint induced by geminin silencing in HME cells [12].…”

Section: Introductionmentioning

confidence: 99%

Geminin overexpression prevents the completion of topoisomerase IIα chromosome decatenation, leading to aneuploidy in human mammary epithelial cells

et al. 2011

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IntroductionThe nuclear enzyme topoisomerase IIα (TopoIIα) is able to cleave DNA in a reversible manner, making it a valuable target for agents such as etoposide that trap the enzyme in a covalent bond with the 5′ DNA end to which it cleaves. This prevents DNA religation and triggers cell death in cancer cells. However, development of resistance to these agents limits their therapeutic use. In this study, we examined the therapeutic targeting of geminin for improving the therapeutic potential of TopoIIα agents.MethodsHuman mammary epithelial (HME) cells and several breast cancer cell lines were used in this study. Geminin, TopoIIα and cell division cycle 7 (Cdc7) silencing were done using specific small interfering RNA. Transit or stable inducible overexpression of these proteins and casein kinase Iε (CKIε) were also used, as well as several pharmacological inhibitors that target TopoIIα, Cdc7 or CKIε. We manipulated HME cells that expressed H2B-GFP, or did not, to detect chromosome bridges. Immunoprecipitation and direct Western blot analysis were used to detect interactions between these proteins and their total expression, respectively, whereas interactions on chromosomal arms were detected using a trapped in agarose DNA immunostaining assay. TopoIIα phosphorylation by Cdc7 or CKIε was done using an in vitro kinase assay. The TopoGen decatenation kit was used to measure TopoIIα decatenation activity. Finally, a comet assay and metaphase chromosome spread were used to detect chromosome breakage and changes in chromosome condensation or numbers, respectively.ResultsWe found that geminin and TopoIIα interact primarily in G2/M/early G1 cells on chromosomes, that geminin recruits TopoIIα to chromosomal decatenation sites or vice versa and that geminin silencing in HME cells triggers the formation of chromosome bridges by suppressing TopoIIα access to chromosomal arms. CKIε kinase phosphorylates and positively regulates TopoIIα chromosome localization and function. CKIε kinase overexpression or Cdc7 kinase silencing, which we show phosphorylates TopoIIα in vitro, restored DNA decatenation and chromosome segregation in geminin-silenced cells before triggering cell death. In vivo, at normal concentration, geminin recruits the deSUMOylating sentrin-specific proteases SENP1 and SENP2 enzymes to deSUMOylate chromosome-bound TopoIIα and promote its release from chromosomes following completion of DNA decatenation. In cells overexpressing geminin, premature departure of TopoIIα from chromosomes is thought to be due to the fact that geminin recruits more of these deSUMOylating enzymes, or recruits them earlier, to bound TopoIIα. This triggers premature release of TopoIIα from chromosomes, which we propose induces aneuploidy in HME cells, since chromosome breakage generated through this mechanism were not sensed and/or repaired and the cell cycle was not arrested. Expression of mitosis-inducing proteins such as cyclin A and cell division kinase 1 was also increased in these cells because of the overexpression of geminin.Conc...

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“…Mitotic slippage occurs most frequently in cancer cells that lack p53 and Rb, components of checkpoints that prevent premature entrance into S phase. In contrast, siRNA depletion of Geminin in synchronized HME cells also suppressed expression of cyclins E and A1, Cdk1 and Cdk2, which would prevent initiation of DNA replication [11]. …”

mentioning

confidence: 99%

“…Conversely, Geminin depletion does not arrest proliferation of non-cancer cells in vitro [9], nor does ablation of the Geminin gene prevent proliferation of all cell types in vivo [12,13]. However, some non-cancer breast cells may arrest in mitosis without inducing DNA re-replication or apoptosis [11]. Over-expression of a nondegradable form of Geminin in primary human fibroblasts arrests them in G1 without apoptosis, whereas over-expression in osteosarcoma cells induces apoptosis [14].…”

mentioning

confidence: 99%

Spotlight on Geminin

DePamphilis

2011

Breast Cancer Res

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In the previous issue of Breast Cancer Research, Gardner and co-workers describe a novel interaction between Geminin, a protein that prevents reinitiation of DNA replication, and Topoisomerase IIα (TopoIIα), an enzyme essential for removing catenated intertwines between sister chromatids. Geminin facilitates the action of TopoIIα, thereby promoting termination of DNA replication at the same time it inhibits initiation. In this manner, Geminin ensures that cells duplicate their genome once, but only once, each time they divide. Remarkably, either depletion of Geminin or over-expression of Geminin inhibits the action of TopoIIα, thereby making Geminin an excellent target for cancer chemotherapy.

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Geminin is bound to chromatin in G2/M phase to promote proper cytokinesis

Cited by 15 publications

References 43 publications

Geminin, Ki67, and minichromosome maintenance 2 in gastric hyperplastic polyps, adenomas, and intestinal-type carcinomas: pathobiological significance

Geminin, Ki67, and minichromosome maintenance 2 in gastric hyperplastic polyps, adenomas, and intestinal-type carcinomas: pathobiological significance

Geminin overexpression prevents the completion of topoisomerase IIα chromosome decatenation, leading to aneuploidy in human mammary epithelial cells

Spotlight on Geminin

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