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Genes Dev
2005 Jul 15;1914:1723-34. doi: 10.1101/gad.1319105.
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Geminin regulates neuronal differentiation by antagonizing Brg1 activity.
Seo S, Herr A, Lim JW, Richardson GA, Richardson H, Kroll KL.
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Precise control of cell proliferation and differentiation is critical for organogenesis. Geminin (Gem) has been proposed to link cell cycle exit and differentiation as a prodifferentiation factor and plays a role in neural cell fate acquisition. Here, we identified the SWI/SNF chromatin-remodeling protein Brg1 as an interacting partner of Gem. Brg1 has been implicated in cell cycle withdrawal and cellular differentiation. Surprisingly, we discovered that Gem antagonizes Brg1 activity during neurogenesis to maintain the undifferentiated cell state. Down-regulation of Gem expression normally precedes neuronal differentiation, and gain- and loss-of-function experiments in Xenopus embryos and mouse P19 cells demonstrated that Gem was essential to prevent premature neurogenesis. Misexpression of Gem also suppressed ectopic neurogenesis driven by Ngn and NeuroD. Gem's activity to block differentiation depended upon its ability to bind Brg1 and could be mediated by Gem's inhibition of proneural basic helix-loop-helix (bHLH)-Brg1 interactions required for bHLH target gene activation. Our data demonstrate a novel mechanism of Gem activity, through regulation of SWI/SNF chromatin-remodeling proteins, and indicate that Gem is an essential regulator of neurogenesis that can control the timing of neural progenitor differentiation and maintain the undifferentiated cell state.
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Figure 3. Brg1 and Gem have overlapping expression patterns but Gem diminishes prior to neuronal differentiation. In situ hybridization for X-Brg1 (A) and X-Gem (D) in Xenopus embryos. (A,D,G) Dorso-lateral views. (C,F) Dorsal views at tail- bud stages; anterior toward left. (B,E,H) Transverse sections at stages shown in A, D, and G, respectively. (I) Transverse section of N-tubulin-stained embryo. In H and I, a dashed line marks the neural plateomite boundary. (J) Expression profile of Gem and other markers during RA-induced neuronal differentiation of P19 cells.
Figure 4. Misexpression of Gem prevents neurogenesis. (A), Two-cell stage Xenopus embryos were injected in one cell as indicated (yellow) with beta-galactosidase mRNA coinjection for lineage tracing and analyzed for NCAM (A) or N-tubulin (DO) expression. (CT) C-terminal region. 3EA is an alanine sub- stitution mutant of acidic amino acids 18890 in Xenopus Gem (which correspond to mouse Gem amino acids 17476). Like GemE174Q (Fig. 2F,G), Xenopus Gem 3EA has severely reduced Brg1 binding (data not shown). Numbers indicate the number of affected embryos over the total number of embryos. In situ for markers is stained purple, and blue X-gal staining marks the injected side. Injected sides were oriented rightward. (P) Expression levels of Gem variants injected into Xenopus embryos. Embryos were injected as indicated at the two-cell stage and harvested at stage 12 to prepare lysates. Ten embryos were used for each sample, and one embryo-equivalent of lysate was loaded per lane for Western blotting with anti-Myc antibody.
igure 6. Loss of Gem activity results in premature neurogenesis. (A) Xenopus embryos were injected with 2.5 ng (A) or 1.5 ng (E,F) of GemMO or 20 ng of control MO (G,H) and probed as indicated (white). Red arrowheads in E and F mark the pos- terior end of N-tubulin expression in the medial stripe on each side of the embryo. (I) Reduction of Gem protein level in P19 cells by RNAi. (J) Reduction of Gem sensi- tized P19 cells to differentiate into neurons at a subthreshold level (50 ng) of NeuroD2. P19 cells were transfected as indicated and probed with TuJ1 antibody to detect neu- rons. GFP expression plasmid was cotrans- fected to trace transfected cells.
Bain,
Embryonic stem cells express neuronal properties in vitro.
1995,
Pubmed Ballabeni,
Human geminin promotes pre-RC formation and DNA replication by stabilizing CDT1 in mitosis.
2004,
Pubmed
,
Xenbase Berkes,
Pbx marks genes for activation by MyoD indicating a role for a homeodomain protein in establishing myogenic potential.
2004,
Pubmed Bertrand,
Proneural genes and the specification of neural cell types.
2002,
Pubmed Brumby,
Drosophila cyclin E interacts with components of the Brahma complex.
2002,
Pubmed Bylund,
Vertebrate neurogenesis is counteracted by Sox1-3 activity.
2003,
Pubmed Chae,
NeuroD: the predicted and the surprising.
2004,
Pubmed
,
Xenbase Chalmers,
Intrinsic differences between the superficial and deep layers of the Xenopus ectoderm control primary neuronal differentiation.
2002,
Pubmed
,
Xenbase Cremisi,
Cell cycle and cell fate interactions in neural development.
2003,
Pubmed de la Serna,
Mammalian SWI/SNF complexes promote MyoD-mediated muscle differentiation.
2001,
Pubmed de la Serna,
MyoD can induce cell cycle arrest but not muscle differentiation in the presence of dominant negative SWI/SNF chromatin remodeling enzymes.
2001,
Pubmed de la Serna,
MyoD targets chromatin remodeling complexes to the myogenin locus prior to forming a stable DNA-bound complex.
2005,
Pubmed Del Bene,
Direct interaction of geminin and Six3 in eye development.
2004,
Pubmed
,
Xenbase Elfring,
Genetic analysis of brahma: the Drosophila homolog of the yeast chromatin remodeling factor SWI2/SNF2.
1998,
Pubmed Farah,
Generation of neurons by transient expression of neural bHLH proteins in mammalian cells.
2000,
Pubmed Francis,
Reconstitution of a functional core polycomb repressive complex.
2001,
Pubmed Gao,
A role of N-cadherin in neuronal differentiation of embryonic carcinoma P19 cells.
2001,
Pubmed Gebuhr,
Pc-G/trx-G and the SWI/SNF connection: developmental gene regulation through chromatin remodeling.
2000,
Pubmed Gonzalez,
Geminin predicts adverse clinical outcome in breast cancer by reflecting cell-cycle progression.
2004,
Pubmed Graham,
SOX2 functions to maintain neural progenitor identity.
2003,
Pubmed Jones-Villeneuve,
Retinoic acid induces embryonal carcinoma cells to differentiate into neurons and glial cells.
1982,
Pubmed Kadam,
Transcriptional specificity of human SWI/SNF BRG1 and BRM chromatin remodeling complexes.
2003,
Pubmed Kingston,
ATP-dependent remodeling and acetylation as regulators of chromatin fluidity.
1999,
Pubmed Kroll,
Geminin, a neuralizing molecule that demarcates the future neural plate at the onset of gastrulation.
1998,
Pubmed
,
Xenbase Lee,
Conversion of Xenopus ectoderm into neurons by NeuroD, a basic helix-loop-helix protein.
1995,
Pubmed
,
Xenbase Lockett,
Rough genes with Deformed homeobox substitutions exhibit rough regulatory specificity during Drosophila eye development.
1993,
Pubmed Luo,
Geminin coordinates cell cycle and developmental control.
2004,
Pubmed Luo,
The cell-cycle regulator geminin inhibits Hox function through direct and polycomb-mediated interactions.
2004,
Pubmed Ma,
Identification of neurogenin, a vertebrate neuronal determination gene.
1996,
Pubmed
,
Xenbase Markey,
Geminin is targeted for repression by the retinoblastoma tumor suppressor pathway through intragenic E2F sites.
2004,
Pubmed Martens,
Recent advances in understanding chromatin remodeling by Swi/Snf complexes.
2003,
Pubmed McBurney,
P19 embryonal carcinoma cells.
1993,
Pubmed McGarry,
Geminin deficiency causes a Chk1-dependent G2 arrest in Xenopus.
2002,
Pubmed
,
Xenbase McGarry,
Geminin, an inhibitor of DNA replication, is degraded during mitosis.
1998,
Pubmed
,
Xenbase Melixetian,
Loss of Geminin induces rereplication in the presence of functional p53.
2004,
Pubmed Mihaylov,
Control of DNA replication and chromosome ploidy by geminin and cyclin A.
2002,
Pubmed Mizuseki,
Xenopus Zic-related-1 and Sox-2, two factors induced by chordin, have distinct activities in the initiation of neural induction.
1998,
Pubmed
,
Xenbase Molofsky,
Bmi-1 dependence distinguishes neural stem cell self-renewal from progenitor proliferation.
2003,
Pubmed Montanari,
Increased expression of geminin stimulates the growth of mammary epithelial cells and is a frequent event in human tumors.
2005,
Pubmed Ohnuma,
Neurogenesis and the cell cycle.
2003,
Pubmed Park,
Bmi-1 is required for maintenance of adult self-renewing haematopoietic stem cells.
2003,
Pubmed Penzel,
Characterization and early embryonic expression of a neural specific transcription factor xSOX3 in Xenopus laevis.
1997,
Pubmed
,
Xenbase Peterson,
Recruitment of chromatin remodeling machines.
2000,
Pubmed Quinn,
The Drosophila Geminin homolog: roles for Geminin in limiting DNA replication, in anaphase and in neurogenesis.
2001,
Pubmed
,
Xenbase Roy,
The myogenic basic helix-loop-helix family of transcription factors shows similar requirements for SWI/SNF chromatin remodeling enzymes during muscle differentiation in culture.
2002,
Pubmed Saxena,
A dimerized coiled-coil domain and an adjoining part of geminin interact with two sites on Cdt1 for replication inhibition.
2004,
Pubmed
,
Xenbase Seo,
The SWI/SNF chromatin remodeling protein Brg1 is required for vertebrate neurogenesis and mediates transactivation of Ngn and NeuroD.
2005,
Pubmed
,
Xenbase Simone,
p38 pathway targets SWI-SNF chromatin-remodeling complex to muscle-specific loci.
2004,
Pubmed Tada,
Repression of origin assembly in metaphase depends on inhibition of RLF-B/Cdt1 by geminin.
2001,
Pubmed
,
Xenbase Vernon,
The cdk inhibitor p27Xic1 is required for differentiation of primary neurones in Xenopus.
2003,
Pubmed
,
Xenbase Vojtek,
Akt regulates basic helix-loop-helix transcription factor-coactivator complex formation and activity during neuronal differentiation.
2003,
Pubmed Whitehouse,
Nucleosome mobilization catalysed by the yeast SWI/SNF complex.
1999,
Pubmed Wohlschlegel,
Inhibition of eukaryotic DNA replication by geminin binding to Cdt1.
2000,
Pubmed
,
Xenbase Wohlschlegel,
Expression of geminin as a marker of cell proliferation in normal tissues and malignancies.
2002,
Pubmed
,
Xenbase Yoshida,
Regulation of Geminin and Cdt1 expression by E2F transcription factors.
2004,
Pubmed Zhu,
Rereplication by depletion of geminin is seen regardless of p53 status and activates a G2/M checkpoint.
2004,
Pubmed
