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The mechanisms by which embryonic stem (ES) cells self-renew while maintaining the ability to differentiate into virtually all adult cell types are not well understood. Polycomb group (PcG) proteins are transcriptional repressors that help to maintain cellular identity during metazoan development by epigenetic modification of chromatin structure. PcG(More)
Covalent modification of histones is important in regulating chromatin dynamics and transcription. One example of such modification is ubiquitination, which mainly occurs on histones H2A and H2B. Although recent studies have uncovered the enzymes involved in histone H2B ubiquitination and a 'cross-talk' between H2B ubiquitination and histone methylation,(More)
The p53 tumor-suppressor protein prevents cancer development through various mechanisms, including the induction of cell-cycle arrest, apoptosis, and the maintenance of genome stability. We have identified a p53-inducible gene named TIGAR (TP53-induced glycolysis and apoptosis regulator). TIGAR expression lowered fructose-2,6-bisphosphate levels in cells,(More)
During neocortical development, neural precursor cells (NPCs, or neural stem cells) produce neurons first and astrocytes later. Although the timing of the fate switch from neurogenic to astrogenic is critical for determining the number of neurons, the mechanisms are not fully understood. Here, we show that the polycomb group complex (PcG) restricts(More)
Polycomb-repressive complex 1 (PRC1) has a central role in the regulation of heritable gene silencing during differentiation and development. PRC1 recruitment is generally attributed to interaction of the chromodomain of the core protein Polycomb with trimethyl histone H3K27 (H3K27me3), catalyzed by a second complex, PRC2. Unexpectedly we find that RING1B,(More)
Two distinct Polycomb complexes, PRC1 and PRC2, collaborate to maintain epigenetic repression of key developmental loci in embryonic stem cells (ESCs). PRC1 and PRC2 have histone modifying activities, catalyzing mono-ubiquitination of histone H2A (H2AK119u1) and trimethylation of H3 lysine 27 (H3K27me3), respectively. Compared to H3K27me3, localization and(More)
In this paper we present ideas and architectural principles upon which we are basing the development of a distributed, open-source infrastructure that, in turn, will support the expression of business models, the dynamic composition of software services, and the optimisation of service chains through automatic self-organising and evolutionary algorithms(More)
The retinoblastoma protein (pRB) plays an important role in the control of cell proliferation, apparently by binding to and regulating cellular transcription factors such as E2F. Here we describe the characterization of a cDNA clone that encodes a protein with properties of E2F. This clone, RBP3, was identified by the ability of its gene product to interact(More)
In Drosophila, the Polycomb group (PcG) of genes is required for the maintenance of homeotic gene repression during development. Here, we have characterized the Drosophila ortholog of the products of the mammalian Ring1/Ring1A and Rnf2/Ring1B genes. We show that Drosophila Ring corresponds to the Sex combs extra (Sce), a previously described PcG gene. We(More)
Cell lineages generated during development and tissue maintenance are derived from self-renewing stem cells by differentiation of their committed progeny. Recent studies suggest that epigenetic mechanisms, and in particular the Polycomb group (PcG) of genes, play important roles in controlling stem cell self-renewal. Here, we address PcG regulation of stem(More)