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<strong>EMBL</strong>-EBI<br />
Differentiation and development<br />
Previous and current research<br />
We investigate the cellular and molecular processes underlying mammalian stem cell differentiation,<br />
using a combination of experimental and computational approaches. Embryonic stem (ES)<br />
cells are similar to the transient population of self-renewing cells within the inner cell mass of the<br />
preimplantation blastocyst (epiblast), capable of pluripotential differentiation to all specialised<br />
cell types comprising the adult organism. These cells undergo continuous self-renewal to produce<br />
identical daughter cells, or can develop into specialised progenitors and terminally differentiated<br />
cells. Each regenerative or differentiative cell division involves a decision whereby an individual<br />
stem cell remains in self-renewal or commits to a particular lineage. Pluripotent ES cells can produce<br />
lineage-specific precursors and tissue-specific stem cells, with an accompanying restriction<br />
in commitment potential. These exist in vivo as self-renewing multipotent progenitors localised in<br />
reservoirs within developed organs and tissues. The properties of proliferation, differentiation and<br />
lineage specialisation are fundamental to cellular diversification and growth patterning during organismal<br />
development, as well as the initiation of cellular repair processes throughout life.<br />
Paul Bertone<br />
PhD 2005, Yale University.<br />
At <strong>EMBL</strong>-EBI since 2005.<br />
Group leader since 2006.<br />
Joint appointment with the<br />
Gene Expression and<br />
Developmental Biology Units.<br />
A number of molecular pathways involved in embryonic development have been elucidated, including<br />
those influencing stem cell differentiation. As a result, we know of a number of key transcriptional regulators and signalling molecules<br />
that play essential roles in manifesting nuclear potency and self-renewal capacity of embryonic and tissue-specific stem cells. Despite<br />
these efforts, however, only a small number of components have been identified and large-scale characterisation of cellular commitment and<br />
terminal differentiation to specific cell types remains incomplete. Our research group applies the latest high-throughput technologies to investigate<br />
the functions of key regulatory proteins and their influence on the changing transcriptome. We focus on early lineage commitment<br />
of ES cells, neural differentiation and nuclear reprogramming. The generation of large-scale data from functional genomic and proteomic experiments<br />
will help to identify and characterise the regulatory influence of key transcription factors, signalling genes and non-coding RNAs<br />
involved in early developmental pathways, leading to a more detailed understanding of the molecular mechanisms of vertebrate embryogenesis.<br />
Future projects and goals<br />
A long-term goal of this work is to elucidate accurate models of stem cell differentiation and lineage commitment at various biological levels.<br />
Despite the importance of transcription factors and the interaction of co-factor proteins on the repression and activation of genes, eukaryotic<br />
cells utilise many layers of regulatory control. These range from histone acetylation and methylation events affecting chromatin<br />
accessibility, variations in transcript splicing producing alternate isoforms in certain cell types or conditions, the attenuation of message levels<br />
and/or inhibition of translation by antisense RNAs, and<br />
myriad post-translational modifications affecting protein<br />
function and subcellular localisation. Computational approaches<br />
will be vital for the analysis and integration of<br />
these data in context with existing knowledge.<br />
We eventually wish to characterise the complex interaction<br />
of signalling pathways, gene regulation by key transcription<br />
factors and non-coding RNAs, and chromatin modifications<br />
that function in concert to induce distinct<br />
morphological and physiological outcomes.<br />
Top: Differentiation into neural stem (NS) cells from<br />
neural-rosette structures. A) ES cell primary culture, B, C)<br />
immunostaining for specific surface markers. Bottom: NS<br />
cells express markers characteristic of radial glia,<br />
permitting both accurate identification of differentiation<br />
stages and efficient FACS selection of homogeneous cell<br />
populations for genomic analysis. (Images: Steve Pollard,<br />
University of Cambridge; adapted from Conti et al., 2005).<br />
Selected references<br />
Kind, J. et al. (2008). Genome-wide analysis reveals MOF as a key<br />
regulator of dosage compensation and gene expression in<br />
Drosophila. Cell, 133, 813-828<br />
Kirstetter, P. et al. (2008). Modeling of C/EBPα mutant acute myeloid<br />
leukemia reveals a common expression signature of committed<br />
myeloid leukemia-initiating cells. Cancer Cell, 13, 299-310<br />
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