In our body there are hundreds of different and highly specialized cells, depending on the organ they are in and the function they perform. However, they all had a common origin in a single cell.
When this initial cell divides, it gives rise to embryonic stem cells, which are also undifferentiated. “For cells to differentiate, and move from stem cells to differentiated cells, it is essential that there is coordinated expression of several genes, hitherto silenced”, explains researcher Lígia Tavares of the Institute of Molecular and Cell Biology of the University of Porto (IBMC ).
This process occurs because there is a set of mechanisms that turn specific genes on and off, in order to determine which ones will be expressed. It is the cell-to-cell differential silencing, that is, the expression of some genes and the inhibition of others, which guarantees the differences between them all.
In an article published in the February 17 edition of the prestigious magazine “Cell”, coordinated by Prof. Neil Brockdorff from Oxford University, whose first author is Lígia Tavares, a PhD student in the GABBA program and currently a researcher at the IBMC, a new complex responsible for the silencing of genes in embryonic stem cells is described.
In this article, Lígia Tavares describes the role of a new complex, called RYBP-PRC1, in gene silencing. Two complexes, PRC1 and PRC2, were known to act on genes and which, until now, were thought to function interconnected, or dependent on each other.
However, the Portuguese scientist demonstrates with this work that RYBP-PRC1 can be mobilized to the DNA without depending on the action of other complexes.
RYBP-PRC1 is responsible for many of the signals that tell the cell which genes to keep silent, signals called epigenetic marks. These have as great an influence on cells as the genes themselves, since they control them.
Therefore, by manipulating the RYBP-PRC1 complex, in conjunction with others, it may be possible to reverse the differentiation process and turn adult cells into stem cells.
These new discoveries, by opening up the possibility of reversing adult cells, create new paths for regenerative therapies, as they will make it possible to overcome all the technical and ethical issues underlying the use of other stem cells, namely those originating from embryos.
On the other hand, this knowledge can be used inversely. In other words, “to use this complex to produce specific and specialized tissues or cells”, which “may be used in implants or replacements for therapeutic purposes”, explains Lígia Tavares.
But “this future still needs a lot of work and research”, he adds. For these reasons, the work was considered innovative enough for one of the most renowned journals in the area of life and health sciences, Cell, to publish it.
About Lígia Tavares: holds a PhD in Biochemistry from Oxford University with Prof. Neil Brockdorff. Lígia, within the scope of the GABBA doctoral program at the University of Porto; she also has a degree in Biology from the University of Porto. Currently, Lígia Tavares is doing post-doctoral work at IBMC. His current interests are directed towards cell specialization and regulators in the interaction between cells of the nervous system using the fruit fly as a model.
Article reference: published in Cell's paper edition 17-02-2012, available in online pre-edit: http://dx.doi.org/10.1016/j.cell.2011.12.029
Complete reference: Lígia Tavares, Emilia Dimitrova, David Oxley, Judith Webster, Raymond Poot, Jeroen Demmers, Karel Bezstarosti, Stephen Taylor, Hiroki Ura, Hiroshi Koide, Anton Wutz, Miguel Vidal, Sarah Elderkin & Neil Brockdorff, (2012). RYBP-PRC1 Mediate H2A Ubiquitylation Complexes at Polycomb Target Sites Independently of PRC2 and H3K27me3. Cell 148, 1-15
Text published within the scope of the project Ciência na Imprensa Regional – Ciência Viva (from the IBMC.INEC press release dated February 16, 2012)
Authors: António Piedade with Júlio Borlido Santos
Comments