All 10 trillion cells in the adult human body are genetically identical, but develop into distinct cell types, such as muscle cells, skin cells or neurons, by activating some genes while inhibiting others. Remarkably, each specialized cell maintains a memory of their individual identity by remembering which genes should be kept on or off, even when making copies of themselves. This type of memory is not written directly into the DNA, yet it is heritable. Instead, such non-genetic or "epigenetic" instructions often appear to be contained in proteins and control not only genes but also how chromosomes are organized.
Lars Jansen and his team, at the Instituto Gulbenkian de Cincia (IGC), have worked out how one of these epigenetic organizing centres is faithfully passed on from mother to daughter cells. Their findings not only elucidate a hitherto mystifying biological process, but provide insight into a key process in cell division, one that can cause cancer when it goes wrong. These findings feature in the latest issue of the journal Developmental Cell.
The team focused on the centromere, a unique protein structure on each chromosome that attaches it to the cell's skeleton (cytoskeleton) during cell division and thus ensures that each daughter cell receives exactly one set of freshly made chromosomes. A properly functioning centromere is critical, as loss in accuracy of this process results in cells with the wrong number of genes, a hallmark of tumor cells.
Mariana Silva, a PhD student in the lab, and first author of the study, explains "When cells divide they make exactly two copies of all genes, to be passed on to exactly two cells. A similar feat has to be pulled off for non-genetic information. But how does the cell copy a protein structure? And, how does it ensure just the right number of copies are made? This question is still mystifying scientists. We focussed our efforts on the centromere because the key protein responsib
|Contact: Ana Godinho|
Instituto Gulbenkian de Ciencia