Brussels, 09 Feb 2006
Researchers from the University of Edinburgh have discovered a protein key to the differentiation of stem cells into specialised cells. The protein, called Mdb3, has been found to be essential to the differentiation process.
Stem cells have two special properties - they are able to divide almost without limit, and they can differentiate into specialised cells, such as skin cell, brain cell, or liver cell.
The team, led by Brian Hendrich, conducted the study on mouse cells. Special mouse stem cells that did not include the Mbd3 protein were engineered, and the researchers found that the stem cells remained stem cells and refused to behave as they should, that is, differentiating into specialised cells when coaxed.
'It is well established that embryonic stem cells need certain factors to sustainably make copies of themselves, that is, to self-renew,' said Dr Hendrich. 'We have now shown, for the first time, that to leave that state and go down the specialisation pathway, cells require the activity of Mdb3; it is not enough simply to remove the self-renewal factors. If Mdb3 is absent, the cells remain in an embryonic stem cell-like state.'
This discovery has also thrown light onto the differences between mouse and human stem cells. Another protein, LIF, is essential in mouse stem cells for those cells to duplicate. Human stem cells do not need LIF. However, during their research, the team discovered that the mouse cells without the Mdb3 protein were also able to duplicate without LIF, just as human cells are.
This opens up a window into the behaviour of both human and animal stem cells, and further studies may be able to show how human cells are able to multiply without the LIF protein.