‘Protein switch’ determines whether stem cells specialize or regenerate

Researchers in the UMCG have identified the protein complex that determines the fate of stem cells. The composition of this protein complex acts as a switch, deciding which stem cells will mature into cells with a specific function in the body and which will ensure the production of new stem cells. The researchers’ findings are published 18 March 2013 in the leading journal Nature Cell Biology.

‘We found evidence of this mechanism in stem cells in the blood,’ says Professor Gerald de Haan, co-director of the European Institute for the Biology of Ageing (ERIBA). ‘If the switch causes stem cells to over-reproduce, the host will develop leukaemia, and if the cells over-specialize, there will be a shortage of blood cells. The research provides fundamental information about the role that stem cells play in the subtle balance between health and disease.’

Ageing

Stem cell research is a very important part of understanding ageing processes. De Haan: ‘We know that blood-forming stem cells function less well as people grow older, but we don’t know exactly which processes change.’ The new information about the effects of the protein complex as a switch could help the researchers to find out how ageing is connected to changes in the balance between regeneration and specialization (maturation) of stem cells.

Composition

Karin Klauke, the PhD student carrying out the research, discovered that the composition of the protein complex varies in line with the presence (or absence) of four different proteins. These proteins compete with each other for the same position within the complex. One of the four, Cbx7, needs to be present to induce cell regeneration. A lack of Cbx7 and presence of one of the other three proteins (Cbx2, 4 or 8) in the complex will curb the production of new stem cells, and stimulate specialization into blood cells.

Many types of stem cells

Although the researchers initially demonstrated the role of the Cbx7 protein in the regeneration of stem cells for blood cells, the protein is also present in early-stage embryonic stem cells. The researchers do not therefore expect the Cbx7 effect to be specific to blood stem cells, but think that it plays a more general role in the way that many types of stem cells work and are regulated.

Link to publication: http://www.nature.com/ncb/journal/vaop/ncurrent/abs/ncb2701.html