Errors in stem cell division can give rise to tumours. By studying stem cells in the fruit fly, scientists at the Institute for Research in Biomedicine (IRB Barcelona) have identified one of the mechanisms that govern how these cells divide. The study appears this week in the scientific journal Developmental Cell.
Stem cells have the extraordinary capacity to divide producing two very distinct cells: one retains stem cell identity and continues to undergo asymmetric division, while the other specializes for a specific function and shows limited capacity to divide. This strategy allows a single stem cell to generate great amounts of tissue during a lifetime.
To ensure the correct differential identity of the resulting cells, the complex apparatus that divides that stem cell in two must form along a pre-established axis. If this does not occur, the division may be symmetric, which will generate two identical stem cells. That is to say, instead of producing tissue, the stem cells with a "disoriented" division axis may give rise to more stem cells; this is potentially dangerous for the organism as it would lead to uncontrolled proliferation of this type of cell.
How is this danger avoided? Researchers headed by Cayetano Gonzlez, ICREA Research Professor at IRB Barcelona, have studied stem cell division and discovered that one of the key factors lies in the behaviour of the intracellular structure known as the centrosome. Most animal cells have two centrosomes before division takes place and their position governs the direction of the division. In cells that divide symmetrically (giving rise to two identical cells), the two centrosomes of cell are practically identical. Surprisingly, Gonzalez and his team found striking differences in the two centrosomes of the stem cells they were studying. One is located in a fixed position and is very active during the entire cell cycle, while the other moves around the cell before coming to a stands
Contact: Sonia Armengou
Institute for Research in Biomedicine (IRB)