A study in the 24 Feb 2005 issue of Nature (Vol. 433, No. 7028, pp. 884-887) goes some way towards solving a conundrum in stem cell biology: how a stem cell can be committed to making a specific type of mature cell, while remaining undifferentiated until it is needed. Understanding this and related mechanisms might help harness adult stem cells for tissue repair and regeneration.
Jonathan Epstein and his co-workers show that a single protein called Pax3 carries out both functions simultaneously in the stem cells that make melanocytes (that is, pigmented skin cells). Pax3 triggers production of Mitf, a protein that drives production of melanocytes and hence commits the stem cell to making this type of cell.
At the same time, Pax3 temporarily keeps the stem cell undifferentiated by interfering with the function of Mitf. When a new melanocyte is needed, a third molecule, called β-catenin, stops Pax3 from repressing Mitf so that the cell can differentiate.
Jonathan Epstein (University of Pennsylvania, Philadelphia, PA, USA)
Tel: +1 215 898 8731
(C) Nature press release.
Message posted by: Trevor M. D'Souza