No.1/May 17, 2001
Skin and Hair
MDC Researchers Discover the Mechanism that Controls Stem Cells
Scientists at the Max Delbrück Center for Molecular Medicine
(MDC) Berlin-Buch, a National Research Laboratory of the Helmholtz Association,
have obtained new insights into the development of skin and hair. Dr. Joerg
Huelsken and Prof. Walter Birchmeier have been able to show how skin stem cells
are controlled. These skin stem cells ensure that both skin cells and hair
follicles develop normally. The two separate programs for development are
controlled by one signal molecule, beta-Catenin. The results obtained by Dr.
Huelsken, Regina Vogel, Dr. Bettina Erdmann,
Dr. George Cotsarelis (University of Pennsylvania, Philadelphia, USA)
and Prof. Birchmeier have just been published in the prestigious American
journal Cell (Vol 105, No. 4, pp.533 – 545*).
For some time, researchers have believed that beta-Catenin was involved in some way in the formation of skin and hair. However, they had no idea how it worked and in which cells. The MDC scientists studied mice that were unable to produce beta-Catenin. To do this, Dr. Huelsken switched off in a very specific manner the gene for beta-Catenin in the mouse, using a process known technically as conditional knock-out. During the period between 20 - 30 days after birth, such mice lose their coat. Subsequently, no more hair follicles are formed in these animals. Instead, cysts develop in the skin, which are not normally found in mice, and these are lined by outer layers of skin cells. The cysts arise from misdirected stem cells in the skin that have lost their ability to form follicle cells. Dr. Huelsken and his group were able to establish two important findings: 1. stem cells in the skin require beta-Catenin in order to be able to form hair follicles; 2. if no beta-Catenin is available, skin cells are formed but no hair.
Beta-Catenin is one of a group of molecules which were discovered some time ago. The research group led by Prof. Birchmeier has been studying this molecule in great detail for the past ten years. Beta-Catenin ensures that information from the cell surface is passed on to the control center of the cell, the cell nucleus. This is where the DNA that is passed from one generation to the next is located. The Genes, sequences encoded in the DNA, govern the processes that go on in all living cells. Many gene products, such as beta-Catenin for example, are involved in the complex signaling pathways that control embryonic development and they are disrupted when a tumor develops. Until now, no one realized that beta-Catenin can also control stem cells. This discovery offers stem cell researchers the opportunity to examine the function of stem cells in much greater detail. The application of stem cells could hopefully lead to the development of new ways of treating a variety of serious diseases. The application of so-called embryonic stem cells is a controversial topic at the moment and is provoking a great deal of public discussion.
*
ӧ-Catenin controls hair follicle morphogenisis and stem cell differentiation
in the skin” Joerg Huelsken, Regina Vogel, Bettina
Erdmann, George Cotsarelis‡, Walter Birchmeier Max Delbrück Center for Molecular Medicine
(MDC) Berlin-Buch, Germany, ‡Department of Dermatology, University of
Pennsylvania , Philadelphia, USA
Barbara Bachtler
Press and Public Affairs
Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch
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