Bonn cell biologists unravel Alzheimer's protein
It has been known for some time that Alzheimer's disease is caused by a specific endogenous protein, the so-called Alzheimer Precursor Protein (APP). However, it is extremely unlikely that an endogenous protein fulfills the sole function of causing a specific disease. Normally diseases are the expression of a malfunction. The cell biologists at the Bonn Biomedicine Forum have now succeeded for the first time in demonstrating the normal mode of action of this protein. This could also result in new pharmaceutical and therapeutic approaches in the future. The starting point of the work were investigations into the growth of so-called epithelial cells, which are cell aggregates such as the skin, the thyroid gland or the intestine. In general, the higher a cell is developed, the lower its ability to divide and thus grow. Epithelial cells are normally prevented from permanent division by their structure. Nevertheless, they know a growth, as is clear, for example, in the normal development to adulthood or in the case of pathological tumor growth. All that was known so far was that thyrotropin, a hormone produced in the pituitary gland, somehow stimulates the division of epithelial cells. The Bonn cell biologists have now succeeded in identifying this previously unknown growth factor and identifying it as part of the Alzheimer's precursor protein.
Proteins always consist of several parts, different peptides. It has long been known that only a small portion triggers Alzheimer's disease. The Bonn scientists discovered that the rest of this protein is necessary to stimulate the normal growth of epithelial cells. As a result, Alzheimer's disease can only occur if this growth protein is cleaved off incorrectly and a specific peptide is released. When this substance accumulates massively, it has a toxic effect on a specific group of nerve cells in the brain.
This finding not only contributes to a better understanding of Alzheimer's disease, it is also particularly important for the development of therapeutic approaches for so-called epithelial disorders, e.g. for thyroid diseases. The thyroid controls a number of functions in the body. If it fails in childhood, for example, or is not present at birth or is only present in rudimentary form, the brain cannot develop sufficiently - mental maldevelopment would be the result. If such a clinical picture is diagnosed in good time, serious diseases can currently be prevented by administering thyroid hormones. However, since the factor that stimulates the growth of epithelial cells is now known thanks to the work of the Bonn cell biologists, the possibility of achieving sufficient growth or even the formation of a thyroid gland through the targeted administration of this protein is now within reach. The body would then be able to produce the required hormones itself. In the other case, there is increased growth of the thyroid cells and goitre formation occurs. For this case, too, it may be possible to find modified therapeutic approaches in the future.
The Bonn Biomedicine Forum was founded almost a year ago as a merger of nine university institutes at Bonn University. Above all, the structure and proximity to application must be regarded as new for the German research landscape. "Because our young people work here unbureaucratically and across institute boundaries and can develop their ideas in groups," says the spokesman for the Bonn Center for Biomedicine, Prof. Herzog, "the forum works very efficiently thanks to this 'enormous push from below'. This is the only way to be able to show some interesting results after a short time.”