Over the course of a lifetime, the heart pumps some 250 million liters of blood through the body. In the order to do this, the muscle fibers of the heart have to be extremely durable. The research group headed by Dr. Wolfgang Rottbauer, vice chair of the Department of Medicine III at Heidelberg University Hospital (Chairman: Prof. Dr. H. A. Katus), has discovered a protein that is responsible for the stability of the smallest muscular unit, the sarcomere. In cooperation with other researchers within the National Genome Research Network (NGFN) which is funded by the German Federal Ministery of Education and Research, especially Prof. Dr. H. Schunkert from the University of Lbeck and Prof. Dr. M. Stoll from the University of Mnster, they proved that mutations of this protein are the cause of a new type of heart failure. The results have been published in the November issue of Nature Medicine.
Primary heart muscle disease with decreased cardiac pump function leading to enlargement of the heart chambers (dilated cardiomyopathy) is one of the most frequent causes of chronic heart failure. Six new cases per 100,000 people occur each year; 20 percent of these cases are genetic. The heart disease weakens cardiac cells and the heart can no longer pump efficiently which leads to dilation of the cardiac chambers.
Muscle activity takes place in the smallest unit of muscle fiber, the sarcomere. In the presence of an appropriate stimulus, actin and myosin filaments interact and contract the muscle. These movable elements are anchored in what are known as Z-disks. With every heartbeat, enormous forces act on the Z-disks.
Torn Z disks weaken the heart
"In our studies of zebrafish, we discovered a protein that is needed to stabilize the Z-disk. If this protein (nexilin) is mutated, the movable muscle elements are no longer anchored firmly enough. The muscles then lose strength and the heart is weakened," explains Dr. Ti
|Contact: Dr. Wolfgang Rottbauer|
University Hospital Heidelberg