A team of DZHK researchers led by Professor Johannes Backs from the Heidelberg/Mannheim partner site have identified a new signaling pathway which, under conditions of pathological stress, leads to heart failure. However, when exercise is the stressor, the signaling chain takes a different path and the heart is protected from damage. Their findings have now been published in Nature Medicine.
At the center of this study is an epigenetic switch called histone deacetylase 4 (HDAC4). A fragment of HDAC4, the HDAC4-NT fragment, was prevalent in mice hearts after physiological stress. In mice that were subjected to a pathological stress load comparable to that produced by high blood pressure, HDAC4-NT was missing however.
According to the researchers, the breaks between periods of stress make a difference: during prolonged stress caused by severe hypertension, protein kinase A activity eventually declines and this causes the HDAC4-NT fragment to disappear. The metabolism of the heart muscle cells then uses more sugar than fat to produce energy. Sugar residues attach to proteins too and some of those altered proteins eventually inhibit the calcium metabolism and thus the contractility of the heart muscle. This leads to a decline in the heart’s pumping power. The researchers say that these novel findings indicate that there is a link from epigenetics via the metabolism to contractility, that is, to cardiac function, and therefore they could form the basis for a new therapeutic principle.