delta-Ca2+/Calmodulin-dependent protein kinase II expression pattern in adult mouse heart and cardiogenic differentiation of embryonic stem cells

delta-isoforms of the Ca2+/calmodulin-dependent protein kinase type II (CaM KII) are considered to substantially influence cardiac functions. However, no data exist on the expression of these isoforms in the mouse heart. We an alyzed the transcript pattern of non-neuronally expressed delta-isoforms in heart and skeletal muscle of adult mice by RT-PCR. For members of the delt a-CaMKII subclass with both variable domains (subclass II), weak transcript ional expression of isoforms delta(2) and delta(3) was found in the heart. In skeletal muscle no delta(3)-specific transcript was detectable. In cardi ac tissue, stronger signals result from amplifications of delta(9) and from members of the subclass I lacking the second variable domain. Western blot ting was performed using a subclass Ii-specific antibody. In murine cardiac and skeletal muscle tissue a delta-CaMKII protein pattern was obtained sim ilar to that described for rat. To gain insight into the expression of delt a-CaMKII during the earliest steps of cardiogenic differentiation,we analyz ed the transcript pattern of murine embryonic stem cell-derived cardiomyocy tes in various differentiation stages. Reproducible RT-PCR signals could be obtained for delta(6) and delta(10), both belonging to the delta-CaMKII su bclass I. transcripts for delta(6) were ubiquitously expressed, whereas tra nscripts for delta(10). were detectable in increasing amounts after 7-10 da ys of the onset of cardiogenic differentiation. Our results point to a diff erentiation-dependent expression of the two delta-CaMKII subclasses, and al so to differences in the expression of individual members of subclass I dur ing the early stages of cardiogenic differentiation. (C) 2000 Wiley-Liss, I nc.