delta-CA2+/Calmodulin-dependent protein kinase II Expression pattern in adult mouse heart and cardiogeneic differentiation of embryonic stem cells

Abstract

{delta}-isoforms of the Ca2+/calmodulin-dependent protein kinase type II (CaMKII) are considered to substantially influence cardiac functions. However, no data exist on the expression of these isoforms in the mouse heart. We analyzed the transcript pattern of non-neuronally expressed {delta}-isoforms in heart and skeletal muscle of adult mice by RT-PCR. For members of the {delta}-CaMKII subclass with both variable domains (subclass II), weak transcriptional expression of isoforms {delta}2 and {delta}3 was found in the heart. In skeletal muscle no {delta}3-specific transcript was detectable. In cardiac tissue, stronger signals result from amplifications of {delta}9 and from members of the subclass I lacking the second variable domain. Western blotting was performed using a subclass II-specific antibody. In murine cardiac and skeletal muscle tissue a {delta}-CaMKII protein pattern was obtained similar to that described for rat. To gain insight into the expression of {delta}-CaMKII during the earliest steps of cardiogenic differentiation, we analyzed the transcript pattern of murine embryonic stem cell-derived cardiomyocytes in various differentiation stages. Reproducible RT-PCR signals could be obtained for {delta}6 and δ10, both belonging to the {delta}-CaMKII subclass I. Transcripts for {delta}6 were ubiquitously expressed, whereas transcripts for {delta}10 were detectable in increasing amounts after 7-10 days of the onset of cardiogenic differentiation. Our results point to a differentiation-dependent expression of the two {delta}-CaMKII subclasses, and also to differences in the expression of individual members of subclass I during the early stages of cardiogenic differentiation