Differentiation-dependent expression of cardiac δ-CaMKII isoforms

✍ Scribed by Brigitte Hoch; Hannelore Haase; Wolfgang Schulze; Dirk Hagemann; Ingo Morano; Ernst-Georg Krause; Peter Karczewski

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 170 KB
• Volume: 68
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(19980201)68:2<259::aid-jcb12>3.0.co;2-a

✦ Synopsis

Despite their important role in controlling the cardiac Ca 2ϩ homeostasis, presence and functions of individual isoforms of the multifunctional Ca 2ϩ /calmodulin-dependent protein kinase in the heart are not well studied.

Here we report on expression of isoforms of the ␦ class in two differentiation states of the embryonic rat heart-derived cell line H9c2 compared to adult rat heart. Reverse transcription coupled polymerase chain reaction analysis revealed specific expression patterns of four variants of the ␦ class (␦ B , ␦ C , ␦ 4 , ␦ 9 ) in adult rat heart, H9c2 myoblasts, and skeletal muscle-like H9c2 myotubes. ␦ C was identified as a common isoform with higher amounts in H9c2 cells and the prominent one in myoblasts. In contrast, expression of ␦ 9 accompanied cardiac as well as skeletal muscle differentiation. Expression of ␦ B , however, was representative for differentiated cardiac muscle, whereas ␦ 4 expression coincided with differentiation into the skeletal muscle-like state. Our results demonstrate differentiation-dependent isoform expression of the ␦ class of the multifunctional Ca 2ϩ /calmodulin-dependent protein kinase of muscle. The identification of cardiac target proteins for this kinase, e.g. the ␣ 1 -subunit of the L-type Ca 2ϩ channel, the sarcoplasmic reticulum Ca 2ϩ -ATPase, phospholamban and the ryanodine receptor define H9c2 myoblasts as a suitable model system for further functional characterization of the identified cardiac ␦ isoforms.