Characterization of a novel cardiac isoform of the cell cycle-related kinase that is regulated during heart failure.
Myocardial infarction (MI) is often followed by heart failure (HF), but the mechanisms precipitating the transition to HF remain largely unknown. A genomic profile was performed in a monkey model of MI, from the myocardium adjacent to chronic (2-month) MI followed by 3 weeks of pacing to develop HF. The ... transcript of the gene encoding the cell cycle-related kinase (CCRK) was down-regulated by 50% in HF heart compared with control (p<0.05), which was confirmed by quantitative PCR. The CCRK sequence cloned from a heart library showed a conservation of the N-terminal kinase domain when compared with the "generic" isoform cloned previously but a different C-terminal half due to alternative splicing with frameshift. The homology of the cardiac sequence was 100% between mice and humans. Expression of the corresponding protein, measured upon generation of a monoclonal antibody, was limited to heart, liver, and kidney. Upon overexpression in cardiac myocytes, both isoforms promote cell growth and reduce apoptosis by chelerythrine (p<0.05 versus control). Using a yeast two-hybrid screening, we found an interaction of the generic but not the cardiac CCRK with cyclin H and casein kinase 2. In addition, only the generic CCRK phosphorylates the cyclin-dependent kinase 2, which was accompanied by a doubling of myocytes in the S and G(2) phases of the cell cycle (p < 0.05 versus control). Therefore, the heart expresses a splice variant of CCRK, which promotes cardiac cell growth and survival; differs from the generic isoform in terms of protein-protein interactions, substrate specificity and regulation of the cell cycle; and is down-regulated significantly in HF.
Mesh Terms:
Amino Acid Sequence, Animals, Base Sequence, Cell Proliferation, Cell Survival, Cells, Cultured, Cloning, Molecular, Cyclin-Dependent Kinases, Disease Models, Animal, Heart Failure, Isoenzymes, Macaca fascicularis, Male, Mice, Molecular Sequence Data, Myocardium, Protein Binding, Rats, Rats, Wistar, Sequence Alignment, Substrate Specificity
Amino Acid Sequence, Animals, Base Sequence, Cell Proliferation, Cell Survival, Cells, Cultured, Cloning, Molecular, Cyclin-Dependent Kinases, Disease Models, Animal, Heart Failure, Isoenzymes, Macaca fascicularis, Male, Mice, Molecular Sequence Data, Myocardium, Protein Binding, Rats, Rats, Wistar, Sequence Alignment, Substrate Specificity
J. Biol. Chem.
Date: Aug. 08, 2008
PubMed ID: 18508765
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