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.
Qiu
Hongyu
H
Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103, USA.
Dai
Huacheng
H
Jain
Komal
K
Shah
Rina
R
Hong
Chull
C
Pain
Jayashree
J
Tian
Bin
B
Vatner
Dorothy E
DE
Vatner
Stephen F
SF
Depre
Christophe
C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018844:Cyclin-Dependent Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D006333:Heart Failure / Q000201:enzymology*; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008252:Macaca fascicularis; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000201:enzymology*; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D016415:Sequence Alignment; D013379:Substrate Specificity
D007527:Isoenzymes; D018844:Cyclin-Dependent Kinases