Activation of mitogen-activated protein kinases and p90 ribosomal S6 kinase in failing human hearts with dilated cardiomyopathy.
OBJECTIVE
A new member of the MAP kinase family, big MAP kinase-1 (BMK1), has been recently identified to promote cell growth and attenuate apoptosis. P90 ribosomal S6 kinase (p90RSK), one of the potentially important substrates of extracellular signal regulated kinase (ERK), regulates gene expression in part via phosphorylation of CREB and the Na(+)/H(+) exchanger. Recently, we have demonstrated that the activity of BMK1, Src (the upstream regulator of BMK1) and p90RSK was increased in hypertrophied myocardium induced by pressure-overload in the guinea pig. However, the abundance and activity of these kinases in human hearts are unknown.


METHODS
In addition to the three classical MAP kinases (ERK, p38 kinase, and c-Jun NH(2)-terminal kinase (JNK)), we examined the protein expression and activity of Src, BMK1, and p90RSK in explanted hearts from patients with dilated cardiomyopathy (n=9). Normal donor hearts, which were not suitable for transplant for technical reasons, were used as controls (n=5).


RESULTS
There were no significant differences in the levels of protein expression of these kinases between normal and failing hearts. ERK1/2 and p90RSK were activated in heart failure compared to control (P<0.01 and P<0.03, respectively), while the activity of p38 kinase was decreased (P<0.05) and the activity of JNK was unchanged in heart failure. By contrast, the activities of Src and BMK1 were significantly reduced in end-stage heart failure compared to normal donor hearts (P<0.05).


CONCLUSIONS
These data suggest that multiple MAP kinases, p90RSK, and Src are differentially regulated in human failing myocardium of patients with idiopathic dilated cardiomyopathy and may be involved in the pathogenesis of this complex disease.
Takeishi
Yasuchika
Y
Department of Medicine, Case Western Reserve University, Cleveland, OH 44106-5029, USA. takeishi@med.id.yamagata-u.ac.jp
Huang
Qunhua
Q
Abe
Jun-ichi
J
Che
Wenyi
W
Lee
Jiing-Dwan
JD
Kawakatsu
Hisaaki
H
Hoit
Brian D
BD
Berk
Bradford C
BC
Walsh
Richard A
RA
D000328:Adult; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000378:metabolism*; D016022:Case-Control Studies; D004789:Enzyme Activation; D006333:Heart Failure / Q000209:etiology / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D008297:Male; D008875:Middle Aged; D048054:Mitogen-Activated Protein Kinase 7; D020929:Mitogen-Activated Protein Kinase Kinases / Q000032:analysis / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology*; D019893:Ribosomal Protein S6 Kinases / Q000032:analysis / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases; D019061:src-Family Kinases / Q000032:analysis / Q000378:metabolism
D019061:src-Family Kinases; D019893:Ribosomal Protein S6 Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048054:Mitogen-Activated Protein Kinase 7; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases