The mixed-lineage kinase 1-3 signalling pathway regulates stress response in cardiac myocytes via GATA-4 and AP-1 transcription factors.
OBJECTIVE
The mixed-lineage kinases (MLKs) act upstream of mitogen-activated protein kinases, but their role in cardiac biology and pathology is largely unknown.


METHODS
We investigated the effect of a MLK1-3 inhibitor CEP-11004 on G protein-coupled receptor agonist-induced stress response in neonatal rat cardiac myocytes in culture.


RESULTS
CEP-11004 administration dose-dependently attenuated phenylephrine and endothelin-1 (ET-1)-induced c-Jun N-terminal kinase activation. MLK inhibition also reduced ET-1- and phenylephrine-induced phosphorylation of p38 mitogen-activated protein kinase. In contrast, phenylephrine-induced extracellular signal-regulated kinase phosphorylation was further up-regulated by CEP-11004. ET-1 increased activator protein-1 binding activity 3.5-fold and GATA-binding protein 4 (GATA-4) binding activity 1.8-fold, both of which were attenuated with CEP-11004 administration by 59% and 63% respectively. Phenylephrine induced activator protein-1 binding activity by 2.6-fold, which was decreased by 81% with CEP-11004 administration. Phenylephrine also induced a 3.7-fold increase in the transcriptional activity of B-type natriuretic peptide (BNP), which was attenuated by 41% with CEP-11004 administration. In agreement, MLK inhibition also reduced hypertrophic agonist-induced secretion of immunoreactive atrial natriuretic peptide and BNP.


CONCLUSIONS
These results showed that inhibition of the MLK1-3 signalling pathway was sufficient for suppressing the activity of key nuclear effectors (GATA-4 and activator protein-1 transcription factors) in cardiac hypertrophy, and attenuated the agonist-induced atrial natriuretic peptide secretion and activation of BNP gene transcription.
Ola
A
A
Institute of Biomedicine, Department of Pharmacology and Toxicology, Biocenter Oulu, University of Oulu, Oulu, Finland.
Kerkelä
R
R
Tokola
H
H
Pikkarainen
S
S
Skoumal
R
R
Vuolteenaho
O
O
Ruskoaho
H
H
D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D002227:Carbazoles; D006332:Cardiomegaly / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D016758:Genes, jun / Q000187:drug effects; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006984:Hypertrophy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D020097:Natriuretic Peptide, Brain / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D010656:Phenylephrine / Q000378:metabolism / Q000494:pharmacology; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11
D009320:Atrial Natriuretic Factor; D002227:Carbazoles; D019332:Endothelin-1; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D020097:Natriuretic Peptide, Brain; D010656:Phenylephrine; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D048051:p38 Mitogen-Activated Protein Kinases; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11; C469298:CEP-11004