Targeted activation of c-Jun N-terminal kinase in vivo induces restrictive cardiomyopathy and conduction defects.
The stress-activated protein kinase, c-Jun N-terminal kinase (JNK), has been implicated in the process of cardiac hypertrophy and apoptosis, yet the specific roles of JNK in heart failure are unclear. To determine the effects of JNK activation in intact heart, we established transgenic animals using a Cre/loxP-mediated gene switch approach to achieve targeted expression of an upstream activator, mitogen-activated protein kinase kinase 7 (D) (MKK7D), in ventricular myocytes. MKK7D expression led to significant JNK activation, robust induction of the fetal gene program, and contractile dysfunction. The animals died approximately 7 weeks after birth with signs of congestive heart failure. Doppler mode echocardiography revealed a marked stiffening of JNK-activated hearts that was associated with the remodeling of specific extracellular matrix components. Gene expression analysis of MKK7D hearts revealed up-regulation of transforming growth factor beta signaling, offering a potential molecular mechanism underlying changes in extracellular matrix composition. In addition, we demonstrated that JNK activation led to specific loss of connexin 43 protein and gap junctions without affecting the expression or localization of other key intercalated disc proteins. This specific and localized gap junction remodeling resulted in significant slowing of ventricular electrical conduction in JNK-activated hearts. These results represent the first characterization of JNK-mediated cardiac pathology in vivo and support an important role for JNK signaling in specific aspects of cardiac remodeling in the pathogenesis of cardiac disease.
Petrich
Brian G
BG
Departments of Anesthesiology and Medicine, UCLA, Los Angeles, California 90095, USA.
Eloff
Benjamin C
BC
Lerner
Deborah L
DL
Kovacs
Attila
A
Saffitz
Jeffrey E
JE
Rosenbaum
David S
DS
Wang
Yibin
Y
D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis; D009202:Cardiomyopathies / Q000378:metabolism*; D018031:Connexin 43 / Q000378:metabolism; D004452:Echocardiography; D004553:Electric Conductivity; D004562:Electrocardiography; D004789:Enzyme Activation; D005109:Extracellular Matrix / Q000378:metabolism; D017629:Gap Junctions; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins; D006321:Heart / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D048031:JNK Mitogen-Activated Protein Kinases; D008164:Luminescent Proteins / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D048688:MAP Kinase Kinase 7; D051379:Mice; D008822:Mice, Transgenic; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009929:Organ Size; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism; D019076:Transgenes; D015854:Up-Regulation
D018031:Connexin 43; D008164:Luminescent Proteins; D016212:Transforming Growth Factor beta; D049452:Green Fluorescent Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048688:MAP Kinase Kinase 7; C482569:MAP2K7 protein, human; C482570:Map2k7 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases