Background: Nuclear Factor (NF)-kappaB and Focal Adhesion Kinase (FAK) signalling are implicated in cardiomyocyte hypertrophy. We investigated whether FAK signalling contributed towards NF-kappaB activation by mechanical stress in cardiac myocytes.
Methods: Experiments were performed with pressure overload rat left ventricle and isolated cardiac myocytes from adult rats and isolated neonatal rat ventricular myocytes (NRVMs) underwent in vitro stretching.
Results: Pressure overload induced NF-kappaB increase in myocardial cell nuclear extracts. Adult rat isolated cardiac myocyte confocal microscopy analysis showed NF-kappaB detected into nuclei. Cyclic stretch increased the amount and NF-kappaB DNA-binding activity in NRVMs nuclear extracts. NRVMs confocal microscopy confirmed NF-kappaB subcellular relocation in stretched cells. Changes in NF-kappaB subcellular location and DNA-binding activity in stretched NRVMs were paralleled by increased FAK phosphorylation, detected in stretched NRVMs by anti-phosphospecific antibody directed to Tyr397. NRVMs treatment with FAK/Src pharmacological inhibitor attenuated NF-kappaB subcelullar relocation and increased DNA binding activity induced by cyclic stretch in cardiac myocytes.
Conclusions: FAK signalling coordinates cardiac myocyte NF-kappaB activation in response to mechanical stress. Further studies are needed to elucidate the influence of this signalling pathway on gene transcription regulation, and cardiac myocyte phenotypic changes in response to mechanical stress.