Role of directionality of pulsatile strain on cell shape and JNK activation

Aortic endothelial cells lining the inner surface of the aorta are exposed to pulsatile strain due to pulsatile changes in blood pressure. We studied the effects of directionality of pulsatile strain on c-Jun N-terminal kinase (JNK) activation and cell shape. Uniaxial pulsatile strain (10%, 1 Hz) results in cell elongation and alignment perpendicular to the direction of strain. Equibiaxial pulsatile strain (10%, 1 Hz), which has no preferential direction, does not result in significant changes in cell shape or orientation. JNK activation is transient following uniaxial pulsatile strain, but sustained following equibiaxial pulsatile strain. After the JNK activation in response to uniaxial pulsatile strain has subsided, changing the direction of uniaxial strain by 90 results in a reactivation of JNK. These results suggest that the perpendicular alignment to the direction of uniaxial strain is an adaptive response of the cell, which is accompanied by a subsidence of JNK activation. In contrast, cells exposed to equibiaxial pulsatile strain do not undergo directional alignment, and there is a sustained JNK activation.