Stress fibers stabilize the position of intranuclear DNA through mechanical connection with the nucleus in vascular smooth muscle cells

Actin stress fibers (SFs) running across the top surface of the nucleus in vascular smooth muscle cells were dissected using laser nano-dissection technique to release its pretension, and the dynamic behavior of SFs, nucleus, and intranuclear DNA were investigated. SFs shortened across the top surface of the nuclei after their dissection. The nuclei moved in the direction of SF retraction, and showed marked local deformation, indicating that SFs firmly connected to the nuclear surface. Intranuclear DNA located near and around the dissected SFs disappeared and their distribution changed markedly. These findings suggest that SFs stabilize the position of intranuclear chromatin through mechanical connection with the nucleus. The tension of SFs may be transmitted mechanically to the nucleus inducing conformational changes of intranuclear chromatin.