Force-induced changes in subnuclear movement and rheology.

Area of Science:

• Cell Biology
• Biophysics
• Mechanobiology

Background:

• Cells respond to extracellular mechanical forces, influencing gene expression.
• The mechanisms for long-term adaptation to mechanical environments are not fully understood, as chemical signaling pathways are transient.

Purpose of the Study:

• To investigate how cells adapt to mechanical forces by examining force-induced changes in nuclear rheology.
• To analyze short- and long-term genome organization and movements in response to mechanical stress.

Main Methods:

• Tracking intranuclear movements of labeled components within HeLa, human umbilical vein endothelial, and osteosarcoma (Saos-2) cells.
• Applying varying levels of shear and compressive forces to cells to observe nuclear responses.

Main Results:

• Two distinct regimes of intranuclear movement were observed under shear stress: an initial increase followed by force-dependent movements.
• Nuclear movements increased significantly after 30 minutes and scaled with the applied shear or compressive stress.
• The nucleus exhibits mechanosensitivity, responding similarly to both shear and compressive forces.

Conclusions:

• Extracellular mechanical forces directly stimulate intranuclear movements.
• These movements lead to the repositioning of nuclear bodies and associated chromatin within the nucleus.
• The nucleus acts as a mechanosensitive element, crucial for cellular adaptation to mechanical environments.