Microtubules mediate changes in membrane cortical elasticity during contractile activation

Area of Science:

• Cell Biology
• Biophysics

Background:

• Cellular mechanical properties are crucial for physiological and pathological processes.
• Microtubules (MT) and actomyosin contractility influence focal adhesion (FA) size and cell elasticity.

Purpose of the Study:

• To investigate the combined effects of MT depolymerization and actomyosin activation on fibroblast cell mechanical properties.
• To understand how these cytoskeletal dynamics modulate cortical elasticity, FA assembly, and cell height over time.

Main Methods:

• Fibroblast cells were treated with calyculin A to enhance contractility and nocodazole to depolymerize MTs.
• The study examined changes in FA size, cell height, and cortical elasticity following individual and sequential treatments.

Main Results:

• Individual MT depolymerization or actomyosin activation increased FA size, decreased cell height, and enhanced cortical elasticity.
• Sequential stimulation of both processes unexpectedly decreased cortical elasticity, led to FA loss, and increased cell height.

Conclusions:

• Loss of MTs impairs fibroblast cells' ability to sustain increased contractility and cortical elasticity.
• Absence of MTs may cause excessive tension at FA sites, leading to disassembly and suggesting an upper limit for tension-mediated FA growth.