[Processes determining changes in the shape of a cell following detachment from a substrate]

Area of Science:

• Cell biology
• Cytoskeleton dynamics
• Biochemistry

Background:

• Living cells exhibit distinct behaviors upon substrate detachment compared to extracted cells.
• Understanding the forces driving cell shape changes is crucial for cell mechanics research.

Purpose of the Study:

• To investigate the mechanisms underlying cell rounding after detachment.
• To determine the role of ATP, microfilaments, and microtubules in cell contraction.
• To elucidate the effect of cytochalasin B (CH) on cellular contractile processes.

Main Methods:

• Utilized glycerin-extracted mouse embryo fibroblasts.
• Applied Adenosine Triphosphate (ATP) to induce cell rounding.
• Observed effects of colcemide and cytochalasin B (CH) on cell behavior.
• Analyzed microfilament orientation changes during contraction.

Main Results:

• Glycerin-extracted fibroblasts do not round up without ATP, indicating active contractile forces are required.
• ATP addition induces rounding in extracted cells, accompanied by loss of microfilament parallel orientation.
• Microtubules are not essential for cell rounding.
• Cytochalasin B (CH) inhibits rounding in living cells but not in extracted cells, suggesting CH inactivates contractile structures.

Conclusions:

• Cell rounding is an active, ATP-dependent contractile process, not driven by elastic forces or surface tension.
• Microfilaments are involved in ATP-induced cell contraction.
• Cytochalasin B (CH) likely inactivates cellular contractile machinery, with additional factors in living cells mediating this effect.