Cell shape, cytoskeletal mechanics, and cell cycle control in angiogenesis

Area of Science:

• Cell Biology
• Biophysics
• Angiogenesis Research

Background:

• Cellular behavior, including growth and differentiation, is influenced by interactions with the extracellular matrix (ECM).
• Cell shape modulation is a key mechanism affecting endothelial cell behavior.

Purpose of the Study:

• To determine when cell shape influences growth during the cell cycle.
• To investigate the role of cytoskeletal structure and mechanics in shape-dependent growth control.

Main Methods:

• Culturing G0-synchronized capillary endothelial cells on fibronectin or RGD-peptide coated dishes with basic fibroblast growth factor (FGF).
• Using trypsin or cytochalasin D to alter cell adhesion and shape at different time points.
• Treating cells with cytochalasin D and nocodazole to disrupt actin microfilaments and microtubules, respectively.
• Measuring cytoskeletal stiffness using magnetic twisting cytometry.

Main Results:

• Cell spreading, nuclear extension, and DNA synthesis increased in parallel with increasing ECM density.
• Cells require approximately 12-15 hours of sustained spreading (most of G1) to enter S phase.
• Actin microfilament disruption inhibited spreading and DNA synthesis, while microtubule disruption had minimal effects.
• Combined disruption of actin and microtubules synergistically inhibited cell spreading and DNA synthesis, indicating microtubule's load-bearing role.

Conclusions:

• Matrix-dependent changes in cell and nuclear shape are critical for regulating capillary endothelial cell growth.
• Cytoskeletal mechanics, particularly the interplay between actin and microtubules, are integral to this growth control mechanism.
• These findings highlight the importance of cytoskeletal dynamics in angiogenesis.