Proteomic analysis of the actin cortex in interphase and mitosis

Area of Science:

• Cell Biology
• Biophysics
• Molecular and Cellular Mechanics

Background:

• Cell shape changes are crucial for morphogenesis and are driven by the actomyosin cortex.
• Actomyosin cortex tension is regulated by myosin activity, actin organization, and composition.
• Understanding how cortex composition changes with tension is vital but remains unclear.

Purpose of the Study:

• To identify proteins involved in regulating cortical tension, particularly during cell division.
• To compare the protein composition of cell cortices under low (interphase) and high (mitosis) tension conditions.
• To investigate the role of specific actin-related proteins, such as septins, in mitotic cell rounding.

Main Methods:

• Purification of cortex-enriched fractions from cells in interphase and mitosis.
• Mass spectrometry analysis to identify and quantify proteins in these fractions.
• Bioinformatic analysis to narrow down candidate regulators of cortical tension.

Main Results:

• Identified 922 proteins consistently present in both interphase and mitotic cortices.
• Focused on actin-related proteins, identifying 238 candidates potentially regulating mitotic cortical tension.
• Discovered a role for septins in controlling cell rounding during mitosis.

Conclusions:

• The study provides a comprehensive dataset of candidate regulators of cortical tension.
• Findings highlight the importance of actin network composition and organization in cell mechanics.
• This work facilitates systematic investigations into the regulation of cell surface mechanics and morphogenesis.