Cell cortex

Cell cortex refers to the specialized layer of cytoplasm on the inner face of the plasma membrane of cells, particularly those of eukaryotes. This layer is involved in various cellular processes including shaping the cell, enabling cell movement, and division. It is rich in actin filaments and other cytoskeletal components, which are crucial for maintaining cell structure and facilitating intracellular transport.

Structure

The cell cortex is typically a dynamic structure composed primarily of a meshwork of actin filaments, myosin motor proteins, and various binding proteins that regulate the assembly and disassembly of the actin network. This actin cortex lies just beneath the plasma membrane and is often associated with membrane-bound proteins that link the cortex to the membrane, providing structural stability and facilitating communication between the cell's interior and its environment.

Function

The functions of the cell cortex are diverse and critical for the cell's life. These include:

• Cell Shape and Rigidity: The actin-myosin network provides mechanical strength to cells, helping to maintain their shape and resist deformation.
• Cell Movement: Through the polymerization and depolymerization of actin filaments, the cell cortex can generate forces that propel the cell forward. This is essential in processes such as migration, wound healing, and embryogenesis.
• Cell Division: During mitosis, the cell cortex plays a crucial role in cytokinesis, the final separation of the two daughter cells. It helps form the contractile ring that pinches the cell into two.
• Signal Transduction: The cell cortex is involved in transmitting signals from the cell surface to the interior, affecting various cellular responses and activities.

Regulation

The dynamics of the cell cortex are regulated by a complex interplay of signaling pathways that control the polymerization and depolymerization of actin, the activity of myosin motors, and the binding of various proteins to actin filaments. Key players in this regulation include Rho family of GTPases, which are master regulators of the actin cytoskeleton, and phosphoinositides, lipids that can act as signaling molecules to recruit and activate proteins involved in actin dynamics.

Clinical Significance

Abnormalities in the cell cortex can lead to a variety of diseases. For example, defects in actin regulation can cause issues with cell movement and division, leading to developmental disorders and contributing to the progression of cancer. Understanding the cell cortex is therefore not only important for basic cell biology but also for developing therapeutic strategies for a range of diseases.