Intracellular transport based on actin polymerization

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Biology

Background:

• Intracellular transport relies on microtubule-based systems and two distinct actin-based systems.
• Actin-based transport involves either myosin motor proteins or unidirectional actin polymerization.
• The actin polymerization system utilizes proteins like WASP/Scar and Arp2/3, forming 'comet-like tails' for cargo movement.

Purpose of the Study:

• To review current understanding of actin polymerization and its regulation.
• To elucidate the mechanisms of intracellular actin-based vesicular transport.
• To highlight the role of actin-binding proteins in cellular transport.

Main Methods:

• Review of existing literature on intracellular transport mechanisms.
• Analysis of high-performance electron microscopy and electron tomography data.
• Examination of cell-free systems, including Xenopus oocyte extracts.

Main Results:

• Two actin-based transport systems exist: actomyosin (myosin-driven) and non-myosin (actin polymerization-driven).
• Actin polymerization forms 'comet-like tails' responsible for moving bacteria, vesicles, and phagosomes.
• This mechanism is essential for various cellular processes, including membrane raft transport and nuclear spindle positioning.

Conclusions:

• Actin polymerization is a key driver of intracellular transport, independent of motor proteins.
• Proteins of the WASP/Scar family and Arp2/3 complex are critical for actin-based transport.
• Understanding these actin-based systems provides insights into fundamental cellular mechanics and disease processes.