Vesicle transport: The role of actin filaments and myosin motors

Abstract

The transport of vesicles and the retention of organelles at specific locations are fundamental processes in cells. Actin filaments and myosin motors have been shown to be required for both of these tasks. Most of the organelles in cells associate with actin filaments and some of the myosin motors required for movement on actin filaments have been identified. Myosin V has been shown to transport endoplasmic reticulum (ER) vesicles in neurons, pigment granules in melanocytes, and the vacuole in yeast. Myosin I has been shown to be involved in the transport of Golgi‐derived vesicles in epithelial cells. Myosin VI has been shown to be associated with Golgi‐derived vesicles, and cytoplasmic vesicles in living Drosophila embryos. Myosin II may be a vesicle motor but its role in vesicle transport has not been resolved. Secretory vesicles, endosomes and mitochondria appear to be transported on actin filaments but the myosin motors on these organelles have not been identified. Mitochondria in yeast may be transported by the dynamic assembly of an actin “tail.” The model that has unified all of these findings is the concept that long‐range movement of vesicles occurs on microtubules and short‐range movement on actin filaments. The details of how the microtubule‐dependent and the actin‐dependent motors are coordinated are important questions in the field. There is now strong evidence that two molecular motors, kinesin and myosin V, interact with each other and perhaps function as a complex on vesicles. An understanding of the interrelationship of microtubules and actin filaments and the motors that move cargo on them will ultimately establish how vesicles and organelles are transported to their specific locations in cells. Microsc. Res. Tech. 47:93–106, 1999. © 1999 Wiley‐Liss, Inc.

Barley MLO Modulates Actin-Dependent and Actin-Independent Antifungal Defense Pathways at the Cell Periphery

“…Recent identification of plasma membrane-resident syntaxins (Arabidopsis AtPEN1 and barley HvROR2) required for non-host and mlo resistance in Arabidopsis and barley, respectively, indicates a potential role for vesicle-mediated exocytosis in antifungal defense (Collins et al, 2003;Schulze-Lefert, 2004). It is conceivable that cytoskeletal rearrangements following fungal attack form the basis for rapid and efficient organelle motility and productive focal exocytosis (DePina and Langford, 1999). Thus, cell polarization in reaction to fungal attack might be the result of an integrated response triggered by mechanosensors and immune receptors.…”

Regulation of Protein Transport from the Golgi Complex to the Endoplasmic Reticulum by CDC42 and N-WASP

“…The involvement of microtubules in intracellular membrane trafficking is well established (Thyberg and Moskalewski, 1999 for review), and the role of actin in membrane traffic is under extensive investigation (DePina and Langford, 1999;Qualmann et al, 2000;Apodaca, 2001 for reviews). In the secretory pathway, actin filaments are required to maintain the organization of the Golgi complex (Valderrama et al, 1998;di Campli et al, 1999) and for protein transport from the Golgi to the plasma membrane and the ER Valderrama et al, 2001).…”

A Dual Role for Actin and Microtubule Cytoskeleton in the Transport of Golgi Units from the Nurse Cells to the Oocyte Across Ring Canals

“…Less is known concerning the role of the actin cytoskeleton and its associated proteins during this process. However, studies have shown the involvement of myosins in the transport of vesicles/organelles in vertebrates neurons (DePina and Langford, 1999) and the transient association of MyoVI with mitochondria during their RC transit in the Drosophila egg chamber (Bohrmann and Schill, 1997), suggesting a role for the actin network in organelle transport.…”