NADPH oxidase complex-derived reactive oxygen species, the actin cytoskeleton, and Rho GTPases in cell migration.

Significance: Rho GTPases are historically known to be central regulators of actin cytoskeleton reorganization. This affects many processes including cell migration. In addition, members of the Rac subfamily are known to be involved in reactive oxygen species (ROS) production through the regulation of NADPH oxidase (Nox) activity. This review focuses on relationships between Nox-regulated ROS, Rho GTPases, and cytoskeletal reorganization, in the context of cell migration.

Recent Advances: It has become clear that ROS participate in the regulation of certain Rho GTPase family members, thus mediating cytoskeletal reorganization.

Critical Issues: The role of the actin cytoskeleton in providing a scaffold for components of the Nox complex needs to be examined in the light of these new advances. During cell migration, Rho GTPases, ROS, and cytoskeletal organization appear to function as a complex regulatory network. However, more work is needed to fully elucidate the interactions between these factors and their potential in vivo importance.

Future Directions: Ultrastructural analysis, that is, electron microscopy, particularly immunogold labeling, will enable direct visualization of subcellular compartments. This in conjunction with the analysis of tissues lacking specific Rho GTPases, and Nox components will facilitate a detailed examination of the interactions of these structures with the actin cytoskeleton. In combination with the analysis of ROS production, including its subcellular location, these data will contribute significantly to our understanding of this intricate network under physiological conditions. Based on this, in vivo and in vitro studies can then be combined to elucidate the signaling pathways involved and their targets.