Invasion of pathogens into host cells is the key process to consequently induce the infection, which depends on the actin cytoskeleton rearrangement. Cofilin in the host cell is one of the most important actin depolymerization factor that is essential responsing to the infection of several viruses, bacteria and fungi. Pathogenic microbes can induce biphasic remodeling of the actin cytoskeleton in host cells, accompanied by changes of phosphorylation of cofilin, which results in changes of cofilin activity. The modulation of host cofilin activity by mutation, knockdown, or overexpression can effectively inhibit the infection. Here we review the function and possible regulatory mechanism of host cofilin during the process of infection.

The actin cytoskeleton plays a central part in the dynamic organization of eukaryotic cell structure. Nucleation of actin filaments is a crucial step in the establishment of new cytoskeletal structures or modification of existing ones, providing abundant targets for regulatory processes. A substantial part of our understanding of actin nucleation derives from studies on yeast and metazoan cells. However, recent advances in structural and functional genome analysis in less traditional models, such as plants or Dictyostelium discoideum, provide an emerging picture of an evolutionarily conserved core of at least two actin nucleation mechanisms, one mediated by the Arp2/3 complex and the other one by the formin-based module. A considerable degree of conservation is found also in the systems controlling the balance between filamentous and globular actin (profilin, actin-depolymerizing factor/cofilin) and even in certain regulatory aspects, such as the involvement of Rho-related small GTPases. Identification of such conserved elements provides a prerequisite for the characterization of evolutionarily variable aspects of actin regulation which may be responsible for the rich morphological diversity of eukaryotic cells.