Multifunctional roles of Tropomodulin-3 in regulating actin dynamics
- Published
- Accepted
- Subject Areas
- Biochemistry, Cell Biology, Molecular Biology, Anatomy and Physiology, Diabetes and Endocrinology
- Keywords
- pointed-end capping, actin filament, actin, tropomyosin, tropomodulin, akt2, lamellipodia, stress fibers, adherens junctions, oocyte
- Copyright
- © 2018 Parreno et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Multifunctional roles of Tropomodulin-3 in regulating actin dynamics. PeerJ Preprints 6:e27172v1 https://doi.org/10.7287/peerj.preprints.27172v1
Abstract
Tropomodulins (Tmods) are proteins that cap the slow growing (pointed) ends of actin filaments (F-actin). The basis for our current understanding of Tmod function comes from studies in cells with relatively stable and highly organized F-actin networks, leading to the view that Tmod capping functions principally to preserve F-actin stability. However, not only is Tmod capping dynamic, but it also can play major roles in regulating diverse cellular processes involving F-actin remodeling. Here, we highlight the multifunctional roles of Tmod with a focus on Tmod3. Like other Tmods, Tmod3 binds tropomyosin (Tpm) and actin, capping pure F-actin at submicromolar and Tpm-coated F-actin at nanomolar concentrations. Unlike other Tmods, Tmod3 can also bind actin monomers and its ability to bind actin is inhibited by phosphorylation of Tmod3 by Akt2. Tmod3 is ubiquitously expressed and present in a diverse array of cytoskeletal structures, including contractile structures such as sarcomere-like units of actomyosin stress fibers and in the F-actin network encompassing adherens junctions. Tmod3 participates in F-actin network remodeling in lamellipodia during cell migration, and in the assembly of specialized F-actin networks during exocytosis. Furthermore, Tmod3 is required for development, regulating F-actin mesh formation during meiosis I of mouse oocytes, erythroblast enucleation in definitive erythropoiesis, and megakaryocyte morphogenesis in the mouse fetal liver. Thus, Tmod3 plays vital roles in dynamic and stable F-actin networks in cell physiology and development, with further research required to delineate the mechanistic details of Tmod3 regulation in the aforementioned processes, or in other yet to be discovered processes.
Author Comment
In this review, we highlight the functional roles of Tropomodulin (Tmod) in regulating actin networks. We focus on Tmod3 which is ubiquitous and has the ability to regulate contractile actin networks (stress fibers/adherens junctions), dynamic actin structures (lamellipodia/exocytotic networks), as well as F-actin in essential developmental processes. Thus, Tmod3 regulates diverse actin filament networks in a broad array of biological processes.