Cytoskeletal Dynamics and Mechanics in Cell Growth, Division, Differentiation and Aging

Cells assemble various types of protein filaments commonly known as the cytoskeleton to provide structural support and mechanical strength to cells, to serve as tracks for cellular transport, and to confer mechano-sensing ability. In eukaryotic cells, the classical cytoskeleton includes actin filaments, microtubules and intermediate filaments. There are several relatively new classes of protein filaments like septins and ESCRT filaments, which could be considered as the cytoskeleton and function together with the classical ones in various biological processes. Like human-made polymers, the cytoskeleton has different mechanical properties depending on the structures or networks they form. However, unlike human-made polymers, the cytoskeleton constantly switches between polymeric states and monomeric states in a fast timescale while performing its functions. Interestingly, both cytoskeletal dynamics and mechanics are crucial for cellular functions of the cytoskeleton.

In the basic life cycle of a cell, the cytoskeleton is tightly related to cellular growth, division, differentiation and aging. In plant and fungal cells, cell growth is dependent on cytoskeleton structures such as actin filaments and microtubules. However, it is less well understood how cell growth is regulated by cytoskeletal dynamics and mechanics, particularly in animal cells. Interestingly, cytoskeletal gene expression scales proportionally to the cell size in animal cells. Whether cytoskeletal dynamics and mechanics respond to the changes of cell size is not clear. During cell division, the cytoskeleton is highly dynamic to adapt to the mechanical requirements of various cellular processes such as chromosome segregation and cytokinesis. Questions remain on how the cytoskeletal dynamics and mechanics are regulated in space and time. Advanced technologies that offer precise control of cytoskeletal dynamics and mechanics will help to understand this regulation. When cells are differentiating into a specific cell type, the cytoskeleton undergoes dynamic remodelling to support new cellular functions with distinct requirements of cytoskeletal dynamics and mechanics, such as cell migratory functions. Illuminating how the cytoskeletal dynamics and mechanics are programmed by the cell differentiation circuitry is interesting and will be insightful for cellular reprogramming in cell therapy. When cells are aging, there is an accompanying change of the cell stiffness. Investigation of the effects of aging on cytoskeletal dynamics and mechanics will advance our knowledge about cellular aging. The emerging functions of septins and ESCRT filaments and their interplay with the classical cytoskeleton will provide a more comprehensive understanding of cellular growth, division, differentiation and aging. Given the essential roles of the cytoskeleton in the life cycle of cells, the lack of proper regulation of cytoskeletal dynamics and mechanics will have consequences on cellular health, impacting organism fitness.

This Research Topic aims to highlight recent advances that address the dynamics and mechanics of cytoskeletal systems in the growth, division, differentiation and aging of eukaryotic cells. We welcome Original Research Articles and Reports, Reviews, Methods, Perspective and Opinion articles. Subtopics include, but are not limited to:

• Roles of cytoskeletal dynamics and mechanics in cell growth, division, differentiation and aging;
• Regulation of cytoskeletal dynamics and mechanics by cytoskeletal motors or associated proteins;
• Cellular signaling controls of cytoskeletal dynamics or mechanics;
• In vitro reconstitution studies of cytoskeletal dynamics and mechanics;
• Advances in imaging or optogenetics tools to document or manipulate cytoskeletal dynamics and mechanics;
• Novel methods or tools including small molecules to study the new classes of cytoskeletal proteins like septins or ESCRT filaments.