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TOPICAL COLLECTIONS

Methods Collection to Understand Cellular Motility and Cytokinesis

Guest Editor

Wasim Sayyad

Yale University

Dr. Wasim Sayyad is an Associate Research Scientist at the Yale University. He obtained his PhD in Neuroscience from the International School for Advanced Studies, Trieste Italy where he studied force generation mechanism in developing neurons by using optical tweezers. Dr. Wasim found that lamellipodia, a sheet-like structure at the end of neuronal growth cone exerts a larger force (20 pN) than a finger-like filopodium (3 pN) and myosin II controls the structural stability of growth cone. He then joined the lab of Prof. Thomas Pollard where his research focused on elucidating the mechanisms of endocytosis and cytokinesis using fission yeast as a very favorable model organism. Using a combination of genetics, quantitative confocal microscopy, and high-speed super-resolution fluorescence photoactivation localization microscopy (FPLAM) in live cells, he found that the assembly of two zones of actin filaments, each smaller than the diffraction limit of light, drives the formation of tubular invaginations of the plasma membrane and push each other to pinch the plasma membrane to form an endocytic vesicle. Recently, he used Airyscan microscopy to show that the number of cytokinesis nodes scales with cell size. These assemblies of proteins are membrane-less organelles (MLOs) attached to the plasma membrane around a nucleus, which serve as precursors for the contractile ring, which divides cells in two at the end of mitosis. Dr. Wasim’s long-term research goal is to understand the molecular mechanisms underlying cellular processes involved in cell morphology and proliferation in enough detail to cure the related diseases caused due to defects in them.

Collection Overview

The innate ability of a cell to move and/or divide is a sign of life. Cellular motility and cytokinesis are essential processes for embryonic development, immune responses, wound healing, and the development of tissues. Defects in these processes cause diseases including cancer or neurodegeneration. Despite the work of more than 50 years in the field, the molecular mechanisms underlying these processes are not fully understood due to the complexities and involvement of a large number of proteins. Cellular motility involves an extension of a leading edge of a cell due to the pushing of a branched network of actin filaments (F-actin) under the plasma membrane. Whereas cytokinesis in amoeba, fungi, and animal cells is driven by a common cell division apparatus called actomyosin contractile ring, which upon constriction divides the cell into two daughter cells. Both fundamental cellular processes require the assembly, disassembly, and maintenance of F-actin networks at specific times and locations within the cell through the coordinated actions of specific sets of actin-binding proteins (ABPs).

With overlapping ABPs how different F-actin networks in a traditional cell are controlled together is not known. Recent advancements in Biophysics, Biochemistry, microscopy, and genetics facilitated this field to reveal the fundamental principles by which cells self-organize various F-actin networks to perform essential cellular functions. The proposed Methods Collection calls for diverse research methodologies in the field of Cellular motility and cytokinesis to serve as a repository for budding researchers.

Abstracts

Reconstitution of myosin-I mediated branched actin assembly at cell leading edge using actin comet tail bead motility assay

Mengqi Xu^*1,

E. Michael Ostap¹

¹Department of Physiology, Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104, USA.