Exploring the Function of Cell Shape and Size during Mitosis

Abstract

Dividing cells almost always adopt a spherical shape. This is true of most eukaryotic cells lacking a rigid cell wall and is observed in tissue culture and single-celled organisms, as well as in cells dividing inside tissues. While the mechanisms underlying this shape change are now well described, the functional importance of the spherical mitotic cell for the success of cell division has been thus far scarcely addressed. Here we discuss how mitotic rounding contributes to spindle assembly and positioning, as well as the potential consequences of abnormal mitotic cell shape and size on chromosome segregation, tissue growth, and cancer.

Mechanical control of mitotic progression in single animal cells

“…Studies of multicellular spheroids indicate that the mechanical pressure of the tissue environment can impair cell proliferation (33,34). Moreover, it has been predicted that cells in stiffer or more densely packed tissue environments, such as of an overgrown tumor, would require a more robust cell cortex and mitotic rounding response (9,35). Indeed, although strategies for chemical perturbation of cell division have been pursued for decades (36), the advent of mechanical approaches opens the door to studies of physical perturbation.…”

“…In mitosis, cells generate actomyosindependent (1) intracellular pressure to round up and optimize geometry for proper function of the mitotic spindle, the machinery that organizes and segregates chromosomes (2,9,10,22). Restricting cell rounding height below 5-8 μm with microfabricated PDMS chambers perturbs mitotic progression in several cell types (2, 10), but the forces that cells can withstand remain unquantified.…”

“…Recent studies in the epithelium and epidermis of various organisms indicate that mitotic cell rounding is involved in tissue organization, development, and homeostasis (4)(5)(6)(7)(8). Abnormal mitotic cell shape can have adverse consequences for chromosome segregation and tissue growth (9), in some cases contributing to tumorigenesis (7). Despite the importance of cell rounding in mitotic progression and tissue organization, the mechanical robustness of mitotic cells remains poorly investigated even in vitro, probably due to a paucity of suitable experimental tools that can apply precise forces to poorly adherent cells.…”

Periodicity of nuclear morphology in human fibroblasts

“…2 In addition, nuclear volume is expected to increase through the cell cycle leading up to division. We looked at the phase of the top fits (all those included in Tables S1 and S4) that had periods according with the cell cycle (15-22 hours) and found that the eccentricity had an average phase of 0.6645 rad, meaning it peaked 1.5 hours after serum was returned to the cells (and every ' 17 hours after that).…”

Epithelial cell division – multiplying without losing touch

“…Abscission eventually resolves the bridge, thereby generating two distinct cells. Therefore, the dividing cell is subjected to various forces that are exerted through its own cytoskeleton (reviewed by Cadart et al, 2014;Kunda and Baum, 2009;Lancaster and Baum, 2014). In cultures of isolated cells, cells are round and exhibit a stiff actomyosin cortex during prometaphase, but upon entry into cytokinesis, cortical tensions become asymmetric -tension at the poles is relaxed, whereas the equator undergoes contraction.…”