Physical properties of the cytoplasm modulate the rates of microtubule polymerization and depolymerization

Molines, Arthur T.; Lemière, Joël; Gazzola, Morgan; Steinmark, I. Emilie; Edrington, Claire H.; Hsu, Chieh-Ting; Real-Calderón, Paula; Suhling, Klaus; Goshima, Gohta; Holt, Liam J.; Théry, Manuel; Brouhard, Gary J.; Chang, Fred

doi:10.1016/j.devcel.2022.02.001

Cited by 72 publications

(89 citation statements)

References 95 publications

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“…First, we analyzed the effect of osmotic shifts on cellular volume. Hyperosmotic shifts of various sorbitol concentrations caused sizable decrease (up to ~54%) in volume of cells, as previously noted ( Atilgan et al, 2015 ; Knapp et al, 2019 ; Molines et al, 2022 , Figure 2—figure supplement 1B–C ). The BVH plot showed that the volume responses were non-linear, indicative of a non-ideal osmometer behavior ( Figure 2D ).…”

Section: Resultssupporting

confidence: 83%

Control of nuclear size by osmotic forces in Schizosaccharomyces pombe

Lemière

Real-Calderón

Holt

et al. 2022

eLife

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The size of the nucleus scales robustly with cell size so that the nuclear-to-cell volume ratio (N/C ratio) is maintained during cell growth in many cell types. The mechanism responsible for this scaling remains mysterious. Previous studies have established that the N/C ratio is not determined by DNA amount but is instead influenced by factors such as nuclear envelope mechanics and nuclear transport. Here, we developed a quantitative model for nuclear size control based upon colloid osmotic pressure and tested key predictions in the fission yeast Schizosaccharomyces pombe. This model posits that the N/C ratio is determined by the numbers of macromolecules in the nucleoplasm and cytoplasm. Osmotic shift experiments showed that the fission yeast nucleus behaves as an ideal osmometer whose volume is primarily dictated by osmotic forces. Inhibition of nuclear export caused accumulation of macromolecules and an increase in crowding in the nucleoplasm, leading to nuclear swelling. We further demonstrated that the N/C ratio is maintained by a homeostasis mechanism based upon synthesis of macromolecules during growth. These studies demonstrate the functions of colloid osmotic pressure in intracellular organization and size control.

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Section: Resultssupporting

confidence: 83%

Control of nuclear size by osmotic forces in Schizosaccharomyces pombe

Lemière

Real-Calderón

Holt

et al. 2022

eLife

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“…Intracellular crowding is increased through intracellular gelation, which is a growing area of research for a range of applications including cancer immunotherapies, organelle imaging, and understanding cell morphogenesis. [ 9,10 ] Local viscosity of the cytosol has been shown to have dramatic effects on nucleic acid structure and function, [ 11,12 ] cytoskeletal reorganization, [ 13 ] and gene expression. [ 14 ] Recent examples of intracellular gelation are based on small molecule and peptide self‐assembly for imaging and antibacterial properties.…”

Section: Introductionmentioning

confidence: 99%

“…Although the concept of suspended animation is usually found in science fiction, it is achieved to an extent in cryptobiotic organisms. When environmental stresses are present nucleic acid structure and function, [11,12] cytoskeletal reorganization, [13] and gene expression. [14] Recent examples of intracellular gelation are based on small molecule and peptide self-assembly for imaging and antibacterial properties.…”

Section: Introductionmentioning

confidence: 99%

Intracellular Crowding by Bio‐Orthogonal Hydrogel Formation Induces Reversible Molecular Stasis

et al. 2022

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To survive extreme conditions, certain animals enter a reversible protective stasis through vitrification of the cytosol by polymeric molecules such as proteins and polysaccharides. In this work, synthetic gelation of the cytosol in living cells is used to induce reversible molecular stasis. Through the sequential lipofectamine‐mediated transfection of complementary poly(ethylene glycol) macromers into mammalian cells, intracellular crosslinking occurs through bio‐orthogonal strain‐promoted azide–alkyne cycloaddition click reactions. This achieves efficient polymer uptake with minimal cell death (99% viable). Intracellular crosslinking decreases DNA replication and protein synthesis, and increases the quiescent population by 2.5‐fold. Real‐time tracking of single cells containing intracellular crosslinked polymers identifies increases in intermitotic time (15 h vs 19 h) and decreases in motility (30 µm h−1 vs 15 µm h−1). The cytosol viscosity increases threefold after intracellular crosslinking and results in disordered cytoskeletal structure in addition to the disruption of cellular coordination in a scratch assay. By incorporating photodegradable nitrobenzyl moieties into the polymer backbone, the effects of intracellular crosslinking are reversed upon exposure to light, thereby restoring proliferation (80% phospho‐Rb+ cells), protein translation, and migration. Reversible intracellular crosslinking provides a novel method for dynamic manipulation of intracellular mechanics, altering essential processes that determine cellular function.

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“…A 20% reduction in volume from either hypertonic shock or confinement was associated with an equivalent percent reduction in speed (Figure 5F), even though cells were more deformed under confinement than hypertonic shock. This substantial volume change during active migration is surprising, given that the cell is only 60-80% water and that many biochemical and diffusive processes are sensitive to protein concentration and cytoplasmic macromolecular crowding (Milo & Phillips, 2016;Molines et al, 2022;Neurohr & Amon, 2020). Nonetheless, similar volume-speed trends have been reported for 1) primary human neutrophils in various media tonicities (Rosengren et al, 1994), 2) cancer cells in 3D hydrogels of various stiffnesses (Wang et al, 2020) and 3) Dictyostelium amoebae under 2D confinement with various applied loads (Srivastava et al, 2020).…”

Section: Discussionmentioning

confidence: 71%

“…Interestingly, osmotic-induced water flux has been recently shown to have a dramatic effect on microtubule polymerization and depolymerization in fission yeast (Molines et al, 2022). Here, volume loss, rather than accelerating polymerization via an increase in tubulin concentration, instead slowed tubulin diffusion and ultimately polymerization and depolymerization.…”

Section: Discussionmentioning

confidence: 99%

Confined keratocytes mimic in vivo migration and reveal volume-speed relationship

Labuz

Footer

Theriot

2022

Preprint

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Fish basal epidermal cells, known as keratocytes, are well-suited for cell migration studies. In vitro, isolated keratocytes adopt a stereotyped shape with a large fan-shaped lamellipodium and a nearly spherical cell body. However, in their native in vivo environment, these cells adopt a significantly different shape during their rapid migration towards wounds. Within the epidermis, keratocytes experience 2D confinement between the outer epidermal cell layer and the basement membrane; these two deformable surfaces constrain keratocyte cell bodies to be flatter in vivo than in isolation. In vivo keratocytes also exhibit a relative elongation of the front-to-back axis and substantially more lamellipodial ruffling, as compared to isolated cells. We have explored the effects of 2D confinement, separated from other in vivo environmental cues, by overlaying isolated cells with an agarose hydrogel with occasional spacers, or with a ceiling made of PDMS elastomer. Under these conditions, isolated keratocytes more closely resemble the in vivo migratory shape phenotype, displaying a flatter apical-basal axis and a longer front-to-back axis than unconfined keratocytes. We propose that 2D confinement contributes to multiple dimensions of in vivo keratocyte shape determination. Further analysis demonstrates that confinement causes a synchronous 20% decrease in both cell speed and volume. Interestingly, we were able to replicate the 20% decrease in speed using a sorbitol hypertonic shock to shrink the cell volume, which did not affect other aspects of cell shape. Collectively, our results suggest that environmentally imposed changes in cell volume may influence cell migration speed, potentially by perturbing physical properties of the cytoplasm.

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Physical properties of the cytoplasm modulate the rates of microtubule polymerization and depolymerization

Cited by 72 publications

References 95 publications

Control of nuclear size by osmotic forces in Schizosaccharomyces pombe

Control of nuclear size by osmotic forces in Schizosaccharomyces pombe

Intracellular Crowding by Bio‐Orthogonal Hydrogel Formation Induces Reversible Molecular Stasis

Confined keratocytes mimic in vivo migration and reveal volume-speed relationship

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