Nuclear mechanosensing: mechanism and consequences of a nuclear rupture

Tissue regeneration at an injured site depends on proliferation, migration, and differentiation of resident stem or progenitor cells, but solid tissues are often sufficiently dense and constricting that nuclei are highly stressed by migration. In this study, constricted migration of myoblastic cell types and mesenchymal stem cells (MSCs) increases nuclear rupture, increases DNA damage, and modulates differentiation. Fewer myoblasts fuse into regenerating muscle in vivo after constricted migration in vitro, and myodifferentiation in vitro is likewise suppressed. Myosin II inhibition rescues rupture and DNA damage, implicating nuclear forces, while mitosis and the cell cycle are suppressed by constricted migration, consistent with a checkpoint. Although perturbed proliferation fails to explain defective differentiation, nuclear rupture mislocalizes differentiation-relevant MyoD and KU80 (a DNA repair factor), with nuclear entry of the DNA-binding factor cGAS. Human MSCs exhibit similar damage, but osteogenesis increases—which is relevant to bone and to calcified fibrotic tissues, including diseased muscle. Tissue repair can thus be modulated up or down by the curvature of pores through which stem cells squeeze.

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Mechanosensing by the Lamina Protects against Nuclear Rupture, DNA Damage, and Cell-Cycle Arrest

Developmental Cell ◽

10.1016/j.devcel.2019.04.020 ◽

2019 ◽

Vol 49 (6) ◽

pp. 920-935.e5 ◽

Cited By ~ 61

Author(s):

Sangkyun Cho ◽

Manasvita Vashisth ◽

Amal Abbas ◽

Stephanie Majkut ◽

Kenneth Vogel ◽

...

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Cell Cycle Arrest ◽

Cycle Arrest ◽

Nuclear Rupture

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Vimentin protects cells against nuclear rupture and DNA damage during migration

The Journal of Cell Biology ◽

10.1083/jcb.201902046 ◽

2019 ◽

Vol 218 (12) ◽

pp. 4079-4092 ◽

Cited By ~ 31

Author(s):

Alison E. Patteson ◽

Amir Vahabikashi ◽

Katarzyna Pogoda ◽

Stephen A. Adam ◽

Kalpana Mandal ◽

...

Keyword(s):

Dna Damage ◽

Mammalian Cells ◽

Nuclear Shape ◽

Null Mouse ◽

Intermediate Filament Protein ◽

Cell Periphery ◽

Damage Repair ◽

Repair Mechanisms ◽

Filament Protein ◽

Nuclear Rupture

Mammalian cells frequently migrate through tight spaces during normal embryogenesis, wound healing, diapedesis, or in pathological situations such as metastasis. Nuclear size and shape are important factors in regulating the mechanical properties of cells during their migration through such tight spaces. At the onset of migratory behavior, cells often initiate the expression of vimentin, an intermediate filament protein that polymerizes into networks extending from a juxtanuclear cage to the cell periphery. However, the role of vimentin intermediate filaments (VIFs) in regulating nuclear shape and mechanics remains unknown. Here, we use wild-type and vimentin-null mouse embryonic fibroblasts to show that VIFs regulate nuclear shape and perinuclear stiffness, cell motility in 3D, and the ability of cells to resist large deformations. These changes increase nuclear rupture and activation of DNA damage repair mechanisms, which are rescued by exogenous reexpression of vimentin. Our findings show that VIFs provide mechanical support to protect the nucleus and genome during migration.

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Gaussian curvature dilutes the nuclear lamina, favoring nuclear rupture, especially at high strain rate

10.1101/2021.10.13.464257 ◽

2021 ◽

Author(s):

Charlotte R Pfeifer ◽

Michael P Tobin ◽

Sangkyun Cho ◽

Manasvita Vashisth ◽

Lawrence J Dooling ◽

...

Keyword(s):

Cancer Cells ◽

Gaussian Curvature ◽

Cell Imaging ◽

High Strain ◽

Nuclear Lamina ◽

Lamin A ◽

Strain Rates ◽

Lamin B ◽

Hypotonic Stress ◽

Nuclear Rupture

Nuclear rupture has long been associated with deficits or defects in lamins, with recent results also indicating a role for actomyosin stress, but key physical determinants of rupture remain unclear. Here, lamin-B stably interacts with the nuclear membrane at sites of low Gaussian curvature yet dilutes at high-curvature to favor rupture, whereas lamin-A depletes similarly but only at high strain-rates. Live cell imaging of lamin-B1 gene-edited cancer cells is complemented by fixed-cell imaging of ruptured nuclei in: iPS-derived cells from progeria patients, cells within beating chick embryo hearts, and cancer cells that develop multiple ruptures in migrating through small pores. Dilution and curvature-dependent rupture fit a parsimonious model of a stiff filament that detaches from a curved surface, suggesting an elastic-type response of lamin-B, but rupture is also modestly suppressed by inhibiting myosin-II and by hypotonic stress, which slow the strain rates. Lamin-A dilution and nuclear rupture likelihood indeed increase above a threshold rate of pulling into small pipettes, suggesting a viscoplastic coupling to the envelope for protection against nuclear rupture.

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Actin assembly ruptures the nuclear envelope by prying the lamina away from nuclear pores and nuclear membranes in starfish oocytes

eLife ◽

10.7554/elife.49774 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 8

Author(s):

Natalia Wesolowska ◽

Ivan Avilov ◽

Pedro Machado ◽

Celina Geiss ◽

Hiroshi Kondo ◽

...

Keyword(s):

Nuclear Envelope ◽

Super Resolution ◽

Germinal Vesicle ◽

Nuclear Pore ◽

Nuclear Pore Complexes ◽

Actin Assembly ◽

Nuclear Membranes ◽

Pore Complexes ◽

Distinct Membrane ◽

Nuclear Rupture

The nucleus of oocytes (germinal vesicle) is unusually large and its nuclear envelope (NE) is densely packed with nuclear pore complexes (NPCs) that are stockpiled for embryonic development. We showed that breakdown of this specialized NE is mediated by an Arp2/3-nucleated F-actin ‘shell’ in starfish oocytes, in contrast to microtubule-driven tearing in mammalian fibroblasts. Here, we address the mechanism of F-actin-driven NE rupture by correlated live-cell, super-resolution and electron microscopy. We show that actin is nucleated within the lamina, sprouting filopodia-like spikes towards the nuclear membranes. These F-actin spikes protrude pore-free nuclear membranes, whereas the adjoining stretches of membrane accumulate NPCs that are associated with the still-intact lamina. Packed NPCs sort into a distinct membrane network, while breaks appear in ER-like, pore-free regions. We reveal a new function for actin-mediated membrane shaping in nuclear rupture that is likely to have implications in other contexts, such as nuclear rupture observed in cancer cells.

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Curvature Dependence of Nuclear Rupture Frequency Revealed by AFM Force Spectroscopy

Biophysical Journal ◽

10.1016/j.bpj.2017.11.3534 ◽

2018 ◽

Vol 114 (3) ◽

pp. 654a

Author(s):

Irena L. Ivanovska ◽

Yuntao Xia ◽

Jerome Irianto ◽

Dennis E. Discher

Keyword(s):

Force Spectroscopy ◽

Curvature Dependence ◽

Nuclear Rupture

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Nuclear envelope rupture drives genome instability in cancer

Molecular Biology of the Cell ◽

10.1091/mbc.e16-02-0098 ◽

2016 ◽

Vol 27 (21) ◽

pp. 3210-3213 ◽

Cited By ~ 21

Author(s):

Sanghee Lim ◽

Ryan J. Quinton ◽

Neil J. Ganem

Keyword(s):

Dna Damage ◽

Nuclear Envelope ◽

Lipid Bilayers ◽

Genome Instability ◽

Genetic Material ◽

Eukaryotic Cells ◽

Accessory Proteins ◽

Physical Barrier ◽

Chromosomal Dna ◽

Nuclear Rupture

The nuclear envelope, composed of two lipid bilayers and numerous accessory proteins, has evolved to house the genetic material of all eukaryotic cells. In so doing, the nuclear envelope provides a physical barrier between chromosomes and the cytoplasm. Once believed to be highly stable, recent studies demonstrate that the nuclear envelope is prone to rupture. These rupture events expose chromosomal DNA to the cytoplasmic environment and have the capacity to promote DNA damage. Thus nuclear rupture may be an unappreciated mechanism of mutagenesis.

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