The LINC complex is required for endothelial cell adhesion and adaptation to shear stress and cyclic stretch

Denis, Kevin; Cabe, Jolene I; Danielsson, Brooke E; Tieu, Katie V; Mayer, Carl R.; Conway, Daniel E.

doi:10.1091/mbc.e20-11-0698

Cited by 29 publications

(28 citation statements)

References 39 publications

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“…Disabling LINC complex function may affect cell fate via number of mechanisms. Our group and others have shown that both dnKASH expression 21,22 and Sun1/2 co-depletion 23,24 alters the force generation and dynamics of focal adhesions. In mesenchymal stem cells (MSC), both approaches impair the activation of signaling molecules FAK (Focal Adhesion Kinase) and Akt (Serine/Threonine Kinase) in response to mechanical vibrations, thus limiting the RhoA mediated increase in cell contractility 25 .…”

Section: Introductionmentioning

confidence: 72%

Depletion of Sun1/2 induces heterochromatin accrual in mesenchymal stem cells during adipogenesis

Goelzer

Howard

Zavala

et al. 2022

Preprint

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Mechanical signals regulate adipogenic differentiation of mesenchymal stem cells (MSCs). Critical to the mechano-regulation of MSCs, Linker of the Nucleoskeleton and Cytoskeleton (LINC) complexes are integral to both nucleo-cytoskeletal signal transduction and structural integrity of the nucleus. The LINC complex is made of Nesprin proteins that associate with the cytoskeleton on the outer nuclear membrane (ONM) and Sun proteins that bound to nuclear lamina and chromatin at the inner nuclear membrane (INM). In addition to their role in the LINC complex function, depletion of Sun1/2 effects chromosomal tethering to the nuclear envelope, nuclear morphology, and chromatin organization. Suggesting that Sun1/2 proteins may regulate chromatin organization and adipogenic differentiation independent of the LINC complex mediated nucleo-cytoskeletal connectivity. To test this hypothesis Sun1/2 depletion was compared to expression of a dominant-negative KASH (dnKASH) domain to decouple nucleus from cytoskeleton by inhibiting Nesprin-SUN association. Sun1/2 depletion inhibited fat droplet formation and production of adipogenic proteins such as Adipoq, which were supported by RNA-seq showing decreased adipogensis. In contrast dnKASH responded oppositely, increasing fat droplet formation, Adipoq and adipogenic gene expression. At the chromatin level, Sun1/2 depletion increased H3K9me3 levels, increased H3K9me3 foci count, and enrichment on Adipoq. No increase of H3K9me3 levels, foci count, or increased H3K9me3 enrichment on Adipoq was found during dnKASH expression. We conclude that physically decoupling of the LINC complex via dnKASH accelerates adipogenesis and that depletion of Sun1/2 increases heterochromatin accrual and inhibits adipogenesis independent of the LINC complex function.

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Section: Introductionmentioning

confidence: 72%

Depletion of Sun1/2 induces heterochromatin accrual in mesenchymal stem cells during adipogenesis

Goelzer

Howard

Zavala

et al. 2022

Preprint

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“…Furthermore, under static conditions, nesprin-1 and -2 knockdown resulted in increased actin stress fiber formation (King et al, 2014). More recently, experiments in endothelial cells expressing a dominant negative KASH construct (DN-KASH), which displaces all endogenous nesprins from binding to their cytoskeletal components demonstrated its importance in promoting endothelial celladhesion, barrier formation, and focal adhesions (Denis et al, 2021). In support of these results, Yang and colleagues observed a role of nesprin-1,-2 in expression of tight junction proteins ZO-1 and occludin (which bind actin and microtubules), under atheroprotective pulsatile flow (Yang et al, 2020).…”

Section: From the Cell Surface To The Nucleus: Roles Of The Cytoskeletonmentioning

confidence: 99%

“…These vimentin cages serve to maintain nuclear integrity in cells migrating across tight spaces and loss of vimentin resulted in DNA-damage following nuclear constriction (Patteson et al, 2019). In addition, DN-KASH expressing endothelial cells also display collapse of the vimentin network suggesting vimentin's close association with the nucleus in ECs likely plays a similar protective role (Denis et al, 2021). Studies on ECs in vitro using nesprin-3 knockdown surprisingly promoted an elongated cell phenotype under static culture conditions and an increase in centrosome to nucleus distance (Morgan et al, 2011).…”

Section: Intermediate Filament Vimentin and Nuclear Resiliencementioning

confidence: 99%

“…Studies of individual LINC components in EC and vSMCs highlighted their critical roles in nuclear mechanosensing and mechanotransduction (Chancellor et al, 2010;Morgan et al, 2011;Anno et al, 2012;King et al, 2014;Han et al, 2015). Consistent with their predicted contributions, genetic inactivation of several of these LINC components result in vascular defects including embryonic death (Ishimura et al, 2006;Denis et al, 2021). Early evidence of nuclear membrane proteins involvement in vascular development was presented by Ishimura and colleagues.…”

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confidence: 95%

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Nuclear Mechanosensation and Mechanotransduction in Vascular Cells

Salvador

Iruela‐Arispe

2022

Front. Cell Dev. Biol.

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Vascular cells are constantly subjected to physical forces associated with the rhythmic activities of the heart, which combined with the individual geometry of vessels further imposes oscillatory, turbulent, or laminar shear stresses on vascular cells. These hemodynamic forces play an important role in regulating the transcriptional program and phenotype of endothelial and smooth muscle cells in different regions of the vascular tree. Within the aorta, the lesser curvature of the arch is characterized by disturbed, oscillatory flow. There, endothelial cells become activated, adopting pro-inflammatory and athero-prone phenotypes. This contrasts the descending aorta where flow is laminar and endothelial cells maintain a quiescent and atheroprotective phenotype. While still unclear, the specific mechanisms involved in mechanosensing flow patterns and their molecular mechanotransduction directly impact the nucleus with consequences to transcriptional and epigenetic states. The linker of nucleoskeleton and cytoskeleton (LINC) protein complex transmits both internal and external forces, including shear stress, through the cytoskeleton to the nucleus. These forces can ultimately lead to changes in nuclear integrity, chromatin organization, and gene expression that significantly impact emergence of pathology such as the high incidence of atherosclerosis in progeria. Therefore, there is strong motivation to understand how endothelial nuclei can sense and respond to physical signals and how abnormal responses to mechanical cues can lead to disease. Here, we review the evidence for a critical role of the nucleus as a mechanosensor and the importance of maintaining nuclear integrity in response to continuous biophysical forces, specifically shear stress, for proper vascular function and stability.

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“…For example, perturbation of the LINC complex using dominant-negative KASH (DN-KASH), which broadly interferes with nesprin-SUN interaction, causes impaired propagation of intracellular forces and disturbs the organization of the perinuclear actin and intermediate filament networks ( Lombardi et al, 2011 ). Endothelial cells expressing DN-KASH alter cell–cell adhesion, barrier function, cell–matrix adhesion, and FA dynamics ( Denis et al, 2021 ). In addition, nesprin-1 depletion in endothelial cells increases the number of FAs, cell traction force, and nuclear height ( Chancellor et al, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

Inner Nuclear Membrane Protein, SUN1, is Required for Cytoskeletal Force Generation and Focal Adhesion Maturation

Ueda

Maekawa

Matsui

et al. 2022

Front. Cell Dev. Biol.

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The linker of nucleoskeleton and cytoskeleton (LINC) complex is composed of the inner nuclear membrane-spanning SUN proteins and the outer nuclear membrane-spanning nesprin proteins. The LINC complex physically connects the nucleus and plasma membrane via the actin cytoskeleton to perform diverse functions including mechanotransduction from the extracellular environment to the nucleus. Mammalian somatic cells express two principal SUN proteins, namely SUN1 and SUN2. We have previously reported that SUN1, but not SUN2, is essential for directional cell migration; however, the underlying mechanism remains elusive. Because the balance between adhesive force and traction force is critical for cell migration, in the present study, we focused on focal adhesions (FAs) and the actin cytoskeleton. We observed that siRNA-mediated SUN1 depletion did not affect the recruitment of integrin β1, one of the ubiquitously expressed focal adhesion molecules, to the plasma membrane. Consistently, SUN1-depleted cells normally adhered to extracellular matrix proteins, including collagen, fibronectin, laminin, and vitronectin. In contrast, SUN1 depletion reduced the activation of integrin β1. Strikingly, the depletion of SUN1 interfered with the incorporation of vinculin into the focal adhesions, whereas no significant differences in the expression of vinculin were observed between wild-type and SUN1-depleted cells. In addition, SUN1 depletion suppressed the recruitment of zyxin to nascent focal adhesions. These data indicate that SUN1 is involved in the maturation of focal adhesions. Moreover, disruption of the SUN1-containing LINC complex abrogates the actin cytoskeleton and generation of intracellular traction force, despite the presence of SUN2. Thus, a physical link between the nucleus and cytoskeleton through SUN1 is required for the proper organization of actin, thereby suppressing the incorporation of vinculin and zyxin into focal adhesions and the activation of integrin β1, both of which are dependent on traction force. This study provides insights into a previously unappreciated signaling pathway from the nucleus to the cytoskeleton, which is in the opposite direction to the well-known mechanotransduction pathways from the extracellular matrix to the nucleus.

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The LINC complex is required for endothelial cell adhesion and adaptation to shear stress and cyclic stretch

Cited by 29 publications

References 39 publications

Depletion of Sun1/2 induces heterochromatin accrual in mesenchymal stem cells during adipogenesis

Depletion of Sun1/2 induces heterochromatin accrual in mesenchymal stem cells during adipogenesis

Nuclear Mechanosensation and Mechanotransduction in Vascular Cells

Inner Nuclear Membrane Protein, SUN1, is Required for Cytoskeletal Force Generation and Focal Adhesion Maturation

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