Extracellular signaling cues for nuclear actin polymerization

Plessner, Matthias; Grosse, Robert

doi:10.1016/j.ejcb.2015.05.009

Cited by 22 publications

(13 citation statements)

References 40 publications

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“…Previous studies suggest that nuclear assembly is crucially involved in gene transcription, but its role in MSCs has not been reported. The sponge‐like actin meshwork in Xenopus oocyte nuclei was the first reported F‐actin in the nucleus . Filamentous actin formed when somatic nuclei were transferred into Xenopus oocytes, showing a role in the re‐activation of pluripotent genes in reprogramming .…”

Section: Discussionmentioning

confidence: 98%

3D culture increases pluripotent gene expression in mesenchymal stem cells through relaxation of cytoskeleton tension

Zhou

Chen

et al. 2017

J Cellular Molecular Medi

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Three‐dimensional (3D) culture has been shown to improve pluripotent gene expression in mesenchymal stem cells (MSCs), but the underlining mechanisms were poorly understood. Here, we found that the relaxation of cytoskeleton tension of MSCs in 3D culture was critically associated with the expressional up‐regulation of Nanog. Cultured in spheroids, MSCs showed decreased integrin‐based cell–matrix adhesion but increased cadherin‐based cell–cell interaction. Different from that in 2D culture, where MSCs exhibited branched and multiple‐directed F‐actin stress bundles at the cell edge and strengthened stress fibres transversing the cell body, MSCs cultured in spheroids showed compact cell body, relaxed cytoskeleton tension with very thin cortical actin filament outlining the cell, and increased expression of Nanog along with reduced levels of Suv39h1 (H3K9 methyltransferase) and H3K9me3. Notably, pharmaceutical inhibition of actin polymerization with cytochalasin D or silencing Suv39h1 expression with siRNA in 2D‐cultured MSCs elevated the expression of Nanog via H3K9 demethylation. Thus, our data suggest that 3D culture increases the expression of Nanog through the relaxation of actin cytoskeleton, which mediates reduced Suv39h1 and H3K9me3 levels.

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Section: Discussionmentioning

confidence: 98%

3D culture increases pluripotent gene expression in mesenchymal stem cells through relaxation of cytoskeleton tension

Zhou

Chen

et al. 2017

J Cellular Molecular Medi

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“…Nuclear localized actin is conserved in both its monomeric and polymeric form [24,28,93,125], yet the amount of nuclear F-actin varies across species and tissues and is dynamic in response to stimuli [7,14,23]. Recent evidence implicates actin and actin interactors in DSB repair [24,44].…”

Section: Discussionmentioning

confidence: 99%

“…Utr230-EN binds F-actin with the first 230 amino acids of utrophin [48]. LifeAct is derived from the first 17 amino acids of the Saccharomyces cerevisiae F-actinbinding protein Abp140 [45] and the actin chromobody is a single-domain antibody that recognizes actin [93]. Both are expressed in living cells fused to an NLS.…”

Section: Actin Staining In Fixed Cellsmentioning

confidence: 99%

Nuclear Actin and Actin-Binding Proteins in DNA Repair

Hurst

Shimada

Gasser

2019

Trends in Cell Biology

115

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Nuclear actin has been implicated in a variety of DNA-related processes including chromatin remodeling, transcription, replication, and DNA repair. However, the mechanistic understanding of actin in these processes has been limited, largely due to a lack of research tools that address the roles of nuclear actin specifically, that is, distinct from its cytoplasmic functions. Recent findings support a model for homology-directed DNA double-strand break (DSB) repair in which a complex of ARP2 and ARP3 (actin-binding proteins 2 and 3) binds at the break and works with actin to promote DSB clustering and homology-directed repair. Further, it has been reported that relocalization of heterochromatic DSBs to the nuclear periphery in Drosophila is ARP2/3 dependent and actin-myosin driven. Here we provide an overview of the role of nuclear actin and actin-binding proteins in DNA repair, critically evaluating the experimental tools used and potential indirect effects. Nuclear Actin: Globular and Filamentous Forms Highlights Methods used to study nuclear actin have major caveats that can lead to biased data interpretation. Globular actin in nuclear remodeling complexes and histone acetyltransferases is often neglected due to a focus on filamentous nuclear actin. Recent evidence implicates nuclear actin and actin-binding proteins in resectiondependent DNA repair. The mechanism is unclear. The field needs further development of tools, the use of technical controls, and a systematic evaluation of alternative interpretations to reveal the function of nuclear actin.

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“…Alternatively, gene expression programs regulated by LINC complexes could indirectly control the actin cytoskeleton. Supporting this possibility are recent data showing that LINC complexes promote the activity of the transcription factor/coactivator complex composed of Serum-Response Factor (SRF) and Megakaryoblastic Leukemia 1 (Mkl1; also known as MRTF-A/Mal; Ho et al , 2014; Plessner and Grosse, 2015; Plessner et al , 2015). SRF/Mkl1 target genes include actin isoforms, myosins, and numerous other actin-binding proteins that contribute to cell migration and contraction (Liu and Olson, 2006; Olson and Nordheim, 2010; Esnault et al , 2014; Rajakylä and Vartiainen, 2014).…”

Section: Introductionmentioning

confidence: 97%

Opposing roles for distinct LINC complexes in regulation of the small GTPase RhoA

Thakar

May

Rogers

et al. 2017

MBoC

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Linker of Nucleoskeleton and Cytoskeleton (LINC) complexes span the nuclear envelope and transduce force from dynamic cytoskeletal networks to the nuclear lamina. Here we show that LINC complexes also signal from the nuclear envelope to critical regulators of the actin cytoskeleton. Specifically, we find that LINC complexes that contain the inner nuclear membrane protein Sun2 promote focal adhesion assembly by activating the small GTPase RhoA. A key effector in this process is the transcription factor/coactivator complex composed of SRF/Mkl1. A constitutively active form of SRF/Mkl1 was not sufficient to induce focal adhesion assembly in cells lacking Sun2, however, suggesting that LINC complexes support RhoA activity through a transcription-independent mechanism. Strikingly, we also find that the inner nuclear membrane protein Sun1 antagonizes Sun2 LINC complexes and inhibits RhoA activation and focal adhesion assembly. Thus different LINC complexes have opposing roles in the transcription-independent control of the actin cytoskeleton through the small GTPase RhoA.

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Extracellular signaling cues for nuclear actin polymerization

Cited by 22 publications

References 40 publications

3D culture increases pluripotent gene expression in mesenchymal stem cells through relaxation of cytoskeleton tension

3D culture increases pluripotent gene expression in mesenchymal stem cells through relaxation of cytoskeleton tension

Nuclear Actin and Actin-Binding Proteins in DNA Repair

Opposing roles for distinct LINC complexes in regulation of the small GTPase RhoA

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