1
|
Felipe-López A, Hansmeier N, Hensel M. Destruction of the brush border by Salmonella enterica sv. Typhimurium subverts resorption by polarized epithelial cells. Front Microbiol 2024; 15:1329798. [PMID: 38894970 PMCID: PMC11183102 DOI: 10.3389/fmicb.2024.1329798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 05/06/2024] [Indexed: 06/21/2024] Open
Abstract
Salmonella enterica serovar Typhimurium is an invasive, facultative intracellular gastrointestinal pathogen that destroys the brush border of polarized epithelial cells (PEC). The brush border is critical for the functions of PEC because it resorbs nutrients from the intestinal lumen and builds a physical barrier to infecting pathogens. The manipuation of PEC during infection by Salmonella was investigated by live-cell imaging and ultrastructural analysed of the brush border. We demonstrate that the destruction of the brush border by Salmonella significantly reduces the resorption surface of PEC along with the abrogation of endocytosis at the apical side of PEC. Both these changes in the physiology of PEC were associated with the translocation of type III secretion system effector protein SopE. Additionally, the F-actin polymerization rate at the apical side of PEC was highly altered by SopE, indicating that reduced endocytosis observed in infected PEC is related to the manipulation of F-actin polymerization mediated by SopE and, to a lesser extent, by effectors SopE2 or SipA. We further observed that in the absence of SopE, Salmonella effaced microvilli and induced reticular F-actin by bacterial accumulation during prolonged infection periods. In contrast to strains translocating SopE, strains lacking SopE did not alter resorption by PEC. Finally, we observed that after engulfment of Salmonella, ezrin was lost from the apical side of PEC and found later in early endosomes containing Salmonella. Our observations suggest that the destruction of the brush border by Salmonella may contribute to the pathogenesis of diarrhea.
Collapse
Affiliation(s)
| | | | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs—Center of Cellular Nanoanalytics Osnabrück, Universität Osnabrück, Osnabrück, Germany
| |
Collapse
|
2
|
Yu W, Yuan R, Liu M, Liu K, Ding X, Hou Y. Effects of rpl1001 Gene Deletion on Cell Division of Fission Yeast and Its Molecular Mechanism. Curr Issues Mol Biol 2024; 46:2576-2597. [PMID: 38534780 DOI: 10.3390/cimb46030164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/27/2024] [Accepted: 03/12/2024] [Indexed: 03/28/2024] Open
Abstract
The rpl1001 gene encodes 60S ribosomal protein L10, which is involved in intracellular protein synthesis and cell growth. However, it is not yet known whether it is involved in the regulation of cell mitosis dynamics. This study focuses on the growth, spore production, cell morphology, the dynamics of microtubules, chromosomes, actin, myosin, and mitochondria of fission yeast (Schizosaccharomyces pombe) to investigate the impact of rpl1001 deletion on cell mitosis. RNA-Seq and bioinformatics analyses were also used to reveal key genes, such as hsp16, mfm1 and isp3, and proteasome pathways. The results showed that rpl1001 deletion resulted in slow cell growth, abnormal spore production, altered cell morphology, and abnormal microtubule number and length during interphase. The cell dynamics of the rpl1001Δ strain showed that the formation of a monopolar spindle leads to abnormal chromosome segregation with increased rate of spindle elongation in anaphase of mitosis, decreased total time of division, prolonged formation time of actin and myosin loops, and increased expression of mitochondrial proteins. Analysis of the RNA-Seq sequencing results showed that the proteasome pathway, up-regulation of isp3, and down-regulation of mfm1 and mfm2 in the rpl1001Δ strain were the main factors underpinning the increased number of spore production. Also, in the rpl1001Δ strain, down-regulation of dis1 caused the abnormal microtubule and chromosome dynamics, and down-regulation of hsp16 and pgk1 were the key genes affecting the delay of actin ring and myosin ring formation. This study reveals the effect and molecular mechanism of rpl1001 gene deletion on cell division, which provides the scientific basis for further clarifying the function of the Rpl1001 protein in cell division.
Collapse
Affiliation(s)
- Wen Yu
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), College of Life Science, China West Normal University, Nanchong 637009, China
| | - Rongmei Yuan
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), College of Life Science, China West Normal University, Nanchong 637009, China
| | - Mengnan Liu
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), College of Life Science, China West Normal University, Nanchong 637009, China
| | - Ke Liu
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), College of Life Science, China West Normal University, Nanchong 637009, China
| | - Xiang Ding
- College of Environmental Science and Engineering, China West Normal University, Nanchong 637009, China
| | - Yiling Hou
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), College of Life Science, China West Normal University, Nanchong 637009, China
| |
Collapse
|
3
|
Sekine S, Tarama M, Wada H, Sami MM, Shibata T, Hayashi S. Emergence of periodic circumferential actin cables from the anisotropic fusion of actin nanoclusters during tubulogenesis. Nat Commun 2024; 15:464. [PMID: 38267421 PMCID: PMC10808230 DOI: 10.1038/s41467-023-44684-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 12/29/2023] [Indexed: 01/26/2024] Open
Abstract
The periodic circumferential cytoskeleton supports various tubular tissues. Radial expansion of the tube lumen causes anisotropic tensile stress, which can be exploited as a geometric cue. However, the molecular machinery linking anisotropy to robust circumferential patterning is poorly understood. Here, we aim to reveal the emergent process of circumferential actin cable formation in a Drosophila tracheal tube. During luminal expansion, sporadic actin nanoclusters emerge and exhibit circumferentially biased motion and fusion. RNAi screening reveals the formin family protein, DAAM, as an essential component responding to tissue anisotropy, and non-muscle myosin II as a component required for nanocluster fusion. An agent-based model simulation suggests that crosslinkers play a crucial role in nanocluster formation and cluster-to-cable transition occurs in response to mechanical anisotropy. Altogether, we propose that an actin nanocluster is an organizational unit that responds to stress in the cortical membrane and builds a higher-order cable structure.
Collapse
Affiliation(s)
- Sayaka Sekine
- Laboratory for Morphogenetic Signaling, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan.
- Laboratory for Histogenetic Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
| | - Mitsusuke Tarama
- Laboratory for Physical Biology, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan.
- Department of Physics, Faculty of Science, Kyushu University, Fukuoka, Japan.
| | - Housei Wada
- Laboratory for Morphogenetic Signaling, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Mustafa M Sami
- Laboratory for Morphogenetic Signaling, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
- Physics and Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Tatsuo Shibata
- Laboratory for Physical Biology, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Shigeo Hayashi
- Laboratory for Morphogenetic Signaling, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
- Kobe University Graduate School of Science, Kobe, Japan
| |
Collapse
|
4
|
Pan L, E T, Xu C, Fan X, Xia J, Liu Y, Liu J, Zhao J, Bao N, Zhao Y, Sun H, Qin G, Farouk MH. The apoptotic effects of soybean agglutinin were induced through three different signal pathways by down-regulating cytoskeleton proteins in IPEC-J2 cells. Sci Rep 2023; 13:5753. [PMID: 37031286 PMCID: PMC10082828 DOI: 10.1038/s41598-023-32951-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 04/05/2023] [Indexed: 04/10/2023] Open
Abstract
Soybean agglutinin (SBA) is a main anti-nutritional factor in soybean. SBA exhibits its anti-nutritional functions by binding to intestinal epithelial cells. Keratin8 (KRT8), Keratin18 (KRT18) and Actin (ACTA) are the representative SBA-specific binding proteins. Such cytoskeletal proteins act a crucial role in different cell activities. However, limited reports reveal what the signal transduction pathway of apoptosis caused by SBA when binding to KRT8, KRT18 and ACTA. We aimed to evaluate the effects of SBA on cell apoptosis and the expression of the cytoskeletal protein (KRT8, KRT18 and ACTA), reveal the roles of these cytoskeletal proteins or their combinations on SBA-induced cell apoptosis in IPEC-J2 cell line, evaluate the influences of SBA on the mitochondria, endoplasmic reticulum stress and death receptor-mediated apoptosis signal pathway and to show the roles of KRT8, KRT18 and ACTA in different apoptosis signal pathways induced by SBA. The results showed that SBA induced the IPEC-J2 cell apoptosis and decreased the mRNA expression of KRT8, KRT18 and ACTA (p < 0.05). The degree of effect of three cytoskeleton proteins on cell apoptosis was ACTA > KRT8 > KRT18. The roles of these three cytoskeletal proteins on IPEC-J2 apoptotic rates had a certain accumulation effect. SBA up-regulated mitochondrial fission variant protein (FIS1) and fusion protein (Mfn2) promoted CytC and AIF in mitochondria to enter the cytoplasm, activated caspase-9 and caspase-3, damaged or declined mitochondrial function and reduced ATP synthesis (p < 0.05). Also, SBA up-regulated the expression of GRP78, XBP-1, eIF2α, p-eIF2α and CHOP (p < 0.05), down-regulated the expression level of ASK1 protein (p < 0.05). SBA led to the recruitment of FADD to the cytoplasmic membrane and increased the expression of FasL, resulting in caspase-8 processing. SBA up-regulated the expression level of Bax protein and decreased cytosolic Bcl-2 and Bid (p < 0.05). In addition, there was a significant negative correlation between the gene expression of cytoskeleton proteins and apoptosis, as well as the expression of key proteins of apoptosis-related signal transduction pathways. In conclusion, SBA induced the activation of the mitochondria, endoplasmic reticulum stress and the death receptor-mediated apoptosis signal pathway and the crosstalk between them. The effect of SBA on these three pathways was mainly exhibited via down-regulation of the mRNA expression of the three cytoskeletal expressions. This study elucidates the molecular mechanism and signaling pathway of SBA that lead to apoptosis from the perspective of cell biology and molecular biology and provides a new perspective on the toxicity mechanism of other food-derived anti-nutrients, medical gastrointestinal health and related cancer treatment.
Collapse
Affiliation(s)
- Li Pan
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Tianjiao E
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Chengyu Xu
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Xiapu Fan
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Jiajia Xia
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Yan Liu
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Jiawei Liu
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Jinpeng Zhao
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Nan Bao
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Yuan Zhao
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Hui Sun
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China
| | - Guixin Qin
- Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Key Laboratory of Animal Nutrition and Feed Science, Jilin Province, College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, People's Republic of China.
| | - Mohammed Hamdy Farouk
- Animal Production Department, Faculty of Agriculture, Al-Azhar University, Nasr City, 11884, Cairo, Egypt.
| |
Collapse
|
5
|
Liebe NL, Mey I, Vuong L, Shikho F, Geil B, Janshoff A, Steinem C. Bioinspired Membrane Interfaces: Controlling Actomyosin Architecture and Contractility. ACS APPLIED MATERIALS & INTERFACES 2023; 15:11586-11598. [PMID: 36848241 PMCID: PMC9999349 DOI: 10.1021/acsami.3c00061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
The creation of biologically inspired artificial lipid bilayers on planar supports provides a unique platform to study membrane-confined processes in a well-controlled setting. At the plasma membrane of mammalian cells, the linkage of the filamentous (F)-actin network is of pivotal importance leading to cell-specific and dynamic F-actin architectures, which are essential for the cell's shape, mechanical resilience, and biological function. These networks are established through the coordinated action of diverse actin-binding proteins and the presence of the plasma membrane. Here, we established phosphatidylinositol-4,5-bisphosphate (PtdIns[4,5]P2)-doped supported planar lipid bilayers to which contractile actomyosin networks were bound via the membrane-actin linker ezrin. This membrane system, amenable to high-resolution fluorescence microscopy, enabled us to analyze the connectivity and contractility of the actomyosin network. We found that the network architecture and dynamics are not only a function of the PtdIns[4,5]P2 concentration but also depend on the presence of negatively charged phosphatidylserine (PS). PS drives the attached network into a regime, where low but physiologically relevant connectivity to the membrane results in strong contractility of the actomyosin network, emphasizing the importance of the lipid composition of the membrane interface.
Collapse
Affiliation(s)
- Nils L. Liebe
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Ingo Mey
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Loan Vuong
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Fadi Shikho
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Burkhard Geil
- Institut
für Physikalische Chemie, Georg-August
Universität, Tammannstr. 6, Göttingen 37077, Germany
| | - Andreas Janshoff
- Institut
für Physikalische Chemie, Georg-August
Universität, Tammannstr. 6, Göttingen 37077, Germany
| | - Claudia Steinem
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
- Max-Planck-Institut
für Dynamik und Selbstorganisation, Am Fassberg 17, Göttingen 37077, Germany
| |
Collapse
|
6
|
Rajan S, Kudryashov DS, Reisler E. Actin Bundles Dynamics and Architecture. Biomolecules 2023; 13:450. [PMID: 36979385 PMCID: PMC10046292 DOI: 10.3390/biom13030450] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/04/2023] Open
Abstract
Cells use the actin cytoskeleton for many of their functions, including their division, adhesion, mechanosensing, endo- and phagocytosis, migration, and invasion. Actin bundles are the main constituent of actin-rich structures involved in these processes. An ever-increasing number of proteins that crosslink actin into bundles or regulate their morphology is being identified in cells. With recent advances in high-resolution microscopy and imaging techniques, the complex process of bundles formation and the multiple forms of physiological bundles are beginning to be better understood. Here, we review the physiochemical and biological properties of four families of highly conserved and abundant actin-bundling proteins, namely, α-actinin, fimbrin/plastin, fascin, and espin. We describe the similarities and differences between these proteins, their role in the formation of physiological actin bundles, and their properties-both related and unrelated to their bundling abilities. We also review some aspects of the general mechanism of actin bundles formation, which are known from the available information on the activity of the key actin partners involved in this process.
Collapse
Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| |
Collapse
|
7
|
Rutkowski DM, Vavylonis D. Discrete mechanical model of lamellipodial actin network implements molecular clutch mechanism and generates arcs and microspikes. PLoS Comput Biol 2021; 17:e1009506. [PMID: 34662335 PMCID: PMC8553091 DOI: 10.1371/journal.pcbi.1009506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/28/2021] [Accepted: 09/30/2021] [Indexed: 01/03/2023] Open
Abstract
Mechanical forces, actin filament turnover, and adhesion to the extracellular environment regulate lamellipodial protrusions. Computational and mathematical models at the continuum level have been used to investigate the molecular clutch mechanism, calculating the stress profile through the lamellipodium and around focal adhesions. However, the forces and deformations of individual actin filaments have not been considered while interactions between actin networks and actin bundles is not easily accounted with such methods. We develop a filament-level model of a lamellipodial actin network undergoing retrograde flow using 3D Brownian dynamics. Retrograde flow is promoted in simulations by pushing forces from the leading edge (due to actin polymerization), pulling forces (due to molecular motors), and opposed by viscous drag in cytoplasm and focal adhesions. Simulated networks have densities similar to measurements in prior electron micrographs. Connectivity between individual actin segments is maintained by permanent and dynamic crosslinkers. Remodeling of the network occurs via the addition of single actin filaments near the leading edge and via filament bond severing. We investigated how several parameters affect the stress distribution, network deformation and retrograde flow speed. The model captures the decrease in retrograde flow upon increase of focal adhesion strength. The stress profile changes from compression to extension across the leading edge, with regions of filament bending around focal adhesions. The model reproduces the observed reduction in retrograde flow speed upon exposure to cytochalasin D, which halts actin polymerization. Changes in crosslinker concentration and dynamics, as well as in the orientation pattern of newly added filaments demonstrate the model's ability to generate bundles of filaments perpendicular (actin arcs) or parallel (microspikes) to the protruding direction.
Collapse
|
8
|
Li Y, Munro E. Filament-guided filament assembly provides structural memory of filament alignment during cytokinesis. Dev Cell 2021; 56:2486-2500.e6. [PMID: 34480876 DOI: 10.1016/j.devcel.2021.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/30/2021] [Accepted: 08/13/2021] [Indexed: 10/24/2022]
Abstract
During cytokinesis, animal cells rapidly remodel the equatorial cortex to build an aligned array of actin filaments called the contractile ring. Local reorientation of filaments by active equatorial compression is thought to underlie the emergence of filament alignment during ring assembly. Here, combining single molecule analysis and modeling in one-cell C. elegans embryos, we show that filaments turnover is far too fast for reorientation of individual filaments by equatorial compression to explain the observed alignment, even if favorably oriented filaments are selectively stabilized. By tracking single formin/CYK-1::GFP particles to monitor local filament assembly, we identify a mechanism that we call filament-guided filament assembly (FGFA), in which existing filaments serve as templates to orient the growth of new filaments. FGFA sharply increases the effective lifetime of filament orientation, providing structural memory that allows cells to build highly aligned filament arrays in response to equatorial compression, despite rapid turnover of individual filaments.
Collapse
Affiliation(s)
- Younan Li
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Edwin Munro
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA; Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA.
| |
Collapse
|
9
|
Homa KE, Zsolnay V, Anderson CA, O'Connell ME, Neidt EM, Voth GA, Bidone TC, Kovar DR. Formin Cdc12's specific actin assembly properties are tailored for cytokinesis in fission yeast. Biophys J 2021; 120:2984-2997. [PMID: 34214524 DOI: 10.1016/j.bpj.2021.06.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 06/07/2021] [Accepted: 06/16/2021] [Indexed: 11/16/2022] Open
Abstract
Formins generate unbranched actin filaments by a conserved, processive actin assembly mechanism. Most organisms express multiple formin isoforms that mediate distinct cellular processes and facilitate actin filament polymerization by significantly different rates, but how these actin assembly differences correlate to cellular activity is unclear. We used a computational model of fission yeast cytokinetic ring assembly to test the hypothesis that particular actin assembly properties help tailor formins for specific cellular roles. Simulations run in different actin filament nucleation and elongation conditions revealed that variations in formin's nucleation efficiency critically impact both the probability and timing of contractile ring formation. To probe the physiological importance of nucleation efficiency, we engineered fission yeast formin chimera strains in which the FH1-FH2 actin assembly domains of full-length cytokinesis formin Cdc12 were replaced with the FH1-FH2 domains from functionally and evolutionarily diverse formins with significantly different actin assembly properties. Although Cdc12 chimeras generally support life in fission yeast, quantitative live-cell imaging revealed a range of cytokinesis defects from mild to severe. In agreement with the computational model, chimeras whose nucleation efficiencies are least similar to Cdc12 exhibit more severe cytokinesis defects, specifically in the rate of contractile ring assembly. Together, our computational and experimental results suggest that fission yeast cytokinesis is ideally mediated by a formin with properly tailored actin assembly parameters.
Collapse
Affiliation(s)
- Kaitlin E Homa
- Department of Molecular Genetics and Cell Biology, Chicago, Illinois
| | - Vilmos Zsolnay
- Graduate Program in Biophysical Sciences, Chicago, Illinois
| | | | | | - Erin M Neidt
- Department of Molecular Genetics and Cell Biology, Chicago, Illinois
| | - Gregory A Voth
- Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics and Computation Institute, Chicago, Illinois
| | - Tamara C Bidone
- Department of Biomedical Engineering, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah.
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, Chicago, Illinois; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois.
| |
Collapse
|
10
|
Bain JM, Alonso MF, Childers DS, Walls CA, Mackenzie K, Pradhan A, Lewis LE, Louw J, Avelar GM, Larcombe DE, Netea MG, Gow NAR, Brown GD, Erwig LP, Brown AJP. Immune cells fold and damage fungal hyphae. Proc Natl Acad Sci U S A 2021; 118:e2020484118. [PMID: 33876755 PMCID: PMC8053999 DOI: 10.1073/pnas.2020484118] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Innate immunity provides essential protection against life-threatening fungal infections. However, the outcomes of individual skirmishes between immune cells and fungal pathogens are not a foregone conclusion because some pathogens have evolved mechanisms to evade phagocytic recognition, engulfment, and killing. For example, Candida albicans can escape phagocytosis by activating cellular morphogenesis to form lengthy hyphae that are challenging to engulf. Through live imaging of C. albicans-macrophage interactions, we discovered that macrophages can counteract this by folding fungal hyphae. The folding of fungal hyphae is promoted by Dectin-1, β2-integrin, VASP, actin-myosin polymerization, and cell motility. Folding facilitates the complete engulfment of long hyphae in some cases and it inhibits hyphal growth, presumably tipping the balance toward successful fungal clearance.
Collapse
Affiliation(s)
- Judith M Bain
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - M Fernanda Alonso
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - Delma S Childers
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - Catriona A Walls
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - Kevin Mackenzie
- Microscopy and Histology Facility, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - Arnab Pradhan
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, EX4 4QD Exeter, United Kingdom
| | - Leanne E Lewis
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - Johanna Louw
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - Gabriela M Avelar
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
| | - Daniel E Larcombe
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, EX4 4QD Exeter, United Kingdom
| | - Mihai G Netea
- Department of Internal Medicine and Radboud Center for Infectious Diseases, Radboud University Medical Center, 6500HB Nijmegen, The Netherlands
- Department for Immunology and Metabolism, Life and Medical Sciences Institute, University of Bonn, 53115 Bonn, Germany
| | - Neil A R Gow
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, EX4 4QD Exeter, United Kingdom
| | - Gordon D Brown
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, EX4 4QD Exeter, United Kingdom
| | - Lars P Erwig
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom
- Johnson-Johnson Innovation, Europe, Middle East and Africa Innovation Centre, London W1G 0BG, United Kingdom
| | - Alistair J P Brown
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, AB25 2ZD Aberdeen, United Kingdom;
- Medical Research Council Centre for Medical Mycology, University of Exeter, EX4 4QD Exeter, United Kingdom
| |
Collapse
|
11
|
Schwebach CL, Kudryashova E, Kudryashov DS. Plastin 3 in X-Linked Osteoporosis: Imbalance of Ca 2+-Dependent Regulation Is Equivalent to Protein Loss. Front Cell Dev Biol 2021; 8:635783. [PMID: 33553175 PMCID: PMC7859272 DOI: 10.3389/fcell.2020.635783] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 12/28/2020] [Indexed: 12/14/2022] Open
Abstract
Osteogenesis imperfecta is a genetic disorder disrupting bone development and remodeling. The primary causes of osteogenesis imperfecta are pathogenic variants of collagen and collagen processing genes. However, recently variants of the actin bundling protein plastin 3 have been identified as another source of osteogenesis imperfecta. Plastin 3 is a highly conserved protein involved in several important cellular structures and processes and is controlled by intracellular Ca2+ which potently inhibits its actin-bundling activity. The precise mechanisms by which plastin 3 causes osteogenesis imperfecta remain unclear, but recent advances have contributed to our understanding of bone development and the actin cytoskeleton. Here, we review the link between plastin 3 and osteogenesis imperfecta highlighting in vitro studies and emphasizing the importance of Ca2+ regulation in the localization and functionality of plastin 3.
Collapse
Affiliation(s)
- Christopher L Schwebach
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States
| | - Elena Kudryashova
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States
| | - Dmitri S Kudryashov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States
| |
Collapse
|
12
|
Cell cycle-dependent phosphorylation of IQGAP is involved in assembly and stability of the contractile ring in fission yeast. Biochem Biophys Res Commun 2020; 534:1026-1032. [PMID: 33131769 DOI: 10.1016/j.bbrc.2020.10.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 10/19/2020] [Indexed: 11/20/2022]
Abstract
Cytokinesis is the final step in cell division and is driven by the constriction of the medial actomyosin-based contractile ring (CR) in many eukaryotic cells. In the fission yeast Schizosaccharomyces pombe, the IQGAP-like protein Rng2 is required for assembly and constriction of the CR, and specifically interacts with actin filaments (F-actin) in the CR after anaphase. However, the mechanism that timely activates Rng2 has not yet been elucidated. We herein tested the hypothesis that the cytokinetic function of Rng2 is regulated by phosphorylation by examining phenotypes of a series of non-phosphorylatable and phosphomimetic rng2 mutant strains. In phosphomimetic mutant cells, F-actin in the CR was unstable. Genetic analyses indicated that phosphorylated Rng2 was involved in CR assembly in cooperation with myosin-II, whereas the phosphomimetic mutation attenuated the localization of Rng2 to CR F-actin. The present results suggest that Rng2 is phosphorylated during CR assembly and then dephosphorylated, which enhances the interaction between Rng2 and CR F-actin to stabilize the ring, thereby ensuring secure cytokinesis.
Collapse
|
13
|
Vorselen D, Labitigan RLD, Theriot JA. A mechanical perspective on phagocytic cup formation. Curr Opin Cell Biol 2020; 66:112-122. [PMID: 32698097 DOI: 10.1016/j.ceb.2020.05.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 05/26/2020] [Accepted: 05/30/2020] [Indexed: 12/23/2022]
Abstract
Phagocytosis is a widespread and evolutionarily conserved process with diverse biological functions, ranging from engulfment of invading microbes during infection to clearance of apoptotic debris in tissue homeostasis. Along with differences in biochemical composition, phagocytic targets greatly differ in physical attributes, such as size, shape, and rigidity, which are now recognized as important regulators of this process. Force exertion at the cell-target interface and cellular mechanical changes during phagocytosis are emerging as crucial factors underlying sensing of such target properties. With technological developments, mechanical aspects of phagocytosis are increasingly accessible experimentally, revealing remarkable organizational complexity of force exertion. An increasingly high-resolution picture is emerging of how target physical cues and cellular mechanical properties jointly govern important steps throughout phagocytic engulfment.
Collapse
Affiliation(s)
- Daan Vorselen
- Department of Biology, University of Washington, Seattle, WA 98105, USA
| | - Ramon Lorenzo D Labitigan
- Department of Biology, University of Washington, Seattle, WA 98105, USA; Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Julie A Theriot
- Department of Biology, University of Washington, Seattle, WA 98105, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98105, USA.
| |
Collapse
|
14
|
Zhou X, Zheng L, Guan L, Ye J, Virag A, Harris SD, Lu L. The Scaffold Proteins Paxillin B and α-Actinin Regulate Septation in Aspergillus nidulans via Control of Actin Ring Contraction. Genetics 2020; 215:449-461. [PMID: 32317285 PMCID: PMC7268981 DOI: 10.1534/genetics.120.303234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/12/2020] [Indexed: 11/29/2022] Open
Abstract
Cytokinesis, as the final step of cell division, plays an important role in fungal growth and proliferation. In the filamentous fungus Aspergillus nidulans, defective cytokinesis is able to induce abnormal multinuclear or nonnucleated cells and then result in reduced hyphal growth and abolished sporulation. Previous studies have reported that a conserved contractile actin ring (CAR) protein complex and the septation initiation network (SIN) signaling kinase cascade are required for cytokinesis and septation; however, little is known about the role(s) of scaffold proteins involved in these two important cellular processes. In this study, we show that a septum-localized scaffold protein paxillin B (PaxB) is essential for cytokinesis/septation in A. nidulans The septation defects observed in a paxB deletion strain resemble those caused by the absence of another identified scaffold protein, α-actinin (AcnA). Deletion of α-actinin (AcnA) leads to undetectable PaxB at the septation site, whereas deletion of paxB does not affect the localization of α-actinin at septa. However, deletion of either α-actinin (acnA) or paxB causes the actin ring to disappear at septation sites during cytokinesis. Notably, overexpression of α-actinin acnA partially rescues the septum defects of the paxB mutant but not vice versa, suggesting AcnA may play a dominant role over that of PaxB for cytokinesis and septation. In addition, PaxB and α-actinin affect the septal dynamic localization of MobA, a conserved component of the SIN pathway, suggesting they may affect the SIN protein complex function at septa. Protein pull-down assays combined with liquid chromatography-mass spectrometry identification indicate that α-actinin AcnA and PaxB likely do not directly interact, but presumably belong to an actin cytoskeleton protein network that is required for the assembly and contraction of the CAR. Taken together, findings in this study provide novel insights into the roles of conserved scaffold proteins during fungal septation in A. nidulans.
Collapse
Affiliation(s)
- Xiaogang Zhou
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 210023, China
| | - Likun Zheng
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 210023, China
| | - Luyu Guan
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 210023, China
| | - Jing Ye
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 210023, China
| | | | - Steven D Harris
- Department of Biological Sciences, University of Manitoba, Winnipeg, Canada
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, 210023, China
| |
Collapse
|
15
|
Long-Range and Directional Allostery of Actin Filaments Plays Important Roles in Various Cellular Activities. Int J Mol Sci 2020; 21:ijms21093209. [PMID: 32370032 PMCID: PMC7246755 DOI: 10.3390/ijms21093209] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/27/2020] [Accepted: 04/30/2020] [Indexed: 12/18/2022] Open
Abstract
A wide variety of uniquely localized actin-binding proteins (ABPs) are involved in various cellular activities, such as cytokinesis, migration, adhesion, morphogenesis, and intracellular transport. In a micrometer-scale space such as the inside of cells, protein molecules diffuse throughout the cell interior within seconds. In this condition, how can ABPs selectively bind to particular actin filaments when there is an abundance of actin filaments in the cytoplasm? In recent years, several ABPs have been reported to induce cooperative conformational changes to actin filaments allowing structural changes to propagate along the filament cables uni- or bidirectionally, thereby regulating the subsequent binding of ABPs. Such propagation of ABP-induced cooperative conformational changes in actin filaments may be advantageous for the elaborate regulation of cellular activities driven by actin-based machineries in the intracellular space, which is dominated by diffusion. In this review, we focus on long-range allosteric regulation driven by cooperative conformational changes of actin filaments that are evoked by binding of ABPs, and discuss roles of allostery of actin filaments in narrow intracellular spaces.
Collapse
|
16
|
Jung W, Fillenwarth LA, Matsuda A, Li J, Inoue Y, Kim T. Collective and contractile filament motions in the myosin motility assay. SOFT MATTER 2020; 16:1548-1559. [PMID: 31942899 PMCID: PMC7342887 DOI: 10.1039/c9sm02082a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cells require mechanical forces for their physiological functions. The forces are generated mainly from molecular interactions between actin filaments, cross-linking proteins, and myosin motors in the actin cytoskeleton. To better understand the molecular interactions, many studies employed myosin motility assays with actin filaments propelled by myosin heads fixed on a surface. Various interesting behaviors of actin filaments have been observed in the motility assay experiments. Despite the popularity of the motility assays, there were only a few computational models designed for simulating the motility assay systems. Most of the previous models have limitations which precluded full understanding of molecular origins for behaviors of actin filaments. In this study, we used an agent-based computational model based on Brownian dynamics for simulating the motility assay system. Our model rigorously describes the mechanics, dynamics, and interactions of actin filaments, cross-linking proteins, and molecular motors. Using the model, we first investigated how properties of actin filaments and motors affect gliding motions of actin filaments without volume-exclusion effects as a base study. We found that actin filaments can continuously glide at relative fast speed only when they are sufficiently longer than the average spacing between neighboring motors and that the gliding speed of F-actins shows a biphasic dependence on processivity of motors. Then, we showed that volume-exclusion effects between actin filaments can induce diverse collective movements and alignment of actin filaments, thus creating thick bundles and ring-like structures in the absence of cross-linking proteins. Lastly, we demonstrated that cross-linking proteins can lead to distinct contractile behaviors of actin networks depending on the density and kinetics of the cross-linking proteins. Results from our study show the ability of our model to simulate the motility assay system under various conditions and provide insights into understanding of different behaviors of actin filaments.
Collapse
Affiliation(s)
- Wonyeong Jung
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907, USA.
| | | | | | | | | | | |
Collapse
|
17
|
Matsuda K, Sugawa M, Yamagishi M, Kodera N, Yajima J. Visualizing dynamic actin cross‐linking processes driven by the actin‐binding protein anillin. FEBS Lett 2019; 594:1237-1247. [DOI: 10.1002/1873-3468.13720] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/26/2019] [Accepted: 12/09/2019] [Indexed: 01/16/2023]
Affiliation(s)
- Kyohei Matsuda
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
| | - Mitsuhiro Sugawa
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
- Komaba Institute for Science The University of Tokyo Japan
| | - Masahiko Yamagishi
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
- Komaba Institute for Science The University of Tokyo Japan
| | - Noriyuki Kodera
- Nano Life Science Institute (WPI‐NanoLSI) Kanazawa University Japan
| | - Junichiro Yajima
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
- Komaba Institute for Science The University of Tokyo Japan
- Research Center for Complex Systems Biology The University of Tokyo Japan
| |
Collapse
|
18
|
Adeli Koudehi M, Rutkowski DM, Vavylonis D. Organization of associating or crosslinked actin filaments in confinement. Cytoskeleton (Hoboken) 2019; 76:532-548. [PMID: 31525281 DOI: 10.1002/cm.21565] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 09/09/2019] [Accepted: 09/12/2019] [Indexed: 12/13/2022]
Abstract
A key factor of actin cytoskeleton organization in cells is the interplay between the dynamical properties of actin filaments and cell geometry, which restricts, confines and directs their orientation. Crosslinking interactions among actin filaments, together with geometrical cues and regulatory proteins can give rise to contractile rings in dividing cells and actin rings in neurons. Motivated by recent in vitro experiments, in this work we performed computer simulations to study basic aspects of the interplay between confinement and attractive interactions between actin filaments. We used a spring-bead model and Brownian dynamics to simulate semiflexible actin filaments that polymerize in a confining sphere with a rate proportional to the monomer concentration. We model crosslinking, or attraction through the depletion interaction, implicitly as an attractive short-range potential between filament beads. In confining geometries smaller than the persistence length of actin filaments, we show rings can form by curving of filaments of length comparable to, or longer than the confinement diameter. Rings form for optimal ranges of attractive interactions that exist in between open bundles, irregular loops, aggregated, and unbundled morphologies. The probability of ring formation is promoted by attraction to the confining sphere boundary and decreases for large radii and initial monomer concentrations, in agreement with prior experimental data. The model reproduces ring formation along the flat plane of oblate ellipsoids.
Collapse
|
19
|
Chandrasekaran A, Upadhyaya A, Papoian GA. Remarkable structural transformations of actin bundles are driven by their initial polarity, motor activity, crosslinking, and filament treadmilling. PLoS Comput Biol 2019; 15:e1007156. [PMID: 31287817 PMCID: PMC6615854 DOI: 10.1371/journal.pcbi.1007156] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 06/06/2019] [Indexed: 12/12/2022] Open
Abstract
Bundled actin structures play a key role in maintaining cellular shape, in aiding force transmission to and from extracellular substrates, and in affecting cellular motility. Recent studies have also brought to light new details on stress generation, force transmission and contractility of actin bundles. In this work, we are primarily interested in the question of what determines the stability of actin bundles and what network geometries do unstable bundles eventually transition to. To address this problem, we used the MEDYAN mechano-chemical force field, modeling several micron-long actin bundles in 3D, while accounting for a comprehensive set of chemical, mechanical and transport processes. We developed a hierarchical clustering algorithm for classification of the different long time scale morphologies in our study. Our main finding is that initially unipolar bundles are significantly more stable compared with an apolar initial configuration. Filaments within the latter bundles slide easily with respect to each other due to myosin activity, producing a loose network that can be subsequently severely distorted. At high myosin concentrations, a morphological transition to aster-like geometries was observed. We also investigated how actin treadmilling rates influence bundle dynamics, and found that enhanced treadmilling leads to network fragmentation and disintegration, while this process is opposed by myosin and crosslinking activities. Interestingly, treadmilling bundles with an initial apolar geometry eventually evolve to a whole gamut of network morphologies based on relative positions of filament ends, such as sarcomere-like organization. We found that apolar bundles show a remarkable sensitivity to environmental conditions, which may be important in enabling rapid cytoskeletal structural reorganization and adaptation in response to intracellular and extracellular cues.
Collapse
Affiliation(s)
- Aravind Chandrasekaran
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
| | - Arpita Upadhyaya
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
- Department of Physics, University of Maryland, College Park, United States of America
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
| |
Collapse
|
20
|
Krueger D, Quinkler T, Mortensen SA, Sachse C, De Renzis S. Cross-linker-mediated regulation of actin network organization controls tissue morphogenesis. J Cell Biol 2019; 218:2743-2761. [PMID: 31253650 PMCID: PMC6683744 DOI: 10.1083/jcb.201811127] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 04/29/2019] [Accepted: 06/04/2019] [Indexed: 11/22/2022] Open
Abstract
Spatio-temporal organization of actomyosin contraction during epithelial morphogenesis in Drosophila is regulated by the developmental modulation of actin cross-linking through induction of Bottleneck. Bottleneck protein restrains contractility by promoting actin bundling, functioning in a similar way to Filamin and in an opposite way to Fimbrin. Contraction of cortical actomyosin networks driven by myosin activation controls cell shape changes and tissue morphogenesis during animal development. In vitro studies suggest that contractility also depends on the geometrical organization of actin filaments. Here we analyze the function of actomyosin network topology in vivo using optogenetic stimulation of myosin-II in Drosophila embryos. We show that early during cellularization, hexagonally arrayed actomyosin fibers are resilient to myosin-II activation. Actomyosin fibers then acquire a ring-like conformation and become contractile and sensitive to myosin-II. This transition is controlled by Bottleneck, a Drosophila unique protein expressed for only a short time during early cellularization, which we show regulates actin bundling. In addition, it requires two opposing actin cross-linkers, Filamin and Fimbrin. Filamin acts synergistically with Bottleneck to facilitate hexagonal patterning, while Fimbrin controls remodeling of the hexagonal network into contractile rings. Thus, actin cross-linking regulates the spatio-temporal organization of actomyosin contraction in vivo, which is critical for tissue morphogenesis.
Collapse
Affiliation(s)
- Daniel Krueger
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Collaboration for joint PhD degree between European Molecular Biology Laboratory and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Theresa Quinkler
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Simon Arnold Mortensen
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Carsten Sachse
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Ernst-Ruska Center for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, Jülich, Germany
| | - Stefano De Renzis
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| |
Collapse
|
21
|
Zhang R, Qu X, Zhang M, Jiang Y, Dai A, Zhao W, Cao D, Lan Y, Yu R, Wang H, Huang S. The Balance between Actin-Bundling Factors Controls Actin Architecture in Pollen Tubes. iScience 2019; 16:162-176. [PMID: 31181400 PMCID: PMC6556835 DOI: 10.1016/j.isci.2019.05.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/29/2019] [Accepted: 05/21/2019] [Indexed: 11/19/2022] Open
Abstract
How actin-bundling factors cooperatively regulate shank-localized actin bundles remains largely unexplored. Here we demonstrate that FIM5 and PLIM2a/PLIM2b decorate shank-localized actin bundles and that loss of function of PLIM2a and/or PLIM2b suppresses phenotypes associated with fim5 mutants. Specifically, knockout of PLIM2a and/or PLIM2b partially suppresses the disorganized actin bundle and intracellular trafficking phenotype in fim5 pollen tubes. PLIM2a/PLIM2b generates thick but loosely packed actin bundles, whereas FIM5 generates thin but tight actin bundles that tend to be cross-linked into networks in vitro. Furthermore, PLIM2a/PLIM2b and FIM5 compete for binding to actin filaments in vitro, and PLIM2a/PLIM2b decorate disorganized actin bundles in fim5 pollen tubes. These data together suggest that the disorganized actin bundles in fim5 mutants are at least partially due to gain of function of PLIM2a/PLIM2b. Our data suggest that the balance between FIM5 and PLIM2a/PLIM2b is crucial for the normal bundling and organization of shank-localized actin bundles in pollen tubes. The transcription of PLIM2a and PLIM2b is upregulated in fim5 pollen tubes Downregulation of PLIM2a and/or PLIM2b suppresses the defects in fim5 pollen tubes Both FIM5 and PLIM2a/PLIM2b decorate shank-localized actin filaments FIM5 can inhibit the binding of PLIM2a and PLIM2b to actin filaments
Collapse
Affiliation(s)
- Ruihui Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Meng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Anbang Dai
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wanying Zhao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dai Cao
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yaxian Lan
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Rong Yu
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hongwei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| |
Collapse
|
22
|
Network Contractility During Cytokinesis-from Molecular to Global Views. Biomolecules 2019; 9:biom9050194. [PMID: 31109067 PMCID: PMC6572417 DOI: 10.3390/biom9050194] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/30/2019] [Accepted: 04/30/2019] [Indexed: 12/28/2022] Open
Abstract
Cytokinesis is the last stage of cell division, which partitions the mother cell into two daughter cells. It requires the assembly and constriction of a contractile ring that consists of a filamentous contractile network of actin and myosin. Network contractility depends on network architecture, level of connectivity and myosin motor activity, but how exactly is the contractile ring network organized or interconnected and how much it depends on motor activity remains unclear. Moreover, the contractile ring is not an isolated entity; rather, it is integrated into the surrounding cortex. Therefore, the mechanical properties of the cell cortex and cortical behaviors are expected to impact contractile ring functioning. Due to the complexity of the process, experimental approaches have been coupled to theoretical modeling in order to advance its global understanding. While earlier coarse-grained descriptions attempted to provide an integrated view of the process, recent models have mostly focused on understanding the behavior of an isolated contractile ring. Here we provide an overview of the organization and dynamics of the actomyosin network during cytokinesis and discuss existing theoretical models in light of cortical behaviors and experimental evidence from several systems. Our view on what is missing in current models and should be tested in the future is provided.
Collapse
|
23
|
The Cytoskeleton-A Complex Interacting Meshwork. Cells 2019; 8:cells8040362. [PMID: 31003495 PMCID: PMC6523135 DOI: 10.3390/cells8040362] [Citation(s) in RCA: 181] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/22/2022] Open
Abstract
The cytoskeleton of animal cells is one of the most complicated and functionally versatile structures, involved in processes such as endocytosis, cell division, intra-cellular transport, motility, force transmission, reaction to external forces, adhesion and preservation, and adaptation of cell shape. These functions are mediated by three classical cytoskeletal filament types, as follows: Actin, microtubules, and intermediate filaments. The named filaments form a network that is highly structured and dynamic, responding to external and internal cues with a quick reorganization that is orchestrated on the time scale of minutes and has to be tightly regulated. Especially in brain tumors, the cytoskeleton plays an important role in spreading and migration of tumor cells. As the cytoskeletal organization and regulation is complex and many-faceted, this review aims to summarize the findings about cytoskeletal filament types, including substructures formed by them, such as lamellipodia, stress fibers, and interactions between intermediate filaments, microtubules and actin. Additionally, crucial regulatory aspects of the cytoskeletal filaments and the formed substructures are discussed and integrated into the concepts of cell motility. Even though little is known about the impact of cytoskeletal alterations on the progress of glioma, a final point discussed will be the impact of established cytoskeletal alterations in the cellular behavior and invasion of glioma.
Collapse
|
24
|
Penny CJ, Gold MG. Mechanisms for localising calcineurin and CaMKII in dendritic spines. Cell Signal 2018; 49:46-58. [DOI: 10.1016/j.cellsig.2018.05.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/23/2018] [Accepted: 05/24/2018] [Indexed: 10/14/2022]
|
25
|
Zhu YH, Hyun J, Pan YZ, Hopper JE, Rizo J, Wu JQ. Roles of the fission yeast UNC-13/Munc13 protein Ync13 in late stages of cytokinesis. Mol Biol Cell 2018; 29:2259-2279. [PMID: 30044717 PMCID: PMC6249806 DOI: 10.1091/mbc.e18-04-0225] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cytokinesis is a complicated yet conserved step of the cell-division cycle that requires the coordination of multiple proteins and cellular processes. Here we describe a previously uncharacterized protein, Ync13, and its roles during fission yeast cytokinesis. Ync13 is a member of the UNC-13/Munc13 protein family, whose animal homologues are essential priming factors for soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex assembly during exocytosis in various cell types, but no roles in cytokinesis have been reported. We find that Ync13 binds to lipids in vitro and dynamically localizes to the plasma membrane at cell tips during interphase and at the division site during cytokinesis. Deletion of Ync13 leads to defective septation and exocytosis, uneven distribution of cell-wall enzymes and components of cell-wall integrity pathway along the division site and massive cell lysis during cell separation. Interestingly, loss of Ync13 compromises endocytic site selection at the division plane. Collectively, we find that Ync13 has a novel function as an UNC-13/Munc13 protein in coordinating exocytosis, endocytosis, and cell-wall integrity during fission yeast cytokinesis.
Collapse
Affiliation(s)
- Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Joanne Hyun
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Yun-Zu Pan
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - James E Hopper
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210
| |
Collapse
|
26
|
Nguyen LT, Swulius MT, Aich S, Mishra M, Jensen GJ. Coarse-grained simulations of actomyosin rings point to a nodeless model involving both unipolar and bipolar myosins. Mol Biol Cell 2018; 29:1318-1331. [PMID: 29851561 PMCID: PMC5994903 DOI: 10.1091/mbc.e17-12-0736] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cytokinesis in many eukaryotic cells is orchestrated by a contractile actomyosin ring. While many of the proteins involved are known, the mechanism of constriction remains unclear. Informed by the existing literature and new three-dimensional (3D) molecular details from electron cryotomography, here we develop 3D coarse-grained models of actin filaments, unipolar and bipolar myosins, actin cross-linkers, and membranes and simulate their interactions. Assuming that local force on the membrane results in inward growth of the cell wall, we explored a matrix of possible actomyosin configurations and found that node-based architectures like those presently described for ring assembly result in membrane puckers not seen in electron microscope images of real cells. Instead, the model that best matches data from fluorescence microscopy, electron cryotomography, and biochemical experiments is one in which actin filaments transmit force to the membrane through evenly distributed, membrane-attached, unipolar myosins, with bipolar myosins in the ring driving contraction. While at this point this model is only favored (not proven), the work highlights the power of coarse-grained biophysical simulations to compare complex mechanistic hypotheses.
Collapse
Affiliation(s)
- Lam T Nguyen
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Matthew T Swulius
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Samya Aich
- Tata Institute of Fundamental Research, Mumbai 400005, India
| | | | - Grant J Jensen
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| |
Collapse
|
27
|
Toyoda Y, Cattin CJ, Stewart MP, Poser I, Theis M, Kurzchalia TV, Buchholz F, Hyman AA, Müller DJ. Genome-scale single-cell mechanical phenotyping reveals disease-related genes involved in mitotic rounding. Nat Commun 2017; 8:1266. [PMID: 29097687 PMCID: PMC5668354 DOI: 10.1038/s41467-017-01147-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/22/2017] [Indexed: 01/01/2023] Open
Abstract
To divide, most animal cells drastically change shape and round up against extracellular confinement. Mitotic cells facilitate this process by generating intracellular pressure, which the contractile actomyosin cortex directs into shape. Here, we introduce a genome-scale microcantilever- and RNAi-based approach to phenotype the contribution of > 1000 genes to the rounding of single mitotic cells against confinement. Our screen analyzes the rounding force, pressure and volume of mitotic cells and localizes selected proteins. We identify 49 genes relevant for mitotic rounding, a large portion of which have not previously been linked to mitosis or cell mechanics. Among these, depleting the endoplasmic reticulum-localized protein FAM134A impairs mitotic progression by affecting metaphase plate alignment and pressure generation by delocalizing cortical myosin II. Furthermore, silencing the DJ-1 gene uncovers a link between mitochondria-associated Parkinson's disease and mitotic pressure. We conclude that mechanical phenotyping is a powerful approach to study the mechanisms governing cell shape.
Collapse
Affiliation(s)
- Yusuke Toyoda
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany.,Division of Cell Biology, Life Science Institute, Kurume University, Hyakunen-Kohen 1-1, Kurume, Fukuoka, 839-0864, Japan
| | - Cedric J Cattin
- Department of Biosystems Science and Engineering (D-BSSE), Eidgenössische Technische Hochschule (ETH) Zurich, Mattenstrasse 26, 4058, Basel, Switzerland
| | - Martin P Stewart
- Department of Biosystems Science and Engineering (D-BSSE), Eidgenössische Technische Hochschule (ETH) Zurich, Mattenstrasse 26, 4058, Basel, Switzerland.,Department of Chemical Engineering, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA, 02139-4307, USA.,The Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA, 02139-4307, USA
| | - Ina Poser
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany
| | - Mirko Theis
- UCC, Medical System biology, Medical Faculty Carl Gustav Carus, University of Technology Dresden, Am Tatzberg 47/49, 01307, Dresden, Germany
| | - Teymuras V Kurzchalia
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany
| | - Frank Buchholz
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany.,UCC, Medical System biology, Medical Faculty Carl Gustav Carus, University of Technology Dresden, Am Tatzberg 47/49, 01307, Dresden, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany.
| | - Daniel J Müller
- Department of Biosystems Science and Engineering (D-BSSE), Eidgenössische Technische Hochschule (ETH) Zurich, Mattenstrasse 26, 4058, Basel, Switzerland.
| |
Collapse
|
28
|
Morita R, Takaine M, Numata O, Nakano K. Molecular dissection of the actin-binding ability of the fission yeast α-actinin, Ain1, in vitro and in vivo. J Biochem 2017; 162:93-102. [PMID: 28338873 DOI: 10.1093/jb/mvx008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 12/27/2016] [Indexed: 02/02/2023] Open
Abstract
A contractile ring (CR) is involved in cytokinesis in animal and yeast cells. Although several types of actin-bundling proteins associate with F-actin in the CR, their individual roles in the CR have not yet been elucidated in detail. Ain1 is the sole α-actinin homologue in the fission yeast Schizosaccharomyces pombe and specifically localizes to the CR with a high turnover rate. S. pombe cells lacking the ain1+ gene show defects in cytokinesis under stress conditions. We herein investigated the biochemical activity and cellular localization mechanisms of Ain1. Ain1 showed weaker affinity to F-actin in vitro than other actin-bundling proteins in S. pombe. We identified a mutation that presumably loosened the interaction between two calponin-homology domains constituting the single actin-binding domain (ABD) of Ain1, which strengthened the actin-binding activity of Ain1. This mutant protein induced a deformation in the ring shape of the CR. Neither a truncated protein consisting only of an N-terminal ABD nor a truncated protein lacking a C-terminal region containing an EF-hand motif localized to the CR, whereas the latter was involved in the bundling of F-actin in vitro. We herein propose detailed mechanisms for how each part of the molecule is involved in the proper cellular localization and function of Ain1.
Collapse
Affiliation(s)
- Rikuri Morita
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
| | - Masak Takaine
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
| | - Osamu Numata
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
| | - Kentaro Nakano
- Department of Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8572, Japan
| |
Collapse
|
29
|
Zimmermann D, Homa KE, Hocky GM, Pollard LW, De La Cruz EM, Voth GA, Trybus KM, Kovar DR. Mechanoregulated inhibition of formin facilitates contractile actomyosin ring assembly. Nat Commun 2017; 8:703. [PMID: 28951543 PMCID: PMC5614989 DOI: 10.1038/s41467-017-00445-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 06/27/2017] [Indexed: 11/20/2022] Open
Abstract
Cytokinesis physically separates dividing cells by forming a contractile actomyosin ring. The fission yeast contractile ring has been proposed to assemble by Search-Capture-Pull-Release from cytokinesis precursor nodes that include the molecular motor type-II myosin Myo2 and the actin assembly factor formin Cdc12. By successfully reconstituting Search-Capture-Pull in vitro, we discovered that formin Cdc12 is a mechanosensor, whereby myosin pulling on formin-bound actin filaments inhibits Cdc12-mediated actin assembly. We mapped Cdc12 mechanoregulation to its formin homology 1 domain, which facilitates delivery of new actin subunits to the elongating actin filament. Quantitative modeling suggests that the pulling force of the myosin propagates through the actin filament, which behaves as an entropic spring, and thereby may stretch the disordered formin homology 1 domain and impede formin-mediated actin filament elongation. Finally, live cell imaging of mechano-insensitive formin mutant cells established that mechanoregulation of formin Cdc12 is required for efficient contractile ring assembly in vivo. The fission yeast cytokinetic ring assembles by Search-Capture-Pull-Release from precursor nodes that include formin Cdc12 and myosin Myo2. The authors reconstitute Search-Capture-Pull in vitro and find that Myo2 pulling on Cdc12-associated actin filaments mechano-inhibits Cdc12-mediated assembly, which enables proper ring assembly in vivo.
Collapse
Affiliation(s)
- Dennis Zimmermann
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 E. 58th St., CSLC 212, Chicago, IL, 60637, USA
| | - Kaitlin E Homa
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 E. 58th St., CSLC 212, Chicago, IL, 60637, USA
| | - Glen M Hocky
- Department of Chemistry, The James Franck Institute and Institute for Biophysical Dynamics and Computation Institute, The University of Chicago, 5735 S. Ellis Ave., Searle Chemistry Laboratory 231, Chicago, IL, 60637, USA
| | - Luther W Pollard
- Department of Molecular Physiology and Biophysics, University of Vermont, 149 Beaumont Ave., HSRF 130, Burlington, VT, 05405, USA
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208114, 266 Whitney Ave., New Haven, CT, 06520-8114, USA
| | - Gregory A Voth
- Department of Chemistry, The James Franck Institute and Institute for Biophysical Dynamics and Computation Institute, The University of Chicago, 5735 S. Ellis Ave., Searle Chemistry Laboratory 231, Chicago, IL, 60637, USA.
| | - Kathleen M Trybus
- Department of Molecular Physiology and Biophysics, University of Vermont, 149 Beaumont Ave., HSRF 130, Burlington, VT, 05405, USA.
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 E. 58th St., CSLC 212, Chicago, IL, 60637, USA. .,Department of Biochemistry and Molecular Biology, The University of Chicago, 920 E. 58th St., CSLC 212, Chicago, IL, 60637, USA.
| |
Collapse
|
30
|
Schwebach CL, Agrawal R, Lindert S, Kudryashova E, Kudryashov DS. The Roles of Actin-Binding Domains 1 and 2 in the Calcium-Dependent Regulation of Actin Filament Bundling by Human Plastins. J Mol Biol 2017; 429:2490-2508. [PMID: 28694070 DOI: 10.1016/j.jmb.2017.06.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 06/30/2017] [Accepted: 06/30/2017] [Indexed: 01/04/2023]
Abstract
The actin cytoskeleton is a complex network controlled by a vast array of intricately regulated actin-binding proteins. Human plastins (PLS1, PLS2, and PLS3) are evolutionary conserved proteins that non-covalently crosslink actin filaments into tight bundles. Through stabilization of such bundles, plastins contribute, in an isoform-specific manner, to the formation of kidney and intestinal microvilli, inner ear stereocilia, immune synapses, endocytic patches, adhesion contacts, and invadosomes of immune and cancer cells. All plastins comprise an N-terminal Ca2+-binding regulatory headpiece domain followed by two actin-binding domains (ABD1 and ABD2). Actin bundling occurs due to simultaneous binding of both ABDs to separate actin filaments. Bundling is negatively regulated by Ca2+, but the mechanism of this inhibition remains unknown. In this study, we found that the bundling abilities of PLS1 and PLS2 were similarly sensitive to Ca2+ (pCa50 ~6.4), whereas PLS3 was less sensitive (pCa50 ~5.9). At the same time, all three isoforms bound to F-actin in a Ca2+-independent manner, suggesting that binding of only one of the ABDs is inhibited by Ca2+. Using limited proteolysis and mass spectrometry, we found that in the presence of Ca2+ the EF-hands of human plastins bound to an immediately adjacent sequence homologous to canonical calmodulin-binding peptides. Furthermore, our data from differential centrifugation, Förster resonance energy transfer, native electrophoresis, and chemical crosslinking suggest that Ca2+ does not affect ABD1 but inhibits the ability of ABD2 to interact with actin. A structural mechanism of signal transmission from Ca2+ to ABD2 through EF-hands remains to be established.
Collapse
Affiliation(s)
- Christopher L Schwebach
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Molecular, Cellular, and Developmental Biology Program, The Ohio State University, Columbus, OH 43210, USA
| | - Richa Agrawal
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Elena Kudryashova
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Dmitri S Kudryashov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Molecular, Cellular, and Developmental Biology Program, The Ohio State University, Columbus, OH 43210, USA.
| |
Collapse
|
31
|
Dor-On E, Raviv S, Cohen Y, Adir O, Padmanabhan K, Luxenburg C. T-plastin is essential for basement membrane assembly and epidermal morphogenesis. Sci Signal 2017; 10:10/481/eaal3154. [PMID: 28559444 DOI: 10.1126/scisignal.aal3154] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The establishment of epithelial architecture is a complex process involving cross-talk between cells and the basement membrane. Basement membrane assembly requires integrin activity but the role of the associated actomyosin cytoskeleton is poorly understood. Here, we identify the actin-bundling protein T-plastin (Pls3) as a regulator of basement membrane assembly and epidermal morphogenesis. In utero depletion of Pls3 transcripts in mouse embryos caused basement membrane and polarity defects in the epidermis but had little effect on cell adhesion and differentiation. Loss-of-function experiments demonstrated that the apicobasal polarity defects were secondary to the disruption of the basement membrane. However, the basement membrane itself was profoundly sensitive to subtle perturbations in the actin cytoskeleton. We further show that Pls3 localized to the cell cortex, where it was essential for the localization and activation of myosin II. Inhibition of myosin II motor activity disrupted basement membrane organization. Our results provide insights into the regulation of cortical actomyosin and its importance for basement membrane assembly and skin morphogenesis.
Collapse
Affiliation(s)
- Eyal Dor-On
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shaul Raviv
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yonatan Cohen
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Orit Adir
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Krishnanand Padmanabhan
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Chen Luxenburg
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| |
Collapse
|
32
|
Ding WY, Ong HT, Hara Y, Wongsantichon J, Toyama Y, Robinson RC, Nédélec F, Zaidel-Bar R. Plastin increases cortical connectivity to facilitate robust polarization and timely cytokinesis. J Cell Biol 2017; 216:1371-1386. [PMID: 28400443 PMCID: PMC5412556 DOI: 10.1083/jcb.201603070] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 01/11/2017] [Accepted: 03/08/2017] [Indexed: 01/23/2023] Open
Abstract
Ding et al. characterize the function of the F-actin bundling protein plastin in the Caenorhabditis elegans zygote. They demonstrate that plastin is important for optimal connectivity in the cortical actomyosin network that drives large-scale contractile processes such as polarization and cytokinesis. The cell cortex is essential to maintain animal cell shape, and contractile forces generated within it by nonmuscle myosin II (NMY-2) drive cellular morphogenetic processes such as cytokinesis. The role of actin cross-linking proteins in cortical dynamics is still incompletely understood. Here, we show that the evolutionarily conserved actin bundling/cross-linking protein plastin is instrumental for the generation of potent cortical actomyosin contractility in the Caenorhabditis elegans zygote. PLST-1 was enriched in contractile structures and was required for effective coalescence of NMY-2 filaments into large contractile foci and for long-range coordinated contractility in the cortex. In the absence of PLST-1, polarization was compromised, cytokinesis was delayed or failed, and 50% of embryos died during development. Moreover, mathematical modeling showed that an optimal amount of bundling agents enhanced the ability of a network to contract. We propose that by increasing the connectivity of the F-actin meshwork, plastin enables the cortex to generate stronger and more coordinated forces to accomplish cellular morphogenesis.
Collapse
Affiliation(s)
- Wei Yung Ding
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Hui Ting Ong
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Yusuke Hara
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Singapore
| | - Jantana Wongsantichon
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology, and Research), Singapore 138673, Singapore
| | - Yusuke Toyama
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Robert C Robinson
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology, and Research), Singapore 138673, Singapore.,Department of Biochemistry, National University of Singapore, Singapore 117597, Singapore
| | - François Nédélec
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Ronen Zaidel-Bar
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore 117583, Singapore
| |
Collapse
|
33
|
Bidone TC, Jung W, Maruri D, Borau C, Kamm RD, Kim T. Morphological Transformation and Force Generation of Active Cytoskeletal Networks. PLoS Comput Biol 2017; 13:e1005277. [PMID: 28114384 PMCID: PMC5256887 DOI: 10.1371/journal.pcbi.1005277] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 11/29/2016] [Indexed: 11/19/2022] Open
Abstract
Cells assemble numerous types of actomyosin bundles that generate contractile forces for biological processes, such as cytokinesis and cell migration. One example of contractile bundles is a transverse arc that forms via actomyosin-driven condensation of actin filaments in the lamellipodia of migrating cells and exerts significant forces on the surrounding environments. Structural reorganization of a network into a bundle facilitated by actomyosin contractility is a physiologically relevant and biophysically interesting process. Nevertheless, it remains elusive how actin filaments are reoriented, buckled, and bundled as well as undergo tension buildup during the structural reorganization. In this study, using an agent-based computational model, we demonstrated how the interplay between the density of myosin motors and cross-linking proteins and the rigidity, initial orientation, and turnover of actin filaments regulates the morphological transformation of a cross-linked actomyosin network into a bundle and the buildup of tension occurring during the transformation.
Collapse
Affiliation(s)
- Tamara Carla Bidone
- Department of Mechanical and Aerospace Engineering, Polytechnic University of Turin, Turin, Italy
| | - Wonyeong Jung
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Daniel Maruri
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Carlos Borau
- Department of Mechanical Engineering, Aragon Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
| | - Roger D. Kamm
- Departments of Biological Engineering and Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Taeyoon Kim
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| |
Collapse
|
34
|
Ojkic N, López-Garrido J, Pogliano K, Endres RG. Cell-wall remodeling drives engulfment during Bacillus subtilis sporulation. eLife 2016; 5. [PMID: 27852437 PMCID: PMC5158138 DOI: 10.7554/elife.18657] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 11/14/2016] [Indexed: 12/30/2022] Open
Abstract
When starved, the Gram-positive bacterium Bacillus subtilis forms durable spores for survival. Sporulation initiates with an asymmetric cell division, creating a large mother cell and a small forespore. Subsequently, the mother cell membrane engulfs the forespore in a phagocytosis-like process. However, the force generation mechanism for forward membrane movement remains unknown. Here, we show that membrane migration is driven by cell wall remodeling at the leading edge of the engulfing membrane, with peptidoglycan synthesis and degradation mediated by penicillin binding proteins in the forespore and a cell wall degradation protein complex in the mother cell. We propose a simple model for engulfment in which the junction between the septum and the lateral cell wall moves around the forespore by a mechanism resembling the ‘template model’. Hence, we establish a biophysical mechanism for the creation of a force for engulfment based on the coordination between cell wall synthesis and degradation. DOI:http://dx.doi.org/10.7554/eLife.18657.001 Some bacteria, such as Bacillus subtilis, form spores when starved of food, which enables them to lie dormant for years and wait for conditions to improve. To make a spore, the bacterial cell divides to make a larger mother cell and a smaller forespore cell. Then the membrane that surrounds the mother cell moves to surround the forespore and engulf it. For this process to take place, a rigid mesh-like layer called the cell wall, which lies outside the cell membrane, needs to be remodelled. This happens once a partition in the cell wall, called a septum, has formed, separating mother and daughter cells. However, it is not clear how the mother cell can generate the physical force required to engulf the forespore under the cramped conditions imposed by the cell wall. To address this question, Ojkic, López-Garrido et al. used microscopy to investigate how B. subtilis makes spores. The experiments show that, in order to engulf the forespore, the mother cell must produce new cell wall and destroy cell wall that is no longer needed. Running a simple biophysical model on a computer showed that coordinating these two processes could generate enough force for a mother cell to engulf a forespore. Ojkic, López-Garrido et al. propose that the junction between the septum and the cell wall moves around the forespore to make room for the mother cell’s membrane for expansion. Other spore-forming bacteria that threaten human health – such as Clostridium difficile, which causes bowel infections, and Bacillus anthracis, which causes anthrax – might form their spores in the same way, but this remains to be tested. More work will also be needed to understand exactly how bacterial cells coordinate the cell wall synthesis and cell wall degradation. DOI:http://dx.doi.org/10.7554/eLife.18657.002
Collapse
Affiliation(s)
- Nikola Ojkic
- Department of Life Sciences, Imperial College London, London, United Kingdom.,Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London, United Kingdom
| | - Javier López-Garrido
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Kit Pogliano
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Robert G Endres
- Department of Life Sciences, Imperial College London, London, United Kingdom.,Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London, United Kingdom
| |
Collapse
|
35
|
Cheffings T, Burroughs N, Balasubramanian M. Actomyosin Ring Formation and Tension Generation in Eukaryotic Cytokinesis. Curr Biol 2016; 26:R719-R737. [DOI: 10.1016/j.cub.2016.06.071] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
36
|
Popov K, Komianos J, Papoian GA. MEDYAN: Mechanochemical Simulations of Contraction and Polarity Alignment in Actomyosin Networks. PLoS Comput Biol 2016; 12:e1004877. [PMID: 27120189 PMCID: PMC4847874 DOI: 10.1371/journal.pcbi.1004877] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/22/2016] [Indexed: 11/29/2022] Open
Abstract
Active matter systems, and in particular the cell cytoskeleton, exhibit complex mechanochemical dynamics that are still not well understood. While prior computational models of cytoskeletal dynamics have lead to many conceptual insights, an important niche still needs to be filled with a high-resolution structural modeling framework, which includes a minimally-complete set of cytoskeletal chemistries, stochastically treats reaction and diffusion processes in three spatial dimensions, accurately and efficiently describes mechanical deformations of the filamentous network under stresses generated by molecular motors, and deeply couples mechanics and chemistry at high spatial resolution. To address this need, we propose a novel reactive coarse-grained force field, as well as a publicly available software package, named the Mechanochemical Dynamics of Active Networks (MEDYAN), for simulating active network evolution and dynamics (available at www.medyan.org). This model can be used to study the non-linear, far from equilibrium processes in active matter systems, in particular, comprised of interacting semi-flexible polymers embedded in a solution with complex reaction-diffusion processes. In this work, we applied MEDYAN to investigate a contractile actomyosin network consisting of actin filaments, alpha-actinin cross-linking proteins, and non-muscle myosin IIA mini-filaments. We found that these systems undergo a switch-like transition in simulations from a random network to ordered, bundled structures when cross-linker concentration is increased above a threshold value, inducing contraction driven by myosin II mini-filaments. Our simulations also show how myosin II mini-filaments, in tandem with cross-linkers, can produce a range of actin filament polarity distributions and alignment, which is crucially dependent on the rate of actin filament turnover and the actin filament’s resulting super-diffusive behavior in the actomyosin-cross-linker system. We discuss the biological implications of these findings for the arc formation in lamellipodium-to-lamellum architectural remodeling. Lastly, our simulations produce force-dependent accumulation of myosin II, which is thought to be responsible for their mechanosensation ability, also spontaneously generating myosin II concentration gradients in the solution phase of the simulation volume. Active matter systems have the distinct ability to convert energy from their surroundings into mechanical work, which gives rise to them having highly dynamic properties. Modeling active matter systems and capturing their complex behavior has been a great challenge in past years due to the many coupled interactions between their constituent parts, including not only distinct chemical and mechanical properties, but also feedback between them. One of the most intriguing biological active matter systems is the cell cytoskeleton, which can dynamically respond to chemical and mechanical cues to control cell structure and shape, playing a central role in many higher-order cellular processes. To model these systems and reproduce their behavior, we present a new modeling approach which combines the chemical, mechanical, and molecular transport aspects of active matter systems, all represented with equivalent complexity, while also allowing for various forms of mechanochemical feedback. This modeling approach, named MEDYAN, and software implementation is flexible so that a wide range of active matter systems can be simulated with a high level of detail, and ultimately can help to describe active matter phenomena, and in particular, the dynamics of the cell cytoskeleton. In this work, we have used MEDYAN to simulate a cytoskeletal network consisting of actin filaments, cross-linking proteins, and myosin II molecular motors. We found that these systems show rich dynamical behaviors, undergoing alignment and bundling transitions, with an emergent contractility, as the concentrations of myosin II and cross-linking proteins, as well as actin filament turnover rates, are varied.
Collapse
Affiliation(s)
- Konstantin Popov
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
| | - James Komianos
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
- Biophysics Graduate Program, University of Maryland, College Park, Maryland, United States of America
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
- * E-mail:
| |
Collapse
|
37
|
Wang N, Lee IJ, Rask G, Wu JQ. Roles of the TRAPP-II Complex and the Exocyst in Membrane Deposition during Fission Yeast Cytokinesis. PLoS Biol 2016; 14:e1002437. [PMID: 27082518 PMCID: PMC4833314 DOI: 10.1371/journal.pbio.1002437] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 03/15/2016] [Indexed: 12/27/2022] Open
Abstract
The cleavage-furrow tip adjacent to the actomyosin contractile ring is believed to be the predominant site for plasma-membrane insertion through exocyst-tethered vesicles during cytokinesis. Here we found that most secretory vesicles are delivered by myosin-V on linear actin cables in fission yeast cytokinesis. Surprisingly, by tracking individual exocytic and endocytic events, we found that vesicles with new membrane are deposited to the cleavage furrow relatively evenly during contractile-ring constriction, but the rim of the cleavage furrow is the main site for endocytosis. Fusion of vesicles with the plasma membrane requires vesicle tethers. Our data suggest that the transport particle protein II (TRAPP-II) complex and Rab11 GTPase Ypt3 help to tether secretory vesicles or tubulovesicular structures along the cleavage furrow while the exocyst tethers vesicles at the rim of the division plane. We conclude that the exocyst and TRAPP-II complex have distinct localizations at the division site, but both are important for membrane expansion and exocytosis during cytokinesis. Two putative vesicle tethers—the exocyst and TRAPP-II complexes—localize differently at the division plane to ensure efficient plasma-membrane deposition along the whole cleavage furrow during cytokinesis in the fission yeast Schizosaccharomyces pombe. Cytokinesis partitions a mother cell into two daughter cells at the end of each cell-division cycle. A significant amount of new plasma membrane is needed at the cleavage furrow during cytokinesis in many cell types. Membrane expansion is achieved through the balance of exocytosis and endocytosis. It is poorly understood where and when the membrane is deposited and retrieved during cytokinesis. By tracking individual vesicles with high spatiotemporal resolution and using electron microscopy, we found that new membrane is deposited relatively evenly along the cleavage furrow in fission yeast, while the rim of the division plane is the predominant site for endocytosis. The secretory vesicles/compartments carrying new membrane are mainly delivered along formin-nucleated actin cables by myosin-V motors. Surprisingly, we find that both exocytosis and endocytosis at the division site are ramped up before contractile-ring constriction and last until daughter-cell separation. We discovered that two putative vesicle tethers, the exocyst and TRAPP-II complexes, localize to different sites at the cleavage furrow to promote tethering of different, yet overlapping, classes of secretory vesicles/compartments for exocytosis and new membrane deposition.
Collapse
Affiliation(s)
- Ning Wang
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - I-Ju Lee
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Galen Rask
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
| |
Collapse
|
38
|
Li Y, Christensen JR, Homa KE, Hocky GM, Fok A, Sees JA, Voth GA, Kovar DR. The F-actin bundler α-actinin Ain1 is tailored for ring assembly and constriction during cytokinesis in fission yeast. Mol Biol Cell 2016; 27:1821-33. [PMID: 27075176 PMCID: PMC4884072 DOI: 10.1091/mbc.e16-01-0010] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/06/2016] [Indexed: 12/18/2022] Open
Abstract
The actomyosin contractile ring is a network of cross-linked actin filaments that facilitates cytokinesis in dividing cells. Contractile ring formation has been well characterized in Schizosaccharomyces pombe, in which the cross-linking protein α-actinin SpAin1 bundles the actin filament network. However, the specific biochemical properties of SpAin1 and whether they are tailored for cytokinesis are not known. Therefore we purified SpAin1 and quantified its ability to dynamically bind and bundle actin filaments in vitro using a combination of bulk sedimentation assays and direct visualization by two-color total internal reflection fluorescence microscopy. We found that, while SpAin1 bundles actin filaments of mixed polarity like other α-actinins, SpAin1 has lower bundling activity and is more dynamic than human α-actinin HsACTN4. To determine whether dynamic bundling is important for cytokinesis in fission yeast, we created the less dynamic bundling mutant SpAin1(R216E). We found that dynamic bundling is critical for cytokinesis, as cells expressing SpAin1(R216E) display disorganized ring material and delays in both ring formation and constriction. Furthermore, computer simulations of initial actin filament elongation and alignment revealed that an intermediate level of cross-linking best facilitates filament alignment. Together our results demonstrate that dynamic bundling by SpAin1 is important for proper contractile ring formation and constriction.
Collapse
Affiliation(s)
- Yujie Li
- Committee on Genetics, Genomics and Systems Biology, University of Chicago, Chicago, IL 60637
| | - Jenna R Christensen
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Kaitlin E Homa
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Glen M Hocky
- Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago, Chicago, IL 60637
| | - Alice Fok
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Jennifer A Sees
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Gregory A Voth
- Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, and Computation Institute, University of Chicago, Chicago, IL 60637
| | - David R Kovar
- Committee on Genetics, Genomics and Systems Biology, University of Chicago, Chicago, IL 60637 Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637 Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637
| |
Collapse
|
39
|
Addario B, Sandblad L, Persson K, Backman L. Characterisation of Schizosaccharomyces pombe α-actinin. PeerJ 2016; 4:e1858. [PMID: 27069798 PMCID: PMC4824898 DOI: 10.7717/peerj.1858] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 03/08/2016] [Indexed: 11/27/2022] Open
Abstract
The actin cytoskeleton plays a fundamental role in eukaryotic cells. Its reorganization is regulated by a plethora of actin-modulating proteins, such as a-actinin. In higher organisms, α-actinin is characterized by the presence of three distinct structural domains: an N-terminal actin-binding domain and a C-terminal region with EF-hand motif separated by a central rod domain with four spectrin repeats. Sequence analysis has revealed that the central rod domain of α-actinin from the fission yeast Schizosaccharomyces pombe consists of only two spectrin repeats. To obtain a firmer understanding of the structure and function of this unconventional α-actinin, we have cloned and characterized each structural domain. Our results show that this a-actinin isoform is capable of forming dimers and that the rod domain is required for this. However, its actin-binding and cross-linking activity appears less efficient compared to conventional α-actinins. The solved crystal structure of the actin-binding domain indicates that the closed state is stabilised by hydrogen bonds and a salt bridge not present in other α-actinins, which may reduce the affinity for actin.
Collapse
Affiliation(s)
- Barbara Addario
- Cell Biology Laboratory, School of Biochemistry and Cell Biology, BioScience Institute, University College Cork , Cork , Ireland
| | - Linda Sandblad
- Department of Molecular Biology, UmeåUniversity , Umeå , Sweden
| | - Karina Persson
- Department of Chemistry, Biological Chemistry , Umeå , Sweden
| | - Lars Backman
- Department of Chemistry, Biological Chemistry , Umeå , Sweden
| |
Collapse
|
40
|
Zhang D, Bidone TC, Vavylonis D. ER-PM Contacts Define Actomyosin Kinetics for Proper Contractile Ring Assembly. Curr Biol 2016; 26:647-53. [PMID: 26877082 DOI: 10.1016/j.cub.2015.12.070] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/24/2015] [Accepted: 12/24/2015] [Indexed: 12/20/2022]
Abstract
The cortical endoplasmic reticulum (ER), an elaborate network of tubules and cisternae [1], establishes contact sites with the plasma membrane (PM) through tethering machinery involving a set of conserved integral ER proteins [2]. The physiological consequences of forming ER-PM contacts are not fully understood. Here, we reveal a kinetic restriction role of ER-PM contacts over ring compaction process for proper actomyosin ring assembly in Schizosaccharomyces pombe. We show that fission yeast cells deficient in ER-PM contacts exhibit aberrant equatorial clustering of actin cables during ring assembly and are particularly susceptible to compromised actin filament crosslinking activity. Using quantitative image analyses and computer simulation, we demonstrate that ER-PM contacts function to modulate the distribution of ring components and to constrain their compaction kinetics. We propose that ER-PM contacts have evolved as important physical modulators to ensure robust ring assembly.
Collapse
Affiliation(s)
- Dan Zhang
- Temasek Life Sciences Laboratory, 1 Research Link, Singapore 117604, Singapore.
| | - Tamara C Bidone
- Department of Physics, Lehigh University, Bethlehem, PA 18015, USA
| | | |
Collapse
|
41
|
Rincon SA, Paoletti A. Molecular control of fission yeast cytokinesis. Semin Cell Dev Biol 2016; 53:28-38. [PMID: 26806637 DOI: 10.1016/j.semcdb.2016.01.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 01/06/2016] [Indexed: 12/29/2022]
Abstract
Cytokinesis gives rise to two independent daughter cells at the end of the cell division cycle. The fission yeast Schizosaccharomyces pombe has emerged as one of the most powerful systems to understand how cytokinesis is controlled molecularly. Like in most eukaryotes, fission yeast cytokinesis depends on an acto-myosin based contractile ring that assembles at the division site under the control of spatial cues that integrate information on cell geometry and the position of the mitotic apparatus. Cytokinetic events are also tightly coordinated with nuclear division by the cell cycle machinery. These spatial and temporal regulations ensure an equal cleavage of the cytoplasm and an accurate segregation of the genetic material in daughter cells. Although this model system has specificities, the basic mechanisms of contractile ring assembly and function deciphered in fission yeast are highly valuable to understand how cytokinesis is controlled in other organisms that rely on a contractile ring for cell division.
Collapse
Affiliation(s)
- Sergio A Rincon
- Institut Curie, Centre de Recherche, PSL Research University, F-75248 Paris, France; CNRS UMR144, F-75248 Paris, France
| | - Anne Paoletti
- Institut Curie, Centre de Recherche, PSL Research University, F-75248 Paris, France; CNRS UMR144, F-75248 Paris, France.
| |
Collapse
|
42
|
Müller KW, Birzle AM, Wall WA. Beam finite-element model of a molecular motor for the simulation of active fibre networks. Proc Math Phys Eng Sci 2016; 472:20150555. [PMID: 26997891 DOI: 10.1098/rspa.2015.0555] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Molecular motors are proteins that excessively increase the efficiency of subcellular transport processes. They allow for cell division, nutrient transport and even macroscopic muscle movement. In order to understand the effect of motors in large biopolymer networks, e.g. the cytoskeleton, we require a suitable model of a molecular motor. In this contribution, we present such a model based on a geometrically exact beam finite-element formulation. We discuss the numerical model of a non-processive motor such as myosin II, which interacts with actin filaments. Based on experimental data and inspired by the theoretical understanding offered by the power-stroke model and the swinging-cross-bridge model, we parametrize our numerical model in order to achieve the effect that a physiological motor has on its cargo. To this end, we introduce the mechanical and mathematical foundations of the model, then discuss its calibration, prove its usefulness by conducting finite-element simulations of actin-myosin motility assays and assess the influence of motors on the rheology of semi-flexible biopolymer networks.
Collapse
Affiliation(s)
- Kei W Müller
- Institute for Computational Mechanics , Technische Universität München , Boltzmannstrasse 15, Garching bei München 85748, Germany
| | - Anna M Birzle
- Institute for Computational Mechanics , Technische Universität München , Boltzmannstrasse 15, Garching bei München 85748, Germany
| | - Wolfgang A Wall
- Institute for Computational Mechanics , Technische Universität München , Boltzmannstrasse 15, Garching bei München 85748, Germany
| |
Collapse
|
43
|
Murphy ACH, Young PW. The actinin family of actin cross-linking proteins - a genetic perspective. Cell Biosci 2015; 5:49. [PMID: 26312134 PMCID: PMC4550062 DOI: 10.1186/s13578-015-0029-7] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/22/2015] [Accepted: 06/23/2015] [Indexed: 01/08/2023] Open
Abstract
Actinins are one of the major actin cross-linking proteins found in virtually all cell types and are the ancestral proteins of a larger family that includes spectrin, dystrophin and utrophin. Invertebrates have a single actinin-encoding ACTN gene, while mammals have four. Mutations in all four human genes have now been linked to heritable diseases or traits. ACTN1 mutations cause macrothrombocytopenia, a platelet disorder characterized by excessive bleeding. ACTN2 mutations have been linked to a range of cardiomyopathies, and ACTN4 mutations cause a kidney condition called focal segmental glomerulosclerosis. Intriguingly, approximately 16 % of people worldwide are homozygous for a nonsense mutation in ACTN3 that abolishes actinin-3 protein expression. This ACTN3 null allele has undergone recent positive selection in specific human populations, which may be linked to improved endurance and adaptation to colder climates. In this review we discuss the human genetics of the ACTN gene family, as well as ACTN gene knockout studies in several model organisms. Observations from both of these areas provide insights into the evolution and cellular functions of actinins.
Collapse
Affiliation(s)
- Anita C H Murphy
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Paul W Young
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| |
Collapse
|
44
|
Cranz-Mileva S, MacTaggart B, Russell J, Hitchcock-DeGregori SE. Evolutionarily conserved sites in yeast tropomyosin function in cell polarity, transport and contractile ring formation. Biol Open 2015; 4:1040-51. [PMID: 26187949 PMCID: PMC4542287 DOI: 10.1242/bio.012609] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Tropomyosin is a coiled-coil protein that binds and regulates actin filaments. The tropomyosin gene in Schizosaccharomyces pombe, cdc8, is required for formation of actin cables, contractile rings, and polar localization of actin patches. The roles of conserved residues were investigated in gene replacement mutants. The work validates an evolution-based approach to identify tropomyosin functions in living cells and sites of potential interactions with other proteins. A cdc8 mutant with near-normal actin affinity affects patch polarization and vacuole fusion, possibly by affecting Myo52p, a class V myosin, function. The presence of labile residual cell attachments suggests a delay in completion of cell division and redistribution of cell patches following cytokinesis. Another mutant with a mild phenotype is synthetic negative with GFP-fimbrin, inferring involvement of the mutated tropomyosin sites in interaction between the two proteins. Proteins that assemble in the contractile ring region before actin do so in a mutant cdc8 strain that cannot assemble condensed actin rings, yet some cells can divide. Of general significance, LifeAct-GFP negatively affects the actin cytoskeleton, indicating caution in its use as a biomarker for actin filaments.
Collapse
Affiliation(s)
- Susanne Cranz-Mileva
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Brittany MacTaggart
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Jacquelyn Russell
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Sarah E Hitchcock-DeGregori
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| |
Collapse
|
45
|
Guzmán-Vendrell M, Rincon SA, Dingli F, Loew D, Paoletti A. Molecular control of the Wee1 regulatory pathway by the SAD kinase Cdr2. J Cell Sci 2015; 128:2842-53. [PMID: 26071525 DOI: 10.1242/jcs.173146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 06/10/2015] [Indexed: 01/14/2023] Open
Abstract
Cell growth and division are tightly coordinated to maintain cell size constant during successive cell cycles. In Schizosaccharomyces pombe, the SAD kinase Cdr2 regulates the cell size at division and the positioning of the division plane. Cdr2 forms nodes on the medial cortex containing factors that constitute an inhibitory pathway for Wee1. This pathway is regulated by polar gradients of the DYRK kinase Pom1, and involves a direct inhibitor of Wee1, the SAD kinase Cdr1. Cdr2 also interacts with the anillin Mid1, which defines the division plane, and with additional components of the medial cortical nodes, including Blt1, which participate in the mitotic-promoting and cytokinetic functions of nodes. Here, we show that the interaction of Cdr2 with Wee1 and Mid1 requires the UBA domain of Cdr2, which is necessary for its kinase activity. In contrast, Cdr1 associates with the C-terminus of Cdr2, which is composed of basic and KA-1 lipid-binding domains. Mid1 also interacts with the C-terminus of Cdr2 and might bridge the N- and C-terminal domains, whereas Blt1 associates with the central spacer region. We propose that the association of Cdr2 effectors with different domains might constrain Cdr1 and Wee1 spatially to promote Wee1 inhibition upon Cdr2 kinase activation.
Collapse
Affiliation(s)
- Mercè Guzmán-Vendrell
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France CNRS UMR144, Paris F-75248, France
| | - Sergio A Rincon
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France CNRS UMR144, Paris F-75248, France
| | - Florent Dingli
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France Laboratory of Mass Spectrometry and Proteomics, Paris F-75248, France
| | - Damarys Loew
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France Laboratory of Mass Spectrometry and Proteomics, Paris F-75248, France
| | - Anne Paoletti
- Institut Curie, Centre de Recherche, PSL Research University, Paris F-75248, France CNRS UMR144, Paris F-75248, France
| |
Collapse
|
46
|
Letort G, Politi AZ, Ennomani H, Théry M, Nedelec F, Blanchoin L. Geometrical and mechanical properties control actin filament organization. PLoS Comput Biol 2015; 11:e1004245. [PMID: 26016478 DOI: 10.1371/journal.pcbi.1004245] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 03/17/2015] [Indexed: 12/23/2022] Open
Abstract
The different actin structures governing eukaryotic cell shape and movement are not only determined by the properties of the actin filaments and associated proteins, but also by geometrical constraints. We recently demonstrated that limiting nucleation to specific regions was sufficient to obtain actin networks with different organization. To further investigate how spatially constrained actin nucleation determines the emergent actin organization, we performed detailed simulations of the actin filament system using Cytosim. We first calibrated the steric interaction between filaments, by matching, in simulations and experiments, the bundled actin organization observed with a rectangular bar of nucleating factor. We then studied the overall organization of actin filaments generated by more complex pattern geometries used experimentally. We found that the fraction of parallel versus antiparallel bundles is determined by the mechanical properties of actin filament or bundles and the efficiency of nucleation. Thus nucleation geometry, actin filaments local interactions, bundle rigidity, and nucleation efficiency are the key parameters controlling the emergent actin architecture. We finally simulated more complex nucleation patterns and performed the corresponding experiments to confirm the predictive capabilities of the model.
Collapse
Affiliation(s)
- Gaëlle Letort
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/UGA, Grenoble, France; Laboratoire d'Imagerie et Systèmes d'Acquisition, CEA, LETI, MINATEC Campus, Grenoble, France, Univ. Grenoble-Alpes, Grenoble, France
| | | | - Hajer Ennomani
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/UGA, Grenoble, France
| | - Manuel Théry
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/UGA, Grenoble, France
| | | | - Laurent Blanchoin
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/UGA, Grenoble, France
| |
Collapse
|
47
|
Cell-sized spherical confinement induces the spontaneous formation of contractile actomyosin rings in vitro. Nat Cell Biol 2015; 17:480-9. [DOI: 10.1038/ncb3142] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 02/19/2015] [Indexed: 12/13/2022]
|
48
|
Jones D, Park D, Anghelina M, Pécot T, Machiraju R, Xue R, Lannutti JJ, Thomas J, Cole SL, Moldovan L, Moldovan NI. Actin grips: circular actin-rich cytoskeletal structures that mediate the wrapping of polymeric microfibers by endothelial cells. Biomaterials 2015; 52:395-406. [PMID: 25818446 PMCID: PMC4418805 DOI: 10.1016/j.biomaterials.2015.02.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 01/13/2023]
Abstract
Interaction of endothelial-lineage cells with three-dimensional substrates was much less studied than that with flat culture surfaces. We investigated the in vitro attachment of both mature endothelial cells (ECs) and of less differentiated EC colony-forming cells to poly-ε-capro-lactone (PCL) fibers with diameters in 5-20 μm range ('scaffold microfibers', SMFs). We found that notwithstanding the poor intrinsic adhesiveness to PCL, both cell types completely wrapped the SMFs after long-term cultivation, thus attaining a cylindrical morphology. In this system, both EC types grew vigorously for more than a week and became increasingly more differentiated, as shown by multiplexed gene expression. Three-dimensional reconstructions from multiphoton confocal microscopy images using custom software showed that the filamentous (F) actin bundles took a conspicuous ring-like organization around the SMFs. Unlike the classical F-actin-containing stress fibers, these rings were not associated with either focal adhesions or intermediate filaments. We also demonstrated that plasma membrane boundaries adjacent to these circular cytoskeletal structures were tightly yet dynamically apposed to the SMFs, for which reason we suggest to call them 'actin grips'. In conclusion, we describe a particular form of F-actin assembly with relevance for cytoskeletal organization in response to biomaterials, for endothelial-specific cell behavior in vitro and in vivo, and for tissue engineering.
Collapse
Affiliation(s)
- Desiree Jones
- Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - DoYoung Park
- Department of Computer Sciences and Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Mirela Anghelina
- Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Thierry Pécot
- Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA; Department of Computer Sciences and Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Raghu Machiraju
- Department of Computer Sciences and Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Ruipeng Xue
- Department of Materials Sciences, The Ohio State University, Columbus, OH, 43210, USA
| | - John J Lannutti
- Department of Materials Sciences, The Ohio State University, Columbus, OH, 43210, USA
| | - Jessica Thomas
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Sara L Cole
- Campus Microscopy and Imaging Facility, The Ohio State University, Columbus, OH, 43210, USA
| | - Leni Moldovan
- Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Nicanor I Moldovan
- Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA.
| |
Collapse
|
49
|
Nie W, Wei MT, Ou-Yang HD, Jedlicka SS, Vavylonis D. Formation of contractile networks and fibers in the medial cell cortex through myosin-II turnover, contraction, and stress-stabilization. Cytoskeleton (Hoboken) 2015; 72:29-46. [PMID: 25641802 DOI: 10.1002/cm.21207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 12/31/2014] [Indexed: 12/24/2022]
Abstract
The morphology of adhered cells depends crucially on the formation of a contractile meshwork of parallel and cross-linked fibers along the contacting surface. The motor activity and minifilament assembly of non-muscle myosin-II is an important component of cortical cytoskeletal remodeling during mechanosensing. We used experiments and computational modeling to study cortical myosin-II dynamics in adhered cells. Confocal microscopy was used to image the medial cell cortex of HeLa cells stably expressing myosin regulatory light chain tagged with GFP (MRLC-GFP). The distribution of MRLC-GFP fibers and focal adhesions was classified into three types of network morphologies. Time-lapse movies show: myosin foci appearance and disappearance; aligning and contraction; stabilization upon alignment. Addition of blebbistatin, which perturbs myosin motor activity, leads to a reorganization of the cortical networks and to a reduction of contractile motions. We quantified the kinetics of contraction, disassembly and reassembly of myosin networks using spatio-temporal image correlation spectroscopy (STICS). Coarse-grained numerical simulations include bipolar minifilaments that contract and align through specified interactions as basic elements. After assuming that minifilament turnover decreases with increasing contractile stress, the simulations reproduce stress-dependent fiber formation in between focal adhesions above a threshold myosin concentration. The STICS correlation function in simulations matches the function measured in experiments. This study provides a framework to help interpret how different cortical myosin remodeling kinetics may contribute to different cell shape and rigidity depending on substrate stiffness.
Collapse
Affiliation(s)
- Wei Nie
- Department of Physics, Lehigh University, Bethlehem, Pennsylvania
| | | | | | | | | |
Collapse
|
50
|
Davidson R, Laporte D, Wu JQ. Regulation of Rho-GEF Rgf3 by the arrestin Art1 in fission yeast cytokinesis. Mol Biol Cell 2014; 26:453-66. [PMID: 25473118 PMCID: PMC4310737 DOI: 10.1091/mbc.e14-07-1252] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The arrestin Art1 and the Rho1 guanine nucleotide exchange factor Rgf3 are interdependent for their localizations to the division site during fission yeast cytokinesis. Art1 physically interacts with Rgf3 to modulate active Rho1 GTPase levels for successful septal formation. Rho GTPases, activated by guanine nucleotide exchange factors (GEFs), are essential regulators of polarized cell growth, cytokinesis, and many other cellular processes. However, the regulation of Rho-GEFs themselves is not well understood. Rgf3 is an essential GEF for Rho1 GTPase in fission yeast. We show that Rgf3 protein levels and localization are regulated by arrestin-related protein Art1. art1∆ cells lyse during cell separation with a thinner and defective septum. As does Rgf3, Art1 concentrates to the contractile ring starting at early anaphase and spreads to the septum during and after ring constriction. Art1 localization depends on its C-terminus, and Art1 is important for maintaining Rgf3 protein levels. Biochemical experiments reveal that the Rgf3 C-terminus binds to Art1. Using an Rgf3 conditional mutant and mislocalization experiments, we found that Art1 and Rgf3 are interdependent for localization to the division site. As expected, active Rho1 levels at the division site are reduced in art1∆ and rgf3 mutant cells. Taken together, these data reveal that the arrestin family protein Art1 regulates the protein levels and localization of the Rho-GEF Rgf3, which in turn modulates active Rho1 levels during fission yeast cytokinesis.
Collapse
Affiliation(s)
- Reshma Davidson
- Graduate Program of Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus, OH 43210 Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Damien Laporte
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
| |
Collapse
|