Spire contains actin binding domains and is related to ascidian posterior end mark-5

Development ◽  
1999 ◽  
Vol 126 (23) ◽  
pp. 5267-5274 ◽  
Author(s):  
A. Wellington ◽  
S. Emmons ◽  
B. James ◽  
J. Calley ◽  
M. Grover ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Posterior Pole ◽  
Actin Binding ◽  
Binding Domains ◽  
Trap System ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
Interaction Trap ◽  
Anterior Posterior

Spire is a maternal effect locus that affects both the dorsal-ventral and anterior-posterior axes of the Drosophila egg and embryo. It is required for localization of determinants within the developing oocyte to the posterior pole and to the dorsal anterior corner. During mid-oogenesis, spire mutants display premature microtubule-dependent cytoplasmic streaming, a phenotype that can be mimicked by pharmacological disruption of the actin cytoskeleton with cytochalasin D. Spire has been cloned by transposon tagging and is related to posterior end mark-5, a gene from sea squirts that encodes a posteriorly localized mRNA. Spire mRNA is not, however, localized to the posterior pole. SPIRE also contains two domains with similarity to the actin monomer-binding WH2 domain, and we demonstrate that SPIRE binds to actin in the interaction trap system and in vitro. In addition, SPIRE interacts with the rho family GTPases RHOA, RAC1 and CDC42 in the interaction trap system. Thus, our evidence supports the model that SPIRE links rho family signaling to the actin cytoskeleton.

scholarly journals Interactions among a Fimbrin, a Capping Protein, and an Actin-depolymerizing Factor in Organization of the Fission Yeast Actin Cytoskeleton

2001 ◽  
Vol 12 (11) ◽  
pp. 3515-3526 ◽  
Author(s):  
Kentaro Nakano ◽  
Kazuomi Satoh ◽  
Akeshi Morimatsu ◽  
Masaaki Ohnuma ◽  
Issei Mabuchi
Keyword(s):  
Actin Cytoskeleton ◽  
Fission Yeast ◽  
Actin Binding ◽  
Cell Cortex ◽  
Cross Linking ◽  
Actin Depolymerizing Factor ◽  
Binding Domains ◽  
Ef Hand ◽  
Actin Cables

We report studies of the fission yeast fimbrin-like protein Fim1, which contains two EF-hand domains and two actin-binding domains (ABD1 and ABD2). Fim1 is a component of both F-actin patches and the F-actin ring, but not of F-actin cables. Fim1 cross-links F-actin in vitro, but a Fim1 protein lacking either EF-hand domains (Fim1A12) or both the EF-hand domains and ABD1 (Fim1A2) has no actin cross-linking activity. Overexpression of Fim1 induced the formation of F-actin patches throughout the cell cortex, whereas the F-actin patches disappear in cells overexpressing Fim1A12 or Fim1A2. Thus, the actin cross-linking activity of Fim1 is probably important for the formation of F-actin patches. The overexpression of Fim1 also excluded the actin-depolymerizing factor Adf1 from the F-actin patches and inhibited the turnover of actin in these structures. Thus, Fim1 may function in stabilizing the F-actin patches. We also isolated the gene encoding Acp1, a subunit of the heterodimeric F-actin capping protein.fim1 acp1 double null cells showed more severe defects in the organization of the actin cytoskeleton than those seen in each single mutant. Thus, Fim1 and Acp1 may function in a similar manner in the organization of the actin cytoskeleton. Finally, genetic studies suggested that Fim1 may function in cytokinesis in cooperation with Cdc15 (PSTPIP) and Rng2 (IQGAP), respectively.

NUANCE, a giant protein connecting the nucleus and actin cytoskeleton

2002 ◽  
Vol 115 (15) ◽  
pp. 3207-3222 ◽  
Author(s):  
Yen-Yi Zhen ◽  
Thorsten Libotte ◽  
Martina Munck ◽  
Angelika A. Noegel ◽  
Elena Korenbaum
Keyword(s):  
Actin Cytoskeleton ◽  
Transmembrane Domain ◽  
Coiled Coil ◽  
Peripheral Blood Lymphocytes ◽  
Binding Domain ◽  
Actin Binding ◽  
Actin Binding Domain ◽  
Microfilament System

NUANCE (NUcleus and ActiN Connecting Element) was identified as a novel protein with an α-actinin-like actin-binding domain. A human 21.8 kb cDNA of NUANCE spreads over 373 kb on chromosome 14q22.1-q22.3. The cDNA sequence predicts a 796 kDa protein with an N-terminal actin-binding domain, a central coiled-coil rod domain and a predicted C-terminal transmembrane domain. High levels of NUANCE mRNA were detected in the kidney, liver,stomach, placenta, spleen, lymphatic nodes and peripheral blood lymphocytes. At the subcellular level NUANCE is present predominantly at the outer nuclear membrane and in the nucleoplasm. Domain analysis shows that the actin-binding domain binds to Factin in vitro and colocalizes with the actin cytoskeleton in vivo as a GFP-fusion protein. The C-terminal transmembrane domain is responsible for the targeting the nuclear envelope. Thus, NUANCE is the firstα-actinin-related protein that has the potential to link the microfilament system with the nucleus.

scholarly journals Tissue Expression and Actin Binding of a Novel N-Terminal Utrophin Isoform

2011 ◽  
Vol 2011 ◽  
pp. 1-18
Author(s):  
Richard A. Zuellig ◽  
Beat C. Bornhauser ◽  
Ralf Amstutz ◽  
Bruno Constantin ◽  
Marcus C. Schaub
Keyword(s):  
Actin Cytoskeleton ◽  
Tissue Expression ◽  
Protein Product ◽  
Binding Domain ◽  
Actin Binding ◽  
Rat Tissues ◽  
Cortical Actin ◽  
Actin Binding Domain ◽  
Spectrin Repeats

Utrophin and dystrophin present two large proteins that link the intracellular actin cytoskeleton to the extracellular matrix via the C-terminal-associated protein complex. Here we describe a novel short N-terminal isoform of utrophin and its protein product in various rat tissues (N-utro, 62 kDa, amino acids 1–539, comprising the actin-binding domain plus the first two spectrin repeats). Using different N-terminal recombinant utrophin fragments, we show that actin binding exhibits pronounced negative cooperativity (affinity constantsK1=∼5×106andK2=∼1×105 M-1) and is Ca2+-insensitive. Expression of the different fragments in COS7 cells and in myotubes indicates that the actin-binding domain alone binds exlusively to actin filaments. The recombinant N-utro analogue binds in vitro to actin and in the cells associates to the membranes. The results indicate that N-utro may be responsible for the anchoring of the cortical actin cytoskeleton to the membranes in muscle and other tissues.

scholarly journals Mechanosensing through direct binding of tensed F-actin by LIM domains

2020 ◽  
Author(s):  
Xiaoyu Sun ◽  
Donovan Y. Z. Phua ◽  
Lucas Axiotakis ◽  
Mark A. Smith ◽  
Elizabeth Blankman ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Point Mutations ◽  
Cytoskeletal Proteins ◽  
Actin Binding ◽  
General Mechanism ◽  
Protein Protein Interaction ◽  
Cytoplasmic Actin ◽  
Lim Domains ◽  
Lim Proteins

SummaryMechanical signals transmitted through the cytoplasmic actin cytoskeleton must be relayed to the nucleus to control gene expression. LIM domains are protein-protein interaction modules found in cytoskeletal proteins and transcriptional regulators; however, it is unclear if there is a direct link between these two functions. Here we identify three LIM protein families (zyxin, paxillin, and FHL) whose members preferentially localize to the actin cytoskeleton in mechanically-stimulated cells through their tandem LIM domains. A minimal actin-myosin reconstitution system reveals that representatives of all three families directly bind F-actin only in the presence of mechanical force. Point mutations at a site conserved in each LIM domain of these proteins selectively disrupt tensed F-actin binding in vitro and cytoskeletal localization in cells, demonstrating a common, avidity-based mechanism. Finally, we find that binding to tensed F-actin in the cytoplasm excludes the cancer-associated transcriptional co-activator FHL2 from the nucleus in stiff microenvironments. This establishes direct force-activated F-actin binding by FHL2 as a mechanosensing mechanism. Our studies suggest that force-dependent sequestration of LIM proteins on the actin cytoskeleton could be a general mechanism for controlling nuclear localization to effect mechanical signaling.

scholarly journals STIP1/HOP Regulates the Actin Cytoskeleton through Interactions with Actin and Changes in Actin-Binding Proteins Cofilin and Profilin

2020 ◽  
Vol 21 (9) ◽  
pp. 3152 ◽  
Author(s):  
Samantha Joy Beckley ◽  
Morgan Campbell Hunter ◽  
Sarah Naulikha Kituyi ◽  
Ianthe Wingate ◽  
Abantika Chakraborty ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Binding Proteins ◽  
Major Effect ◽  
Vital Role ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Nuclear Accumulation ◽  
Actin Binding Proteins ◽  
Hsp90 Chaperone

Cell migration plays a vital role in both health and disease. It is driven by reorganization of the actin cytoskeleton, which is regulated by actin-binding proteins cofilin and profilin. Stress-inducible phosphoprotein 1 (STIP1) is a well-described co-chaperone of the Hsp90 chaperone system, and our findings identify a potential regulatory role of STIP1 in actin dynamics. We show that STIP1 can be isolated in complex with actin and Hsp90 from HEK293T cells and directly interacts with actin in vitro via the C-terminal TPR2AB-DP2 domain of STIP1, potentially due to a region spanning two putative actin-binding motifs. We found that STIP1 could stimulate the in vitro ATPase activity of actin, suggesting a potential role in the modulation of F-actin formation. Interestingly, while STIP1 depletion in HEK293T cells had no major effect on total actin levels, it led to increased nuclear accumulation of actin, disorganization of F-actin structures, and an increase and decrease in cofilin and profilin levels, respectively. This study suggests that STIP1 regulates the cytoskeleton by interacting with actin, or via regulating the ratio of proteins known to affect actin dynamics.

scholarly journals Structure of artificial and natural VE-cadherinbased adherens junctions

2008 ◽  
Vol 36 (2) ◽  
pp. 189-193 ◽  
Author(s):  
Jean-Christophe Taveau ◽  
Mathilde Dubois ◽  
Olivier Le Bihan ◽  
Sylvain Trépout ◽  
Sébastien Almagro ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Actin Cytoskeleton ◽  
Self Assembly ◽  
Adherens Junctions ◽  
Actin Binding ◽  
Vascular Endothelial ◽  
Vascular Integrity ◽  
Trans Orientation ◽  
Annexin 2

In vascular endothelium, adherens junctions between endothelial cells are composed of VE-cadherin (vascular endothelial cadherin), an adhesive receptor that is crucial for the proper assembly of vascular structures and the maintenance of vascular integrity. As a classical cadherin, VE-cadherin links endothelial cells together by homophilic interactions mediated by its extracellular part and associates intracellularly with the actin cytoskeleton via catenins. Although, from structural crystallographic data, a dimeric structure arranged in a trans orientation has emerged as a potential mechanism of cell–cell adhesion, the cadherin organization within adherens junctions remains controversial. Concerning VE-cadherin, its extracellular part possesses the capacity to self-associate in solution as hexamers consisting of three antiparallel cadherin dimers. VE-cadherin-based adherens junctions were reconstituted in vitro by assembly of a VE-cadherin EC (extracellular repeat) 1–EC4 hexamer at the surfaces of liposomes. The artificial adherens junctions revealed by cryoelectron microscopy appear as a two-dimensional self-assembly of hexameric structures. This cadherin organization is reminiscent of that found in native desmosomal junctions. Further structural studies performed on native VE-cadherin junctions would provide a better understanding of the cadherin organization within adherens junctions. Homophilic interactions between cadherins are strengthened intracellularly by connection to the actin cytoskeleton. Recently, we have discovered that annexin 2, an actin-binding protein connects the VE-cadherin–catenin complex to the actin cytoskeleton. This novel link is labile and promotes the endothelial cell switch from a quiescent to an angiogenic state.

Rho family GTPases

2012 ◽  
Vol 40 (6) ◽  
pp. 1378-1382 ◽  
Author(s):  
Alan Hall
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpases ◽  
Cellular Response ◽  
Molecular Switches ◽  
Effector Proteins ◽  
Eukaryotic Cells ◽  
Cell Behaviour ◽  
Wide Range ◽  
Rho Family Gtpases ◽  
Rho Family

Rho GTPases comprise a family of molecular switches that control signal transduction pathways in eukaryotic cells. A conformational change induced upon binding GTP promotes an interaction with target (effector) proteins to generate a cellular response. A highly conserved function of Rho GTPases from yeast to humans is to control the actin cytoskeleton, although, in addition, they promote a wide range of other cellular activities. Changes in the actin cytoskeleton drive many dynamic aspects of cell behaviour, including morphogenesis, migration, phagocytosis and cytokinesis, and the dysregulation of Rho GTPases is associated with numerous human diseases and disorders.

scholarly journals The Uptake and Degradation of Matrix-bound Lipoproteins by Macrophages Require an Intact Actin Cytoskeleton, Rho Family GTPases, and Myosin ATPase Activity

2001 ◽  
Vol 276 (40) ◽  
pp. 37649-37658 ◽  
Author(s):  
Sana W. Sakr ◽  
Robert J. Eddy ◽  
Holger Barth ◽  
Fengwei Wang ◽  
Steven Greenberg ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Actin Cytoskeleton ◽  
Myosin Atpase ◽  
Myosin Atpase Activity ◽  
Rho Family Gtpases ◽  
Matrix Bound ◽  
Rho Family

scholarly journals Molecular basis for coupling the plasma membrane to the actin cytoskeleton during clathrin-mediated endocytosis

2012 ◽  
Vol 109 (38) ◽  
pp. E2533-E2542 ◽  
Author(s):  
Michal Skruzny ◽  
Thorsten Brach ◽  
Rodolfo Ciuffa ◽  
Sofia Rybina ◽  
Malte Wachsmuth ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Actin Filaments ◽  
Lipid Binding ◽  
Actin Binding ◽  
Dependent Manner ◽  
Vesicle Budding ◽  
Cooperative Action ◽  
Binding Domains ◽  
Membrane Invagination

Dynamic actin filaments are a crucial component of clathrin-mediated endocytosis when endocytic proteins cannot supply enough energy for vesicle budding. Actin cytoskeleton is thought to provide force for membrane invagination or vesicle scission, but how this force is transmitted to the plasma membrane is not understood. Here we describe the molecular mechanism of plasma membrane–actin cytoskeleton coupling mediated by cooperative action of epsin Ent1 and the HIP1R homolog Sla2 in yeast Saccharomyces cerevisiae. Sla2 anchors Ent1 to a stable endocytic coat by an unforeseen interaction between Sla2’s ANTH and Ent1’s ENTH lipid-binding domains. The ANTH and ENTH domains bind each other in a ligand-dependent manner to provide critical anchoring of both proteins to the membrane. The C-terminal parts of Ent1 and Sla2 bind redundantly to actin filaments via a previously unknown phospho-regulated actin-binding domain in Ent1 and the THATCH domain in Sla2. By the synergistic binding to the membrane and redundant interaction with actin, Ent1 and Sla2 form an essential molecular linker that transmits the force generated by the actin cytoskeleton to the plasma membrane, leading to membrane invagination and vesicle budding.

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