scholarly journals Requirement of the F-actin-binding activity of l-afadin for enhancing the formation of adherens and tight junctions

2018 ◽  
Vol 23 (3) ◽  
pp. 185-199 ◽  
Author(s):  
Shotaro Sakakibara ◽  
Tomohiko Maruo ◽  
Muneaki Miyata ◽  
Kiyohito Mizutani ◽  
Yoshimi Takai
Keyword(s):  
Tight Junctions ◽  
Binding Activity ◽  
Actin Binding

scholarly journals eEF1A Isoforms Change in Abundance and Actin-Binding Activity during Maize Endosperm Development

2003 ◽  
Vol 133 (3) ◽  
pp. 1285-1295 ◽  
Author(s):  
Jose A. Lopez-Valenzuela ◽  
Bryan C. Gibbon ◽  
Peter A. Hughes ◽  
Theo W. Dreher ◽  
Brian A. Larkins
Keyword(s):  
Endosperm Development ◽  
Binding Activity ◽  
Actin Binding ◽  
Maize Endosperm

scholarly journals The Two ADF-H Domains of Twinfilin Play Functionally Distinct Roles in Interactions with Actin Monomers

2002 ◽  
Vol 13 (11) ◽  
pp. 3811-3821 ◽  
Author(s):  
Pauli J. Ojala ◽  
Ville O. Paavilainen ◽  
Maria K. Vartiainen ◽  
Roman Tuma ◽  
Alan G. Weeds ◽  
...  
Keyword(s):  
Binding Site ◽  
Binding Activity ◽  
Size Exclusion ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Actin Monomer ◽  
Wild Type ◽  
Native Page ◽  
Exclusion Chromatography

Twinfilin is a ubiquitous and abundant actin monomer–binding protein that is composed of two ADF-H domains. To elucidate the role of twinfilin in actin dynamics, we examined the interactions of mouse twinfilin and its isolated ADF-H domains with G-actin. Wild-type twinfilin binds ADP-G-actin with higher affinity (K D = 0.05 μM) than ATP-G-actin (K D = 0.47 μM) under physiological ionic conditions and forms a relatively stable (k off = 1.8 s−1) complex with ADP-G-actin. Data from native PAGE and size exclusion chromatography coupled with light scattering suggest that twinfilin competes with ADF/cofilin for the high-affinity binding site on actin monomers, although at higher concentrations, twinfilin, cofilin, and actin may also form a ternary complex. By systematic deletion analysis, we show that the actin-binding activity is located entirely in the two ADF-H domains of twinfilin. Individually, these domains compete for the same binding site on actin, but the C-terminal ADF-H domain, which has >10-fold higher affinity for ADP-G-actin, is almost entirely responsible for the ability of twinfilin to increase the amount of monomeric actin in cosedimentation assays. Isolated ADF-H domains associate with ADP-G-actin with rapid second-order kinetics, whereas the association of wild-type twinfilin with G-actin exhibits kinetics consistent with a two-step binding process. These data suggest that the association with an actin monomer induces a first-order conformational change within the twinfilin molecule. On the basis of these results, we propose a kinetic model for the role of twinfilin in actin dynamics and its possible function in cells.

scholarly journals Involvement of Actinin-4 in the Recruitment of JRAB/MICAL-L2 to Cell-Cell Junctions and the Formation of Functional Tight Junctions

2008 ◽  
Vol 28 (10) ◽  
pp. 3324-3335 ◽  
Author(s):  
Hiroyoshi Nakatsuji ◽  
Noriyuki Nishimura ◽  
Rie Yamamura ◽  
Hiro-omi Kanayama ◽  
Takuya Sasaki
Keyword(s):  
Tight Junctions ◽  
Binding Protein ◽  
Cell Junctions ◽  
Actin Binding ◽  
Deletion Mutants ◽  
Yeast Two Hybrid ◽  
Yeast Two Hybrid System ◽  
Interfering Rna ◽  
Two Hybrid ◽  
Cell Cell

ABSTRACT Tight junctions (TJs) are cell-cell adhesive structures that undergo continuous remodeling. We previously demonstrated that Rab13 and a junctional Rab13-binding protein (JRAB)/molecule interacting with CasL-like 2 (MICAL-L2) localized at TJs and mediated the endocytic recycling of the integral TJ protein occludin and the formation of functional TJs. Here, we investigated how JRAB/MICAL-L2 was targeted to TJs. Using a series of deletion mutants, we found the plasma membrane (PM)-targeting domain within JRAB/MICAL-L2. We then identified actinin-4, which was originally isolated as an actin-binding protein associated with cell motility and cancer invasion/metastasis, as a binding protein for the PM-targeting domain of JRAB/MICAL-L2, using a yeast two-hybrid system. Actinin-4 was colocalized with JRAB/MICAL-L2 at cell-cell junctions and linked JRAB/MICAL-L2 to F-actin. Although actinin-4 bound to JRAB/MICAL-L2 without Rab13, the actinin-4-JRAB/MICAL-L2 interaction was enhanced by Rab13 activation. Depletion of actinin-4 by using small interfering RNA inhibited the recruitment of occludin to TJs during the Ca2+ switch. During the epithelial polarization after replating, JRAB/MICAL-L2 was recruited from the cytosol to cell-cell junctions. This JRAB/MICAL-L2 recruitment as well as the formation of functional TJs was delayed in actinin-4-depleted cells. These results indicate that actinin-4 is involved in recruiting JRAB/MICAL-L2 to cell-cell junctions and forming functional TJs.

scholarly journals Gelsolin variant (Asn-187) in familial amyloidosis, Finnish type

1990 ◽  
Vol 272 (3) ◽  
pp. 827-830 ◽  
Author(s):  
J Ghiso ◽  
M Haltia ◽  
F Prelli ◽  
J Novello ◽  
B Frangione
Keyword(s):  
Amyloid Fibrils ◽  
Corneal Dystrophy ◽  
Binding Activity ◽  
Actin Binding ◽  
Cranial Neuropathy ◽  
Protein Subunit ◽  
Plasma Gelsolin ◽  
Sequence Identity ◽  
Finnish Type ◽  
Repetitive Motif

Familial amyloidosis, Finnish type (FAF), is an inherited form of systemic amyloidosis clinically characterized by cranial neuropathy and lattice corneal dystrophy. We have demonstrated that the protein subunit isolated from amyloid fibrils shows considerable sequence identity with gelsolin, an actin-binding protein. We have purified the amyloid subunit from a second case and further analysed different fractions from the previous one. Sequence analysis shows that, in both cases, the amyloid subunit starts at position 173 of the mature molecule; it has a heterogeneous N-terminus and contains one amino acid substitution, namely asparagine for aspartic acid, at position 15 (gelsolin residue 187), that is due to a guanine-to-adenine transversion corresponding to nucleotide-654 of human plasma gelsolin cDNA. The substitution maps in a fragment with actin-binding activity and is located in a repetitive motif highly conserved among species. Thus FAF is the first human disease known to be caused by an internal abnormal degradation of a gelsolin variant. We designate this variant of gelsolin-associated amyloidosis ‘Agel Asn-187’.

scholarly journals Focal segmental glomerulosclerosis ACTN4 mutants binding to actin: regulation by phosphomimetic mutations

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hanshuang Shao ◽  
Bentley Wingert ◽  
Astrid Weins ◽  
Martin R. Pollak ◽  
Carlos Camacho ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Focal Segmental Glomerulosclerosis ◽  
Actin Filaments ◽  
Binding Activity ◽  
Binding Domain ◽  
Actin Binding ◽  
Dominant Form ◽  
Cell Functions ◽  
Segmental Glomerulosclerosis ◽  
Actin Binding Domain

Abstract Natural mutations such as lysine 255 to glutamic acid (K to E), threonine 259 to isoleucine (T to I) and serine 262 to proline (S to P) that occur within the actin binding domain of alpha-actinin-4 (ACTN4) cause an autosomal dominant form of focal segmental glomerulosclerosis (FSGS) in affected humans. This appears due to elevated actin binding propensity in podocytes resulting in a ‘frozen’ cytoskeleton. What is challenging is how this cellular behavior would be compatible with other cell functions that rely on cytoskeleton plasticity. Our previous finding revealed that wild type ACTN4 can be phosphorylated at tyrosine 4 and 31 upon stimulation by epidermal growth factor (EGF) to reduce the binding to actin cytoskeleton. We queried whether the elevated actin binding activity of FSGS mutants can be downregulated by EGF-mediated phosphorylation, to discern a mechanism by which the actin-cytoskeleton can be released in FSGS. In this manuscript, we first constructed variants with Y4/31E to mimic the phosphorylation at tyrosines 4 and 31 based on earlier modeling simulations that predicted that this would bury the actin binding domains and lead to a decrease in actin binding activity. We found that Y4/31E significantly reduced the actin binding activity of K255E, T259I and S262P, dramatically preventing them from aggregating in, and inhibiting motility of, podocytes, fibroblasts and melanoma cells. A putative kinase target site at Y265 in the actin binding domain was also generated as a phosphomimetic ACTN4 Y265E that demonstrated even greater binding to actin filaments than K255E and the other FSGS mutants. That the tyrosine kinase regulation of FSGS mutation binding to actin filaments can occur in cells was shown by phosphorylation on Y4 and Y31 of the K225E after extended exposure of cells to EGF, with a decrease in ACTN4 aggregates in fibroblasts. These findings will provide evidence for targeting the N-termini of FSGS ACTN4 mutants to downregulate their actin binding activities for ameliorating the glomerulosclerotic phenotype of patients.

scholarly journals α-Catenin-independent Recruitment of ZO-1 to Nectin-based Cell-Cell Adhesion Sites through Afadin

2001 ◽  
Vol 12 (6) ◽  
pp. 1595-1609 ◽  
Author(s):  
Shigekazu Yokoyama ◽  
Kouichi Tachibana ◽  
Hiroyuki Nakanishi ◽  
Yasunori Yamamoto ◽  
Kenji Irie ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Actin Cytoskeleton ◽  
Tight Junctions ◽  
Cell Lines ◽  
Adhesion Molecule ◽  
Binding Protein ◽  
Actin Binding ◽  
Actin Binding Protein ◽  
Adhesion Sites ◽  
Cell Cell

ZO-1 is an actin filament (F-actin)–binding protein that localizes to tight junctions and connects claudin to the actin cytoskeleton in epithelial cells. In nonepithelial cells that have no tight junctions, ZO-1 localizes to adherens junctions (AJs) and may connect cadherin to the actin cytoskeleton indirectly through β- and α-catenins as one of many F-actin–binding proteins. Nectin is an immunoglobulin-like adhesion molecule that localizes to AJs and is associated with the actin cytoskeleton through afadin, an F-actin–binding protein. Ponsin is an afadin- and vinculin-binding protein that also localizes to AJs. The nectin-afadin complex has a potency to recruit the E-cadherin–β-catenin complex through α-catenin in a manner independent of ponsin. By the use of cadherin-deficient L cell lines stably expressing various components of the cadherin-catenin and nectin-afadin systems, and α-catenin–deficient F9 cell lines, we examined here whether nectin recruits ZO-1 to nectin-based cell-cell adhesion sites. Nectin showed a potency to recruit not only α-catenin but also ZO-1 to nectin-based cell-cell adhesion sites. This recruitment of ZO-1 was dependent on afadin but independent of α-catenin and ponsin. These results indicate that ZO-1 localizes to cadherin-based AJs through interactions not only with α-catenin but also with the nectin-afadin system.

scholarly journals EPLIN regulates actin dynamics by cross-linking and stabilizing filaments

2003 ◽  
Vol 160 (3) ◽  
pp. 399-407 ◽  
Author(s):  
Raymond S. Maul ◽  
Yuhong Song ◽  
Kurt J. Amann ◽  
Sachi C. Gerbin ◽  
Thomas D. Pollard ◽  
...  
Keyword(s):  
Actin Filament ◽  
Actin Polymerization ◽  
Binding Activity ◽  
Stress Fibers ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Membrane Ruffling ◽  
Cross Links ◽  
As Stress ◽  
Kinetics Of

Epithelial protein lost in neoplasm (EPLIN) is a cytoskeleton-associated protein encoded by a gene that is down-regulated in transformed cells. EPLIN increases the number and size of actin stress fibers and inhibits membrane ruffling induced by Rac. EPLIN has at least two actin binding sites. Purified recombinant EPLIN inhibits actin filament depolymerization and cross-links filaments in bundles. EPLIN does not affect the kinetics of spontaneous actin polymerization or elongation at the barbed end, but inhibits branching nucleation of actin filaments by Arp2/3 complex. Side binding activity may stabilize filaments and account for the inhibition of nucleation mediated by Arp2/3 complex. We propose that EPLIN promotes the formation of stable actin filament structures such as stress fibers at the expense of more dynamic actin filament structures such as membrane ruffles. Reduced expression of EPLIN may contribute to the motility of invasive tumor cells.

scholarly journals Interaction between Mitochondria and the Actin Cytoskeleton in Budding Yeast Requires Two Integral Mitochondrial Outer Membrane Proteins, Mmm1p and Mdm10p

1998 ◽  
Vol 141 (6) ◽  
pp. 1371-1381 ◽  
Author(s):  
Istvan Boldogh ◽  
Nikola Vojtov ◽  
Sharon Karmon ◽  
Liza A. Pon
Keyword(s):  
Membrane Proteins ◽  
Actin Cytoskeleton ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Protein S ◽  
Binding Activity ◽  
Actin Binding ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Movement ◽  
Mitochondrial Motility

Transfer of mitochondria to daughter cells during yeast cell division is essential for viable progeny. The actin cytoskeleton is required for this process, potentially as a track to direct mitochondrial movement into the bud. Sedimentation assays reveal two different components required for mitochondria–actin interactions: (1) mitochondrial actin binding protein(s) (mABP), a peripheral mitochondrial outer membrane protein(s) with ATP-sensitive actin binding activity, and (2) a salt-inextractable, presumably integral, membrane protein(s) required for docking of mABP on the organelle. mABP activity is abolished by treatment of mitochondria with high salt. Addition of either the salt-extracted mitochondrial peripheral membrane proteins (SE), or a protein fraction with ATP-sensitive actin-binding activity isolated from SE, to salt-washed mitochondria restores this activity. mABP docking activity is saturable, resistant to high salt, and inhibited by pre-treatment of salt-washed mitochondria with papain. Two integral mitochondrial outer membrane proteins, Mmm1p (Burgess, S.M., M. Delannoy, and R.E. Jensen. 1994. J.Cell Biol. 126:1375–1391) and Mdm10p, (Sogo, L.F., and M.P. Yaffe. 1994. J.Cell Biol. 126:1361– 1373) are required for these actin–mitochondria interactions. Mitochondria isolated from an mmm1-1 temperature-sensitive mutant or from an mdm10 deletion mutant show no mABP activity and no mABP docking activity. Consistent with this, mitochondrial motility in vivo in mmm1-1 and mdm10Δ mutants appears to be actin independent. Depolymerization of F-actin using latrunculin-A results in loss of long-distance, linear movement and a fivefold decrease in the velocity of mitochondrial movement. Mitochondrial motility in mmm1-1 and mdm10Δ mutants is indistinguishable from that in latrunculin-A–treated wild-type cells. We propose that Mmm1p and Mdm10p are required for docking of mABP on the surface of yeast mitochondria and coupling the organelle to the actin cytoskeleton.

scholarly journals Actin-binding Verprolin Is a Polarity Development Protein Required for the Morphogenesis and Function of the Yeast Actin Cytoskeleton

1997 ◽  
Vol 139 (7) ◽  
pp. 1821-1833 ◽  
Author(s):  
Gabriela Vaduva ◽  
Nancy C. Martin ◽  
Anita K. Hopper
Keyword(s):  
Actin Cytoskeleton ◽  
Binding Proteins ◽  
Mitochondrial Protein ◽  
Binding Activity ◽  
Actin Binding ◽  
Live Cells ◽  
Growth Defect ◽  
Protein Distribution ◽  
Cycle Dependent ◽  
And Function

Yeast verprolin, encoded by VRP1, is implicated in cell growth, cytoskeletal organization, endocytosis and mitochondrial protein distribution and function. We show that verprolin is also required for bipolar bud-site selection. Previously we reported that additional actin suppresses the temperature-dependent growth defect caused by a mutation in VRP1. Here we show that additional actin suppresses all known defects caused by vrp1-1 and conclude that the defects relate to an abnormal cytoskeleton. Using the two-hybrid system, we show that verprolin binds actin. An actin-binding domain maps to the LKKAET hexapeptide located in the first 70 amino acids. A similar hexapeptide in other acting-binding proteins was previously shown to be necessary for actin-binding activity. The entire 70– amino acid motif is conserved in novel higher eukaryotic proteins that we predict to be actin-binding, and also in the actin-binding proteins, WASP and N-WASP. Verprolin-GFP in live cells has a cell cycle-dependent distribution similar to the actin cortical cytoskeleton. In fixed cells hemagglutinin-tagged Vrp1p often co-localizes with actin in cortical patches. However, disassembly of the actin cytoskeleton using Latrunculin-A does not alter verprolin's location, indicating that verprolin establishes and maintains its location independent of the actin cytoskeleton. Verprolin is a new member of the actin-binding protein family that serves as a polarity development protein, perhaps by anchoring actin. We speculate that the effects of verprolin upon the actin cytoskeleton might influence mitochondrial protein sorting/function via mRNA distribution.

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