Novel PKCa-mediated phosphorylation site(s) on cofilin and their potential role in terminating histamine release.
AuthorsSakuma M, Shirai Y, Yoshino K, Kuramasu M, Nakamura T, Yanagita T, Mizuno K, Hide I, Nakata Y, Saito N,
JournalMol Biol Cell
PubMed ID22855535
Using specific inhibitors, kinase-negative mutants, and small interfering RNA against protein kinase Ca (PKCa) or PKCßI, we find that PKCßI positively regulates degranulation in rat basophilic leukemia-2H3 cells, whereas PKCa negatively regulates degranulation. Mass spectrometric and mutagenic analyses reveal that PKCa phosphorylates cofilin at Ser-23 and/or Ser-24 during degranulation. Overexpression ... More
Development of a fluorescent F-actin blot overlay assay for detection of F-actin binding proteins.
AuthorsHitt AL, Laing SD, Olson S
JournalAnal Biochem
PubMed ID12413475
'Interactions between cellular proteins and filamentous (F) actin are key to many cellular functions, e.g., cell motility, endocytosis, cell:cell adhesion, and cell:substrate adhesion. Previously, a functional assay using 125I-labeled F-actin to detect a subset of F-actin binding proteins by blot overlay was developed. We have modified this assay to use ... More
Antagonism between Ena/VASP Proteins and Actin Filament Capping Regulates Fibroblast Motility.
Authors Bear James E; Svitkina Tatyana M; Krause Matthias; Schafer Dorothy A; Loureiro Joseph J; Strasser Geraldine A; Maly Ivan V; Chaga Oleg Y; Cooper John A; Borisy Gary G; Gertler Frank B;
JournalCell
PubMed ID12086607
'Cell motility requires lamellipodial protrusion, a process driven by actin polymerization. Ena/VASP proteins accumulate in protruding lamellipodia and promote the rapid actin-driven motility of the pathogen Listeria. In contrast, Ena/VASP negatively regulate cell translocation. To resolve this paradox, we analyzed the function of Ena/VASP during lamellipodial protrusion. Ena/VASP-deficient lamellipodia protruded ... More
Stress release drives symmetry breaking for actin-based movement.
Authorsvan der Gucht J, Paluch E, Plastino J, Sykes C
JournalProc Natl Acad Sci U S A
PubMed ID15911773
'By using a simple assay composed of purified proteins, we studied the spontaneous polarization of actin networks polymerizing on spherical beads, which subsequently undergo movement. We show evidence that this symmetry breaking is based on the release of elastic energy, analogous to the fracture of polymer gels. The dynamics of ... More
A transcription co-factor integrates cell adhesion and motility with the p53 response.
AuthorsCoutts AS, Weston L, La Thangue NB,
JournalProc Natl Acad Sci U S A
PubMed ID19897726
Despite its obvious importance in tumorigenesis, little information is available on the mechanisms that integrate cell motility and adhesion with nuclear events. JMY is a transcription co-factor that regulates the p53 response. In addition, JMY contains a series of WH2 domains that facilitate in vitro actin nucleation. We show here ... More
Actin reorganization is required for the formation of polarized B cell receptor signalosomes in response to both soluble and membrane-associated antigens.
AuthorsLiu C, Miller H, Orlowski G, Hang H, Upadhyaya A, Song W,
JournalJ Immunol
PubMed ID22387556
B cells encounter both soluble Ag (sAg) and membrane-associated Ag (mAg) in the secondary lymphoid tissue, yet how the physical form of Ag modulates B cell activation remains unclear. This study compares actin reorganization and its role in BCR signalosome formation in mAg- and sAg-stimulated B cells. Both mAg and ... More
A balance of Bruton's tyrosine kinase and SHIP activation regulates B cell receptor cluster formation by controlling actin remodeling.
AuthorsLiu C, Miller H, Hui KL, Grooman B, Bolland S, Upadhyaya A, Song W,
JournalJ Immunol
PubMed ID21622861
The activation of the BCR, which initiates B cell activation, is triggered by Ag-induced self-aggregation and clustering of receptors at the cell surface. Although Ag-induced actin reorganization is known to be involved in BCR clustering in response to membrane-associated Ag, the underlying mechanism that links actin reorganization to BCR activation ... More
Defining mechanisms of actin polymerization and depolymerization during dendritic spine morphogenesis.
Dendritic spines are small protrusions along dendrites where the postsynaptic components of most excitatory synapses reside in the mature brain. Morphological changes in these actin-rich structures are associated with learning and memory formation. Despite the pivotal role of the actin cytoskeleton in spine morphogenesis, little is known about the mechanisms ... More
Vertical silicon nanowires as a universal platform for delivering biomolecules into living cells.
AuthorsShalek AK, Robinson JT, Karp ES, Lee JS, Ahn DR, Yoon MH, Sutton A, Jorgolli M, Gertner RS, Gujral TS, Macbeath G, Yang EG, Park H,
JournalProc Natl Acad Sci U S A
PubMed ID20080678
A generalized platform for introducing a diverse range of biomolecules into living cells in high-throughput could transform how complex cellular processes are probed and analyzed. Here, we demonstrate spatially localized, efficient, and universal delivery of biomolecules into immortalized and primary mammalian cells using surface-modified vertical silicon nanowires. The method relies ... More
Control of local actin assembly by membrane fusion-dependent compartment mixing.
AuthorsYu HY, Bement WM
JournalNat Cell Biol
PubMed ID17237773
Local actin assembly is associated with sites of exocytosis in processes ranging from phagocytosis to compensatory endocytosis. Here, we examine whether the trigger for actin-coat assembly around exocytosing Xenopus egg cortical granules is 'compartment mixing'--the union of the contents of the plasma membrane with that of the secretory granule membrane. ... More
Actin filament uncapping localizes to ruffling lamellae and rocketing vesicles.
AuthorsAllen PG
JournalNat Cell Biol
PubMed ID14557819
Regulated actin filament assembly is critical for eukaryotic cell physiology. Actin filaments are polar structures, and those with free high affinity or barbed ends are crucial for actin dynamics and cell motility. Actin filament barbed-end-capping proteins inhibit filament elongation after binding, and their regulated disassociation is proposed to provide a ... More
Two activities of cofilin, severing and accelerating directional depolymerization of actin filaments, are affected differentially by mutations around the actin-binding helix.
AuthorsMoriyama K, Yahara I
JournalEMBO J
PubMed ID10581248
The biochemical activities of cofilin are controversial. We demonstrated that porcine cofilin severs actin filaments and accelerates monomer release at the pointed ends. At pH 7.1, 0.8 microM cofilin cut filaments (2.2 microM actin) about every 290 subunits and increased the depolymerization rate 6.4-fold. A kink in the major alpha-helix ... More
Deformations in actin comets from rocketing beads.
AuthorsPaluch E, van der Gucht J, Joanny JF, Sykes C
JournalBiophys J
PubMed ID16877512
The mechanical and dynamical properties of the actin network are essential for many cellular processes like motility or division, and there is a growing body of evidence that they are also important for adhesion and trafficking. The leading edge of migrating cells is pushed out by the polymerization of actin ... More
Early Steps in Cell Infection by Parvoviruses: Host-Specific Differences in Cell Receptor Binding but Similar Endosomal Trafficking
Canine parvovirus (CPV) and feline panleukopenia virus (FPV) are closely related parvoviruses that differ in their host ranges for cats and dogs. Both viruses bind their host transferrin receptor (TfR), enter cells by clathrin-mediated endocytosis, and traffic with that receptor through endosomal pathways. Infection by these viruses appears to be ... More
Actin-dependent propulsion of endosomes and lysosomes by recruitment of N-WASP.
AuthorsTaunton J, Rowning BA, Coughlin ML, Wu M, Moon RT, Mitchison TJ, Larabell CA
JournalJ Cell Biol
PubMed ID10662777
We examined the spatial and temporal control of actin assembly in living Xenopus eggs. Within minutes of egg activation, dynamic actin-rich comet tails appeared on a subset of cytoplasmic vesicles that were enriched in protein kinase C (PKC), causing the vesicles to move through the cytoplasm. Actin comet tail formation ... More