Search results for "Microfilament"
showing 9 items of 109 documents
Fertility and Polarized Cell Growth Depends on eIF5A for Translation of Polyproline-Rich Formins in Saccharomyces cerevisiae
2014
eIF5A is an essential and evolutionary conserved translation elongation factor, which has recently been proposed to be required for the translation of proteins with consecutive prolines. The binding of eIF5A to ribosomes occurs upon its activation by hypusination, a modification that requires spermidine, an essential factor for mammalian fertility that also promotes yeast mating. We show that in response to pheromone, hypusinated eIF5A is required for shmoo formation, localization of polarisome components, induction of cell fusion proteins, and actin assembly in yeast. We also show that eIF5A is required for the translation of Bni1, a proline-rich formin involved in polarized growth during …
Effects of tri-n-butyltin(IV) chloride on neurulation of Ciona intestinalis (Tunicata, Ascidiacea): an ultrastructural study
2005
This paper reports the cytotoxic effects of tri-n-butyltin (IV) chloride, TBTCl, on the neurulation process of the ascidian Ciona intestinalis. Exposure of the embryos at early neurula stage in 10−5 and 10−7M TBT (IV) chloride solutions for 1–2 h provoked the irreversible arrest of their development. Morphological and ultrastructural observations suggested that most probably there are two principal causes determining the neurulation process block. The first is due to the TBT effects of inhibiting the polymerization and/or degradation of microfilaments and microtubules, proteins that constitute the cytoskeleton. The lack of orientation and extension of both microtubules and microfilaments of…
Novel structural insights into F-actin-binding and novel functions of calponin homology domains.
2008
Tandem calponin homology (CH) domains are well-known actin filaments (F-actin) binding motifs. There has been a continuous debate about the details of CH domain-actin interaction, mainly because atomic level structures of F-actin are not available. A recent electron microscopy study has considerably advanced our structural understanding of CH domain:F-actin complex. On the contrary, it has recently also been shown that CH domains can bind other macromolecular systems: two CH domains from separate polypeptides Ncd80, Nuf2 can form a microtubule-binding site, as well as tandem CH domains in the EB1 dimer, while the single C-terminal CH domain of alpha-parvin has been observed to bind to a alp…
Imaging of Keratin Dynamics during the Cell Cycle and in Response to Phosphatase Inhibition
2004
Publisher Summary The characterization and development of autofluorescent proteins, most prominently of the green florescent protein, have provided tools to label cellular structures such that they can be examined in living cells. This chapter highlights the potential of live cell imaging in providing novel and unprecedented insights into the dynamic organization of the keratin cytoskeleton and outlines the important aspects of this method. The live cell imaging experiments suggest that the driving force behind the vectorial and dynamic keratin distribution patterns relies both on microtubules and microfilaments and their associated factors. The studies on the dynamics of the keratin cytosk…
Differential VASP phosphorylation controls remodeling of the actin cytoskeleton
2009
Proteins of the Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) family link signal transduction pathways to actin cytoskeleton dynamics. VASP is substrate of cAMP-dependent, cGMP-dependent and AMP-activated protein kinases that primarily phosphorylate the sites S157, S239 and T278, respectively. Here, we systematically analyzed functions of VASP phosphorylation patterns for actin assembly and subcellular targeting in vivo and compared the phosphorylation effects of Ena/VASP family members. Methods used were the reconstitution of VASP-null cells with `locked' phosphomimetic VASP mutants, actin polymerization of VASP mutants in vitro and in living cells, site-specific kinase-mediated…
Stabilization of Perivascular Mast Cells by Endothelial CNP (C-Type Natriuretic Peptide)
2020
Objective: Activated perivascular mast cells (MCs) participate in different cardiovascular diseases. Many factors provoking MC degranulation have been described, while physiological counterregulators are barely known. Endothelial CNP (C-type natriuretic peptide) participates in the maintenance of vascular barrier integrity, but the target cells and mechanisms are unclear. Here, we studied whether MCs are regulated by CNP. Approach and Results: In cultured human and murine MCs, CNP activated its specific GC (guanylyl cyclase)-B receptor and cyclic GMP signaling. This enhanced cyclic GMP–dependent phosphorylation of the cytoskeleton-associated VASP (vasodilator-stimulated phosphoprotein) and…
NADPH Oxidase Accounts for Enhanced Superoxide Production and Impaired Endothelium-Dependent Smooth Muscle Relaxation in BKβ1 −/− Mice
2006
Objective— Nitric oxide (NO)-induced vasorelaxation involves activation of large conductance Ca 2+ -activated K + channels (BK). A regulatory BKβ1 subunit confers Ca 2+ , voltage, and NO/cGMP sensitivity to the BK channel. We investigated whether endothelial function and NO/cGMP signaling is affected by a deletion of the β1-subunit. Methods and Results— Vascular superoxide in BKβ1 −/− was measured using the fluorescent dye hydroethidine and lucigenin-enhanced chemiluminescence. Vascular NO formation was analyzed using electron paramagnetic resonance (EPR), expression of NADPH oxidase subunits, the endothelial NO synthase (eNOS), the soluble guanylyl cyclase (sGC), as well as the activity a…
Microtubules and microfilaments in HSV-Infected rabbit-kidney cells.
1981
In rabbit kidney cells infected with strains of Herpes simplex virus producing either cell-rounding or polycaryocytosis. Vinblastine induced paracrystals. This could be shown by phase-contrast- and electron-microscopy. Infections were done under one-step-growth conditions or at low MOI. 90 per cent noninfected cells contained stress fibers as detected by Servablue R250-staining. Shortly after recruitment into polycaryocytes, stress fibres of normal length appearing in criss-cross arrangement can be seen in the periphery of these cells. Later they polymerize to very long fibers and finally they are partially destroyed. The time of destruction depends on the MOI employed. By using Actinomycin…
Conservation of the positions of metazoan introns from sponges to humans
2002
Abstract Sponges (phylum Porifera) are the phylogenetic oldest Metazoa still extant. They can be considered as reference animals (Urmetazoa) for the understanding of the evolutionary processes resulting in the creation of Metazoa in general and also for the metazoan gene organization in particular. In the marine sponge Suberites domuncula , genes encoding p38 and JNK kinases contain nine and twelve introns, respectively. Eight introns in both genes share the same positions and the identical phases. One p38 intron slipped for six bases and the JNK gene has three more introns. However, the sequences of the introns are not conserved and the introns in JNK gene are generally much longer. Intron…