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Actin pip2

Alex T Ritter, Senta M Kapnick, Sricharan Murugesan, Pamela L Schwartzberg, Gillian M Griffiths, Jennifer Lippincott-Schwartz
CD8(+) cytotoxic T lymphocytes (CTLs) eliminate virally infected cells through directed secretion of specialized lytic granules. Because a single CTL can kill multiple targets, degranulation must be tightly regulated. However, how CTLs regulate the termination of granule secretion remains unclear. Previous work demonstrated that centralized actin reduction at the immune synapse precedes degranulation. Using a combination of live confocal, total internal reflection fluorescence, and superresolution microscopy, we now show that, after granule fusion, actin recovers at the synapse and no further secretion is observed...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
Maulik D Badmalia, Shikha Singh, Renu Garg, Ashish
This is the first report describing temperature based initiation of gelsolin's F-actin depolymerization activity, even in absence of free Ca(2+) or low pH. Small angle X-ray scattering (SAXS) and circular dichroism (CD) studies revealed that temperature in the range of 30-40 °C is capable of opening the G1 domain alone, as remaining domains are held together by the Ca(2+)-sensitive C-tail latch without any loss in the secondary structural content. Full opening of all domains of tail-less gelsolin, and retention of closed shape for G2-G6 gelsolin merely by heating, further substantiated our findings...
July 5, 2017: Scientific Reports
Deepa Bedi, John C Dennis, Edward E Morrison, Tim D Braden, Robert L Judd
Adiponectin is a protein secreted by white adipocytes that plays an important role in insulin action, energy homeostasis and the development of atherosclerosis. The intracellular localization and trafficking of GLUT4 and leptin in adipocytes has been well studied, but little is known regarding the intracellular trafficking of adiponectin. Recent studies have demonstrated that constitutive adiponectin secretion is dependent on PIP2 levels and the integrity of cortical F-actin. Non-muscle myosin II is an actin-based motor that is associated with membrane vesicles and participates in vesicular trafficking in mammalian cells...
August 19, 2017: Biochemical and Biophysical Research Communications
Lianwei Li, Xiaolin Chen, Shengpei Zhang, Jun Yang, Deng Chen, Muxing Liu, Haifeng Zhang, Xiaobo Zheng, Ping Wang, Youliang Peng, Zhengguang Zhang
Actin organization is a conserved cellular process that regulates the growth and development of eukaryotic cells. It also governs the virulence process of pathogenic fungi, such as the rice blast fungus Magnaporthe oryzae, with mechanisms not yet fully understood. In a previous study, we found that actin-regulating kinase MoArk1 displays conserved functions important in endocytosis and actin organization, and MoArk1 is required for maintaining the growth and full virulence of M. oryzae. To understand how MoArk1 might function, we identified capping protein homologs from M...
May 2017: PLoS Genetics
Xiaoyu Liu, Xiaoyun Liu, Dandan Chen, Xiuying Jiang, Wei Ma
Phospholipase D2 (PLD2) is involved in cytoskeletal reorganization, cell migration, cell cycle progression, transcriptional control and vesicle trafficking. There is no evidence about PLD2 function in oocytes during meiosis. Herein, we analyzed PLD2 expression and its relationship with spindle formation and positioning in mouse oocyte meiosis. High protein level of PLD2 was revealed in oocytes by Western blot, which remained consistently stable from prophase I with intact germinal vesicle (GV) up to metaphase II (MII) stage...
2017: PeerJ
Thaher Pelaseyed, Cécile Sauvanet, Raghuvir Viswanatha, Joshua J Filter, Michael L Goldberg, Anthony Bretscher
How cells specify morphologically distinct plasma membrane domains is poorly understood. Prior work has shown that restriction of microvilli to the apical aspect of epithelial cells requires the localized activation of the membrane-F-actin linking protein ezrin. Using an in vitro system, we now define a multi-step process whereby the kinase LOK specifically phosphorylates ezrin to activate it. Binding of PIP2 to ezrin induces a conformational change permitting the insertion of the LOK C-terminal domain to wedge apart the membrane and F-actin-binding domains of ezrin...
April 21, 2017: ELife
Paul-Christian Burda, Reto Caldelari, Volker T Heussler
A crucial step in the life cycle of Plasmodium parasites is the transition from the liver stage to the blood stage. Hepatocyte-derived merozoites reach the blood vessels of the liver inside host cell-derived vesicles called merosomes. The molecular basis of merosome formation is only partially understood. Here we show that Plasmodium berghei liver stage merozoites, upon rupture of the parasitophorous vacuole membrane, destabilize the host cell membrane (HCM) and induce separation of the host cell actin cytoskeleton from the HCM...
April 11, 2017: MBio
Maya Mikami, Yi Zhang, Jennifer Danielsson, Tiarra Joell, Hwan Mee Yong, Elizabeth Townsend, Seema Khurana, Steven S An, Charles W Emala
Diverse classes of ligands have recently been discovered that relax airway smooth muscle (ASM) despite a transient increase in intracellular calcium concentrations ([Ca(2+)]i). However, the cellular mechanisms are not well understood. Gelsolin is a calcium-activated actin-severing and -capping protein found in many cell types, including ASM cells. Gelsolin also binds to phosphatidylinositol 4,5-bisphosphate, making this substrate less available for phospholipase Cβ-mediated hydrolysis to inositol triphosphate and diacylglycerol...
May 2017: American Journal of Respiratory Cell and Molecular Biology
Peter M Thompson, Srinivas Ramachandran, Lindsay B Case, Caitlin E Tolbert, Arpit Tandon, Mihir Pershad, Nikolay V Dokholyan, Clare M Waterman, Sharon L Campbell
Vinculin, a scaffolding protein that localizes to focal adhesions (FAs) and adherens junctions, links the actin cytoskeleton to the adhesive super-structure. While vinculin binds to a number of cytoskeletal proteins, it can also associate with phosphatidylinositol 4,5-bisphosphate (PIP2) to drive membrane association. To generate a structural model for PIP2-dependent interaction of vinculin with the lipid bilayer, we conducted lipid-association, nuclear magnetic resonance, and computational modeling experiments...
February 7, 2017: Structure
Brian P Ziemba, G Hayden Swisher, Glenn Masson, John E Burke, Roger L Williams, Joseph J Falke
Amoeboid cells that employ chemotaxis to travel up an attractant gradient possess a signaling network assembled on the leading edge of the plasma membrane that senses the gradient and remodels the actin mesh and cell membrane to drive movement in the appropriate direction. In leukocytes such as macrophages and neutrophils, and perhaps in other amoeboid cells as well, the leading edge network includes a positive feedback loop in which the signaling of multiple pathway components is cooperatively coupled. Cytoplasmic Ca(2+) is a recently recognized component of the feedback loop at the leading edge where it stimulates phosphoinositide-3-kinase (PI3K) and the production of its product signaling lipid phosphatidylinositol 3,4,5-trisphosphate (PIP3)...
November 22, 2016: Biochemistry
Prasath Thiruketheeswaran, Hartmut Greven, Jochen D'Haese
Rearrangements of the filamentous actin network involve a broad range of actin binding proteins. Among these, the gelsolin proteins sever actin filaments, cap their fast growing end and nucleate actin assembly in a calcium-dependent manner. Here, we focus on the gelsolin of the onychophoran Peripatoides novaezealandiae and the eutardigrade Hypsibius dujardini. From the cDNA of P. novaezealandiae we obtained the complete coding sequence with an open reading frame of 2178bp. It encodes a protein of 726 amino acids with a calculated molecular mass of 82,610...
January 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
Jieli Li, Michael A Mkrtschjan, Ying-Hsi Lin, Brenda Russell
Much diseased human myocardial tissue is fibrotic and stiff, which increases the work that the ventricular myocytes must perform to maintain cardiac output. The hypothesis tested is that the increased load due to greater stiffness of the substrata drives sarcomere assembly of cells, thus strengthening them. Neonatal rat ventricular myocytes (NRVM) were cultured on polyacrylamide or polydimethylsiloxane substrates with stiffness of 10 kPa, 100 kPa, or 400 kPa, or glass with stiffness of 61.9 GPa. Cell size increased with stiffness...
June 15, 2016: Canadian Journal of Physiology and Pharmacology
Nicla Porciello, Martina Kunkl, Antonella Viola, Loretta Tuosto
Phosphatidylinositol 4,5-biphosphate kinases (PIP5Ks) are critical regulators of T cell activation being the main enzymes involved in the synthesis of phosphatidylinositol 4,5-biphosphate (PIP2). PIP2 is indeed a pivotal regulator of the actin cytoskeleton, thus controlling T cell polarization and migration, stable adhesion to antigen-presenting cells, spatial organization of the immunological synapse, and co-stimulation. Moreover, PIP2 also serves as a precursor for the second messengers inositol triphosphate, diacylglycerol, and phosphatidylinositol 3,4,5-triphosphate, which are essential for the activation of signaling pathways regulating cytokine production, cell cycle progression, survival, metabolism, and differentiation...
2016: Frontiers in Immunology
Yu-Hsiu Wang, Robert Bucki, Paul A Janmey
The lateral distribution of phosphatidylinositol 4,5-bisphosphate (PIP2) in lipid bilayers is affected both by divalent cation-mediated attractions and cholesterol-dependent phase demixing. The effects of lateral redistribution of PIP2 within a membrane on PIP2-protein interactions are explored with an N-terminal fragment of gelsolin (NtGSN) that severs actin in a Ca(2+)-insensitive manner. The extent of NtGSN inhibition by PIP2-containing large unilamellar vesicles (LUVs) depends on the lateral organization of the membrane as quantified by an actin-severing assay...
June 21, 2016: Biochemistry
Brian P Ziemba, John E Burke, Glenn Masson, Roger L Williams, Joseph J Falke
In chemotaxing ameboid cells, a complex leading-edge signaling circuit forms on the cytoplasmic leaflet of the plasma membrane and directs both actin and membrane remodeling to propel the leading edge up an attractant gradient. This leading-edge circuit includes a putative amplification module in which Ca(2+)-protein kinase C (Ca(2+)-PKC) is hypothesized to phosphorylate myristoylated alanine-rich C kinase substrate (MARCKS) and release phosphatidylinositol-4,5-bisphosphate (PIP2), thereby stimulating production of the signaling lipid phosphatidylinositol-3,4,5-trisphosphate (PIP3) by the lipid kinase phosphoinositide-3-kinase (PI3K)...
April 26, 2016: Biophysical Journal
Fernando Martínez, Guillermo Rodrigo, Verónica Aragonés, Marta Ruiz, Iris Lodewijk, Unai Fernández, Santiago F Elena, José-Antonio Daròs
BACKGROUND: The genomes of plant viruses have limited coding capacity, and to complete their infectious cycles, viral factors must target, direct or indirectly, many host elements. However, the interaction networks between viruses and host factors are poorly understood. The genus Potyvirus is the largest group of plus-strand RNA viruses infecting plants. Potyviral nuclear inclusion a (NIa) plays many roles during infection. NIa is a polyprotein consisting of two domains, viral protein genome-linked (VPg) and protease (NIaPro), separated by an inefficiently utilized self-proteolytic site...
February 1, 2016: BMC Genomics
Anna C Abbattiscianni, Maria Favia, Maria T Mancini, Rosa A Cardone, Lorenzo Guerra, Stefania Monterisi, Stefano Castellani, Onofrio Laselva, Francesca Di Sole, Massimo Conese, Manuela Zaccolo, Valeria Casavola
The most common mutation of the cystic fibrosis transmembrane regulator (CFTR) gene, F508del, produces a misfolded protein resulting in its defective trafficking to the cell surface and an impaired chloride secretion. Pharmacological treatments partially rescue F508del CFTR activity either directly by interacting with the mutant protein and/or indirectly by altering the cellular protein homeostasis. Here, we show that the phosphorylation of ezrin together with its binding to phosphatidylinositol-4,5-bisphosphate (PIP2) tethers the F508del CFTR to the actin cytoskeleton, stabilizing it on the apical membrane and rescuing the sub-membrane compartmentalization of cAMP and activated PKA...
March 15, 2016: Journal of Cell Science
Marinos Kallikourdis, Anna Elisa Trovato, Giuliana Roselli, Michela Muscolini, Nicla Porciello, Loretta Tuosto, Antonella Viola
Phosphatidylinositol 4,5-biphosphate (PIP2) is critical for T lymphocyte activation serving as a substrate for the generation of second messengers and the remodeling of actin cytoskeleton necessary for the clustering of lipid rafts, TCR, and costimulatory receptors toward the T:APC interface. Spatiotemporal analysis of PIP2 synthesis in T lymphocytes suggested that distinct isoforms of the main PIP2-generating enzyme, phosphatidylinositol 4-phosphate 5-kinase (PIP5K), play a differential role on the basis of their distinct localization...
February 15, 2016: Journal of Immunology: Official Journal of the American Association of Immunologists
Kellie R Machlus, Stephen K Wu, Deborah J Stumpo, Thomas S Soussou, David S Paul, Robert A Campbell, Hermann Kalwa, Thomas Michel, Wolfgang Bergmeier, Andrew S Weyrich, Perry J Blackshear, John H Hartwig, Joseph E Italiano
Platelets are essential for hemostasis, and thrombocytopenia is a major clinical problem. Megakaryocytes (MKs) generate platelets by extending long processes, proplatelets, into sinusoidal blood vessels. However, very little is known about what regulates proplatelet formation. To uncover which proteins were dynamically changing during this process, we compared the proteome and transcriptome of round vs proplatelet-producing MKs by 2D difference gel electrophoresis (DIGE) and polysome profiling, respectively...
March 17, 2016: Blood
Duy T Tran, Andrius Masedunskas, Roberto Weigert, Kelly G Ten Hagen
The actin cytoskeleton plays crucial roles in many cellular processes, including regulated secretion. However, the mechanisms controlling F-actin dynamics in this process are largely unknown. Through 3D time-lapse imaging in a secreting organ, we show that F-actin is actively disassembled along the apical plasma membrane at the site of secretory vesicle fusion and re-assembled directionally on vesicle membranes. Moreover, we show that fusion pore formation and PIP2 redistribution precedes actin and myosin recruitment to secretory vesicle membranes...
December 7, 2015: Nature Communications
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