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Actin pip2

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 (PIP2) making this substrate less available for phospholipase Cβ-mediated hydrolysis to inositol triphosphate (IP3) and diacylglycerol...
January 24, 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
Carsten Schulte, Gian Maria Sarra Ferraris, Amanda Oldani, Massimiliano Galluzzi, Alessandro Podestà, Luca Puricelli, Valentina de Lorenzi, Cristina Lenardi, Paolo Milani, Nicolai Sidenius
The molecular clutch (MC) model proposes that actomyosin-driven force transmission permits integrin-dependent cell migration. To investigate the MC, we introduced diverse talin (TLN) and integrin variants into Flp-In™ T-Rex™ HEK293 cells stably expressing uPAR. Vitronectin variants served as substrate providing uPAR-mediated cell adhesion and optionally integrin binding. This particular system allowed us to selectively analyse key MC proteins and interactions, effectively from the extracellular matrix substrate to intracellular f-actin, and to therewith study mechanobiological aspects of MC engagement also uncoupled from integrin/ligand binding...
January 2016: European Journal of Cell Biology
Bastian Rouven Brückner, Anna Pietuch, Stefan Nehls, Jan Rother, Andreas Janshoff
Plasma membrane tension is responsible for a variety of cellular functions such as motility, cell division, and endocytosis. Since membrane tension is dominated by the attachment of the actin cortex to the inner leaflet of the plasma membrane, we investigated the importance of ezrin, a major cross-linker of the membrane-cytoskeleton interface, for cellular mechanics of confluent MDCK II cells. For this purpose, we carried out ezrin depletion experiments and also enhanced the number of active ezrin molecules at the interface...
2015: Scientific Reports
Yanfeng Hu, Xiaofan Na, Jiaolong Li, Lijing Yang, Jia You, Xiaolei Liang, Jianfeng Wang, Liang Peng, Yurong Bi
The present study documented the action of a potential allelochemical, narciclasine, on auxin transport in Arabidopsis by mainly affecting subcellular trafficking of PIN and AUX1 proteins and through interfering actin cytoskeletal organization. Narciclasine (NCS), an Amaryllidaceae alkaloid isolated from Narcissus tazetta bulbs, has potential allelopathic activity and affects auxin transport. However, little is known about the cellular mechanism of this inhibitory effect of NCS on auxin transport. The present study characterizes the effects of NCS at the cellular level using transgenic Arabidopsis plants harboring the promoters of PIN, in combination with PIN-GFP proteins or AUX1-YFP fusions...
December 2015: Planta
Oanh Thi Tu Le, Oh Yeon Cho, Mai Hoang Tran, Jung Ah Kim, Sunghoe Chang, Ilo Jou, Sang Yoon Lee
The type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family members and their lipid product, phosphatidylinositol 4,5-bisphosphate (PIP2) are important regulators of actin cytoskeleton. PIP5Kγ 90kDa (PIP5Kγ90), an isoform of PIP5K, localizes to focal adhesions (FAs) and is activated via its interaction with the cytoskeletal protein, talin. Currently, regulatory signaling pathways of talin-PIP5Kγ90 interaction related to FA dynamics and cell motility are not well understood. Considering the presence of Akt consensus motifs in PIP5Kγ90, we examined a potential link of Akt activation to talin-PIP5Kγ90 interaction...
October 2015: Biochimica et Biophysica Acta
Abdel A Alli, Hui-Fang Bao, Bing-Chen Liu, Ling Yu, Summer Aldrugh, Darrice S Montgomery, He-Ping Ma, Douglas C Eaton
Phosphatidylinositol bisphosphate (PIP2) regulates epithelial sodium channel (ENaC) open probability. In turn, myristoylated alanine-rich C kinase substrate (MARCKS) protein or MARCKS-like protein 1 (MLP-1) at the plasma membrane regulates the delivery of PIP2 to ENaC. MARCKS and MLP-1 are regulated by changes in cytosolic calcium; increasing calcium promotes dissociation of MARCKS from the membrane, but the calcium-regulatory mechanisms are unclear. However, it is known that increased intracellular calcium can activate calmodulin and we show that inhibition of calmodulin with calmidazolium increases ENaC activity presumably by regulating MARCKS and MLP-1...
September 1, 2015: American Journal of Physiology. Renal Physiology
Bar Megnagi, Maya Finkelstein, Ortal Shabtay, Haim Breitbart
The spermatozoon is capable of fertilizing an oocyte only after undergoing several biochemical changes in the female reproductive tract, referred to as capacitation. The capacitated spermatozoon interacts with the egg zona pellucida and undergoes the acrosome reaction, which enables its penetration into the egg and fertilization. Actin dynamics play a major role throughout all these processes. Actin polymerization occurs during capacitation, whereas prior to the acrosome reaction, F-actin must undergo depolymerization...
December 2015: Cell and Tissue Research
J Weisser-Thomas, H Kempelmann, G Nickenig, C Grohe, P Djoufack, K Fink, R Meyer
Ion channels involved in cardiac excitation-contraction coupling are linked to the cytoskeleton. Therefore changes in the cytoskeletal actin filaments may influence cardiac membrane currents and electro-mechanical coupling. Depolymerization of actin filaments by gelsolin (gsn) is involved in the organisation of the cytoskeleton by leading to a lower polymerization state. Gsn is activated by Ca(2+) and inhibited by phosphoinositol-bisphosphate (PIP2). Furthermore, gsn has been linked to pathological conditions with reduced contractility like heart failure, amyloidosis and apoptosis...
June 2015: Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society
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