PubMed Central (PMC3 - NLM DTD)
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Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).
Mostrando recursos 121 - 140 de 9,978
121.
Enhancement of Actin-depolymerizing Factor/Cofilin-dependent Actin Disassembly by Actin-interacting Protein 1 Is Required for Organized Actin Filament Assembly in the Caenorhabditis elegans Body Wall MuscleD? - Mohri, Kurato; Ono, Kanako; Yu, Robinson; Yamashiro, Sawako; Ono, Shoichiro
Regulated disassembly of actin filaments is involved in several cellular processes that require dynamic rearrangement of the actin cytoskeleton. Actin-interacting protein (AIP) 1 specifically enhances disassembly of actin-depolymerizing factor (ADF)/cofilin-bound actin filaments. In vitro, AIP1 actively disassembles filaments, caps barbed ends, and binds to the side of filaments. However, how AIP1 functions in the cellular actin cytoskeletal dynamics is not understood. We compared biochemical and in vivo activities of mutant UNC-78 proteins and found that impaired activity of mutant UNC-78 proteins to enhance disassembly of ADF/cofilin-bound actin filaments is associated with inability to regulate striated organization of actin filaments in...
122.
The Fission Yeast Transforming Acidic Coiled Coilrelated Protein Mia1p/Alp7p Is Required for Formation and Maintenance of Persistent Microtubule-organizing Centers at the Nuclear EnvelopeD?V? - Zheng, Liling; Schwartz, Cindi; Wee, Liangmeng; Oliferenko, Snezhana
Microtubule-organizing centers (MTOCs) concentrate microtubule nucleation, attachment and bundling factors and thus restrict formation of microtubule arrays in spatial and temporal manner. How MTOCs occur remains an exciting question in cell biology. Here, we show that the transforming acidic coiled coilrelated protein Mia1p/Alp7p functions in emergence of large MTOCs in interphase fission yeast cells. We found that Mia1p was a microtubule-binding protein that preferentially localized to the minus ends of microtubules and was associated with the sites of microtubule attachment to the nuclear envelope. Cells lacking Mia1p exhibited less microtubule bundles. Microtubules could be nucleated and bundled but were frequently...
123.
Neural Cell Adhesion Molecule Induces Intracellular Signaling via Multiple Mechanisms of Ca2+ Homeostasis - Kiryushko, Darya; Korshunova, Irina; Berezin, Vladimir; Bock, Elisabeth
The neural cell adhesion molecule (NCAM) plays a pivotal role in the development of the nervous system, promoting neuronal differentiation via homophilic (NCAMNCAM) as well as heterophilic (NCAM-fibroblast growth factor receptor [FGFR]) interactions. NCAM-induced intracellular signaling has been shown to affect and be dependent on the cytoplasmic Ca2+ concentration ([Ca2+]i). However, the molecular basis of this remains unclear. In this study, we determined [Ca2+]i regulating mechanisms involved in intracellular signaling induced by NCAM. To mimic the effect of homophilic NCAM interaction on [Ca2+]i in vitro, we used a peptide derived from a homophilic binding site of NCAM, termed P2, which...
124.
Function of the Neuron-specific Alternatively Spliced Isoforms of Nonmuscle Myosin II-B during Mouse Brain Development - Ma, Xuefei; Kawamoto, Sachiyo; Uribe, Jorge; Adelstein, Robert S.
We report that the alternatively spliced isoforms of nonmuscle myosin heavy chain II-B (NHMC II-B) play distinct roles during mouse brain development. The B1-inserted isoform of NMHC II-B, which contains an insert of 10 amino acids near the ATP-binding region (loop 1) of the myosin heavy chain, is involved in normal migration of facial neurons. In contrast, the B2-inserted isoform, which contains an insert of 21 amino acids near the actin-binding region (loop 2), is important for postnatal development of cerebellar Purkinje cells. Deletion of the B1 alternative exon, together with reduced expression of myosin II-B, results in abnormal migration...
125.
Compartmentalization of the Exocyst Complex in Lipid Rafts Controls Glut4 Vesicle TetheringD? - Inoue, Mayumi; Chiang, Shian-Huey; Chang, Louise; Chen, Xiao-Wei; Saltiel, Alan R.
Lipid raft microdomains act as organizing centers for signal transduction. We report here that the exocyst complex, consisting of Exo70, Sec6, and Sec8, regulates the compartmentalization of Glut4-containing vesicles at lipid raft domains in adipocytes. Exo70 is recruited by the G protein TC10 after activation by insulin and brings with it Sec6 and Sec8. Knockdowns of these proteins block insulin-stimulated glucose uptake. Moreover, their targeting to lipid rafts is required for glucose uptake and Glut4 docking at the plasma membrane. The assembly of this complex also requires the PDZ domain protein SAP97, a member of the MAGUKs family, which binds...
126.
Arl2 and Arl3 Regulate Different Microtubule-dependent ProcessesV? - Zhou, Chengjing; Cunningham, Leslie; Marcus, Adam I.; Li, Yawei; Kahn, Richard A.
Arl2 and Arl3 are closely related members of the Arf family of regulatory GTPases that arose from a common ancestor early in eukaryotic evolution yet retain extensive structural, biochemical, and functional features. The presence of Arl3 in centrosomes, mitotic spindles, midzones, midbodies, and cilia are all supportive of roles in microtubule-dependent processes. Knockdown of Arl3 by siRNA resulted in changes in cell morphology, increased acetylation of ?-tubulin, failure of cytokinesis, and increased number of binucleated cells. We conclude that Arl3 binds microtubules in a regulated manner to alter specific aspects of cytokinesis. In contrast, an excess of Arl2 activity, achieved...
127.
Protein Kinase C? Mediates Insulin-induced Glucose Transport through Actin Remodeling in L6 Muscle Cells - Liu, Li-Zhong; Zhao, Hai-Lu; Zuo, Jin; Ho, Stanley K.S.; Chan, Juliana C.N.; Meng, Yan; Fang, Fu-De; Tong, Peter C.Y.
Protein kinase C (PKC) ? has been implicated in insulin-induced glucose uptake in skeletal muscle cell, although the underlying mechanism remains unknown. In this study, we investigated the effect of PKC? on actin remodeling and glucose transport in differentiated rat L6 muscle cells expressing myc-tagged glucose transporter 4 (GLUT4). On insulin stimulation, PKC? translocated from low-density microsomes to plasma membrane accompanied by increase in GLUT4 translocation and glucose uptake. Z-scan confocal microscopy revealed a spatial colocalization of relocated PKC? with the small GTPase Rac-1, actin, and GLUT4 after insulin stimulation. The insulin-mediated colocalization, PKC? distribution, GLUT4 translocation, and glucose uptake...
128.
Specific and Nonspecific Membrane-binding Determinants Cooperate in Targeting Phosphatidylinositol Transfer Protein ?-Isoform to the Mammalian Trans-Golgi Network - Phillips, Scott E.; Ile, Kristina E.; Boukhelifa, Malika; Huijbregts, Richard P.H.; Bankaitis, Vytas A.
Phosphatidylinositol transfer proteins (PITPs) regulate the interface between lipid metabolism and specific steps in membrane trafficking through the secretory pathway in eukaryotes. Herein, we describe the cis-acting information that controls PITP? localization in mammalian cells. We demonstrate PITP? localizes predominantly to the trans-Golgi network (TGN) and that this localization is independent of the phospholipid-bound state of PITP?. Domain mapping analyses show the targeting information within PITP? consists of three short C-terminal specificity elements and a nonspecific membrane-binding element defined by a small motif consisting of adjacent tryptophan residues (the W202W203 motif). Combination of the specificity elements with the W202W203 motif...
129.
The ESCRT-III Subunit hVps24 Is Required for Degradation but Not Silencing of the Epidermal Growth Factor Receptor - Bache, Kristi G.; Stuffers, Susanne; Malerød, Lene; Slagsvold, Thomas; Raiborg, Camilla; Lechardeur, Delphine; Wälchli, Sébastien; Lukacs, Gergely L.; Brech, Andreas; Stenmark, Harald
The endosomal sorting complexes required for transport, ESCRT-I, -II, and -III, are thought to mediate the biogenesis of multivesicular endosomes (MVEs) and endosomal sorting of ubiquitinated membrane proteins. Here, we have compared the importance of the ESCRT-I subunit tumor susceptibility gene 101 (Tsg101) and the ESCRT-III subunit hVps24/CHMP3 for endosomal functions and receptor signaling. Like Tsg101, endogenous hVps24 localized mainly to late endosomes. Depletion of hVps24 by siRNA showed that this ESCRT subunit, like Tsg101, is important for degradation of the epidermal growth factor (EGF) receptor (EGFR) and for transport of the receptor from early endosomes to lysosomes. Surprisingly, however,...
130.
Nuclear RanGAP Is Required for the Heterochromatin Assembly and Is Reciprocally Regulated by Histone H3 and Clr4 Histone Methyltransferase in Schizosaccharomyces pombe - Nishijima, Hitoshi; Nakayama, Jun-ichi; Yoshioka, Tomoko; Kusano, Ayumi; Nishitani, Hideo; Shibahara, Kei-ichi; Nishimoto, Takeharu
Although the Ran GTPase-activating protein RanGAP mainly functions in the cytoplasm, several lines of evidence indicate a nuclear function of RanGAP. We found that Schizosaccharomyces pombe RanGAP, SpRna1, bound the core of histone H3 (H3) and enhanced Clr4-mediated H3-lysine 9 (K9) methylation. This enhancement was not observed for methylation of the H3-tail containing K9 and was independent of SpRna1RanGAP activity, suggesting that SpRna1 itself enhances Clr4-mediated H3-K9 methylation via H3. Although most SpRna1 is in the cytoplasm, some cofractionated with H3. Sprna1ts mutations caused decreases in Swi6 localization and H3-K9 methylation at all three heterochromatic regions of S. pombe. Thus,...
132.
A Discoidin Domain Receptor 1/SHP-2 Signaling Complex Inhibits ?2?1-Integrinmediated Signal Transducers and Activators of Transcription 1/3 Activation and Cell Migration - Wang, Chau-Zen; Su, Hsiao-Wen; Hsu, Yu-Chih; Shen, Meng-Ru; Tang, Ming-Jer
Regulation of cell migration is an important step for the development of branching tubule morphogenesis in collagen gel. Here, we showed that discoidin domain receptor (DDR) 1a/b inhibited collagen-induced tyrosine phosphorylation of signal transducers and activators of transcription (Stat) 1/3 and cell migration triggered by ?2?1-integrin. Overexpression of DDR1a/b increased the interaction of DDR1 with SHP-2 and up-regulated the tyrosine phosphatase activity of SHP-2. Expression of catalytically inactive SHP-2 in DDR1-transfected cells restored the tyrosine phosphorylation of Stat3 and cell migration. We demonstrated that the Src homology-2 (SH2)-SH2 and phosphotyrosyl phosphatase (PTP) domains of SHP-2 were responsible for interaction with...
133.
In Vivo Dynamics of Rac-Membrane Interactions - Moissoglu, Konstadinos; Slepchenko, Boris M.; Meller, Nahum; Horwitz, Alan F.; Schwartz, Martin A.
The small GTPase Rac cycles between the membrane and the cytosol as it is activated by nucleotide exchange factors (GEFs) and inactivated by GTPase-activating proteins (GAPs). Solubility in the cytosol is conferred by binding of Rac to guanine-nucleotide dissociation inhibitors (GDIs). To analyze the in vivo dynamics of Rac, we developed a photobleaching method to measure the dissociation rate constant (koff) of membrane-bound GFP-Rac. We find that koff is 0.048 s?1 for wtRac and ?10-fold less (0.004 s?1) for G12VRac. Thus, the major route for dissociation is conversion of membrane-bound GTP-Rac to GDP-Rac; however, dissociation of GTP-Rac occurs at a...
134.
Members of the NIMA-related Kinase Family Promote Disassembly of Cilia by Multiple Mechanisms - Wloga, Dorota; Camba, Amy; Rogowski, Krzysztof; Manning, Gerard; Jerka-Dziadosz, Maria; Gaertig, Jacek
The genome of Tetrahymena thermophila contains 39 loci encoding NIMA-related kinases (NRKs), an extraordinarily large number for a unicellular organism. Evolutionary analyses grouped these sequences into several subfamilies, some of which have orthologues in animals, whereas others are protist specific. When overproduced, NRKs of three subfamilies caused rapid shortening of cilia. Ultrastructural studies revealed that each NRK triggered ciliary resorption by a distinct mechanism that involved preferential depolymerization of a subset of axonemal microtubules, at either the distal or proximal end. Overexpression of a kinase-inactive variant caused lengthening of cilia, indicating that constitutive NRK-mediated resorption regulates the length of cilia....
135.
The Kinesin KIF1C and Microtubule Plus Ends Regulate Podosome Dynamics in Macrophages - Kopp, Petra; Lammers, Reiner; Aepfelbacher, Martin; Woehlke, Günther; Rudel, Thomas; Machuy, Nikolaus; Steffen, Walter; Linder, Stefan
Microtubules are important for the turnover of podosomes, dynamic, actin-rich adhesions implicated in migration and invasion of monocytic cells. The molecular basis for this functional dependency, however, remained unclear. Here, we show that contact by microtubule plus ends critically influences the cellular fate of podosomes in primary human macrophages. In particular, we identify the kinesin KIF1C, a member of the Kinesin-3 family, as a plus-endenriched motor that targets regions of podosome turnover. Expression of mutation constructs or small interfering RNA-/short hairpin RNA-based depletion of KIF1C resulted in decreased podosome dynamics and ultimately in podosome deficiency. Importantly, protein interaction studies showed...
136.
The Function and Regulation of Budding Yeast Swe1 in Response to Interrupted DNA Synthesis - Liu, Hong; Wang, Yanchang
Periodically regulated cyclin-dependent kinase (Cdk) is required for DNA synthesis and mitosis. Hydroxyurea (HU) inhibits DNA synthesis by depleting dNTPs, the basic unit for DNA synthesis. HU treatment triggers the S-phase checkpoint, which arrests cells at S-phase, inhibits late origin firing and stabilizes replication forks. Using budding yeast as a model system, we found that Swe1, a negative regulator of Cdk, appears at S-phase and accumulates in HU treatment cells. Interestingly, this accumulation is not dependent on S-phase checkpoint. ?hsl1, ?hsl7, and cdc5-2 mutants, which have defects in Swe1 degradation, show HU sensitivity because of high Swe1 protein levels. We...
137.
The rab Exchange Factor Sec2p Reversibly Associates with the Exocyst - Medkova, Martina; France, Y. Ellen; Coleman, Jeff; Novick, Peter
Activation of the rab GTPase, Sec4p, by its exchange factor, Sec2p, is needed for polarized transport of secretory vesicles to exocytic sites and for exocytosis. A small region in the C-terminal half of Sec2p regulates its localization. Loss of this region results in temperature-sensitive growth and the depolarized accumulation of secretory vesicles. Here, we show that Sec2p associates with the exocyst, an octameric effector of Sec4p involved in tethering secretory vesicles to the plasma membrane. Specifically, the exocyst subunit Sec15p directly interacts with Sec2p. This interaction normally occurs on secretory vesicles and serves to couple nucleotide exchange on Sec4p to...
138.
RINT-1 Regulates the Localization and Entry of ZW10 to the Syntaxin 18 Complex - Arasaki, Kohei; Taniguchi, May; Tani, Katsuko; Tagaya, Mitsuo
RINT-1 was first identified as a Rad50-interacting protein that participates in radiation-induced G2/M checkpoint control. We have recently reported that RINT-1, together with the dynamitin-interacting protein ZW10 and others, is associated with syntaxin 18, an endoplasmic reticulum (ER)-localized SNARE involved in membrane trafficking between the ER and Golgi. To address the role of RINT-1 in membrane trafficking, we examined the effects of overexpression and knockdown of RINT-1 on Golgi morphology and protein transport from the ER. Overexpression of the N-terminal region of RINT-1, which is responsible for the interaction with ZW10, caused redistribution of ZW10. Concomitantly, ER-to-Golgi transport was blocked...
139.
The Regulation of Microtubule Dynamics in Saccharomyces cerevisiae by Three Interacting Plus-End Tracking Proteins - Wolyniak, Michael J.; Blake-Hodek, Kristina; Kosco, Karena; Hwang, Eric; You, Liru; Huffaker, Tim C.
Microtubule plus-end tracking proteins (+TIPs) are a diverse group of molecules that regulate microtubule dynamics and interactions of microtubules with other cellular structures. Many +TIPs have affinity for each other but the functional significance of these associations is unclear. Here we investigate the physical and functional interactions among three +TIPs in S. cerevisiae, Stu2, Bik1, and Bim1. Two-hybrid, coimmunoprecipitation, and in vitro binding assays demonstrate that they associate in all pairwise combinations, although the interaction between Stu2 and Bim1 may be indirect. Three-hybrid assays indicate that these proteins compete for binding to each other. Thus, Stu2, Bik1, and Bim1 interact...
140.
Centromere Targeting of the Chromosomal Passenger Complex Requires a Ternary Subcomplex of Borealin, Survivin, and the N-Terminal Domain of INCENP - Klein, Ulf R.; Nigg, Erich A.; Gruneberg, Ulrike
The chromosomal passenger complex (CPC), consisting of the serine/threonine kinase Aurora B, the inner centromere protein INCENP, Survivin, and Borealin/DasraB, has essential functions at the centromere in ensuring correct chromosome alignment and segregation. Despite observations that small interfering RNA-mediated knockdown of any one member of the CPC abolishes localization of the other subunits, it remains unclear how the complex is targeted to the centromere. We have now identified a ternary subcomplex of the CPC comprising Survivin, Borealin, and the N-terminal 58 amino acids of INCENP in vitro and in vivo. This subcomplex was found to be essential and sufficient for...
121.
