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Proper Localization (proper + localization)
Selected AbstractsA critical step for postsynaptic F-actin organization: Regulation of Baz/Par-3 localization by aPKC and PTENDEVELOPMENTAL NEUROBIOLOGY, Issue 9 2009Preethi Ramachandran Abstract Actin remodeling has emerged as a critical process during synapse development and plasticity. Thus, understanding the regulatory mechanisms controlling actin organization at synapses is exceedingly important. Here, we used the highly plastic Drosophila neuromuscular junction (NMJ) to understand mechanisms of actin remodeling at postsynaptic sites. Previous studies have suggested that the actin-binding proteins Spectrin and Coracle play a critical role in NMJ development and the anchoring of glutamate receptors most likely through actin regulation. Here, we show that an additional determinant of actin organization at the postsynaptic region is the PDZ protein Baz/Par-3. Decreasing Baz levels in postsynaptic muscles has dramatic consequences for the size of F-actin and spectrin domains at the postsynaptic region. In turn, proper localization of Baz at this site depends on both phosphorylation and dephosphorylation events. Baz phosphorylation by its binding partner, atypical protein kinase C (aPKC), is required for normal Baz targeting to the postsynaptic region. However, the retention of Baz at this site depends on its dephosphorylation mediated by the lipid and protein phosphatase PTEN. Misregulation of the phosphorylation state of Baz by genetic alterations in PTEN or aPKC activity has detrimental consequences for postsynaptic F-actin and spectrin localization, synaptic growth, and receptor localization. Our results provide a novel mechanism of postsynaptic actin regulation through Baz, governed by the antagonistic actions of aPKC and PTEN. Given the conservation of these proteins from worms to mammals, these results are likely to provide new insight into actin organization pathways. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009 [source] In vivo disruption of T cell development by expression of a dominant-negative polypeptide designed to abolish the SLP-76/Gads interactionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2007Martha Abstract Multi-molecular complexes nucleated by adaptor proteins play a central role in signal transduction. In T cells, one central axis consists of the assembly of several signaling proteins linked together by the adaptors linker of activated T cells (LAT), Src homology,2 domain-containing leukocyte-specific phosphoprotein of 76,kDa (SLP-76), and Grb2-related adaptor downstream of Shc (Gads). Each of these adaptors has been shown to be important for normal T cell development, and their proper sub-cellular localization is critical for optimal function in cell lines. We previously demonstrated in Jurkat T cells and a rat basophilic leukemic cell line that expression of a 50-amino acid polypeptide identical to the site on SLP-76 that binds to Gads blocks proper localization of SLP-76 and SLP-76-dependent signaling events. Here we extend these studies to investigate the ability of this polypeptide to inhibit TCR-induced integrin activity in Jurkat cells and to inhibit in vivo thymocyte development and primary T cell function. These data provide evidence for the in vivo function of a dominant-negative peptide based upon the biology of SLP-76 action and suggest the possibility of therapeutic potential of targeting the SLP-76/Gads interaction. [source] DPPA4 modulates chromatin structure via association with DNA and core histone H3 in mouse embryonic stem cellsGENES TO CELLS, Issue 4 2010Hisaharu Masaki Developmental pluripotency associated 4 (DPPA4) is one of the uncharacterized genes that is highly expressed in embryonic stem (ES) cells. DPPA4 is associated with active chromatin and involved in the pluripotency of mouse ES cells. However, the biological function of DPPA4 remains poorly understood. In this study, we performed fluorescence recovery after photobleaching (FRAP) analysis to examine the dynamics of DPPA4 in ES cells. FRAP analysis showed that the mobility of DPPA4 is similar to that of histone H1. In addition, biochemical analysis with purified proteins and immunoprecipitation analysis showed that DPPA4 directly binds to both DNA and core histone H3. The analysis using truncated proteins indicated that DPPA4 is associated with DNA via the N-terminal region and histone H3 via the C-terminal region. In vitro assembled chromatin showed resistance to micrococcal nuclease (MNase) digestion in the presence of DPPA4. Moreover, MNase assay and FRAP analysis with the truncated proteins implies that DPPA4 binding to both DNA and histone H3 is necessary for the chromatin structure resistant to MNase and for the proper localization of DPPA4 in ES cell nuclei. These results suggest that DPPA4 modulates the chromatin structure in association with DNA and histone H3 in ES cells. [source] Caenorhabditis elegans DYF-11, an orthologue of mammalian Traf3ip1/MIP-T3, is required for sensory cilia formationGENES TO CELLS, Issue 1 2008Hirofumi Kunitomo Cilia and flagella play critical roles in cell motility, development and sensory perception in animals. Formation and maintenance of cilia require a conserved protein transport system called intraflagellar transport (IFT). Here, we show that Caenorhabditis elegans dyf-11 encodes an evolutionarily conserved protein required for cilium biogenesis. dyf-11 is expressed in most of the ciliated neurons and is regulated by DAF-19, a crucial transcription factor for ciliary genes in C. elegans. dyf-11 mutants exhibit stunted cilia, fluorescent dye-filling defects (Dyf) of sensory neurons, and abnormal chemotaxis (Che). Cell- and stage-specific rescue experiments indicated that DYF-11 is required for formation and maintenance of sensory cilia in cell-autonomous manner. Fluorescent protein-tagged DYF-11 localizes to cilia and moves antero- and retrogradely via IFT. Analysis of DYF-11 movement in bbs mutants further suggested that DYF-11 is likely associated with IFT complex B. Domain analysis using DYF-11 deletion constructs revealed that the coiled-coil region is required for proper localization and ciliogenesis. We further show that Traf3ip1/MIP-T3, the mammalian orthologue of DYF-11, localizes to cilia in the MDCK renal epithelial cells. [source] Bir1/Cut17 moving from chromosome to spindle upon the loss of cohesion is required for condensation, spindle elongation and repairGENES TO CELLS, Issue 9 2001Jun Morishita Background In mammals, proteins containing BIR domains (IAPs and survivin) are implicated in inhibiting apoptosis and sister chromatid separation. In the nematode, Bir1 is required for a proper localization of aurora kinase, which moves from the mitotic chromosome in metaphase to the spindle midzone in anaphase as a passenger. Fission yeast Bir1/Pbh1 is essential for normal mitosis. Results A temperature sensitive mutant cut17-275 exhibits the defect in condensation and spindle elongation at 36 °C, while securin is degraded. Gene cloning shows that the cut17+ gene is identical to bir1+/pbh1+. At 26 °C, cut17-275 is UV sensitive as the repair of DNA damage is severely compromised. Bir1/Cut17 is a nuclear protein in interphase, which is then required for recruiting condensin to the mitotic nucleus, and concentrates to form a discrete number of dots from prometaphase to metaphase. Once the chromatids are separated, Bir1/Cut17 no longer binds to kinetochores and instead moves to the middle of spindle. Chromatin immunoprecipitation suggested that Bir1/Cut17 associates with the outer repetitious centromere region in metaphase. Following the initiation of anaphase the protein switches from being a chromosomal protein to a spindle protein. This transit is stringently regulated by the state of sister chromatid cohesion proteins Mis4 and Rad21. Ark1, is an aurora kinase homologue whose mitotic distribution is identical to, and under the control of Bir1/Cut17. Conclusions Bir1/Cut17 and Ark1 act as ,passengers' but they may play a main role as a recruitment factor, essential for condensation, spindle elongation and DNA repair. Bir1/Cut17 should have roles both in mitotic and in interphase chromosome. The proper location of Ark1 requires Bir1/Cut17, and the mitotic localization of Bir1/Cut17 requires sister cohesion. [source] Direct MinE,membrane interaction contributes to the proper localization of MinDE in E. coliMOLECULAR MICROBIOLOGY, Issue 2 2010Cheng-Wei Hsieh Summary Dynamic oscillation of the Min system in Escherichia coli determines the placement of the division plane at the midcell. In addition to stimulating MinD ATPase activity, we report here that MinE can directly interact with the membrane and this interaction contributes to the proper MinDE localization and dynamics. The N-terminal domain of MinE is involved in direct contact between MinE and the membranes that may subsequently be stabilized by the C-terminal domain of MinE. In an in vitro system, MinE caused liposome deformation into membrane tubules, a property similar to that previously reported for MinD. We isolated a mutant MinE containing residue substitutions in R10, K11 and K12 that was fully capable of stimulating MinD ATPase activity, but was deficient in membrane binding. Importantly, this mutant was unable to support normal MinDE localization and oscillation, suggesting that direct MinE interaction with the membrane is critical for the dynamic behavior of the Min system. [source] | ||||||||||