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Cell Polarization (cell + polarization)
Selected AbstractsCytoskeleton and Early Development in Fucoid AlgaeJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2007Sherryl R. Bisgrove Abstract Cell polarization and asymmetric cell divisions play important roles during development in many multicellular eukaryotes. Fucoid algae have a long history as models for studying early developmental processes, probably because of the ease with which zygotes can be observed and manipulated in the laboratory. This review discusses cell polarization and asymmetric cell divisions in fucoid algal zygotes with an emphasis on the roles played by the cytoskeleton. [source] Connexins, cell motility, and the cytoskeletonCYTOSKELETON, Issue 11 2009Stephan Olk Abstract Connexins (Cx) comprise a family of transmembrane proteins, which form intercellular channels between plasma membranes of two adjoining cells, commonly known as gap junctions. Recent reports revealed that Cx proteins interact with diverse cellular components to form a multiprotein complex, which has been termed "Nexus". Potential interaction partners include proteins such as cytoskeletal proteins, scaffolding proteins, protein kinases and phosphatases. These interactions allow correct subcellular localization of Cxs and functional regulation of gap junction-mediated intercellular communication. Evidence is accruing that Cxs might have channel-independent functions, which potentially include regulation of cell migration, cell polarization and growth control. In the current review, we summarize recent knowledge on Cx interactions with cytoskeletal proteins and highlight some aspects of their role in cellular motility. Cell Motil. Cytoskeleton 66: 1000,1016, 2009. © 2009 Wiley-Liss, Inc. [source] A proposed mechanism for cell polarization with no external cuesCYTOSKELETON, Issue 2 2004Barbara W. Bernstein First page of article [source] Postembryonic development of the cranial lateral line canals and neuromasts in zebrafishDEVELOPMENTAL DYNAMICS, Issue 3 2003Jacqueline F. Webb Abstract The development of the cranial lateral line canals and neuromast organs are described in postembryonic zebrafish (0,80 days postfertilization). Cranial canal development commences several weeks after hatch, is initiated in the vicinity of individual neuromasts, and occurs in four discrete stages that are described histologically. Neuromasts remain in open canal grooves for several weeks during which they dramatically change shape and increase in size by adding hair cells at a rate one-tenth that in the zebrafish inner ear. Scanning electron microscopy demonstrates that neuromasts elongate perpendicular to the canal axis and the axis of hair cell polarization and that they lack a prominent nonsensory cell population surrounding the hair cells,features that make zebrafish neuromasts unusual among fishes. These results demand a reassessment of neuromast and lateral line canal diversity among fishes and highlight the utility of the lateral line system of postembryonic zebrafish for experimental and genetic studies of the development and growth of hair cell epithelia. Developmental Dynamics, 2003. © 2003 Wiley-Liss, Inc. [source] NK cells of human secondary lymphoid tissues enhance T cell polarization via IFN-, secretionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2006Barbara Morandi Abstract Human secondary lymphoid tissues harbor NK cells that predominantly secrete cytokines in response to activation. Here, we demonstrate that these immunoregulatory NK cells assist in the Th1 polarization of primary immune responses, induced by dendritic cells. Tonsilar, but not peripheral blood NK cells enhanced the expansion of IFN-,-producing CD4+ T cells via their superior ability to produce IFN-,. Addition of IFN-, increased Th1 polarization while antibody blocking of this cytokine abolished NK cell-dependent Th1 polarization. Our data suggest that NK cells in secondary lymphoid organs assist priming of Th1 cells via cytokine secretion and this effect should be harnessed during vaccination against viruses and tumors. [source] Vav1 transduces TCR signals required for LFA-1 function and cell polarization at the immunological synapseEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2003Laurence Ardouin Abstract Activation of T lineage cells through the TCR by peptide,MHC complexes on APC is critically dependent on rearrangement of the actin cytoskeleton. Vav1 is a guanine nucleotide exchange factor for members of the Rho/Rac family of GTPases which is activated following TCR stimulation, suggesting that it may transduce TCR signals to the activation of some or all actin-controlled processes. Weshow that Vav1-deficient double-positive thymocytes are less efficient at forming conjugates with APC presenting agonist peptide than wild-type cells are. Furthermore we demonstrate that Vav1 is required for TCR-induced activation of the integrin LFA-1, which is likely to explain the defect in conjugate formation. However, once Vav1-deficient cells form a conjugate, the assembly of proteins into an immunological synapse at the conjugate interface is normal. In contrast, thymocyte polarization is defective in the absence of Vav1, as judged by the relocalization of the microtubule-organizing center. These data demonstrate that Vav1 transduces signals to only a subset of cytoskeleton-dependent events at the immunological synapse. [source] The modulatory effects of lipopolysaccharide-stimulated B cells on differential T-cell polarizationIMMUNOLOGY, Issue 2 2008Hui Xu Summary Lipopolysaccharide (LPS) is a major component of environmental microbial products. Studies have defined the LPS dose as a critical determining factor in driving differential T-cell polarization but the direct effects of LPS on individual antigen-presenting cells is unknown. Here, we investigated the effects of LPS doses on naive B cells and the subsequent modulatory effects of these LPS-activated B cells on T-cell polarization. The LPS was able to induce a proliferative response starting at a dose of 100 ng/ml and was capable of enhancing antigen internalization at a dose of 1 ,g/ml in naive B cells. Following LPS stimulation, up-regulation of the surface markers CD40, CD86, I-Ad, immunoglobulin M, CD54 and interleukin-10 production, accompanied by down-regulation of CD5 and CD184 (CXCR4) were observed in a LPS dose-dependent manner. Low doses (< 10 ng/ml) of LPS-activated B cells drove T helper type 2 polarization whereas high doses (> 0·1 ,g/ml) of LPS-activated B cells resulted in T regulatory type 1 cell polarization. In conclusion, LPS-activated B cells acquire differential modulatory effects on T-cell polarization. Such modulatory effects of B cells are dependent on the stimulation with LPS in a dose-dependent manner. These observations may provide one of the mechanistic explanations for the influence of environmental microbes on the development of allergic diseases. [source] Cytoskeleton and Early Development in Fucoid AlgaeJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2007Sherryl R. Bisgrove Abstract Cell polarization and asymmetric cell divisions play important roles during development in many multicellular eukaryotes. Fucoid algae have a long history as models for studying early developmental processes, probably because of the ease with which zygotes can be observed and manipulated in the laboratory. This review discusses cell polarization and asymmetric cell divisions in fucoid algal zygotes with an emphasis on the roles played by the cytoskeleton. [source] Hepatocyte Growth Factor Receptor, c-Met, in Human Embryo Salivary Glands.ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2010An Immunohistochemical Study With 3 figures and 1 table Summary Salivary gland morphogenesis involves complex, coordinated events that include epithelial,mesenchymal interactions. Mesenchymal,epithelial transition factor (c-Met) is the hepatocyte growth factor (HGF) receptor. The latter is a hepatotropic factor originally identified in rat serum and platelets. It is essential in fetal tissue development, where it regulates complex morphogenetic processes including extracellular matrix invasion, cell migration, cell polarization and tubulogenesis. The c-Met/HGF system is believed to participate in epithelial,mesenchymal interactions during development. Twelve human embryonic minor salivary glands were studied by immunohistochemistry to investigate the role of c-Met in human salivary gland development. Strong c-Met immunopositivity in the glands demonstrated that the molecule is involved in their development and suggested a role for the c-Met/HGF system in this process. [source] GATA-3 protects against severe joint inflammation and bone erosion and reduces differentiation of Th17 cells during experimental arthritisARTHRITIS & RHEUMATISM, Issue 3 2009Jan Piet van Hamburg Objective Rheumatoid arthritis is associated with the infiltration of T helper cells into the joints. It is unclear whether interferon-, (IFN,),producing Th1 cells or the novel T helper subset, interleukin-17 (IL-17),producing Th17 cells, are the pathogenic mediators of joint inflammation in chronic nonautoimmune arthritis. Therefore, this study was aimed at examining whether the Th2-specific transcription factor GATA-3 can regulate arthritis, in an experimental murine model, by modulating Th1 and/or Th17 cell polarization. Methods Arthritis was induced with methylated bovine serum albumin (mBSA) in both wild-type and CD2 T cell,specific GATA-3 (CD2,GATA-3),transgenic mice. At days 1 and 7 after the induction of arthritis, knee joints were scored macroscopically for arthritis severity and for histologic changes. Single-cell suspensions were generated from the spleens, lymph nodes, and inflamed knee joints. Cytokine expression by CD4+ T cells was determined using flow cytometry, and IL-17 expression in the inflamed knee joints was determined by enzyme-linked immunosorbent assay. Analyses of gene expression were performed for Th17-associated factors. Results Wild-type mice developed severe joint inflammation, including massive inflammatory cell infiltration and bone erosion that increased significantly over time, reaching maximal arthritis scores at day 7. In contrast, only mild joint inflammation was observed in CD2,GATA-3,transgenic mice. This mild effect was further accompanied by systemic and local reductions in the numbers of IL-17+IFN,, and IL-17+IFN,+, but not IL-17,IFN,+, CD4+ T cells, and by induction of Th2 cytokine expression. Moreover, GATA-3 overexpression resulted in reduced gene expression of the Th17-associated transcription factor retinoic acid,related orphan receptor ,t. Conclusion These results indicate that enforced GATA-3 expression protects against severe joint inflammation and bone erosion in mice, accompanied by reduced differentiation of Th17 cells, but not Th1 cells, during mBSA-induced arthritis. [source] Electricity generation from the treatment of wastewater with a hybrid up-flow microbial fuel cellBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010Krishna P. Katuri Abstract The performance of a prototype up-flow single-chambered microbial fuel cell (MFC) for electrical power generation using brewery wastewater as fuel is reported. The designed reactor consisted of three zones, namely a lower anaerobic digestion zone, a central MFC zone, and an upper effluent clarifier zone. Tests were conducted in batch mode using a beer wastewater as the fuel/electron donor (COD concentration: 430,mg/L) and mixed consortia (both sewage microflora and anaerobic sludge) as a source of electrogenic bacteria. A stable current density of ,2,270,mA/m2 was generated under continuous polarization with a constant external resistance (0.01,k,) and cell polarization gave a peak power density of 330,mW/m2 at a current density of 1,680,mA/m2. Electrochemical impedance analysis showed that the overall internal resistance of the reactor was quite low, that is, 8.0,,. Cyclic voltammetric analysis of the anodic biofilm at low scan rate revealed quite complex processes at the anode, with three redox peaks, at potentials of 116, 214, and 319,mV (vs. NHE). Biotechnol. Bioeng. 2010;107: 52,58. © 2010 Wiley Periodicals, Inc. [source] PTEN: a promising pharmacological target to enhance epithelial wound healingBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2007M Zhao PI3Ks (phosphoinositide-3 kinases) produce PIP3 (phosphatidylinositol(3,4,5)-trisphosphate) which mediates signals for cell survival and proliferation. The tumour suppressor PTEN (phosphatase and tensin homologue) dephosphorylates PIP3 and is a key negative regulator of PI3K signalling. Recent research highlighted important roles for PI3K/PTEN in cell polarization and directional cell migration, pointing to a significant role for PTEN in wound healing where spatially organized tissue growth is essential. Lai et al. (in this issue of British Journal of Pharmacology) have moved a step closer in utilizing PTEN for wound healing through pharmacological inhibition. Two vanadium derivative inhibitors targeting PTEN significantly elevated the level of phosphorylated Akt (protein kinase B) and nearly doubled the wound healing rate in monolayer cultures of lung and airway epithelial cells. Damage to airway and lung epithelia underlies a wide spectrum of significant clinical conditions. With further experiments, this promising approach may find potential clinical use in situations where enhanced wound healing of pulmonary and other epithelia is important. British Journal of Pharmacology (2007) 152, 1141,1144; doi:10.1038/sj.bjp.0707503; published online 8 October 2007 [source] Nectins and nectin-like molecules: Roles in cell adhesion, migration, and polarizationCANCER SCIENCE, Issue 8 2003Yoshimi Takai Nectins are a family of Ca2+ -independent immunoglobulin-like cell-cell adhesion molecules consisting of four members, which homophilically and heterophilically trans-interact and cause cell-cell adhesion. Nectin-based cell-cell adhesion is involved in the formation of cadherin-based adherens junctions in epithelial cells and fibroblasts. The nectin-based cell-cell adhesion induces activation of Cdc42 and Rac small G proteins, which eventually regulate the formation of adherens junctions through reorganization of the actin cytoskeleton, gene expression through activation of a mitogen-activated protein kinase cascade, and cell polarization through cell polarity proteins. Five nectin-like molecules (necls), which have domain structures similar to those of nectins, have recently been identified and appear to play different roles from those of nectins. One of them, named necl-5, which does not homophilically trans -interact, but heterophilically trans -interacts with nectin-3, regulates cell migration and adhesion. In this article, the roles and modes of action of nectins and necls in cell adhesion, migration, and polarization are reviewed. [source] CD1a expression defines an interleukin-12 producing population of human dendritic cellsCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2009M. Cernadas Summary Human and murine dendritic cell (DC) subsets are often defined by phenotypic features that predict their functional characteristics. In humans and mice, DC have been shown to have the ability to polarize naive CD4 T cells to a T helper type 1 (Th1) or Th2 phenotype. However, human myeloid DC generated from monocytes (monocyte-derived DC) have often been regarded as a homogeneous population, both phenotypically and functionally. Monocytes give rise to subpopulations of DC in vitro that can be separated on the basis of their expression of CD1a, a well-described DC subset marker. Importantly, we show that the CD1a+ DC subset produces significant quantities of interleukin-12p70 (IL-12p70) upon stimulation and, similar to the murine CD8,+ DC subset, can polarize naive CD4+ T cells to a Th1 phenotype. In contrast, CD1a, DC, similar to murine CD8,, DC, do not produce significant amounts of IL-12p70 upon stimulation or polarize T cells to a Th1 phenotype. Like monocyte-derived DC, CD1a+ and CD1a, DC subsets obtained from CD34+ haematopoietic progenitors under distinct culture conditions were found to have these same features, suggesting that CD1a expression is a marker for myeloid DC that are a major source of IL-12 and Th1 CD4+ T cell polarization in man. [source] | |||||||||||||