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Cytoskeleton Dynamics (cytoskeleton + dynamics)
Selected AbstractsThe Drosophila nucleoporin gene nup154 is required for correct microfilament dynamics and cell death during oogenesisCYTOSKELETON, Issue 8 2007Maria Giovanna Riparbelli Abstract The Drosophila nucleoporin gene nup154 is required in both male and female germline for successful gametogenesis. Mutant flies lack differentiated sperm and lay abnormal eggs. We demonstrated that the egg phenotype was associated with specific alterations of the actin cytoskeleton at different stages of oogenesis. Actually, mutant egg chambers displayed an abnormal organization of both subcortical microfilaments and cytoplasmic actin bundles, that led to defective nurse cell dumping. TUNEL analysis also showed that the dumpless phenotype was associated with delayed apoptosis. The nup154 gene product was localized by conventional immunofluorescence microscopy to the nuclear envelope in a distinct punctuate pattern, characteristic of nuclear pore complex components. TEM analysis revealed that the protein was mainly distributed along filamentous structures that extended radially on the nuclear side of the pore, suggesting that Nup154 could be an integral component of the basket filaments associated with the nuclear pore complexes. We propose that Nup154 is necessary for correct nuclear pore complex functions and that the proper regulation of the actin cytoskeleton dynamics strongly relies upon nuclear pore integrity. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source] The expression of metastasis suppressor MIM/MTSS1 is regulated by DNA methylationINTERNATIONAL JOURNAL OF CANCER, Issue 10 2006Jochen Utikal Abstract MIM/MTSS1 was initially described as a gene missing in invasive bladder cancer cell lines. Functional analysis revealed that MIM is an actin binding protein involved in the regulation of actin cytoskeleton dynamics. MIM was shown to be sonic hedgehog (Shh) signaling dependent and synergizes with the effects of Gli transcription factors. Overexpression of MIM in cell lines leads to the inhibition of cell proliferation. In this study, we showed that the inhibition of cell growth by MIM is anchorage independent. We identified and cloned the promoter region of MIM and located the main promoter activity to 276 bp of 5, flanking sequence sited within a CpG island. Analysis of DNA methylation using bisulphite sequencing revealed that MIM promoter is methylated in its 5, region in cells and tissue samples with reduced endogenous MIM expression. Using luciferase reporter assay, we demonstrated that nonmethylated MIM promoter has a similar activity in cell lines with different endogenous MIM expression. Inhibition of DNA methylation by 5-Aza-2,-deoxycytidine led to upregulation of MIM expression in a low expressing cell line. In conclusion, we clearly demonstrate here that the expression of metastasis suppressor MIM is regulated by DNA methylation of a CpG island within its promoter region. © 2006 Wiley-Liss, Inc. [source] Cyclic GMP phosphodiesterase inhibition alters the glial inflammatory response, reduces oxidative stress and cell death and increases angiogenesis following focal brain injuryJOURNAL OF NEUROCHEMISTRY, Issue 3 2010Paula Pifarré J. Neurochem. (2010) 112, 807,817. Abstract Recent evidence obtained in cultured glial cells indicates that cGMP-mediated pathways regulate cytoskeleton dynamics, glial fibrillary acidic protein expression and motility in astrocytes, as well as inflammatory gene expression in microglia, suggesting a role in the regulation of the glial reactive phenotype. The aim of this work was to examine if cGMP regulates the glial inflammatory response in vivo following CNS damage caused by a focal cryolesion onto the cortex in rats. Results show that treatment with the cGMP phosphodiesterase inhibitor zaprinast (10 mg/kg i.p.) 2 h before and 24 and 48 h after the lesion results 3 days post-lesion in notably enhanced astrogliosis manifested by increased glial fibrillary acidic protein immunoreactivity and protein levels around the lesion. In contrast, zaprinast decreased the number of round/ameboid lectin-positive cells and the expression of the activated microglia/macrophage markers Iba-1 and CD11b indicating decreased recruitment and activation of these cells. This altered inflammatory response is accompanied by a decrease in protein oxidative stress, apoptotic cell death and neuronal degeneration. In addition, zaprinast enhanced angiogenesis in the lesioned cortex probably as a result of vascular endothelial growth factor expression in reactive astrocytes. These results suggest that regulation of the glial inflammatory response may contribute to the reported neuroprotective effects of cGMP-phosphodiesterase inhibitors in brain injury. [source] The cyclic GMP-protein kinase G pathway regulates cytoskeleton dynamics and motility in astrocytesJOURNAL OF NEUROCHEMISTRY, Issue 1 2007Mariela Susana Borán Abstract We have previously demonstrated that inflammatory compounds that increase nitric oxide (NO) synthase expression have a biphasic effect on the level of the NO messenger cGMP in astrocytes. In this work, we demonstrate that NO-dependent cGMP formation is involved in the morphological change induced by lipopolysaccharide (LPS) in cultured rat cerebellar astroglia. In agreement with this, dibutyryl-cGMP, a permeable cGMP analogue, and atrial natriuretic peptide, a ligand for particulate guanylyl cyclase, are both able to induce process elongation and branching in astrocytes resulting from a rapid, reversible and concentration-dependent redistribution of glial fibrillary acidic protein (GFAP) and actin filaments without significant change in protein levels. These effects are also observed in astrocytes co-cultured with neurons. The cytoskeleton rearrangement induced by cGMP is prevented by the specific protein kinase G inhibitor Rp-8Br-PET-cGMPS and involves downstream inhibition of RhoA GTPase since is not observed in cells transfected with constitutively active RhoA. Furthermore, dibutyryl-cGMP prevents RhoA-membrane association, a step necessary for its interaction with effectors. Stimulation of the cGMP-protein kinase G pathway also leads to increased astrocyte migration in an in vitro scratch-wound assay resulting in accelerated wound closure, as seen in reactive gliosis following brain injury. These results indicate that cGMP-mediated pathways may regulate physio-pathologically relevant responses in astroglial cells. [source] Crystallization and preliminary X-ray analysis of the EVH1 domain of Vesl-2bACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2000Melanie Barzik Proteins of the Homer/Vesl family are enriched at excitatory synapses and selectively bind to a proline-rich consensus sequence in group 1 metabotropic glutamate receptors via a domain that shows a strong similarity to the Ena/VASP homology 1 (EVH1) domains. EVH1 domains play an important role in actin cytoskeleton dynamics. Crystals of the EVH1 domain of murine Vesl-2b were obtained that diffract X-rays to 2.4,Ĺ resolution. They belong to space group C2, with unit-cell parameters a = 112.8, b = 69.9, c = 54.9,Ĺ, , = 110.7°, consistent with three molecules per asymmetric unit and a solvent content of 53%. [source] Chemotaxis of Entamoeba histolytica towards the pro-inflammatory cytokine TNF is based on PI3K signalling, cytoskeleton reorganization and the Galactose/N-acetylgalactosamine lectin activityCELLULAR MICROBIOLOGY, Issue 8 2008Samantha Blazquez Summary Entamoeba histolytica is the protozoan parasite responsible for human amoebiasis. During invasive amoebiasis, migration is an essential process and it has previously been shown that the pro-inflammatory compound tumour necrosis factor (TNF) is produced and that it has a migratory effect on E. histolytica. This paper focuses on the analysis of parasite signalling and cytoskeleton changes leading to directional motility. TNF-induced signalling was PI3K-dependent and could lead to modifications in the polarization of certain cytoskeleton-related proteins. To analyse the effect of TNF signalling on gene expression, we used microarray analysis to screen for genes encoding proteins that were potentially important during chemotaxis towards TNF. Interestingly, we found that elements of the galactose/N-acetylgalactosamine lectin (Gal/GalNAc lectin) were upregulated during chemotaxis as well as genes encoding proteins involved in cytoskeleton dynamics. The ,-actinin protein appeared to be an important candidate to link the Gal/GalNAc lectin to the cytoskeleton during chemotaxis signalling. Dominant negative parasites blocked for Gal/GalNAc lectin signalling were no longer able to chemotax towards TNF. These results have given us an insight on how E. histolytica changes its cytoskeleton dynamics during chemotaxis and revealed the capital role of PI3K and Gal/GalNAc lectin signalling in chemotaxis. 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