Homocysteine Induces Hypophosphorylation of Intermediate Filaments and Reorganization of Actin Cytoskeleton in C6 Glioma Cells

Abstract

In this study, we investigated the actions of high homocysteine (Hcy) levels (100 and 500 microM) on the cytoskeleton of C6 glioma cells. Results showed that the predominant cytoskeletal response was massive formation of actin-containing filopodia at the cell surface that could be related with Cdc42 activation and increased vinculin immunocontent. In cells treated with 100 microM Hcy, folic acid, trolox, and ascorbic acid, totally prevented filopodia formation, while filopodia induced by 500 microM Hcy were prevented by ascorbic acid and attenuated by folic acid and trolox. Moreover, competitive NMDA ionotropic antagonist DL-AP5 totally prevented the formation of filopodia in both 100 and 500 microM Hcy treated cells, while the metabotropic non-selective group I/II antagonist MCPG prevented the effect of 100 microM Hcy but only slightly attenuated the effect induced by of 500 microM Hcy on actin cytoskeleton. The competitive non-NMDA ionotropic antagonist CNQX was not able to prevent the effects of Hcy on the reorganization of actin cytoskeleton in the two concentrations used. Also, Hcy-induced hypophosphorylation of vimentin and glial fibrillary acidic protein (GFAP) and this effect was prevented by DL-AP5, MCPG, and CNQX. In conclusion, our results show that Hcy target the cytoskeleton of C6 cells probably by excitoxicity and/or oxidative stress mechanisms. Therefore, we could propose that the dynamic restructuring of the actin cytoskeleton of glial cells might contribute to the response to the injury provoked by elevated Hcy levels in brain.

NMDA Receptors and Oxidative Stress Induced by the Major Metabolites Accumulating in HMG Lyase Deficiency Mediate Hypophosphorylation of Cytoskeletal Proteins in Brain From Adolescent Rats: Potential Mechanisms Contributing to the Neuropathology of This Disease

“…** P \ 0.01, *** P \ 0.001 compared with each kinase subunit control; # P \ 0.05, ## P \ 0.01, ### P \ 0.001 compared with each kinase subunit HMG Neurotox Res an effective scavenger of peroxyl radicals, normalized the reduction of protein kinases and the phosphorylating levels of IF provoked by HMG, suggest that lipid peroxidation induced these effects. This is in accordance with the previously reported modulation of the cytoskeleton in conditions of redox imbalance in different cell types and under stress conditions (Loureiro et al 2010a(Loureiro et al , b, 2013Zamoner et al 2008a, b).…”

A poly(amidoamine) dendrimer-based drug carrier for delivering DOX to gliomas cells

“…That might be owing to the limited FRs expression on C6 cells. 4 In the competition assay, the uorescence intensity of cells incubated with G4-FA-PEG/DOX was reduced aer presaturation with free FA (62.44 for B2), illustrating that the decreased cellular uptake of G4-FA-PEG/DOX was due to the competitively binding of free FA with FRs on the C6 cell, [42][43][44] which further conrmed the targeting effect of FA to C6 cells through FRmediated endocytosis.…”

Cross-Talk among Intracellular Signaling Pathways Mediates the Diphenyl Ditelluride Actions on the Hippocampal Cytoskeleton of Young Rats

“…We have previously demonstrated that the low stoichiometry of IF phosphorylation under basal conditions increases about 30% in rat brain slices exposed to toxic levels of metabolites , or toxins. ,, Conversely, hypophosphorylation has also been observed, reflecting misregulation of the phosphorylating system in response to different signals. − In this context, different concentrations of (PhTe) 2 , from 5 to 100 μM, induced hypophosphorylation of GFAP and NF subunits mediated by activation of protein phosphatase 1 (PP1) in cerebral cortex of 9 and 15 day-old animals . Also, intracellular Ca 2+ levels were identified to be upstream of the signaling pathways targeting the cytoskeleton.…”