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41 p.-9 fig.-1 graph. abst. ; The type III intermediate filament protein glial fibrillary acidic protein (GFAP) contributes to the homeostasis of astrocytes, where it co-polymerizes with vimentin. Conversely, alterations in GFAP assembly or degradation cause intracellular aggregates linked to astrocyte dysfunction and neurological disease. Moreover, injury and inflammation elicit extensive GFAP organization and expression changes, which underline reactive gliosis. Here we have studied GFAP as a target for modification by electrophilic inflammatory mediators. We show that the GFAP cysteine, C294, is targeted by lipoxidation by cyclopentenone prostaglandins (cyPG) in vitro and in cells. Electrophilic modification of GFAP in cells leads to a striking filament rearrangement, with retraction from the cell periphery and juxtanuclear condensation in thick bundles. Importantly, the C294S mutant is resistant to cyPG addition and filament disruption, thus highlighting the critical role of this residue as a sensor of oxidative damage. However, GFAP C294S shows defective or delayed network formation in GFAP-deficient cells, including SW13/cl.2 cells and GFAP- and vimentin-deficient primary astrocytes. Moreover, GFAP C294S does not effectively integrate with and even disrupts vimentin filaments in the short-term. Interestingly, short-spacer bifunctional cysteine crosslinking produces GFAP-vimentin heterodimers, suggesting that a certain proportion of cysteine residues from both proteins are spatially close. Collectively, these results support that the conserved cysteine residue in type III intermediate filament proteins serves as an electrophilic stress sensor and structural element. Therefore, oxidative modifications of this cysteine could contribute to GFAP disruption or aggregation in pathological situations associated with oxidative or electrophilic stress. ; This work was supported by grant SAF2015–68590-R from MINECO/FEDER, the European Union's Horizon 2020 research and innovation program under the Marie Sklowdowska-Curie grant agreement number 675132"Masstrplan", Instituto de Salud Carlos III/FEDER, RETIC Aradyal RD16/0006/0021, by Swedish Medical Research Council (11548), ALF Gothenburg (11392), Söderberg's Foundations, Hjärnfonden, Hagströmer's Foundation Millennium, and the Swedish Stroke Foundation. Álvaro Viedma is supported by the FPI Program from MINECO reference: BES-2016–076965. Interaction between MP and DPS laboratories was part of the COST Action CA15214 "EuroCellNet". ; Peer reviewed

19 p.-9 fig.-1 tab. ; The vimentin network displays remarkable plasticity to support basic cellular functions and reorganizes during cell division. Here, we show that in several cell types vimentin filaments redistribute to the cell cortex during mitosis, forming a robust framework interwoven with cortical actin and affecting its organization. Importantly, the intrinsically disordered tail domain of vimentin is essential for this redistribution, which allows normal mitotic progression. A tailless vimentin mutant forms curly bundles, which remain entangled with dividing chromosomes leading to mitotic catastrophes or asymmetric partitions. Serial deletions of vimentin tail domain gradually impair cortical association and mitosis progression. Disruption of f-actin, but not of microtubules, causes vimentin bundling near the chromosomes. Pathophysiological stimuli, including HIV-protease and lipoxidation, induce similar alterations. Interestingly, full filament formation is dispensable for cortical association, which also occurs in vimentin particles. These results unveil implications of vimentin dynamics in cell division through its interplay with the actin cortex. ; This work has been funded by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement number 675132, Masstrplan (http://cordis.europa.eu/project/rcn/198275_en.html), and by grants from the Spanish Ministerio de Economía y Competitividad (MINECO/FEDER, http://www.mineco.gob.es/portal/site/mineco/idi) SAF2015-68590R and RTI2018- 097624-B-I00, and from Instituto de Salud Carlos III/FEDER, RETIC Aradyal RD16/ 0006/0021. A.V.-P. is supported by the FPI Program from MINECO, reference: BES- 2016-076965. Feedback from the EU COST Action CA15214 EuroCellNet is gratefully acknowledged. ; Peer reviewed

25 p.-3 fig.-3 tab. ; Protein lipoxidation is a non-enzymatic post-translational modification that consists of the covalent addition of reactive lipid species to proteins. This occurs under basal conditions but increases in situations associated with oxidative stress. Protein targets for lipoxidation include metabolic and signalling enzymes, cytoskeletal proteins, and transcription factors, among others. There is strong evidence for the involvement of protein lipoxidation in disease, including atherosclerosis, neurodegeneration, and cancer. Nevertheless, the involvement of lipoxidation in cellular regulatory mechanisms is less understood. Here we review basic aspects of protein lipoxidation and discuss several features that could support its role in cell signalling, including its selectivity, reversibility, and possibilities for regulation at the levels of the generation and/or detoxification of reactive lipids. Moreover, given the great structural variety of electrophilic lipid species, protein lipoxidation can contribute to the generation of multiple structurally and functionally diverse protein species. Finally, the nature of the lipoxidised proteins and residues provides a frameshift for a complex interplay with other post-translational modifications, including redox and redox-regulated modifications, such as oxidative modifications and phosphorylation, thus strengthening the importance of detailed knowledge of this process. ; Work at DPS laboratory is supported by RTI2018-097624-B-I00 from Agencia Estatal de Investigación, MICINN/ERDF, and RETIC ARADYAL RD16/0006/0021 from ISCIII/ERDF, Spain Work at CMS laboratory (including I.C.M. and O.L.) is supported by funding from the European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement No 847419 (MemTrain). Á.V.P. and P.G.J. are the recipients of predoctoral contracts BES-2016-076965 and PRE2019-088194, respectively, from MICINN, Spain. ; Peer reviewed