Search

19 p.-9 fig., The SARS-CoV-2 Spike protein mediates docking of the virus onto cells prior to viral invasion. Several cellular receptors facilitate SARS-CoV-2 Spike docking at the cell surface, of which ACE2 plays a key role in many cell types. The intermediate filament protein vimentin has been reported to be present at the surface of certain cells and act as a co-receptor for several viruses; furthermore, its potential involvement in interactions with Spike proteins has been proposed. Nevertheless, the potential colocalization of vimentin with Spike and its receptors on the cell surface has not been explored. Here we have assessed the binding of Spike protein constructs to several cell types. Incubation of cells with tagged Spike S or Spike S1 subunit led to discrete dotted patterns at the cell surface, which consistently colocalized with endogenous ACE2, but sparsely with a lipid raft marker. Vimentin immunoreactivity mostly appeared as spots or patches unevenly distributed at the surface of diverse cell types. Of note, vimentin could also be detected in extracellular particles and in the cytoplasm underlying areas of compromised plasma membrane. Interestingly, although overall colocalization of vimentin-positive spots with ACE2 or Spike was moderate, a selective enrichment of the three proteins was detected at elongated structures, positive for acetylated tubulin and ARL13B. These structures, consistent with primary cilia, concentrated Spike binding at the top of the cells. Our results suggest that a vimentin-Spike interaction could occur at selective locations of the cell surface, including ciliated structures, which can act as platforms for SARS-CoV-2 docking., This work was supported by grants from Consejo Superior de Investigaciones Científicas, CSIC PTI Global Health (PIE 202020E223/CSIC-COV19-100), RTI2018-097624-B-I00 from Ministerio de Ciencia e Innovación, Micinn (Agencia Estatal de Investigación), Spain, and European Regional Development Fund, EDRF (. Á.V.P. and P.G.J. are the recipients of predoctoral contracts BES-2016-076965 and PRE2019-088194, respectively, from Ministerio de Ciencia e Innovación, Spain.

1 p. (Abtracts of SFRR-International 2021 Virtual Meeting), H2020 grant-675132, “Masstrplan”; RTI2018-097624-B-100 (MCINN, ERDF); RETIC-Aradyal RD16/0006/0021 (ISCIII-ERDF); MICINN BES-2016-076965 (AVP), PRE2019-088194 (PG).

16 p.-5 fig., Intermediate filaments (IFs) play key roles in cell mechanics, signaling and homeostasis. Their assembly and dynamics are finely regulated by posttranslational modifications. The type III IFs, vimentin, desmin, peripherin and glial fibrillary acidic protein (GFAP), are targets for diverse modifications by oxidants and electrophiles, for which their conserved cysteine residue emerges as a hot spot. Pathophysiological examples of these modifications include lipoxidation in cell senescence and rheumatoid arthritis, disulfide formation in cataracts and nitrosation in endothelial shear stress, although some oxidative modifications can also be detected under basal conditions. We previously proposed that cysteine residues of vimentin and GFAP act as sensors for oxidative and electrophilic stress, and as hinges influencing filament assembly. Accumulating evidence indicates that the structurally diverse cysteine modifications, either per se or in combination with other posttranslational modifications,elicit specific functional outcomes inducing distinct assemblies or network rearrangements, including filament stabilization, bundling or fragmentation. Cysteine-deficient mutants are protected from these alterations but show compromised cellular performance in network assembly and expansion, organelle positioning and aggresome formation, revealing the importance of this residue. Therefore, the high susceptibility to modification of the conserved cysteine of type III IFs and its cornerstone position in filament architecture sustains their role in redox sensing and integration of cellular responses. This has deep pathophysiological implications and supports the potential of this residue as a drug target., This work was supported by Grants from Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación (MCI, Spain) and European Regional Development Fund, RTI2018-097624-B-I00,Instituto de Salud Carlos III (Spain) RETIC AraDyal RD16/0006/0021,and CSIC PTI Global Health (PIE202020E223/CSIC-COV19-100). AV-P is supported by the FPI program from MCI, reference BES-2016-076965.