Biology subjects

Merino, A.

Publications and source records attributed to Merino, A..

4 recordsLinked to original sources

bioRxiv2026

Investigating the Role of Different Co-receptors on T-cell Activation Through IFN-γ Secretion Using Spatially Controlled Cell Monitoring Platform

Conventional methods for studying T-cell activation typically assess receptor engagement and downstream functional outputs in separate experimental formats, thereby obscuring the spatial correlation between initial receptor arrangement and localized functional outputs. This makes it difficult to examine the individual and combined effects of receptors and co-receptors engagement within the immunological synapse within the same controlled cellular microenvironment. Building upon the recently published CellStudio platform, previously validated for monitoring growth factor interactions in adherent cell models like mesenchymal stem cells and HeLa cells, we adapted this modular system to investigate non-adherent immune cells. This platform integrates Printing and Vacuum Lithography (PnVlitho) with bead-based immunoassays to generate defined activation patterns surrounded by cytokine capture antibodies, establishing a "present-and-measure" framework for localized biosensing. Jurkat T-cells were patterned on fibronectin alone or in combination with anti-CD3 and/or anti-CD4 antibodies, enabling precise engagement and activation of the co-receptors. Cell capture, basal contact morphology, and IFN-{gamma} secretion were evaluated for each condition. While CD4 engagement alone had a minimal effect, presenting anti-CD3 and anti-CD4 together caused the cells to spread into wide, circular contact zones and trigger the strongest local IFN-{gamma} signals. These findings show that first adaptation of CellStudio for suspension cells enables the standardized comparison of receptor-dependent differences in Jurkat-cell capture, contact morphology, and local cytokine-associated signals within a spatially defined assay, emerging as a powerful tool for understanding co-receptor cooperation in T-cell function and immunotherapy.

cell biology↗

bioRxiv2025

Molecular basis for cellular compartmentalization by an ancient membrane fission mechanism

The emergence of cell compartmentalization depends on membrane fission to create the endomembrane compartments. In eukaryotes, membrane fission is commonly executed by ESCRT-III, a protein complex conserved in all domains of life. However, whether membrane fission was an ancestral ESCRT-III activity predating eukaryogenesis remains unknown. Here we show that ESCRT-IIIA from Asgard Heimdallarchaeota, the closest archaeal relatives of eukaryotes, performs membrane fission through an N-terminal amphipathic helix, which we term Hofund. In eukaryotes, Hofund is fragmented across ESCRT-IIIA paralogs, and disrupting these regions causes severe fission defect in yeast. Remarkably, Heimdallarchaeota Hofund restores fission when fused to defective eukaryotic paralogs. These findings suggest that ESCRT-III-mediated fission arose before eukaryogenesis and later diversified to support the regulatory complexity of eukaryotic compartmentalization.

cell biology↗

bioRxiv2023

Mechanism for Vipp1 spiral formation, ring biogenesis and membrane repair

ESCRT-III family proteins build dynamic filaments that remodel membrane. Although the transition of planar filaments into 3D membrane budding structures is fundamental for their function, the geometric changes in polymer architecture driving the transition remain obscure. Here we show how bacterial Vipp1 polymerises into dynamic planar sheets and spirals on membrane. The spirals converge to form a central ring like those known to bud membrane. To probe how Vipp1 morphs between polymers, we determine the architecture of multiple helical filaments. As well as describing filament constriction and membrane tubulation, the geometric relationship between helical and planar lattices enables Vipp1 sheets and spirals to be modelled. Moreover, the helical structures show filaments twisting - a process needed for Vipp1 to transition between planar and 3D architectures. Given the structural conservation between Vipp1 and ESCRT-III, our results may represent the broad changes in geometry required for some ESCRT-III filaments to switch between 2D and 3D forms.

microbiology↗

bioRxiv2021

Immunolocalization studies of vimentin and ACE2 on the surface of cells exposed to SARS-CoV-2 Spike proteins

The Spike protein from SARS-CoV-2 mediates docking of the virus onto cells and contributes to viral invasion. Several cellular receptors are involved in SARS-CoV-2 Spike docking at the cell surface, including ACE2 and neuropilin. 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. Here we have explored the binding of Spike protein constructs to several cell types using low-temperature immunofluorescence approaches in live cells, to minimize internalization. Incubation of cells with tagged Spike S or Spike S1 subunit led to discrete dotted patterns at the cell surface, which showed scarce colocalization with a lipid raft marker, but consistent coincidence with ACE2. Under our conditions, vimentin immunoreactivity appeared as spots or patches unevenly distributed at the surface of diverse cell types. Remarkably, several observations including potential antibody internalization and adherence to cells of vimentin-positive structures present in the extracellular medium exposed the complexity of vimentin cell surface immunoreactivity, which requires careful assessment. Notably, overall colocalization of Spike and vimentin signals markedly varied with the cell type and the immunodetection sequence. In turn, vimentin-positive spots moderately colocalized with ACE2; however, a particular enrichment was detected at elongated structures positive for acetylated tubulin, consistent with primary cilia, which also showed Spike binding. Thus, these results suggest that vimentin-ACE2 interaction could occur at selective locations near the cell surface, including ciliated structures, which can act as platforms for SARS-CoV-2 docking.

cell biology↗