Biology subjects

Bizzarri, R.

Publications and source records attributed to Bizzarri, R..

3 recordsLinked to original sources

bioRxiv2025

The extremely low mechanical force generated by nano-pulling induces global changes in the microtubule network, nuclear morphology, and chromatin transcription in neurons

Mechanical force plays a pivotal role in every aspect of axon development. In this paper, we explore the use of nano-pulling, a technology that enables the intracellular generation of extremely low mechanical forces. We demonstrate that force-mediated axon growth also exerts global effects that extend to the nuclear level. Our mechanistic studies support a model in which exogenous forces induce stabilization of microtubules, and a significant remodeling of perinuclear microtubules, which preferentially align perpendicularly to the nuclear envelope. We observed an increase in the lateral tension of the nucleus, leading to substantial remodelling of nuclear morphology, characterized by an increase in nuclear grooves and higher sphericity index (indicating less flattened nuclei). Notably, these changes in nuclear shape are linked to chromatin remodelling, resulting in global transcriptional activation.

neuroscience↗

bioRxiv2022

Nanoscale engagement of immune checkpoint inhibitor PD-L1 in membrane lipid rafts

Programmed death ligand 1 (PD-L1) plays a key role in several human tumors, and it has recently become a crucial target for cancer therapy. Yet, its subtle regulatory roles beside the well characterized immunosuppression in PD-1/PD-L1 immune checkpoint are still obscure and should be strictly related to its molecular properties in different cell settings. In this study we targeted the plasma membrane organization of PD-L1 in a Non-Small Cell Lung Cancer (NSCLC) cell line by a multiscale fluorescence imaging toolbox that included super-resolution microscopy approaches to reach the nanoscale. Our findings revealed for the first time that PD-L1 is prevalently engaged in the cholesterol-enriched "raft" regions of the cell membrane. Clusterization and engagement in membrane rafts may afford novel targets for the immuno-oncology strategies in the framework of NSCLC and, possibly, other tumor types.

biophysics↗

bioRxiv2021

A spatial multi-scale fluorescence microscopy toolbox discloses entry checkpoints of SARS-CoV-2 variants in VeroE6 cells

We exploited a multi-scale microscopy imaging toolbox to address some major issues related to SARS-CoV-2 interactions with host cells. Our approach harnesses both conventional and super-resolution fluorescence microscopy and easily matches the spatial scale of single-virus/cell checkpoints. We deployed this toolbox to characterize subtle issues related to the entry phase of SARS-CoV-2 variants in Vero E6 cells. Our results suggest that in these cells the variant of concern B.1.1.7, (aka Alpha variant), became the predominant circulating variant in several countries by a clear transmission advantage. In fact, in these cells B.1.1.7 outcompetes its ancestor B.1.177 in terms of a much faster kinetics of entry. Given the cell-entry scenario dominated by the endosomal "late pathway", the faster internalization of B.1.1.7 could be directly related to the N501Y mutation in the S protein, which is known to strengthen the binding of Spike receptor binding domain with ACE2. Remarkably, we also directly observed the main role of clathrin as mediator of late-entry endocytosis, reconciling it with the membrane localization of the ACE2 receptor previously attributed to caveolin-enriched rafts. Overall, we believe that our fluorescence microscopy-based approach represents a fertile strategy to investigate the molecular features of SARS-CoV-2 interactions with cells.

biophysics↗