Biology subjects

Pezzano, F.

Publications and source records attributed to Pezzano, F..

6 recordsLinked to original sources

bioRxiv2025

De novo E-cadherin/catenin complex formation controls basal epithelial mechanics and force transmission for apoptotic cell clearance

Beyond serving as cohesive barriers, epithelia clear apoptotic cells to regulate development, homeostasis and inflammation. How epithelial cells remodel their shape during phagocytosis while preserving tissue integrity, and the role of adhesion receptors in this process, remain unclear. Using live in vivo imaging of phagocyte-target interactions in zebrafish (Danio rerio) embryos, we show that basal and apical epithelial domains are mechanically decoupled, enabling engulfment without disrupting tissue cohesion. We identify a dynamic assembly of E-cadherin/catenin complexes at the basal epithelial surface in contact with apoptotic cells. Targeted perturbations reveal two critical functions of de novo E-cadherin/catenin complex formation at the phagocytic synapse: -catenin acts as a physical linker transmitting actin-generated forces required for engulfment, while p120-catenin restrains Myosin II activity, enabling efficient clearance. We further demonstrate the conservation of E-cadherin-dependent apoptotic cell clearance in the mouse trophectoderm. These findings reveal that the E-cadherin/catenin complex is repurposed at the phagocytic synapse as a mechano-regulator of epithelial efferocytosis beyond its canonical role in tissue cohesion.

cell biology↗

bioRxiv2025

Targeting RhoA activity rejuvenates aged hematopoietic stem cells

Biomechanical alterations contribute to the decreased regenerative capacity of hematopoietic stem cells (HSCs) upon aging. RhoA is a key regulator of mechano-signaling but its role for mechanotransduction in stem cell aging has not been investigated yet. Here, we show that murine HSCs respond to increased nuclear envelope (NE) tension by inducing NE translocation of P-cPLA2, which cell intrinsically activates RhoA. Interestingly, aged HSCs experience physiologically higher intrinsic NE tension, associated with increased NE P-cPLA2 and RhoA activity. Reducing RhoA activity lowers NE tension in aged HSCs. Feature image analysis of HSC nuclei reveals that chromatin remodeling is associated to RhoA inhibition, which includes the restoration of youthful levels of the heterochromatin marker H3K9me2 and a decrease in chromatin accessibility and transcription at retrotransposons. Eventually, we demonstrate that RhoA inhibition upregulates Klf4 expression and transcriptional activity, improving aged HSCs regenerative capacity and lympho/myeloid skewing in vivo. Overall, our data support that an intrinsic mechano-signaling axis dependent on RhoA can be pharmacologically targeted to rejuvenate stem cell function upon aging.

cell biology↗

bioRxiv2023

Mitochondria-derived nuclear ATP surge protects against confinement-induced proliferation defects

The physical microenvironment regulates cell behaviour. However, whether physical confinement rewires the subcellular localisation of organelles and affect metabolism is unknown. Proteomics analysis revealed that cellular confinement induces a strong enrichment of mitochondrial proteins within the nuclear compartment. High-resolution microscopy confirmed that mechanical cell confinement leads to a rapid re-localisation of mitochondria to the nuclear periphery. This nuclear-mitochondrial proximity is mediated by an endoplasmic reticulum-based net that entraps the mitochondria in an actin-dependent manner. Functionally, the mitochondrial proximity results in a nuclear ATP surge, which can be reverted by the pharmacological inhibition of mitochondrial ATP production or via actin depolymerisation. Inhibition of the confinement-derived nuclear ATP surge reveals long-term effects on cell fitness which arise from alterations of chromatin states, delayed DNA damage repair, and impaired cell cycle progression. Together, our data describe a confinement-induced metabolic adaptation that is required to enable prompt DNA damage repair and cell cycle progression by allowing chromatin state transitions.

cell biology↗

bioRxiv2023

Adaptation to ARF6-depletion in KRAS-driven PDAC is abolished by targeting TLR2

Metastasis is responsible for nearly 90% of all cancer-related deaths. Despite global efforts to prevent aggressive tumours, cancers such as pancreatic ductal adenocarcinoma (PDAC) are poorly diagnosed in the primary stage, resulting in lethal metastatic disease. RAS mutations are known to promote tumour spread, with mutant KRAS present in up to 90% of cases. Until recently, mutant KRAS remained untargeted and, despite the recent development of inhibitors, results show that tumour cells develop resistance. Another strategy for targeting mutant KRAS-dependent PDAC proliferation and metastasis may come from targeting the downstream effectors of KRAS. One such axis, which controls tumour proliferation, invasiveness and immune evasion, is represented by ARF6-ASAP1. Here we show that targeting ARF6 results in adaptive rewiring that can restore proliferation and invasion potential over time. Using time-series RNA and ATAC sequencing approaches, we identified TLR-dependent NF{kappa}B, TNF and hypoxia signalling as key drivers of adaptation in ARF6-depleted KRAS-dependent PDAC. Using in vitro and in vivo assays, we show that knocking down TLR2 with ARF6 significantly reduces proliferation, migration and invasion. Taken together, our data shed light on a novel co-targeting strategy with the therapeutic potential to counteract PDAC proliferation and metastasis. GRAPHICAL SUMMARY O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/569405v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@192ac2org.highwire.dtl.DTLVardef@4659e5org.highwire.dtl.DTLVardef@b7e225org.highwire.dtl.DTLVardef@6019aa_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Active microrheology with a single, time-shared laser trap

Recording the mechanical response of biological samples, the cells interior and complex fluids in general, would enable deeper understanding of cellular differentiation, ageing and drug discovery. Here, we present a time-shared optical tweezer microrheology (TimSOM) pipeline to determine the frequency- and age-dependent viscoelastic properties of biological materials. Our approach consists in splitting a single laser beam into two near-instantaneous time-shared optical traps to carry out simultaneous force and displacement measurements with sub-nanometer and sub-picoNewton accuracy during sinusoidal perturbations. Leveraging numerical and analytical models, we find solutions to commonly encountered deviations, to build a practical and robust nanorheometer. We demonstrate the versatility of the technique by 1) measuring the phase transitions of an ageing biomolecular condensate, 2) quantifying the complex viscoelastic properties of three intracellular compartments of zebrafish progenitor cells, and, 3) using Caenorhabditis elegans, we uncover how mutations causing nuclear envelopathies soften the cytosol of intestinal cells during organismal age. Together, our advances afford rapid phenotyping of material properties inside cells and proteins blends, opening avenues for biomedical and drug screening applications.

biophysics↗

bioRxiv2019

The nucleus measures shape deformation for cellular proprioception and regulates adaptive morphodynamics

The physical microenvironment regulates cell behavior during tissue development and homeostasis. How single cells decode information about their geometrical shape under mechanical stress and physical space constraints within their local environment remains largely unknown. Here we show that the nucleus, the biggest cellular organelle, functions as a non-dissipative cellular shape deformation gauge that enables cells to continuously measure shape variations on the time scale of seconds. Inner nuclear membrane unfolding together with the relative spatial intracellular positioning of the nucleus provides physical information on the amplitude and type of cellular shape deformation. This adaptively activates a calcium-dependent mechano-transduction pathway, controlling the level of actomyosin contractility and migration plasticity. Our data support that the nucleus establishes a functional module for cellular proprioception that enables cells to sense shape variations for adapting cellular behaviour to their microenvironment. One Sentence SummaryThe nucleus functions as an active deformation sensor that enables cells to adapt their behavior to the tissue microenvironment.

cell biology↗