Biology subjects

Zurzolo, C.

Publications and source records attributed to Zurzolo, C..

17 recordsLinked to original sources

bioRxiv2026

Tunneling nanotubes mediate mitochondrial homeostasis in cancer

Tumor progression is driven by cancer cells ability to establish a cellular network through tunneling nanotube-like connections (TNTs), which enable mitochondrial exchange both within the tumor cells and with the tumor microenvironment (TME). However, the effects of mitochondrial transfer between tumor and non-tumor cells, and its occurrence in vivo, remain poorly understood. In this study, we demonstrate bidirectional mitochondrial transfer: damaged mitochondria from Glioblastoma (GBM) cells trigger mitophagy in non-tumoral astrocytes (AS), while healthy mitochondria from AS enhance the metabolic activity of GBM cells. Furthermore, intravital subcellular microscopy (ISMic) in a live animal model, allowed the visualization of TNT connections with characteristics similar to those observed in vitro and supported TNT-mediated mitochondrial transfer in vivo. These findings provide critical insights into TME interactions and their contribution to cancer resilience, highlighting TNTs as a potential target for therapeutic intervention and paving the way for further research into their role in cancer.

Cancer Biology↗

bioRxiv2026

A NAPE-LRRK2 metabolic axis controls lysosomal homeostasis in Parkinson's disease

N-acylphosphatidylethanolamines (NAPEs) are atypical glycerophospholipids that accumulate in response to cellular stress, yet their roles beyond serving as precursors of fatty-acid ethanolamines (FAEs) remain largely unexplored. Here, we identify NAPEs as endogenous regulators of leucine-rich repeat kinase 2 (LRRK2), a master controller of lysosomal homeostasis and a genetic driver of Parkinsons disease. We show that increasing NAPE synthesis or blocking their hydrolysis inhibits LRRK2 kinase activity, enhances lysosomal function, and promotes the clearance of -synuclein aggregates. Conversely, cells in which NAPE hydrolysis is enhanced display increased LRRK2 activation and lysosomal dysfunction. Importantly, in induced pluripotent stem cell-derived dopaminergic neurons carrying the LRRK2-G2019S variant, pharmacological inhibition of NAPE-PLD - the enzyme that degrades NAPEs - restores lysosomal activity and favors the clearance of preformed -synuclein fibrils. Together, our findings identify NAPEs as previously unrecognized lipid regulators of LRRK2 signaling and lysosomal function, revealing a metabolic axis with therapeutic potential in Parkinsons disease. TeaserBoosting neuronal NAPEs silences LRRK2 hyperactivity and clears -synuclein: a lipid-based strategy for Parkinsons disease.

cell biology↗

bioRxiv2025

Tunneling Nanotube-like Connections in the Developing Cerebellum: Distinct from Cytokinetic and Intercellular Bridges

Intercellular communication is essential for brain development. While classical modes--paracrine, juxtacrine, and synaptic signaling--are well characterized, emerging evidence suggests that membranous bridges, such as tunneling nanotubes (TNTs), forming de novo between cells and mainly described in vitro, may also contribute. Yet their presence and function in vivo remain unclear, partly due to the difficulty of distinguishing them from other intercellular connections (ICs). Building on connectomic observations in fixed tissue reporting ICs in the external granule layer (EGL) of the developing cerebellum, we examined their nature in postnatal day 7 (P7) mice. Using immunofluorescence, sparse genetic labelling, and live imaging, we distinguished division-independent ICs from cytokinetic bridges (CBs) and intercellular bridges (IBs). CBs were detected in the EGL, whereas IBs were not observed in this region. In addition to CBs, we identified membranous protrusions which appeared to link clonally and non-clonally related cells. The presence of these ICs reinforces previous connectomic evidence in fixed tissue and raises the possibility that they may participate in intercellular communication during cerebellar development. These findings warrant further investigation into a potentially underexplored mode of communication in the developing brain.

neuroscience↗

bioRxiv2025

N-Cadherin/α-Catenin Drive Adhesion and Actin Regulation to Orchestrate Tunneling Nanotube Formation

Cell-to-cell communication is essential for maintaining homeostasis in multicellular organisms. Tunneling nanotubes (TNTs)--actin-based membranous connections--mediate the exchange of diverse cargoes between distant cells. Unlike other cellular protrusions, TNTs exhibit unique ultrastructural features and are enriched in the adhesion molecule N-Cadherin. Here, we dissect the role of N-Cadherin in the formation and function of TNTs in SH-SY5Y human neuronal-like cells. We show that N-Cadherin, via its effectors -Catenin and p120-Catenin, is a central regulator of TNT architecture and their cargo transfer capability. Regulators of cortical tension p120-Catenin, ROCK, and non-muscle myosin II also emerge as critical for TNT functionality, highlighting a mechanosensitive component to TNT regulation. Moreover, we reveal that NMIIA can be processive inside TNTs and transfer through them using actins retrograde flow. Finally, we identify the Cdc42-IRSp53-N-WASP pathway as a downstream effector axis enhancing intercellular transfer downstream of N-Cadherin. Together, our findings uncover a structural and functional link between N-Cadherin signaling and TNT-mediated intercellular communication.

cell biology↗

bioRxiv2025

α-Synuclein aggregates induce mitochondrial damage and trigger innate immunity to drive neuron-microglia communication

Tunneling nanotubes (TNTs) enable direct intercellular transfer of macromolecules, organelles, and pathogenic protein aggregates. While -synuclein (-Syn) aggregates are known to promote TNT formation, the underlying mechanisms remain poorly defined. Here, using human neuronal and microglial cell lines, as well as iPSC-derived dopaminergic neurons and microglia, we show that -Syn aggregates induce severe mitochondrial damage, leading to cytosolic release of mitochondrial DNA (mtDNA) and activation of the cGAS-STING-NF- {kappa}B-IRF3 pathway. This innate immune response drives actin cytoskeleton remodeling and the formation of TNT-like structures, promoting intercellular transfer of -Syn from neurons to microglia. Additionally, neuronal cells transfer damaged mitochondria to microglia, where they undergo lysosome-mediated degradation. Neuron-to-microglia communication under -Syn- induced stress also triggers a bystander inflammatory response in microglia, suggesting a neuroimmune activation. Our findings identify mitochondrial damage and STING-mediated inflammation as key drivers of TNT formation and -Syn propagation, highlighting new potential targets to modulate disease progression in Synucleinopathies.

cell biology↗

bioRxiv2024

Proteostasis dysregulation in p.A53T-α-Synuclein iPSC-derived astrocytes exacerbates neurodegeneration in a Parkinson's disease model with Lewy-like pathology

Alpha-Synuclein (Syn) plays a central role in Parkinsons disease (PD) and the p.A53T mutation causes an early-onset familial form of PD with severe manifestations. The pathological effects of the p.A53T-Syn mutation have been extensively investigated in neurons, yet the consequences on astrocytes and astrocytic contribution to PD pathology are understudied. Here, we differentiated induced pluripotent stem cells from PD patients carrying the p.A53T-Syn mutation to astrocytes, which uncovered cell-intrinsic phenotypes, including calcium dyshomeostasis and accumulation of protein aggregates. Proteomic profiling and functional analyses revealed perturbed protein catabolic processes, involving the proteasome and autophagy, associated with lysosomal malfunction. Dopamine neurons co-cultured with p.A53T-Syn astrocytes displayed exacerbated neurodegeneration with hallmark Lewy-like pathologies, reversed by control astrocytes at least due to their ability to resolve neuronal Syn aggregates by endocytic clearance. Our findings underscore a critical impact of p.A53T-Syn on astrocytic protein quality control mechanisms, positioning astrocytes as important contributors to PD neuropathology. HighlightsO_LIiPSC-derived astrocytes from PD patients with the p.A53T-Syn mutation display cell-autonomous pathological phenotypes and toxic Syn accumulation C_LIO_LIProteome and functional analyses reveal failure of major proteostasis mechanisms in p.A53T-Syn astrocytes, largely related to lysosomal malfunction C_LIO_LIInherent Lewy-like pathological features are identified in p.A53T-Syn astrocyte-neuron co-cultures C_LIO_LIp.A53T-Syn astrocytes induce PD-relevant neuropathology to healthy neurons C_LIO_LIControl but not p.A53T-Syn astrocytes alleviate neuropathology in co-cultured neurons C_LI

neuroscience↗

bioRxiv2024

Differential alpha-Synuclein-induced Autophagy Dysfunction in Neuronal and Microglial Cells drives Tunneling Nanotubes and Aggregate Spread to Microglia

Tunneling nanotubes (TNTs) play a crucial role in intercellular communication, enabling a dynamic network for the transfer of molecular cargo over long distances between connected cells. Previous studies have demonstrated efficient, directional transfer of -Synuclein (-Syn) aggregates from neurons to microglia, with endosomal trafficking and lysosomal processing identified as the primary events following -Syn internalization. Using human neuronal and microglial cell lines, we found that microglia exhibit higher lysosomal turnover, particularly through lysophagy, whereas neuronal lysosomes display compromised degradative capacity and impaired autophagic flux. This deficiency results in less efficient degradation of aggregates in neurons. Moreover, perturbation of autophagy enhances TNT-mediated transfer of aggregate from neuronal cells to microglia. In contrast, microglia co-cultured with -Syn-containing neurons upregulate autophagy flux, enabling efficient degradation of the transferred aggregates. These findings were further validated using human induced pluripotent stem cells (hiPSC)-derived neurons and microglia. Overall, our study highlights the distinct responses of neurons and microglia to -Syn aggregates and identifies dysfunctional autophagy in neurons as a key driver of the preferential and directional transfer of aggregates to microglia.

cell biology↗

bioRxiv2023

Tunneling nanotubes enable intercellular transfer in zebrafish embryos

Tunneling nanotubes (TNTs) are thin intercellular connections facilitating the transport of diverse cargoes, ranging from ions to organelles. While TNT studies have predominantly been conducted in cell cultures, the existence of open-ended TNTs within live organisms remains unverified. Despite the observation of intercellular connections during embryonic development across various species, their functional role has not been confirmed. In this study, we performed mosaic labeling of gastrula cells in zebrafish embryos to demonstrate the coexistence of TNT-like structures alongside other cellular protrusions. These embryonic TNT-like connections exhibited similar morphology to TNTs described in cell culture, appeared to have similar formation mechanisms and could be induced by Eps8 overexpression and CK666 treatment. Most notably, to classify them as TNTs, we demonstrated their capability to transfer both soluble cargoes and organelles, which is a defining feature of open-ended TNTs. This study marks the first demonstration of functional TNTs in a living embryo.

cell biology↗

bioRxiv2023

CellWalker: A user-friendly and modular computational pipeline for morphological analysis of microscopy images

The implementation of computational tools for analysis of microscopy images has been one of the most important technological innovations in biology, providing researchers unmatched capabilities to comprehend cell shape and connectivity. Most available tools frequently focus either on segmentation or morphological analysis, thus not providing an inclusive pipeline. We introduce CellWalker, a computational pipeline that streamlines and connects the segmentation step with the morphological analysis in a modular manner. This python-based pipeline starts with visible-source IPython notebooks for segmentation of 2D/3D microscopy images using deep learning and visualization of the segmented images. The next module of CellWalker runs inside Blender, an open-source computer graphics software. This addon provides several morphometric analysis tools that can be used to calculate distances, volume, surface areas and to determine cross-sectional properties. It also includes tools to build skeletons, calculate distributions of sub-cellular organelles. Overall, CellWalker provides practical tools for segmentation and morphological analysis of microscopy images in the form of an open-source and modular pipeline which allows a complete access to fine-tuning of algorithms through visible source code while still retaining a result-oriented interface. Contactharshkhare@gmail.com, chiara.zurzolo@pasteur.fr Availability and implementationCellWalker source code is available on GitHub (https://github.com/utraf-pasteur-institute/CellWalker-notebooks and https://github.com/utraf-pasteur-institute/CellWalker-blender) under a GPL-3 license.

bioinformatics↗

bioRxiv2023

N-Cadherin and alpha-catenin regulate formation of functional tunneling nanotubes

Cell-to-cell communication it is a fundamental mechanism by which unicellular and multicellular organisms maintain relevant functions as development or homeostasis. Tunneling nanotubes (TNTs) are a type of contact-mediated cell-to-cell communication defined by being membranous structures based on actin that allow the exchange of different cellular material. TNTs have been shown to have unique structural features compared with other cellular protrusions and to contain the cell adhesion molecule N-Cadherin. Here, we investigated the possible role of N-Cadherin and of its primary linker to the actin cytoskeleton, -Catenin in regulating the formation and transfer function of TNTs. Our data indicate that N-Cadherin through its downstream effector -Catenin is a major regulator of TNT formation, ultrastructure, as well as of their ability to transfer material to other cells.

cell biology↗

bioRxiv2022

Proteomic landscape of tunneling nanotubes reveals CD9 and CD81 tetraspanins as key regulators

Tunneling nanotubes (TNTs) are open actin- and membrane-based channels, connecting remote cells and allowing direct transfer of cellular material (e.g. vesicles, mRNAs, protein aggregates) from cytoplasm to cytoplasm. Although they are important especially in pathological conditions (e.g., cancers, neurodegenerative diseases), their precise composition and their regulation were still poorly described. Here, using a biochemical approach allowing to separate TNTs from cell bodies and from extracellular vesicles and particles (EVPs), we obtained the full composition of TNTs compared to EVPs. We then focused to two major components of our proteomic data, the CD9 and CD81 tetraspanins, and further investigated their specific roles in TNT formation and function. We show that these two tetraspanins have distinct non-redundant functions: CD9 participates in stabilizing TNTs, whereas CD81 expression is required to allow the functional transfer of vesicle in the newly formed TNTs, possibly by regulating docking to or fusion with the opposing cell.

cell biology↗

bioRxiv2022

Tunneling nanotubes between neuronal and microglial cells allow bi-directional transfer of α-Synuclein and mitochondria

Tunneling Nanotubes (TNTs) facilitate contact-mediated intercellular communication over long distances. Material transfer via TNTs can range from ions and intracellular organelles to protein aggregates and pathogens. Prion-like toxic protein aggregates accumulating in several disorders, such as Alzheimers, Parkinsons, and Huntingtons diseases have been shown to spread via TNTs not only between neurons, but also between neurons-astrocytes, and neurons-pericytes, indicating the importance of TNTs in mediating neuron-glia interactions. TNT-like structures were also reported between microglia, however their roles in neuron-microglia interaction remain elusive. In this work, we quantitatively characterise microglial TNTs and their cytoskeletal composition, and demonstrate that TNTs form between human neuronal and microglial cells. We show that -Synuclein (-Syn) aggregates increase the global TNT-mediated connectivity between cells, along with the number of TNT connections per cell pair. Homotypic TNTs formed between microglial cells, and heterotypic TNTs between neuronal and microglial cells are furthermore shown to be functional, allowing movement of both -Syn and mitochondria. Quantitative analysis shows that -Syn aggregates are transferred predominantly from neuronal to microglial cells, possibly as a mechanism to relieve the burden of accumulated aggregates. By contrast, microglia transfer mitochondria preferably to -Syn burdened neuronal cells over the healthy ones, likely as a potential rescue mechanism. Besides describing novel TNT-mediated communication between neurons and microglia, this work allows us to better understand the cellular mechanisms of spreading of neurodegenerative diseases, shedding light on the role of microglia.

cell biology↗

bioRxiv2022

Arp2/3 inhibition switches Eps8's network associations to favour longer actin filament formation necessary for tunneling nanotubes

Tunneling nanotubes (TNTs) connect distant cells and mediate cargo transfer for intercellular communication in physiological and pathological contexts. How cells generate these actin-mediated protrusions to span lengths beyond those attainable by canonical filopodia remains unknown. Through a combination of micropatterning, microscopy and optical tweezer-based approaches, we demonstrate that TNTs forming through the outward extension of actin (not through cellular dislodgement) achieve distances greater than the mean length of filopodia, and that branched Arp2/3-dependent pathways attenuate the extent to which actin polymerizes in nanotubes, limiting TNT occurrence. Proteomic analysis using Epidermal growth factor receptor kinase substrate 8 (Eps8) as a positive effector of TNTs showed that upon Arp2/3 inhibition, proteins enhancing filament turnover and depolymerization were reduced and Eps8 instead exhibited heightened interactions with the inverted Bin/Amphiphysin/Rvs (I-BAR) domain protein IRSp53 that provides a direct connection with linear actin polymerases. Our data reveals how common protrusion players (Eps8 and IRSp53) form TNTs, and that when competing pathways overutilizing such proteins and monomeric actin in Arp2/3 networks are inhibited, processes promoting linear actin growth dominate to favour TNT formation. Thus, this work reinforces a general principle for actin network control for cellular protrusions where simple shifts in the balance between processes that inhibit actin growth versus those that promote growth dictate protrusion formation and the ultimate length scales protrusions achieve.

cell biology↗

bioRxiv2022

3D reconstruction of the cerebellar germinal layer reveals intercytoplasmic connections between developing granule cells

SummaryThe difficulty of retrieving high-resolution, in vivo evidence of the proliferative- and migratory processes occurring in neural germinal zones has limited our understanding of neurodevelopmental mechanisms. Here, we employed a connectomic approach using a high-resolution, serial-sectioning scanning electron microscopy volume to investigate the laminar cytoarchitecture of the transient external granular layer (EGL) of the developing cerebellum, where granule cells coordinate a series of mitotic and migratory events. By integrating image segmentation, 3D reconstruction, and deep learning approaches, we discovered and characterized anatomically complex intercellular connections bridging pairs of cerebellar granule cells throughout the EGL. Connected cells were either mitotic, migratory, or transitioning between these two cell stages, displaying a chronological continuum of proliferative and migratory events never previously observed in vivo at this resolution. This unprecedented ultra-structural characterization poses intriguing hypotheses about intercellular connectivity between developing progenitors, and its possible role in the development of the central nervous system (CNS).

neuroscience↗

bioRxiv2021

Tunneling nanotubes provide a novel route for SARS-CoV-2 spreading between permissive cells and to non-permissive neuronal cells.

SARS-CoV-2 entry into host cells is mediated by the binding of its spike glycoprotein to the angiotensin-converting enzyme 2 (ACE2) receptor, highly expressed in several organs, but very low in the brain. The mechanism through which SARS-CoV-2 infects neurons is not understood. Tunneling nanotubes (TNTs), actin-based intercellular conduits that connect distant cells, allow the transfer of cargos, including viruses. Here, we explored the neuroinvasive potential of SARS-CoV-2 and whether TNTs are involved in its spreading between cells in vitro. We report that neuronal cells, not permissive to SARS-CoV-2 through an exocytosis/endocytosis dependent pathway, can be infected when co-cultured with permissive infected epithelial cells. SARS-CoV-2 induces TNTs formation between permissive cells and exploits this route to spread to uninfected permissive cells in co-culture. Correlative Cryo-electron tomography reveals that SARS-CoV-2 is associated with the plasma membrane of TNTs formed between permissive cells and virus-like vesicular structures are inside TNTs established both between permissive cells and between permissive and non-permissive cells. Our data highlight a potential novel mechanism of SARS-CoV-2 spreading which could serve as route to invade non-permissive cells and potentiate infection in permissive cells.

cell biology↗

bioRxiv2020

A new form of actin assembly around the Shigella-containing vacuole regulates its intracellular niche

The enteroinvasive bacterium Shigella flexneri forces its uptake into non-phagocytic host cells through the translocation of T3SS effectors that subvert the actin cytoskeleton. Here, we report de novo actin polymerization after cellular entry around the bacterial containing vacuole (BCV) leading to the formation of a dynamic actin cocoon. This cocoon is thicker than any described cellular actin structure and functions as a gatekeeper for the cytosolic access of the pathogen. Host Cdc42, Toca-1, N-WASP, WIP, the Arp2/3 complex, cortactin, coronin, and cofilin are recruited to the actin cocoon. They are subverted by T3SS effectors, such as IpgD, IpgB1, and IcsB. IcsB immobilizes components of the actin polymerization machinery at the BCV. This represents a novel microbial subversion strategy through localized entrapment of host actin regulators causing massive actin assembly. We propose that the cocoon protects Shigellas niche from canonical maturation or host recognition.

cell biology↗

bioRxiv2018

Mapping of TNTs using Correlative Cryo-Electron Microscopy Reveals a Novel Structure

The harmonious orchestration of intercellular communication is essential for multicellular organisms. One mechanism by which cells communicate is through long, actin-rich membranous protrusions, called tunneling nanotubes, that allow for the intercellular transport of various cargoes, including viruses, organelles, and proteins between the cytoplasm of distant cells in vitro and in vivo. Over the last decade, studies have focused on their functional role but information regarding their structure and the differences with other cellular protrusions such as filopodia, is still lacking. Here, we report the structural characterization of tunneling nanotubes using correlative light- and cryo-electron microscopy approaches. We demonstrate their structural identity compared to filopodia by showing that they are comprised of a bundle of functional individual Tunneling Nanotubes containing membrane-bound compartments and allowing organelle transfer.

cell biology↗