Biology subjects

Dingli, F.

Publications and source records attributed to Dingli, F..

At least 19 recordsLinked to original sources

bioRxiv2026

Cell-specific isolation and functional analysis of primary cardiomyocyte-derived large extracellular vesicles from infarcted mouse hearts

Extracellular vesicles (EVs) are membrane-bound particles secreted by all cells and serve as critical mediators of intercellular communication in both physiological and pathological contexts. However, elucidating the precise functions of endogenous EVs remains challenged by a fundamental technical bottleneck: current isolation methodologies depend on shared physical properties or generic surface markers, preventing the selective enrichment of cell-type-specific EVs within complex tissues. Consequently, EVs recovered from biofluids or tissue extracts represent heterogeneous populations, confounding the direct attribution of biochemical signatures and biological activities to distinct cellular origins. Here, we describe a versatile genetic-labeling and affinity-based purification strategy that enables the selective isolation of cell-specific primary EV. Using cardiomyocyte-derived EV (CM-EVs) as a proof-of-concept, we crossed Myh6-Cre mice with the ROSA26-mTmG reporter line to restrict membrane-targeted GFP expression to cardiomyocytes. Following myocardial infarction, cardiac EV were recovered and GFP-positive CM-EVs were selectively purified by anti-GFP nanobody-based magnetic pulldown. This approach yields highly enriched, functional cardiomyocyte-derived extracellular vesicles (CM-EVs). To accommodate diverse analytical needs, we established two distinct elution workflows: (i) a denaturing protocol optimized for downstream proteomics and immunoblotting, and (ii) a gentle, non-denaturing protocol that preserves vesicle integrity and biological activity for downstream in vitro and in vivo functional assays. Using this method, we characterized CM-EVs size distribution and proteomic signature, and demonstrated their capacity to transfer functional cargo to target cells in vitro. Because the purification approach relies solely on targeting a genetically restricted membrane tag rather than assumed surface markers, it is immediately adaptable to virtually any cell type for which a validated Cre driver exists. This method removes a long-standing bottleneck in EV research and provides a broadly applicable platform for deciphering the biochemical composition and in-vivo functions of cell-type-specific primary EV in physiological and pathological settings.

cell biology↗

bioRxiv2026

Functional analysis of novel microneme proteins from Plasmodium vivax blood stages identifies vaccine candidates

Host cell invasion by malaria parasites requires specific molecular interactions with host receptors. Plasmodium vivax merozoite invasion of reticulocytes is mediated by P. vivax Duffy binding protein (PvDBP) and its homolog, P. vivax erythrocyte binding protein (PvEBP). Here, we identify and characterize two novel P. vivax merozoite proteins, PvMP45 and PvMP36, which co- localize with PvDBP and PvEBP in the micronemes and bind reticulocyte receptors. PvMP45 and PvMP36 share high sequence identity with their P. knowlesi homologs, PkMP45 and PkMP36, which form a complex with other invasion related proteins. Field studies reveal that naturally acquired antibodies against PvMP36, PvEBP and PvDBP are associated with protection against clinical P. vivax malaria. We demonstrate that naturally acquired antibodies to PvEBP bind Fcy receptors and likely mediate protection by enabling opsonic phagocytosis. In addition, we show that combining antibodies against PvDBP and PvMP36 results in an additive invasion inhibitory effect against P. vivax blood stages. These results suggest that combining PvDBP, PvEBP and PvMP36 in a multivalent blood stage vaccine could elicit diverse immune mechanisms against P. vivax to achieve high efficacy. ImportanceAll the clinical symptoms of malaria are attributed to the blood stage of malaria parasites during which merozoites invade and multiply within red blood cells. A clear understanding of the host- parasite interactions that enable invasion can open paths for development of novel methods to block parasite growth and prevent malaria. Here, we identify and characterize two novel invasion related proteins from P. vivax merozoites that form an invasion complex and bind host RBC receptors. We demonstrate that antibodies targeting these proteins can block RBC invasion by P. vivax and naturally acquired antibodies that develop following P. vivax infection against one of these proteins are associated with protection against P. vivax malaria. These studies not only expand our understanding of the molecular mechanisms that enable host cell invasion by P. vivax but open new avenues for development of vaccines to protect against P. vivax malaria.

microbiology↗

bioRxiv2026

Nuclear acetyl-CoA production by acetyl-CoA synthetase enables dynamic histone acetylation and gene expression in Plasmodium falciparum

A complex transcriptional cascade drives the two-day intraerythrocytic developmental cycle of the most virulent human malaria parasite, Plasmodium falciparum, in the human host. Genes are rapidly activated at specific times, then silenced as quickly. Transcriptional activity correlates with histone acetylation, which is modulated by acetyltransferases that use acetyl-CoA and deacetylases that produce acetate. Acetyl-CoA synthetase (ACAS) uses acetate to produce acetyl-CoA and has been implicated in histone acetylation, providing an interesting link between parasite metabolism and transcription. Here, we show that ACAS becomes enriched in the nucleus at a time during the life cycle when the parasite undergoes rapid growth and increased levels of transcription. We use mass spectrometry to show that ACAS inhibition results in a rapid and global depletion of histone acetylation, which leads to a general decrease in chromatin accessibility at gene promoters. These widespread alterations in chromatin composition disrupted the transcriptional cascade, resulting in cell cycle arrest. Our study provides evidence that ACAS plays an important nuclear role in the histone acetylation cycle and insight into the dynamic nature and essentiality of histone acetylation in the parasites complex transcriptional program driving infection of the human host.

molecular biology↗

bioRxiv2026

Dynamic phosphoproteomics and proteomics uncover Leishmania donovani-driven ferritin hijacking, contributing to the control of iron homeostasis and iron-related oxidative stress

Leishmania donovani, the causative agent of visceral leishmaniasis, survives within the parasitophorous vacuole (PV) of mammalian macrophages by extensively rewiring host cellular pathways. Although transcriptional and proteomic changes in infected macrophages have been characterized, the impact on the host phosphoproteome, a pivotal, reversible regulator of signalling, remains largely unexplored. To address this gap, we combined time-resolved quantitative phosphoproteomics and proteomics to map the dynamic response of murine macrophages to L. donovani infection. Early after infection, the parasite rapidly attenuates the macrophage signaling cascades normally triggered by phagocytosis. Between 24 h and 48 h post-infection we observed a progressive de-phosphorylation of proteins involved in innate immunity, apoptosis and other stress-responsive pathways, consistent with a partial shutdown of multiple host kinases. From 24 h onward, a global decline in protein abundance was also detected, most notably within lysosomal network. Strikingly, only five host proteins were consistently up-regulated, suggesting their importance for parasite survival. Ferritin light chain (Ftl1) displayed the largest increase. Immunofluorescence and transmission-electron microscopy revealed that Ftl1 accumulates within the parasitophorous vacuole, colocalizes with the ferritin receptor Ncoa4, and yet fails to undergo degradation, indicating that Leishmania co-opts ferritin as its own intracellular iron-storage compartment. Ferritin is not confined to the PV; it is also internalized by the parasite. Within L. donovani, ferritin accumulates not only in the cytoplasm but also in the nucleus, where it may function both as an iron-storage depot and as an iron buffer that protects the parasite from oxidative damage. Finally, we demonstrate that Leishmania donovani pre-conditions its host macrophage for the iron-rich environments of the liver and spleen by driving the assembly of ferritin particles enriched in ferritin-light chain. This contrasts with L. amazonensis, which, residing in the iron-poor skin, induces ferritin predominated by ferritin-heavy chain (Fth1). Knock-down of Ftl1 did not decrease parasite survival because macrophages compensated for its loss by up-regulating Hspb1, which encodes a protein that limits lipid peroxidation by inhibiting the Fenton reaction. Although this response protects the host cell, it also diminishes iron import, imposing a metabolic cost on Leishmania. Hspb1 represents only one example; additional, as yet unidentified, compensatory pathways are likely activated by the parasite to mitigate the loss of ferritin-light chain. Collectively, our data uncover a previously unknown strategy whereby L. donovani hijacks host ferritin trafficking to create a protected iron reservoir, thereby preventing ferroptosis. This mechanism sets Leishmania, a eukaryotic intracellular parasite, apart from the canonical iron-acquisition tactics employed by bacteria and fungi.

microbiology↗

bioRxiv2025

CD133 shapes extracellular vesicle cargo and angiogenic function in basal-like triple-negative breast cancer

Extracellular vesicles (EVs) are central mediators of tumor-stroma communication, yet the mechanisms governing their biogenesis and functional cargo remain poorly understood. Here, we identify CD133 (Prominin-1), selectively expressed in basal-like triple-negative breast cancer (BL-TNBC) cells, as a key regulator of EV production and cargo composition. CD133 localizes to plasma membrane protrusions and lipid rafts, maintaining membrane architecture, promoting EV release, and shaping selective protein loading, including the pro-angiogenic factor CD105. Functionally, CD133 EVs potently induce endothelial tubulogenesis in a CD105-dependent manner, independently of EV uptake or endothelial proliferation. In vivo, these EVs preferentially accumulate in the lung and liver, highlighting organ-specific communication. Mechanistically, CD133 maintains lipid raft integrity, facilitating CD105 selective incorporation into vesicles, thereby establishing a spatially coordinated CD133-CD105 axis. Together, our findings define a subtype-specific EV population whose identity and angiogenic activity are dictated by membrane organization. By linking protrusion architecture to vesicle-mediated signaling, this study highlights CD133-enriched EVs as potential biomarkers and therapeutic targets in aggressive BL-TNBC.

cell biology↗

bioRxiv2025

Characterization of the dual functions of Leishmania CK1.2 in both the parasite and the macrophage using integrated proteomics and spatial mapping

Leishmania CK1.2 (L-CK1.2) is a serine/threonine protein kinase essential for the survival of the protozoan parasite Leishmania, the causative agent of Leishmaniasis. This study investigates the dynamic localization pattern of L-CK1.2 and the broad spectrum of its interacting partners within the parasite. Using proteomic analysis and confocal microscopy, we identified 230 L-CK1.2-associated proteins across the parasite life stages, promastigotes (in the insect vector), and amastigotes, (in the phagolysosomes of host macrophages). This analysis revealed the ubiquitous presence of L-CK1.2 in various cellular structures, including the cytoskeleton, basal body, and flagellum. Using an in vitro system, sixty-four host L-CK1.2-associated proteins, involved in critical host biological processes such as immune response, apoptosis, and purine biosynthesis, were shown to interact with L-CK1.2. These processes are known to be regulated by Leishmania during infection. The study highlights the dual function of L-CK1.2, in the parasite (cis) and within the host cell (trans), positioning this kinase as a key player in host-pathogen interactions. This work provides a comprehensive map of L-CK1.2 interactions and suggest its potential importance in regulating intracellular Leishmania survival, providing potential therapeutic targets for Leishmaniasis. Furthermore, given the evolutionary conservation of CK1.2 across other parasitic organisms, our findings may have broader implications for understanding and managing parasitic infections.

microbiology↗

bioRxiv2025

A Catalytically Inactive Protein Kinase C alpha Mutation Drives Chordoid Glioma by Pathway Rewiring

Abstract SummaryChordoid glioma (ChG) is a rare, low-grade brain tumor characterized by a novel recurrent point mutation, D463H, in the kinase domain of protein kinase C alpha (PKC). The mutation is invariably an Asp to His substitution, suggesting it endows a unique function beyond catalytic inactivation associated with other cancer-associated PKC mutations. Here we use in vitro and in cellulo activity assays to show that PKCD463H is catalytically inactive, functions as a dominant-negative mutant to suppress endogenous PKC and uniquely rewires the cellular interactome. Specifically, phosphoproteomic, proximity labeling, and co-immunoprecipitation mass-spectrometry data from cells overexpressing PKCD463H identify altered phosphorylation of substrates and binding to multiple proteins involved in cell-cell junctions compared to WT enzyme. Lastly, single nuclei RNAseq reveals that ChG derives from specialized tanycytes. Our data suggest that this disease-defining, fully penetrant mutation promotes neomorphic non-catalytic scaffolding to impair cell junction function.

molecular biology↗

bioRxiv2025

Identification of a shared persistence program in triple-negative breast cancer across treatments and patients

Acquisition of resistance to anti-cancer therapies is a multistep process, which initiates with the survival of drug persister cells. Understanding the mechanisms driving the emergence of persister cells remains challenging, primarily because of their limited accessibility in patients. Here, using mouse models to isolate persister cells from patient tumors, we determine the identity features of persister cells from eight patients with triple-negative breast cancer (TNBC). Combining over 80 transcriptome studies, we reveal hallmarks of the persister state across patient models and treatment modalities: high expression of basal keratins together with activation of a stress response and inflammation pathways. Patient-derived persister cells are transcriptionally plastic and return to a common treatment-naive like state upon relapse, regardless of the treatment they have been exposed to. Leveraging gene regulatory networks, we identify AP-1, NFKB and IRF/STAT as the key drivers of this hallmark persister state. As a proof of concept, we show that FOSL1 - an AP-1 member - is sufficient to drive cells to the persister state by binding enhancers and reprogramming the transcriptome of cancer cells. On the contrary, cancer cells without FOSL1 have a decreased ability to reach the persister state. By defining hallmarks of drug persistence to multiple therapies of the standard of care, our study provides a resource to design novel combination therapeutic strategies to limit resistance.

cancer biology↗

bioRxiv2023

Ku-binding motifs in RAG2, XLF, PAXX and MRI support functional redundancy during V(D)J recombination

The interaction of several partners with Ku through Ku-binding motifs (KBMs) in their sequences governs their enrolment in NHEJ repair complexes. Here, we first established more specifically the function of KBMs in V(D)J recombination as the molecular basis of functional redundancy between XLF and the NHEJ proteins MRI and PAXX. Then, given the functional redundancy between RAG2 and XLF, we explored the hypothesis of a KBM-mediated interaction between RAG2 and Ku. Through sequence alignment and biophysical methods, we identified a KBM at the C-terminus of RAG2 (R2CT) that mediates its interaction with Ku both in vitro and in cellulo. Notably, we showed that R2CT/Ku interaction is independent of the RAG nuclease activity. Finally, we demonstrated that the respective KBMs of RAG2 and XLF support their functional redundancy for V(D)J recombination.

molecular biology↗

bioRxiv2023

Inhibition of the macrophage demethylase LSD1 reverses Leishmania amazonensis-induced transcriptomic changes and causes a decrease in parasite load

Intracellular pathogens exploit host cell functions to favor their own survival. In recent years, the subversion of epigenetic regulation has emerged as a key microbial strategy to modify host cell gene expression and evade antimicrobial immune responses. Using the protozoan parasite Leishmania as a model system, we have recently demonstrated that infection causes histone H3 hypomethylation, which is associated with the establishment of an anti-inflammatory phenotype, suggesting that host cell demethylases may play a role in the intracellular survival of these parasites. In this study, we combined pharmacological inhibition with RNA sequencing and quantitative immune-precipitation analysis to investigate the role of the macrophage lysine demethylase LSD1 (KDM1a) in Leishmania intracellular infection in vitro. Treatment of infected macrophages with validated, LSD1-specific inhibitors resulted in a significant reduction in parasite burden. We confirmed the impact of these inhibitors on LSD1 activity within macrophage nuclear extracts using an in vitro demethylase assay and established their LSD1 target engagement in situ by cellular thermal shift assay. RNA-seq analysis of infected and inhibitor-treated macrophages linked parasite killing to a partial reversion of infection-dependent expression changes, restoring the macrophage anti-microbial response and limiting cholesterol biosynthesis. While we ruled out any impact of Leishmania on LSD1 expression or localization, we uncovered significant alterations in LSD1 complex formation within infected macrophages, involving unique interactions with host cell regulatory proteins such as Rcor-1. Our study sheds important new light on the epigenetic mechanisms of macrophage immuno-metabolic subversion by intracellular Leishmania and identifies LSD1 as a potential candidate for host-directed, anti-leishmanial therapy.

cell biology↗

bioRxiv2023

RNA polymerase III is involved in regulating Plasmodium falciparum virulence

While often undetected and untreated, persistent seasonal asymptomatic malaria infections remain a global public health problem. Despite the presence of parasites in the peripheral blood, no symptoms develop. Disease severity is correlated with the levels of infected red blood cells (iRBCs) adhering within blood vessels. Changes in iRBC adhesion capacity have been linked to seasonal asymptomatic malaria infections, however how this is occurring is still unknown. Here we present evidence that RNA polymerase III (RNA Pol III) transcription in Plasmodium falciparum is downregulated in field isolates obtained from asymptomatic individuals during the dry season. Through experiments with in vitro cultured parasites, we have uncovered an RNA Pol III-dependent mechanism that controls pathogen proliferation and expression of a major virulence factor in response to external stimuli. Our findings establish a connection between P. falciparum cytoadhesion and a non-coding RNA family transcribed by Pol III. Additionally, we have identified P. falciparum Maf1 as a pivotal regulator of Pol III transcription, both for maintaining cellular homeostasis and responding adaptively to external signals. These results introduce a novel perspective that contributes to our understanding of P. falciparum virulence. Furthermore, they establish a connection between this regulatory process and the occurrence of seasonal asymptomatic malaria infections.

microbiology↗

bioRxiv2023

Identification of the Intracellular Protein Targets of a Bio-active Clickable Half-Sandwich Iridium Complex by Chemical Proteomics

Identification of intracellular targets of anticancer drug candidates provides key information on their mechanism of action. Exploiting the ability of the anticancer (C^N)-chelated half-sandwich iridium(III) complexes to covalently bind proteins, click chemistry with a bioorthogonal azido probe was used to localize a phenyloxazoline-chelated iridium complex within cells and profile its interactome at the proteome-wide scale. Proteins involved in protein folding and actin cytoskeleton regulation were identified as high affinity targets. Upon iridium complex treatment, HSP90 folding activity was inhibited in vitro and major cytoskeleton disorganization was observed. We used a wide array of imaging and biochemical methods to validate selected targets and obtain a multiscale overview of the effects of this complex on live human cells. We demonstrate that it behaves as a dual agent, inducing both electrophilic and oxidative stresses in cells that account for its cytotoxicity.

biochemistry↗

bioRxiv2023

Polθ is phosphorylated by Polo-like kinase 1 (PLK1) to enable repair of DNA double strand breaks in mitosis

DNA double strand breaks (DSBs) are deleterious lesions that challenge genome integrity. To mitigate this threat, human cells rely on the activity of multiple DNA repair machineries that are tightly regulated throughout the cell cycle1. In interphase, DSBs are mainly repaired by non-homologous end joining (NHEJ) and homologous recombination (HR)2. However, these pathways are completely inhibited in mitosis3-5, leaving the fate of mitotic DSBs unknown. Here we show that DNA polymerase theta (Pol{theta})6 repairs mitotic DSBs and thereby maintains genome integrity. In contrast to other DSB repair factors, Pol{theta} function is activated in mitosis upon phosphorylation by the Polo-like kinase 1 (PLK1). Phosphorylated Pol{theta} is recruited to mitotic DSBs, where it mediates joining of broken DNA ends, while halting mitotic progression. The lack of Pol{theta} leads to a shortening of mitotic duration and defective repair of mitotic DSBs, resulting in a loss of genome integrity. In addition, we identify mitotic Pol{theta} repair as the underlying cause of the synthetic lethality between Pol{theta} and HR. Our findings reveal the critical importance of mitotic DSB repair for maintaining genome stability.

cell biology↗

bioRxiv2023

Structural characterization of stem cell factors Oct4, Sox2, Nanog and Esrrb disordered domains, and a method to identify their phospho-dependent binding partners.

The combined expression of a handful of pluripotency transcription factors (PluriTFs) in somatic cells can generate induced pluripotent stem cells (iPSCs). Here, we report the structural characterization of disordered regions contained in four important PluriTFs, namely Oct4, Sox2, Nanog and Esrrb. Moreover, many post-translational modifications (PTMs) have been detected on PluriTFs, whose roles are not yet characterized. To help in their study, we also present a method i) to produce well-characterized phosphorylation states of PluriTFs, using NMR analysis, and ii) to use them for pull-downs in stem cell extracts analyzed by quantitative proteomics to identify of Sox2 binders.

biochemistry↗

bioRxiv2023

Specific subcellular localization drives the different functions of CDC42 isoforms during migration

The small G-protein CDC42 is an evolutionary conserved polarity protein and a key regulator of numerous polarized cell functions, including directed cell migration. In vertebrates, alternative splicing gives rise to two CDC42 proteins: the ubiquitously expressed isoform (CDC42u) and the brain isoform (CDC42b), whose specific roles are not fully elucidated. The two isoforms only differ in their carboxy-terminal sequence, which includes the CAAX motif essential for CDC42 interaction with membrane. Here we show that these divergent sequences do not directly affect the range of CDC42s potential binding partners, but indirectly influence CDC42-driven signaling by controlling the specific subcellular localization of the two isoforms. In astrocytes and neural precursors, which naturally express both variants, CDC42u is mainly cytosolic and associates with the leading-edge plasma membrane of migrating cells where it recruits the Par6-PKC{zeta} complex to fulfill its polarity function. In contrast, CDC42b mainly localizes to intracellular membrane compartments, where it interacts with N-WASP. CDC42b does not participate in cell polarization but embodies the major isoform regulating endocytosis. Both CDC42 isoforms act in concert by contributing their specific functions to promote chemotaxis of neural precursors, demonstrating that the expression pattern of the two isoforms is decisive for the tissue-specific behavior of cells.

cell biology↗

bioRxiv2023

The oncogenic role of Streptococcus gallolyticus subsp. gallolyticus is linked to activation of multiple cancer-related signaling pathways

Streptococcus gallolyticus subsp. gallolyticus (SGG), an opportunistic gram-positive pathogen responsible for septicemia and endocarditis in the elderly, is often associated with colon cancer (CRC). In this work, we investigated the oncogenic role of SGG strain UCN34 using the azoxymethane (AOM)-induced CRC model in vivo, organoid formation ex vivo and proteomic and phosphoproteomic analyses from murine colons. We showed that SGG UCN34 accelerates colon tumor development in the murine CRC model. Full proteome and phosphoproteome analysis of murine colons chronically colonized by SGG UCN34 or the closely related non-pathogenic S. gallolyticus subsp. macedonicus (SGM) revealed that 164 proteins and 725 phosphorylation sites were differentially regulated following colonization by SGG UCN34. Ingenuity Pathway Analysis (IPA) indicates a pro-tumoral shift specifically induced following colonization by SGG UCN34, as most proteins and phosphoproteins identified were associated with digestive cancer. Comprehensive analysis of the altered phosphoproteins using ROMA software revealed significantly elevated activities in several cancer hallmark pathways affecting tumoral cells and their microenvironment, i.e. MAPK (ERK, JNK and p38), mTOR and integrin/ILK/actin signaling, in SGG UCN34 colonized colon. Importantly, analysis of protein arrays of human colon tumors colonized with SGG showed up-regulation of PI3K/Akt/mTOR and MAPK pathways, providing clinical relevance to our findings. To test SGGs capacity to induce pre-cancerous transformation of the murine colonic epithelium, we grew ex vivo organoids which revealed unusual structures with compact morphology following exposure to SGG. Taken together, our results reveal that the oncogenic role of SGG UCN34 is associated with activation of multiple cancer-related signaling pathways. Author SummaryColorectal cancer is the third most common cause of cancer mortality worldwide. The colon is a very singular organ, colonized by a vast and complex community of microorganisms, known as the gut microbiota. Strong evidence supports a role of the microbiota in colon cancer development. Streptococcus gallolyticus subsp. gallolyticus (SGG), a gut commensal, was one of the first bacteria to be associated with colorectal cancer. A better understanding of the role of SGG in colon cancer development is critical to developing novel strategies to improve clinical diagnosis and treatment of this disease. Here, using a global proteomic analysis of mouse colonic tissue colonized by SGG, we show that over 90% of the proteins with altered levels are involved in cancer. SGG colonization promotes autocrine and paracrine pro-tumor signals contributing to transformation of the colonic epithelium but also modifying the stromal microenvironment, which in turn sustains tumor development. Importantly, two tumor hallmark pathways (PI3K/Akt/mTOR and MAPK) identified in our mouse model were also found in human colon tumor biopsies colonized by SGG, strengthening the clinical relevance to our study.

microbiology↗

bioRxiv2023

Atheroprone shear stress stimulates noxious endothelial extracellular vesicle uptake by MCAM and PECAM-1 cell adhesion molecules

Atherosclerotic lesions mainly form in arterial areas exposed to low shear stress (LSS), where endothelial cells express a senescent and inflammatory phenotype. Conversely, high shear stress (HSS) has atheroprotective effects on the endothelium. Endothelial cell-derived extracellular vesicles have been shown to regulate inflammation, senescence and angiogenesis and therefore play a crucial role in vascular homeostasis and disease. While previous studies have shown links between hemodynamic forces and extracellular vesicle release, the exact consequences of shear stress on the release and uptake of endothelial EVs remains elusive. Our aim is therefore to decipher the interplay between these processes in endothelial cells exposed to atheroprone or atheroprotective shear stress. Confluent human umbilical vein endothelial cells (HUVEC) were exposed to either LSS or HSS for 24 hours. Large and small EVs were isolated from conditioned medium by sequential centrifugation and size exclusion chromatography. They were characterized by TEM, Western blot analysis of EV markers, tunable resistive pulse sensing, flow cytometry and proteomics. Uptake experiments were performed using fluorescently-labeled EVs and differences between groups were assessed by flow cytometry and confocal microscopy. We found that levels of large and small EVs in HUVEC conditioned media were fifty and five times higher in HSS than in LSS conditions, respectively. In vivo and in vitro uptake experiments revealed greater EV incorporation by cells exposed to LSS conditions compared to HSS. Additionally, endothelial LSS-EVs appeared to have a greater affinity for HUVECs than HSS-EVs or EVs derived from platelets, red blood cells, granulocytes and peripheral blood mononuclear cells. Proteomic analysis revealed that LSS-EVs were enriched in adhesion proteins such as PECAM1, MCAM, which were involved in EV uptake by endothelial cells. LSS-EVs also carried mitochondrial material, which may be involved in elevating reactive oxygen species levels in recipient cells. These findings suggest that endothelial shear stress has a significant impact during EV biogenesis and uptake. Given the major role of EVs and shear stress in vascular health, deciphering the relation between these processes may yield innovative strategies for the early detection and treatment of endothelial dysfunction.

cell biology↗

bioRxiv2022

CTNND2 moderates neuronal excitation and links human evolution to prolonged synaptic development in the neocortex

Human-specific genes are potential drivers of brain evolution. Among them, SRGAP2C has contributed to the emergence of features characterizing human cortical synapses, including their extended period of maturation. SRGAP2C inhibits its ancestral copy, the postsynaptic protein SRGAP2A; yet the synaptic molecular pathways differentially regulated in humans by SRGAP2 proteins remain largely unknown. Here, we identify CTNND2, a protein implicated in severe intellectual disability (ID) in the Cri-du-Chat syndrome, as an SRGAP2 effector. We demonstrate that CTNND2 slows down synaptic maturation and promotes neuronal homeostasis. During postnatal development, CTNND2 moderates neuronal excitation and excitability. In adults, it supports synapse maintenance. While CTNND2 deficiency is deleterious and results in the synaptic loss of SYNGAP1, another major ID-associated protein, the human-specific protein SRGAP2C enhances CTNND2 synaptic accumulation in human neurons. Our findings reveal that CTNND2 regulation by SRGAP2C contributes to synaptic neoteny in humans, and link human-specific and ID genes at the synapse.

neuroscience↗