Biology subjects

Mendez, M.

Publications and source records attributed to Mendez, M..

At least 19 recordsLinked to original sources

bioRxiv2026

Integrated multi-omic analysis of pediatric metastatic osteosarcoma reveals endothelial cell plasticity and lineage infidelity.

While recent research has increasingly focused on the role of fibroblasts and macrophages in osteosarcoma, the tumor vasculature remains poorly understood, particularly in metastatic disease. To address this gap, we performed single-nuclei multi-ome (RNA+ATAC) sequencing on 24 human metastatic osteosarcoma specimens. We found that endothelial cells adopt a hybrid endothelial-mesenchymal state resembling endothelial-to-mesenchymal transition (EndMT) and that a subset of diploid endothelial cells expresses osteoblastic transcriptional profiles and gene regulatory networks (GRN). Joint copy-number analysis further identified osteosarcoma cells with endothelial transcriptional programs and GRNs, consistent with vascular mimicry. In vitro assays and syngeneic lineage-tracing experiments validated that tumor educated endothelial cells acquire osteoblast-like features. Together, these findings reveal substantial plasticity among endothelial and osteosarcoma cells in human and murine metastatic osteosarcoma, provide new insight into the how the metastatic microenvironment shapes the tumor vasculature, and challenge current models of osteosarcoma biology.

cancer biology↗

bioRxiv2025

Pediatric Long COVID Is Characterized by Myeloid CCR6 Suppression and Immune Dysregulation

The biological mechanisms underlying long COVID in the pediatric population are poorly understood. Our study aimed to characterize the immune pathophysiology of long COVID in children and young people (CYP). We analyzed major immune cell compartments in PBMCs, as well as specific SARS-CoV-2 antibody response in CYP with (n=99) and without (n=18) long COVID at three months following acute infection. Our findings indicate that pediatric long COVID is associated with a dysregulated immune response characterized by altered innate immunity and overactivated T-, B- and NK-cell responses. Furthermore, CYP with long COVID had an impaired humoral response to SARS-CoV-2 marked by a dysregulated B-cell compartment and lower levels of anti-RBD IgG and IgA. This correlated with reduced neutralizing capacity against SARS-CoV-2. Random forest analysis identified CCR6 expression on myeloid cells as the most relevant biomarker that distinguishes long COVID from control individuals with 79% accuracy. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=154 SRC="FIGDIR/small/671713v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1145480org.highwire.dtl.DTLVardef@1b7a635org.highwire.dtl.DTLVardef@fb13org.highwire.dtl.DTLVardef@63a49a_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

Spatial profiling identifies regionally distinct microenvironments and targetable immunosuppressive mechanisms in pediatric osteosarcoma pulmonary metastases.

Osteosarcoma is the most common malignant bone tumor in young patients and remains a significant clinical challenge, particularly in the context of metastatic disease. Despite extensive documentation of genomic alterations in osteosarcoma, studies detailing the immunosuppressive mechanisms within the metastatic osteosarcoma microenvironment are lacking. Our objective was to characterize the spatial transcriptional landscape of metastatic osteosarcoma to reveal these immunosuppressive mechanisms and identify promising therapeutic targets. Here, we performed spatial transcriptional profiling on a cohort of osteosarcoma pulmonary metastases from pediatric patients. We reveal a conserved spatial gene expression pattern resembling a foreign body granuloma, characterized by peripheral inflammatory signaling, fibrocollagenous encapsulation, lymphocyte exclusion, and peritumoral macrophage accumulation. We also show that the intratumoral microenvironment of these lesions lack inflammatory signaling. Additionally, we identified CXCR4 as an actionable immunomodulatory target that bridges both the intratumoral and extratumoral microenvironments and highlights the spatial heterogeneity and complexity of this pathway. Collectively, this study reveals that metastatic osteosarcoma specimens are comprised of multiple regionally distinct immunosuppressive microenvironments.

cancer biology↗

bioRxiv2025

Tissue-dependent mechanosensing by cells derived from human tumors

Alterations of the extracellular matrix (ECM), including both mechanical (such as stiffening of the ECM) and chemical (such as variation of adhesion proteins and deposition of hyaluronic acid (HA)) changes, in malignant tissues have been shown to mediate tumor progression. To survey how cells from different tissue types respond to various changes in ECM mechanics and composition, we measured physical characteristics (adherent area, shape, cell stiffness, and cell speed) of 25 cancer and 5 non-tumorigenic cell lines on 7 different substrate conditions. Our results indicate substantial heterogeneity in how cell mechanics changes within and across tissue types in response to mechanosensitive and chemosensitive changes in ECM. The analysis also underscores the role of HA in ECM with some cell lines showing changes in cell mechanics in response to presence of HA in soft substrate that are similar to those observed on stiff substrate. This pan-cancer investigation also highlights the importance of tissue-type and cell line specificity for inferences made based on comparison between physical properties of cancer and normal cells. Lastly, using unsupervised machine learning, we identify phenotypic classes that characterize the physical plasticity, i.e. the distribution of physical feature values attainable, of a particular cell type in response to different ECM-based conditions.

biophysics↗

bioRxiv2024

ALMS1 KO rat: a new model of metabolic syndrome with spontaneous hypertension

ALMS1 is a protein initially associated with Alstrom syndrome. This is a rare human disorder characterized by metabolic dysfunction, hypertension, obesity and hyperinsulinemia. In addition, ALMS1 gene was linked to hypertension status in a multipoint linkage population analysis. However, the mechanisms by which ALMS1 contributes to the development of obesity, insulin resistance and other metabolic disturbances are unknown. To study the role of ALMS1 in blood pressure regulation and renal function we previously generated an ALMS1 knockout rat model, where we found these rats are hypertensive. In this study, we further characterized the ALMS1 knockout rat, and found that they exhibit most characteristics of metabolic syndrome including hypertension and higher body weight by 10-12 weeks of age. In contrast, obesity, hyperinsulinemia and vascular dysfunction manifested at around 14-16 weeks of age. Interestingly, ALMS1 KO rats developed hyperleptinemia prior to the development of obesity rapidly after weaning by 7 weeks of age, suggesting an early role for ALMS1 in the hormonal control of leptin. We also found that female ALMS1 KO rats develop severe metabolic syndrome with hypertension similar to their male counterparts, lacking any protection often associated with better cardiovascular outcomes. Therefore, ALMS1 is an essential gene for sex-and age-dependent metabolic function. The ALMS1 knockout rat provides an invaluable pre-clinical animal model that recapitulates most symptoms present in patients and allows the study of new drugs and mechanisms that cause metabolic syndrome.

physiology↗

bioRxiv2024

Integrated surveillance of sandflies as vectors of leishmaniasis reveals the presence of a new Leishmania species with possible implication in human health in Europe

Leishmaniasis, endemic in Spain, displays rising incidence rates, notably in the Region of Murcia. Sandfly surveillance and Leishmania screening in 2021 uncovered Leishmania infantum and L. adleri. While current Leishmania diagnostic methods primarily target L. infantum, our study underscores the importance of broader Leishmania species surveillance for accurate diagnosis and understanding of disease dynamics. The detection of L. adleri, previously undescribed in Europe, highlights the need for expanded research to investigate its presence and implications for human and animal health.

zoology↗

bioRxiv2024

Traits related to pollination and mating result in diverse reproductive strategies in angiosperms

O_LIFlowering plants have many modes of sexual reproduction, notably varying from selfing to outcrossing, and from bisexual flowers to individuals with separate sexes (dioecy). These reproductive modes are associated with floral and life-history traits that have evolved together, making it difficult to interpret correlations between traits. C_LIO_LIWe analysed variation in 21 traits related to flowers, pollination, mating, sexual systems and life history from 361 species representative of flowering plant diversity. C_LIO_LIOutcrossing was mainly found among long-lived, large-stature plants, but hermaphroditic outcrossers and dioecious species appeared as largely non-overlapping strategies in the trait space. Level of floral investment was the main difference between these strategies, with dioecious species having generally smaller, less rewarding flowers, a pattern that also occurred in biotically pollinated species. C_LIO_LIThis multi-trait study shows that pollination can be achieved in many, often contrasting, ways. Despite extensive variation in reproductive traits, dioecy stands out as being linked to floral traits primarily, while correlations with lifespan and dispersal traits appear spurious. We provide a conceptual framework based on lifespan, floral investment, and sexual separation that can be used to integrate pollination, reproduction and plant growth in future research on plant evolution and ecology. C_LI

evolutionary biology↗

bioRxiv2023

Segzoo: a turnkey system that summarizes genome annotations

Segmentation and automated genome annotation (SAGA) techniques, such as Segway and ChromHMM, assign labels to every part of the genome, identifying similar patterns across multiple genomic input signals. Inferring biological meaning in these patterns remains challenging. Doing so requires a time-consuming process of manually downloading reference data, running multiple analysis methods, and interpreting many individual results. To simplify these tasks, we developed the turnkey system Segzoo. As input, Segzoo only requires a genome annotation file in browser extensible data (BED) format. It automatically downloads the rest of the data required for comparisons. Segzoo performs analyses using these data and summarizes results in a single visualization. Availability and ImplementationSource code for Python [≥]3.7 on Linux freely available for download at https://github.com/hoffmangroup/segzoo under the GNU General Public License (GPL) version 2. Segzoo is also available in the Bioconda package segzoo: https://anaconda.org/bioconda/segzoo.

bioinformatics↗

bioRxiv2023

Next-generation interaction proteomics for quantitative Jumbophage-bacteria interaction mapping

Host-pathogen interactions (HPIs) are pivotal in regulating establishment, progression, and outcome of an infection. Affinity-purification mass spectrometry has become instrumental for the characterization of HPIs, however the targeted nature of exogenously expressing individual viral proteins has limited its utility to the analysis of relatively small pathogens. Here we present the use of co-fractionation mass spectrometry (SEC-MS) for the high-throughput analysis of HPIs from native viral infections of two jumbophages ({phi}KZ and{phi} PA3) in Pseudomonas aeruginosa. This enabled the detection >6000 unique host-pathogen and >200 pathogen-pathogen interactions for each phage, encompassing >50% of the phage proteome. Interactome-wide comparison across phages showed similar perturbed protein interactions suggesting fundamentally conserved mechanisms of phage predation within the KZ-like phage family. Prediction of novel ORFs revealed a{phi} PA3 complex showing strong structural and sequence similarity to{phi} KZ nvRNAp, suggesting{phi} PA3 also possesses two RNA polymerases acting at different stages of the infection cycle. We further expanded our understanding on the molecular organization of the virion packaged and injected proteome by identifying 23 novel virion components and 5 novel injected proteins, as well as providing the first evidence for interactions between KZ-like phage proteins and the host ribosome. To enable accessibility to this data, we developed PhageMAP, an online resource for network query, visualization, and interaction prediction (https://phagemap.ucsf.edu/). We anticipate this study will lay the foundation for the application of co-fractionation mass spectrometry for the scalable profiling of hostpathogen interactomes and protein complex dynamics upon infection.

systems biology↗

bioRxiv2022

Trait-dependent diversification in angiosperms: patterns, models and data

Variation in species richness across the tree of life, accompanied by the incredible variety of ecological and morphological characteristics found in nature, has inspired many studies to link traits with species diversification. Angiosperms are a highly diverse group that has fundamentally shaped life on earth since the Cretaceous, and illustrate how species diversification affects ecosystem functioning. Numerous traits and processes have been linked to differences in species richness within this group, but we know little about how these interact and their relative importance. Here, we synthesized data from 152 studies that used state-dependent speciation and extinction (SSE) models on angiosperm clades. Intrinsic traits related to reproduction and morphology were often linked to diversification but a set of universal drivers did not emerge as traits did not have consistent effects across clades. Importantly, dataset properties were correlated to SSE model results - trees that were larger, older, or less well-sampled tended to yield trait-dependent outcomes. We compared these properties to recommendations for SSE model use and provide a set of best practices to follow when designing studies and reporting results. Finally, we argue that SSE model inferences should be considered in a larger context incorporating species ecology, demography and genetics.

evolutionary biology↗

bioRxiv2022

The {varphi}PA3 Phage Nucleus is Enclosed by a Self-Assembling, 2D Crystalline Lattice

A growing number of jumbo bacteriophages, with genomes exceeding 200 kb, have been found to establish a Phage Nucleus--a micron-scale, proteinaceous structure encompassing the replicating phage DNA. Bacteriophage and host proteins associated with replication and transcription are concentrated inside the Phage Nucleus while nucleotide synthesis, translation, and numerous other host and exogenous proteins are effectively excluded, including CRISPR-Cas and restriction endonuclease host defense systems. Here, we show that fragments of the Phage Nucleus isolated from {phi}PA3 infected Pseudomonas aeruginosa cells form a square lattice and demonstrate that the recombinantly purified primary Phage Nuclear Enclosure (PhuN) protein spontaneously assembles into sheets also constructed from a square lattice which we resolve to 3.8 [A] by cryo-EM. Our structure reveals that the flexible termini and large loops mediate adaptable inter-tetramer contacts that drive shell assembly into a C2-symmetric lattice. While the interfaces between subunits are mostly well packed, two of the interfaces are open, forming clear channels that likely have important functional implications for the transport of proteins, mRNA, and small molecules.

biochemistry↗

bioRxiv2021

Automated identification of cell-type-specific genes and alternative promoters

BackgroundIdentifying key transcriptional features, such as genes or transcripts, involved in cellular differentiation remains a challenging problem. Current methods for identifying key transcriptional features predominantly rely on pairwise comparisons among different cell types. These methods also identify long lists of differentially expressed transcriptional features. Combining the results from many such pairwise comparisons to find the transcriptional features specific only to one cell type is not straightforward. Thus, one must have a principled method for amalgamating pairwise cell type comparisons that makes full use of prior knowledge about the developmental relationships between cell types. MethodWe developed Cell Lineage Analysis (CLA), a computational method which identifies transcriptional features with expression patterns that discriminate cell types, incorporating Cell Ontology knowledge on the relationship between different cell types. CLA uses random forest classification with a stratified bootstrap to increase the accuracy of binary classifiers when each cell type have a different number of samples. Regularized random forest results in a classifier that selects few but important transcriptional features. For each cell type pair, CLA runs multiple instances of regularized random forest and reports the transcriptional features consistently selected. CLA not only discriminates individual cell types but can also discriminate lineages of cell types related in the developmental hierarchy. ResultsWe applied CLA to Functional Annotation of the Mammalian Genome 5 (FANTOM5) data and identified discriminative transcription factor and long non-coding RNA(lncRNA) genes for 71 human cell types.With capped analysis of gene expression (CAGE) data, CLA identified individual cell-type-specific alternative promoters for cell surface markers. Compared to random forest with a standard bootstrap approach, CLAs stratified bootstrap approach improved the accuracy of gene expression classification models for more than 95% of 2060 cell type pairs examined. Applied on 10X Genomics single-cell RNA-seq data for CD14+ monocytes and FCGR3A+ monocytes, CLA selected only 13 discriminative genes. These genes included the top 9 out of 370 significantly differentially expressed genes obtained from conventional differential expression analysis methods. DiscussionOur CLA method combines tools to simplify the interpretation of transcriptome datasets from many cell types. It automates the identification of the most differentially expressed genes for each cell type pairs CLAs lineage score allows easy identification of the best transcriptional markers for each cell type and lineage in both bulk and single-cell transcriptomic data. AvailabilityCLA is available at https://cla.hoffmanlab.org. We deposited the version of the CLA source with which we ran our experiments at https://doi.org/10.5281/zenodo.3630670. We deposited other analysis code and results at https://doi.org/10.5281/zenodo.5735636.

bioinformatics↗

bioRxiv2021

Cuban history of CRF19 recombinant subtype of HIV-1

CRF19 is a recombinant form of HIV-1 subtypes D, A1 and G, which was first sampled in Cuba in 1999, but was already present there in 1980s. CRF19 was reported almost uniquely in Cuba, where it accounts for ~25% of new HIV-positive patients and causes rapid progression to AIDS (~ 3 years). We analyzed a large data set comprising ~ 350 pol and env sequences sampled in Cuba over the last 15 years and ~ 350 from Los Alamos database. This data set contained both CRF19 (~ 315), and A1, D and G sequences. We performed and combined analyses for the three A1, G and D regions, using fast maximum likelihood approaches, including: (1) phylogeny reconstruction, (2) spatio-temporal analysis of the virus spread, and ancestral character reconstruction for (3) transmission mode and (4) drug resistance mutations (DRMs). This allowed us to acquire new insights on the CRF19 origin and transmission patterns. We showed that CRF19 recombined between 1966 and 1977, most likely in Cuban community stationed in Congo region. We further investigated CRF19 spread on the Cuban province level, and discovered that the epidemic started in 1970s, most probably in Villa Clara, that it was at first carried by heterosexual transmissions, and then quickly spread in the 1980s within the "men having sex with men" (MSM) community, with multiple transmissions back to heterosexuals. The analysis of the transmission patterns of common DRMs showed mostly acquired drug resistance rather than transmitted one. Our results show a very early introduction of CRF19 in Cuba, which could explain its local epidemiological success. Ignited by a major founder event, the epidemic then followed a similar pattern as other subtypes and CRFs in Cuba. The reason for the short time to AIDS remains to be understood and requires specific surveillance, in Cuba and elsewhere. Author summaryCRF19 is a recombinant form of HIV-1, which causes rapid progression to AIDS (~ 3 years versus 5 - 10 years for other subtypes and CRFs). CRF19 is reported almost uniquely in Cuba, where it is highly prevalent (~ 25%) among newly detected HIV-1 patients. In this study, we found that CRF19 most likely recombined around the 1970s in the Cuban community that was stationed in Democratic Republic of the Congo and Angola at that time. It was introduced very early into the Cuban province of Villa Clara, from where it had several introductions to La Habana in the 1980s and then further spread to other Cuban provinces. The CRF19 epidemic most probably started with heterosexual transmissions, followed in the 1980s by multiple introductions into "men having sex with men" (MSM) community, followed by multiple transmissions back to heterosexuals (often females). The early introduction of CRF19 into Cuba most likely explains its success, not observed in other parts of the world. However, importantly, its rapid progression to AIDS makes it crucial to survey CRF19 sub-epidemics not only in Cuba, but also in other parts of the world having regular exchanges with Cuba.

bioinformatics↗

bioRxiv2021

Functional annotation of human long noncoding RNAs using chromatin conformation data

The human genome is pervasively transcribed and produces a wide variety of long non-coding RNAs (lncRNAs), constituting the majority of transcripts across human cell types. Studying lncRNAs is challenging due to their low expression level, cell type-specific occurrence, poor sequence conservation between orthologs, and lack of information about RNA domains. LncRNAs direct the regulatory factors in the locations that are in cis to their transcription sites. We designed a model to predict if an lncRNA acts in cis based on its features and trained it using RNA-chromatin interaction data. The trained model is cell type-independent and does not require RNA-chromatin data. Combining RNA-chromatin and Hi-C data, we showed that lncRNA-chromatin binding sites are determined by chromosome conformation. For each lncRNA, the spatially proximal genes were identified as their potential targets by combining Hi-C and Cap Analysis Gene Expression (CAGE) data in 18 human cell types. RNA-protein and RNA-chromatin interaction data suggested that lncRNAs act as scaffolds to recruit regulatory proteins to target promoters and enhancers. We provide the data through an interactive visualization web portal at https://fantom.gsc.riken.jp/zenbu/reports/#F6_3D_lncRNA.

genomics↗

bioRxiv2020

Novel Cluster AZ Arthrobacter phages Powerpuff, Lego, and YesChef exhibit close functional relationships with Microbacterium phages

Bacteriophages exhibit a vast spectrum of relatedness and there is increasing evidence of close genomic relationships independent of host genus. The variability in phage similarity at the nucleotide, amino acid, and gene content levels confounds attempts at quantifying phage relatedness, especially as more novel phages are isolated. This study describes three highly similar novel Arthrobacter globiformis phages-Powerpuff, Lego, and YesChef-which were assigned to Cluster AZ using a nucleotide-based clustering parameter. Phages in Cluster AZ and Microbacterium Cluster EH, as well as the former Microbacterium singleton Zeta1847, exhibited low nucleotide similarity but gene content similarity in excess of the recently adopted Microbacterium clustering parameter, which resulted in the reassignment of Zeta1847 to Cluster EH. Additionally, Clusters AZ and EH phages encode a shared integrase indicative of a lysogenic life cycle; in the first experimental verification of a Cluster AZ phages life cycle, we show that phage Powerpuff is a true temperate phage and forms stable lysogens that exhibit immunity to superinfection by related phages, despite lacking identifiable repressors typically required for lysogenic maintenance and superinfection immunity. The ability of phage Powerpuff to undergo and maintain lysogeny suggests that other closely related phages encoding an integrase but lacking an identified repressor may be temperate as well. Our findings further highlight the importance of using multiple metrics to capture phage relatedness, provide additional evidence of significant shared phage genomic content spanning multiple actinobacterial host genera, and demonstrate the continued need for verification and characterization of life cycles in newly isolated phages.

microbiology↗

bioRxiv2020

Mass mortality of foundation species on rocky shores: another reason why monitoring programs are relevant

Global concern around substantial losses of biodiversity has led to the development of a number of large-scale long-term monitoring programs. In the past few decades, networks were established to obtain appropriate data on the spatial and temporal variation of marine species on rocky shores. Recently, the Marine Biodiversity Observation Network Pole to Pole of the Americas program (MBON P2P) was established and is coordinating biodiversity surveys along coastal areas throughout the continent. In this context, the goal of this paper was to demonstrate whether the proposed MBON P2P sampling protocol is capable of detecting rapid declines in cover of foundation species on Patagonian rocky shores. Changes in mussel beds cover were studied on monitored sites in northern Patagonia. Concurrently, long-term mussel bed dynamics were assessed based on existing data. Results showed that a mussel mortality event could be detected with this methodology. It took less than a year for mussel cover to drop from 90 to almost 0% despite the fact that significant changes in mussel bed cover were not registered in the previous 20 years at the study area. Therefore, yearly monitoring is needed, as a minimum, in order to timely perceive this kind of process. Real-time detection offers the opportunity of properly understanding the causes that lead to the loss of key community components such as these foundation species. Furthermore, it would provide early warning to decision makers enhancing the chances of conservation of natural environments and their key ecosystem services.

systems biology↗

bioRxiv2020

Development and pre-clinical characterization of two therapeutic equine formulations towards SARS-CoV-2 proteins for the potential treatment of COVID-19

In the current global emergency due to SARS-CoV-2 outbreak, passive immunotherapy emerges as a promising treatment for COVID-19. Among animal-derived products, equine formulations are still the cornerstone therapy for treating envenomations due to animal bites and stings. Therefore, drawing upon decades of experience in manufacturing snake antivenom, we developed and preclinically evaluated two anti-SARS-CoV-2 polyclonal equine formulations as potential alternative therapy for COVID-19. We immunized two groups of horses with either S1 (anti-S1) or a mixture of S1, N, and SEM mosaic (anti-Mix) viral recombinant proteins. Horses reached a maximum anti-viral antibody level at 7 weeks following priming, and showed no major adverse acute or chronic clinical alterations. Two whole-IgG formulations were prepared via hyperimmune plasma precipitation with caprylic acid and then formulated for parenteral use. Both preparations had similar physicochemical and microbiological quality and showed ELISA immunoreactivity towards S1 protein and the receptor binding domain (RBD). The anti-Mix formulation also presented immunoreactivity against N protein. Due to high anti-S1 and anti-RBD antibody content, final products exhibited high in vitro neutralizing capacity of SARS-CoV-2 infection, 80 times higher than a pool of human convalescent plasma. Pre-clinical quality profiles were similar among both products, but clinical efficacy and safety must be tested in clinical trials. The technological strategy we describe here can be adapted by other producers, particularly in low- and middle-income countries.

microbiology↗

bioRxiv2020

SUMOylation regulates protein cargo in Astrocyte-derived small extracellular vesicles

Recent studies have described a new mechanism of intercellular communication mediated by various types of extracellular vesicles (EVs). In particular, exosomes are small EVs (sEVs) released to the extracellular environment by the fusion of the endosomal pathway-related multivesicular bodies (containing intraluminal vesicles) with the plasma membrane. sEVs contain a molecular cargo consisting of lipids, proteins, and nucleic acids. However, the loading mechanisms for this complex molecular cargo have not yet been completely elucidated. In that line, the post translational modification SUMO (Small Ubiquitin-like Modifier) has been shown to impact the incorporation of select proteins into sEVs. We therefore decided to investigate whether SUMOylation is a mechanism that defines protein loading to sEVs. In order to investigate the role of SUMOylation in cargo loading into sEVs, we utilized astrocytes, an essential cell type of the central nervous system with homeostatic functions, to study the impact of SUMOylation on the protein cargo of sEVs. Following SUMO overexpression, achieved by transfection of SUMO plasmids or experimental conditions that modulate SUMOylation in primary astrocyte cultures, we detected proteins related to cell division, translation, and transcription by mass-spectrometry. In astrocyte cultures treated with the general SUMOylation inhibitor 2-D08 (2',3',4'-trihydroxy-flavone, 2-(2,3,4-Trihydroxyphenyl)-4H-1-Benzopyran-4-one) we observed an increase in the number of sEVs and a decreased amount of protein cargo within them. In turn, in astrocytes treated with the stress hormone corticosterone, we found an increase of SUMO-2 conjugated proteins and sEVs from these cells contained an augmented protein cargo. In this case, the proteins detected with mass-spectrometry were mostly proteins related to protein translation. To test whether astrocyte-derived sEVs obtained in these experimental conditions could modulate protein synthesis in target cells, we incubated primary neurons with astrocyte-derived sEVs. sEVs from corticosterone-treated astrocytes stimulated protein synthesis while no difference was found with sEVs derived from 2-D08-treated astrocytes. Our results show that SUMO conjugation plays a fundamental role in defining the protein cargo of sEVs impacting the physiological function of target cells.

cell biology↗