Biology subjects

Piacentini, M.

Publications and source records attributed to Piacentini, M..

4 recordsLinked to original sources

bioRxiv2026

Endothelial AMBRA1 loss contributes to vascular dysregulation facilitating metastatic progression in early-stage melanoma

Validated biomarkers for identifying patients with early-stage melanomas at high risk of metastasis are limited. We have previously shown that loss of Activating Molecule in Beclin-1-Regulated Autophagy (AMBRA1) and loricrin in the epidermal microenvironment is associated with tumour recurrence. Here we show that endothelial AMBRA1 deficiency contributes to vascular dysfunction and melanoma progression. Melanoma-conditioned media or exposure to TGF{beta}1-3 ligands induced post-transcriptional loss of AMBRA1 in endothelial cells. Transcriptomic profiling in both in vitro and human melanoma single-cell RNA sequencing datasets showed activation of cell-cycle and metabolic programmes alongside suppression of endothelial junction, adhesion and immune-supportive pathways in AMBRA1-deficient endothelial cells. Functionally, AMBRA1 loss increased endothelial cell proliferation, accelerated early tubulogenesis, impaired three-dimensional spheroid adhesion, stabilised endothelial-to-mesenchymal transition-associated transcription factors Slug and Snail, and reduced Claudin-5, VE-cadherin and N-cadherin, indicative of endothelial plasticity and dysfunction. Furthermore, loss of AMBRA1 in a subset of intratumoural and peritumoural blood and lymphatic vessels correlated significantly with metastatic progression in a cohort of 121 non-ulcerated primary AJCC stage I/II melanomas classified as AMBLor at-risk. Collectively, these findings position endothelial AMBRA1 as a regulator of vascular plasticity, dysfunction, and immune-supportive endothelial function in early-stage melanomas, and a marker of a permissive microenvironment associated with metastasis.

cancer biology↗

bioRxiv2024

Epigenetic modulation of RIPK3 by Transglutaminase 2-dependent serotonylation of H3K4me3 affects necroptosis

The receptor interacting protein kinase 3 (RIPK 3) is the main player in the activation of necroptosis, a pro-inflammatory regulated cell death modality induced by many different stimuli. RIPK3 is epigenetically regulated by DNA methylation and can be expressed when its promoter is associated with H3K4me3 histone. In this study, we show that Transglutaminase 2 protein (TG2) is necessary to induce necroptosis pathway allowing the expression of Ripk3 gene. Indeed, cells lacking TG2 show a strong downregulation of Ripk3 gene and are resistant to necroptotic stimuli. TG2 is known to promote the serotonylation of H3K4me3 histone (H3K4me3Q5ser) regulating in this way the target gene expression. Interestingly, we find that TG2 interacts with both histones H3K4me3 and H3K4me3Q5ser and these post-translational modifications are associated with the Ripk3 promoter only in presence of TG2. In addition, the absence of the H3K4me3Q5ser, in cells lacking TG2, is correlated with Ripk3 gene methylation. Altogether, these results indicate that RIPK3 expression requires TG2 mediated serotonylation of H3K4me3 to prevent Ripk3 promoter methylation, thus favouring its expression and necroptosis induction. HIGHLIGHTS- Transglutaminase 2 protein (TG2) is necessary to induce necroptosis. - Cells lacking TG2 show a strong downregulation of Ripk3 gene. - TG2 allows Ripk3 gene expression by promoting the serotonylation on H3K4me3 histone. SYNOPSIS O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/619049v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@12c95c6org.highwire.dtl.DTLVardef@1cfbcaorg.highwire.dtl.DTLVardef@d6be1forg.highwire.dtl.DTLVardef@5bfb31_HPS_FORMAT_FIGEXP M_FIG C_FIG - TG2 serotonylates histone H3K4me3, associated to Ripk3 promoter, favoring its expression. - TG2 dependent serotonylation of histone H3K4me3 prevents DNA methylation. - TG2 favours the expression of Ripk3 making cells susceptible to necroptosis. - In the absence of TG2, neither serotonylation nor methylation occur on histone H3, associated to Ripk3 promoter. - In the absence of TG2, Ripk3 promoter is methylated, thus blocking the activation of necroptosis.

cell biology↗

bioRxiv2023

The purinergic receptor P2X7 and the NLRP3 inflammasome are druggable host factors required for SARS-CoV-2 infection

Purinergic receptors and NOD-like receptor protein 3 (NLRP3) inflammasome regulate inflammation and viral infection, but their effects on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remain poorly understood. Here, we report that the purinergic receptor P2X7 and NLRP3 inflammasome are cellular host factors required for SARS-CoV-2 infection. Lung autopsies from patients with severe coronavirus disease 2019 (COVID-19) reveal that NLRP3 expression is increased in host cellular targets of SARS-CoV-2 including alveolar macrophages, type II pneumocytes and syncytia arising from the fusion of infected macrophages, thus suggesting a potential role of NLRP3 and associated signaling pathways to both inflammation and viral replication. In vitro studies demonstrate that NLRP3-dependent inflammasome activation is detected upon macrophage abortive infection. More importantly, a weak activation of NLRP3 inflammasome is also detected during the early steps of SARS-CoV-2 infection of epithelial cells and promotes the viral replication in these cells. Interestingly, the purinergic receptor P2X7, which is known to control NLRP3 inflammasome activation, also favors the replication of D614G and alpha SARS-CoV-2 variants. Altogether, our results reveal an unexpected relationship between the purinergic receptor P2X7, the NLRP3 inflammasome and the permissiveness to SARS-CoV-2 infection that offers novel opportunities for COVID-19 treatment.

microbiology↗

bioRxiv2020

Looking for pathways related to COVID-19 phenotypes: Confirmation of pathogenic mechanisms by SARS-CoV-2 - Host interactome.

In the last months, many studies have clearly described several mechanisms of SARS-CoV-2 infection at cell and tissue level. Host conditions and comorbidities were identified as risk factors for severe and fatal disease courses, but the mechanisms of interaction between host and SARS-CoV-2 determining the grade of COVID- 19 severity, are still unknown. We provide a network analysis on protein-protein interactions (PPI) between viral and host proteins to better identify host biological responses, induced by both whole proteome of SARS-CoV-2 and specific viral proteins. A host-virus interactome was inferred on published PPI, using an explorative algorithm (Random Walk with Restart) triggered by all the 28 proteins of SARS-CoV-2, or each single viral protein one-by-one. The functional analysis for all proteins, linked to many aspects of COVID-19 pathogenesis, allows to identify the subcellular districts, where SARS-CoV-2 proteins seem to be distributed, while in each interactome built around one single viral protein, a different response was described, underlining as ORF8 and ORF3a modulated cardiovascular diseases and pro-inflammatory pathways, respectively. Finally, an explorative network-based approach was applied to Bradykinin Storm, highlighting a possible direct action of ORF3a and NS7b to enhancing this condition. This network-based model for SARS-CoV-2 infection could be a framework for pathogenic evaluation of specific clinical outcomes. We identified possible host responses induced by specific proteins of SARS-CoV-2, underlining the important role of specific viral accessory proteins in pathogenic phenotypes of severe COVID-19 patients.

microbiology↗