Biology subjects

Gaspari, M.

Publications and source records attributed to Gaspari, M..

5 recordsLinked to original sources

bioRxiv2025

Non-neuronal, TGF-β- extracellular matrix restructuring promotes neurodegeneration in a PSP-Richardson syndrome model

Progressive supranuclear palsy-Richardson syndrome (PSP-RS) is a rapidly progressive tauopathy lacking effective therapies. Although tau aggregation is a defining feature, the initiating mechanisms remain elusive. Here we used patient-derived induced pluripotent stem cell midbrain organoids, integrating single-cell transcriptomics, bulk RNA profiling, and quantitative proteomics, to dissect early pathogenic events. We identified vascular leptomeningeal-like cells (VLMCs) as the first altered population, exhibiting TGF-{beta}-driven extracellular matrix (ECM) remodeling enriched in collagens, integrins, and TGFBI. The resulting pathological ECM increased stiffness, induced integrin clustering, and activated RhoA-ROCK-mediated cytoskeletal disorganization. These changes sustained PI3K-AKT and MAPK-ERK signaling, suppressed PP2A, hyperactivated mTOR, and impaired autophagy, culminating in tau hyperphosphorylation and mislocalization. Pharmacological inhibition of TGF-{beta}, AKT, ERK, or mTORC1 restored autophagic flux, reduced tau burden, and rescued neuronal architecture. Our findings establish non-neuronal, matrix-producing niche cells as upstream drivers of tauopathy and reveal TGF-{beta}-mediated ECM restructuring as a mechanochemical trigger of neurodegeneration, opening multiple therapeutic avenues for PSP-RS and related tauopathies.

neuroscience↗

bioRxiv2021

TRAP1 and cyclophilin D compete at OSCP subunit to regulate enzymatic activity and permeability transition pore opening by F-ATP synthase

Binding of the mitochondrial chaperone TRAP1 to client proteins shapes cell bioenergetic and proteostatic adaptations, but the panel of TRAP1 clients is only partially defined. Here we show that TRAP1 interacts with F-ATP synthase, the protein complex that provides most cellular ATP. TRAP1 competes with the peptidyl-prolyl cis-trans isomerase cyclophilin D (CyPD) for binding to the oligomycin sensitivity-conferring protein (OSCP) subunit of F-ATP synthase, increasing its catalytic activity and counteracting the inhibitory effect of CyPD. Moreover, TRAP1 inhibits opening of the permeability transition pore (PTP) formed by F-ATP synthase and effectively antagonizes the PTP-inducing effect of CyPD, which elicits mitochondrial depolarization and cell death. Consistently, electrophysiological measurements indicate that TRAP1 and CyPD compete in the modulation of channel activity of purified F-ATP synthase, resulting in PTP inhibition and activation, respectively, and outcompeting each other effect on the channel. Moreover, TRAP1 counteracts PTP induction by CyPD, whereas CyPD reverses TRAP1-mediated PTP inhibition. Our data identify TRAP1 as a F-ATP synthase regulator that can influence cell bioenergetics and survival and can be targeted in pathological conditions where these processes are dysregulated, such as cancer.

cell biology↗

bioRxiv2021

Intra-epithelial non-canonical Activin A signalling safeguards prostate progenitor quiescence

The healthy prostate is a relatively quiescent tissue. Yet, prostate epithelium overgrowth is a common condition during ageing, associated with urinary dysfunction and tumorigenesis. For over thirty years, TGF-{beta} ligands have been known to induce cytostasis in a large variety of epithelia, but the intracellular pathway mediating this signal in the prostate, as well as its relevance for quiescence, have remained elusive. Here, using mouse prostate organoids to model epithelial progenitors, we found that intra-epithelial non-canonical Activin A signalling inhibited cell proliferation in a Smad-independent manner. Mechanistically, Activin A triggered Tak1 and p38 MAPK activity, leading to p16 and p21 nuclear import. Spontaneous evasion from this quiescent state occurred upon prolonged culture, due to reduced Activin A secretion, a condition associated with DNA replication stress and aneuploidy. Organoids capable to escape quiescence in vitro were also able to implant with increased frequency into immunocompetent mice. Our study demonstrates that non-canonical Activin A signalling safeguards epithelial quiescence in the healthy prostate, with potential implications for the understanding of cancer initiation, and the development of therapies targeting quiescent tumour progenitors.

cancer biology↗

bioRxiv2020

Primate heart regeneration via migration and fibroblast repulsion by human heart progenitors

SUMMARYHuman heart regeneration is one of the most critical unmet clinical needs at a global level1. Muscular regeneration is hampered both by the limited renewing capacity of adult cardiomyocytes2-4 and the onset of cardiac fibrosis5,6, resulting in reduced compliance of the tissue. Primate have proven to be ideal models for pluripotent stem cell strategies for heart regeneration, but unravelling specific approaches to drive cell migration to the site of injury and inhibition of subsequent fibrosis have been elusive. Herein, by combining human cardiac progenitor lineage tracing and single-cell transcriptomics in injured non-human primate heart bio-mimics, we uncover the coordinated muscular regeneration of the primate heart via directed migration of human ventricular progenitors to sites of injury, subsequent fibroblast repulsion targeting fibrosis, and ultimate functional replacement of damaged cardiac muscle by differentiation and electromechanical integration. Single-cell RNAseq captured distinct modes of action, uncovering chemoattraction mediated by CXCL12/CXCR4 signalling and fibroblast repulsion regulated by SLIT2/ROBO1 guidance in organizing cytoskeletal dynamics. Moreover, transplantation of human cardiac progenitors into hypo-immunogenic CAG-LEA29Y transgenic porcine hearts following injury proved their chemotactic response and their ability to generate a remuscularized scar without the risk of arrhythmogenesis in vivo. Our study demonstrates that inherent developmental programs within cardiac progenitors are sequentially activated in the context of disease, allowing the cells to sense and counteract injury. As such, they may represent an ideal bio-therapeutic for functional heart rejuvenation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cell biology↗

bioRxiv2017

3’UTR Remodelling of Axonal Transcripts in Sympathetic Neurons

The 3 untranslated regions (3UTRs) of messenger RNAs (mRNA) are non-coding sequences that regulate several aspects of mRNA metabolism, including intracellular localisation and translation. Here, we show that in sympathetic neuron axons, the 3UTRs of many transcripts undergo cleavage, generating both translatable isoforms expressing a shorter 3UTR, and 3UTR fragments. 3end RNA sequencing indicated that 3UTR cleavage is a potentially widespread event in axons, which is mediated by a protein complex containing the endonuclease Ago2 and the RNA binding protein HuD. Analysis of the Inositol monophosphatase 1 (Impa1) mRNA revealed that a stem loop structure within the 3UTR is necessary for Ago2 cleavage. Thus, remodeling of the 3UTR provides an alternative mechanism that simultaneously regulates local protein synthesis and generates a new class of 3UTR RNAs with yet unknown functions.

neuroscience↗