Biology subjects

Pinson, B.

Publications and source records attributed to Pinson, B..

10 recordsLinked to original sources

bioRxiv2026

Microbiota-gut-brain axis modulation drives glioblastoma progression and therapy resistance

Glioblastoma is a highly aggressive brain tumour with poor prognosis, whose aetiology, progression, and therapeutic resistance remain incompletely understood. While the microbiota-gut-brain axis has emerged as a key regulator of neurological disorders, its role in glioblastoma biology and treatment response is still largely unexplored. Using a clinically relevant immunocompetent murine model combining glioblastoma stem cell implantation, dextran sodium sulfate-induced gut inflammation, and a full Stupp-like therapeutic protocol, we investigated bidirectional gut-brain communication in glioblastoma. Tumour growth and recurrence were monitored by bioluminescence imaging, tumour transcriptomic profiles were analysed by RNA sequencing, and brain and colon tissues were subjected to histological and molecular analyses. Gut microbiota composition was assessed by 16S rRNA sequencing, while systemic metabolites and cytokines were quantified in plasma. Cross-compartment association bioinformatic analyses were performed to correlate multi-organ readouts. Gut inflammation enhanced glioblastoma growth and promoted tumour recurrence following therapy. Tumour progression was associated with increased infiltration of immunosuppressive macrophages, whereas recurrence correlated with elevated oxidative DNA damage. Remarkably, glioblastoma exerted systemic immunomodulatory effects, attenuating intestinal and systemic inflammatory responses, and induced profound remodelling of gut microbiota composition and predicted metabolic function, including enrichment of Akkermansia and depletion of Lactobacillus. Systemic metabolic profiling was investigated as a route of communication within the gut-brain axis and revealed adaptations in DSS-treated mice associated with tumour burden and therapeutic response. Multi-compartment correlation and multivariable association analyses identified specific bacterial genera and circulating metabolites associated with tumour volume, intestinal inflammation, and genomic instability. These findings uncover a dynamic, bidirectional microbiota-gut-brain axis in glioblastoma and identify intestinal inflammation as a critical determinant of tumour progression and therapeutic outcome. Targeting gut disturbances and microbiota-associated metabolic pathways may represent novel strategies to modulate glioblastoma aggressiveness and treatment response.

cancer biology↗

bioRxiv2025

Resistance to Atrial Fibrillation Domestication and Mitochondrial Dysfunction in Sheep: a potential key role of the TCA Cycle and mitochondrial redox state

BackgroundAtrial fibrillation (AF) often progresses from paroxysmal to more stable forms. It is well-recognized that patients vary in their AF progression, but underlying mechanisms remain unclear. This work, performed in a sheep AF-model, aimed to identify atrial redox and energetic status differences between animals developing stable AF (AF-S) versus those resistant to AF-stabilization (AF-R). MethodsAF was monitored with telemetry and maintained with bursts of atrial tachystimulation whenever sinus rhythm resumed. Electrophysiological remodeling was assessed via contact mapping. Structural remodeling was described by histology. Proteomic, metabolomic, enzymatic and bioenergetic remodeling were evaluated using frozen left atrial appendage (LAA) tissues and isolated LAA mitochondria. Healthy young rats were used to investigate if an induced metabolic challenge could stabilize AF episodes upon transesophageal atrial tachypacing challenge. ResultsAF-S sheep developed stable AF (>24-hours self-sustained) after 13 days on average, whereas AF-R sheep failed to develop self-sustained AF despite 120 days of electrically-maintained AF. Contact mapping and histological analysis revealed similar electro-structural remodeling in both groups. Metabolic analysis showed significant differences in tricarboxylic acid (TCA) cycle enzymes activities and a 45% increase in AF-S LAA succinate content versus AF-R. AF-S mitochondria showed abnormal mitochondrial succinate oxidation, associated with a significant 20% decrease in ATP synthesis rate, 22% increase in ROS emission and mitochondrial inner membrane hyperpolarization. The ratios of ATP to ADP, NAD+ to NADH, and Complex I/II were disturbed in AF-S compared to AF-R. Calculated mitochondrial NAD+ to NADH ratios suggest a reduced state of in-vivo AF-R mitochondria compared to the oxidized state of AF-S. Exogenous succinate was metabolized when incubated with rat atrial cardiomyocytes and altered redox balance, while intravenous succinate stabilized atrial arrhythmias induced by tachypacing in vivo. ConclusionsSheep resistant to AF-progression showed specific TCA cycle, energetic and redox adaptations compared to animals that developed self-sustained AF. In this animal model, mitochondrial TCA cycle remodeling and associated redox and energetic responses determined the resistance to AF domestication, with potential relevance to identify new mechanistic determinants of AF progression in humans.

pathology↗

bioRxiv2025

Proteomic profiling of advanced hepatocellular carcinoma identifies predictive signatures of response to treatments

PurposeHepatocellular carcinoma (HCC) is the most common form of liver cancer with a bad prognosis in case of advanced HCC, only eligible for palliative systemic therapies. After a decade of exclusive sorafenib monotherapy, with a response rate of <10%, the advent of immunotherapies represents a revolution in HCC. The combination of atezolizumab/bevacizumab is recommended as the first-line systemic treatment, with a response rate around 30%. However, there are currently no predictive factors for response to these treatment options. Experimental DesignWe profiled, by high-resolution mass spectrometry-based proteomics combined with machine learning analysis, a selected cohort of fixed biopsies of advanced HCC. We grouped subjects according to their objective response to treatments, corresponded to a tumor regression vs tumor progression at 4 months after treatment. ResultsWe generated a proteome database of 50 selected HCC samples. We compared the relative protein abundance between tumoral and non-tumoral liver tissues from advanced HCC patients treated. The clear distinction of these two groups for each treatment is based on deregulation for 141 protein or 87 for atezolizumab/bevacizumab and sorafenib treatment, respectively. These specific proteomic signatures were sufficient to predict the response to treatment, and revealed biological pathways involved in treatments resistance. Particularly, we validated a shift in tumor cell metabolism with an immunosuppressive environment involved in the resistance to atezolizumab/bevacizumab combination. ConclusionsWe performed an in-depth analysis of quantitative proteomic data from HCC biopsies to predict the treatment response to advanced HCC giving the ability to optimize patient management.

cancer biology↗

bioRxiv2024

Novel IF1 mechanism preventing ATP hydrolysis by the ATP synthase subcomplex in Saccharomyces cerevisiae

The mitochondrial F1F0-ATP synthase is crucial for maintaining the ATP/ADP balance which is critical for cell metabolism, ion homeostasis, cell division, proliferation and motility. This enzyme, conserved across evolution, is found in the mitochondria or chloroplasts of eukaryotic cells and the plasma membrane of bacteria. In vitro studies have shown that the mitochondrial F1F0-ATP synthase is reversible, capable of hydrolyzing instead of synthesizing ATP. In vivo, its reversibility is inhibited by the endogenous peptide If1 (Inhibitory Factor 1), which specifically prevents ATP hydrolysis in a pH-dependent manner. Despite its presumed importance, the loss of If1 in various model organisms does not cause severe phenotypes, suggesting its role may be confined to specific stress or metabolic conditions yet to be discovered. In this study, we explored the structural and physiological importances of If1 inhibitory peptides in Saccharomyces cerevisiae. Our analyses indicate that inhibitory peptides are crucial in mitigating metabolic adverse outcomes caused by mitochondrial depolarizing stress under glyco-oxidative metabolic conditions. Under glyco-oxidative metabolic state, the energy maintenance relies both on glycolysis and oxidative phosphorylation. Additionally, we found that the absence of If1 destabilizes the nuclear-encoded free F1 subcomplex. This novel mechanism of action highlights the role of If1 in preventing harmful ATP wastage, offering new insights into its function under physiological and pathological conditions.

biochemistry↗

bioRxiv2024

Mitochondrial maintenance is involved in the exceptional longevity of reproductive queens of the eusocial ant Lasius niger

Most social insects are characterized by a wide disparity in life-history traits between individuals of the same species. Sterile workers live for months or years while queens may live for decades. Theories of ageing emphasise the importance of metabolism and oxidative stress in explaining longevity, with mitochondrial bioenergetics standing at the crossroads of energy and reactive oxygen species production. Studying mitochondrial functioning therefore takes on its full relevance in determining the nature of the mechanisms that explain the contrasting longevities between insect social castes. We addressed this question in an eusocial species, the black garden ant Lasius niger. We found that caste differences in mitochondrial bioenergetics and oxidative balance only partially match with predictions of the oxidative stress theory of ageing. Long-lived queens were characterized by a lower metabolic rate, lower mitochondrial density yet not necessarily lower levels of mitochondrial oxidative damages. Despite this, queens did not show reduced ATP content; rather, they even possessed a higher energy load in their mitochondria. Converging clues suggested better mitochondrial maintenance in queen ants, with enhanced dynamics of mitochondrial fission and fusion and a more marked expression of mitochondrial enzymes of the Krebs cycle. Overall, our data paves the way for studying deeper into how the rate of ATP production per mitochondria is related to the investment in mitochondrial and somatic cellular maintenance, and whether it has specifically been selected as a key mechanism in defining the still unexplained paradoxical longevity of the queen reproductive caste.

physiology↗

bioRxiv2023

Purine biosynthesis pathways are required for myogenesisin Xenopus laevis

Purines are required for fundamental biological processes and alterations in their metabolism lead to severe genetic diseases associated with developmental defects whose etiology remains unclear. Here, we studied the developmental requirements for purine metabolism using the amphibian Xenopus laevis as a vertebrate model. We provide the first functional characterization of purine pathway-genes and show that these genes are mostly expressed in nervous and muscular embryonic tissues. Morphants were generated to decipher the functions of these genes, with a focus on the adenylosuccinate lyase (ADSL), an enzyme required for both salvage and de novo purine pathways. adsl.L knock-down leads to severe reduction in the expression of the Myogenic Regulatory Factors (MRFs: Myod1, Myf5 and Myogenin), thus resulting in defects in somitogenesis and in the formation and/or migration of both craniofacial and hypaxial muscle progenitors. Similar alterations were observed upon reduced expression of hprt1.L and ppat, two genes specific to the salvage and the de novo pathways, respectively. In conclusion, our data shows for the first time that de novo and recycling purine pathways are essential for myogenesis and highlight new mechanisms in the regulation of MRFs gene expression.

developmental biology↗

bioRxiv2022

Antiviral effect of thiazolides relies on mitochondrial mild uncoupling

BackgroundViruses are dependent on cellular energy metabolism for their replication, the drug Nitazoxanide (Alinia) was shown to interfere with both. An effect of Alinia on cellular energy metabolism is the uncoupling of mitochondrial oxidative phosphorylation (OXPHOS). Our hypothesis was that uncoupling grounds the antiviral properties of Alinia. MethodsAlinia or an unrelated uncoupler were applied to a viral releasing cell line to obtain the same increasing levels of uncoupling hence identical interference with OXPHOS. FindingsDecrease in infectious viral particles release reflected the intensity of interference irrespective of the nature of the drug and was significant with modest deviation ([≤]25%) from normal. InterpretationsA mild interference on cellular energy metabolism impacts significantly on viral replication cycle. This would explain Alinias antiviral properties in vitro moreover antiviral action of Alinia is supported by clinical trials. PerspectivesAltogether this indicates that moderate interference with mitochondrial bioenergetics should be considered as a ground for a therapeutic effect. In addition, Alinia would constitute example for a safe therapeutical use of an uncoupler, which deserves consideration for a wider range of applications.

biochemistry↗

bioRxiv2022

The Dct-/- mouse model to unravel retinogenesis misregulation in patients with albinism

We have recently identified DCT encoding dopachrome tautomerase (DCT) as the 8th gene for oculocutaneous albinism (OCA). Patients with loss of function of DCT suffer from eye hypopigmentation and retinal dystrophy. Here we investigate the eye phenotype in Dct-/- mice. We show that their retinal pigmented epithelium (RPE) is severely hypopigmented from early stages contrasting with the darker melanocytic tissues. Multimodal imaging reveals specific RPE cellular defects. Melanosomes are fewer with correct subcellular localization but disrupted melanisation. RPE cell size is globally increased and heterogeneous. P-cadherin labeling of Dct-/- newborn RPE reveals a defect in adherens junctions similar to what has been described in tyrosinase-deficient Tyrc/c embryos. The first intermediate of melanin biosynthesis, dihydroxyphenylalanine (L-Dopa), which is thought to control retinogenesis, is detected in substantial yet significantly reduced amounts in Dct-/- postnatal mouse eyecups. L-Dopa synthesis in the RPE alone remains to be evaluated during the critical period of retinogenesis. The Dct-/- mouse should prove useful in understanding the molecular regulation of retinal development and aging of the hypopigmented eye. This may guide therapeutic strategies to prevent vision deficits in patients with albinism.

genetics↗

bioRxiv2021

Fungal gasdermin-like proteins are controlled by proteolytic cleavage

Gasdermins are a family of pore-forming proteins controlling an inflammatory cell death reaction in the mammalian immune system. The pore-forming ability of the gasdermin proteins is released by proteolytic cleavage with the removal of their inhibitory C-terminal domain. Recently, gasdermin-like proteins have been discovered in fungi and characterized as cell death-inducing toxins in the context of conspecific non-self discrimination (allorecognition). Although functional analogies have been established between mammalian and fungal gasdermins, the molecular pathways regulating gasdermin activity in fungi remain largely unknown. Here, we characterize a gasdermin-based cell death reaction, controlled by the het-Q allorecognition genes in the filamentous fungus Podospora anserina. We show that the cytotoxic activity of the HET-Q1 gasdermin is controlled by proteolysis. HET-Q1 loses a [~]5 kDa C-terminal fragment during the cell death reaction in presence of a subtilisin-like serine protease, termed HET-Q2. Mutational analyses and successful reconstitution of the cell death reaction in a heterologous host (Saccharomyces cerevisiae) suggest that HET-Q2 directly cleaves HET-Q1 to induce cell death. By analysing the genomic landscape of het-Q1 homologs in fungi, we uncovered that the vast majority of the gasdermin genes are clustered with protease-encoding genes. These HET-Q2-like proteins carry either subtilisin-like or caspase-related proteases, which in some cases correspond to the N-terminal effector domain of NOD-like receptor proteins (NLRs). This study thus reveals the proteolytic regulation of gasdermins in fungi and establishes evolutionary parallels between fungal and mammalian gasdermin-dependent cell death pathways. SignificanceThe recent discovery of gasdermin-like proteins in fungi have brought to light that this family of pore-forming proteins controls cell death in two of the major eukaryotic kingdoms, fungi and mammals. Yet, the regulation of cytotoxicity of the fungal gasdermins and their molecular pathways remain uncharacterized. Here, we describe the regulation through proteolytic cleavage of the fungal gasdermin HET-Q1 and uncover that majority of fungal gasdermins are genomically clustered with protease-encoding genes. Some of these genes encode proteins with caspase-related domains and/or are members of a family of immune receptors in mammals and plants. Overall, this work contributes towards our understanding of the evolution of gasdermin-dependent cell death, enlightening multiple evolutionary parallels between signaling pathways in mammals and fungi.

genetics↗

bioRxiv2018

Adenylosuccinate Lyase activity in the Purine recycling pathway is essential for developmental timing, germline maintenance and muscle integrity in C. elegans.

Purine homeostasis is ensured through a metabolic network widely conserved from prokaryotes to humans. Purines can either be synthesized de novo, reused, or produced by interconversion of extant metabolites using the so-called recycling pathway. Although thoroughly characterized in microorganisms, such as yeast or bacteria, little is known about the regulation of this biosynthesis network in metazoans. In humans, several diseases are linked to purine biosynthesis deficiencies through yet poorly understood etiologies. Particularly, the deficiency in Adenylosuccinate Lyase (ADSL), one enzyme involved both in the purine de novo and recycling pathways, causes severe muscular and neuronal symptoms. In order to address the mechanisms underlying this deficiency, we established Caenorhabditis elegans as a metazoan model organism to study purine metabolism, while focusing on ADSL. We show that the purine biosynthesis network is functionally conserved in C. elegans. Moreover, ADSL is required for developmental timing and germline stem cell maintenance, and muscle integrity. Our results allow to ascribe developmental and tissue specific phenotypes to separable steps of the purine metabolic network in an animal model. Particularly, the muscle, germline and developmental defects are linked specifically to the ADSL role in the purine recycling pathway.

genetics↗