Publications by authors named "Franck Peiretti"

Background: Inherited platelet diseases are bleeding disorders characterized by either defects in platelet count or platelet function, the latter being less common and very heterogeneous. Numerous gene variants associated with abnormal receptors, granules, and signaling pathways have been reported. Despite significant advancements in our understanding, many patients still lack a precise diagnosis.

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  • The thrombomodulin (TM) variant c.1611C>A causes the production of a truncated protein (TM536) lacking a cytoplasmic tail and with a shorter transmembrane domain, but little is known about how it is released from cells.
  • Research using different endothelial cells showed that TM536 is released through a unique mechanism involving its insertion into the endoplasmic reticulum, where it escapes and enters the typical secretory pathway without being broken down.
  • This abnormal release process leads to a soluble TM536 that is less effective at performing its role in activating protein C and is also retained in the early secretory pathway, making it more susceptible to degradation and reducing its presence on the cell surface
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  • The insulin receptor (IR) is crucial for insulin signaling, and defects in its function are linked to type 2 diabetes.
  • This study explores how the removal of sialic acid from N-glycan chains of the IR affects its function, particularly in 3T3-L1 adipocytes.
  • Findings show that desialylation reduces the autophosphorylation activity of the IR and weakens its ability to interact with insulin, potentially contributing to insulin resistance in diabetes.
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Abetalipoproteinemia (FHBL-SD1) and chylomicron retention disease (FHBL-SD3) are rare recessive disorders of lipoprotein metabolism due to mutations in and genes, respectively, which lead to defective chylomicron formation and secretion. This results in lipid and fat-soluble vitamin malabsorption, which induces severe neuro-ophthalmic complications. Currently, treatment combines a low-fat diet with high-dose vitamin A and E supplementation but still fails in normalizing serum vitamin E levels and providing complete ophthalmic protection.

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Objective: Systemic sclerosis (SSc) is an autoimmune disorder characterized by excessive fibrosis, immune dysfunction, and vascular damage, in which the expression of many growth factors is deregulated. CD146 was recently described as a major actor in SSc. Since CD146 also exists as a circulating soluble form (sCD146) that acts as a growth factor in numerous angiogenic- and inflammation-related pathologies, we sought to identify the mechanisms underlying the generation of sCD146 and to characterize the regulation and functions of the different variants identified in SSc.

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Background: GATA1 is an essential transcription factor for both polyploidization and megakaryocyte (MK) differentiation. The polyploidization defect observed in GATA1 variant carriers is not well understood.

Objective: To extensively phenotype two pedigrees displaying different variants in the GATA1 gene and determine if GATA1 controls MYH10 expression levels, a key modulator of MK polyploidization.

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The cleavage of the insulin receptor by β-secretase 1 (BACE1) in the liver increases during diabetes, which contributes to reduce insulin receptor levels and impair insulin signaling. However, the precise signaling events that lead to this increased cleavage are unclear. We showed that BACE1 cleaves the insulin receptor in the early secretory pathway.

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Rare variants outside the classical coagulation cascade might cause inherited thrombosis. We aimed to identify the variant(s) causing venous thromboembolism (VTE) in a family with multiple relatives affected with unprovoked VTE and no thrombophilia defects. We identified by whole exome sequencing an extremely rare Arg to Gln variant (Arg89Gln) in the Microtubule Associated Serine/Threonine Kinase 2 (MAST2) gene that segregates with VTE in the family.

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Ethnopharmacological Relevance: Citrullus colocynthis (L.) Schrad is a common fruit in traditional medicine and used as remedy against various diseases, especially diabetes. Up to now, its anti-diabetic effects have been fully attributed to its enhancement of pancreatic insulin secretion.

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Fluorophore 2',7'-dichlorofluorescin (DCF) is the most frequently used probe for measuring oxidative stress in cells, but many aspects of DCF remain to be revealed. Here, DCF was used to study the Fenton reaction in detail, which confirmed that in a cell-free system, the hydroxyl radical was easily measured by DCF, accompanied by the consumption of H2O2 and the conversion of ferrous iron into ferric iron. DCF fluorescence was more specific for hydroxyl radicals than the measurement of thiobarbituric acid (TBA)-reactive 2-deoxy-D-ribose degradation products, which also detected H2O2.

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Thermogenic brown and brite adipocytes convert chemical energy from nutrients into heat. Therapeutics that regulate brown adipocyte recruitment and activity represent interesting strategies to control fat mass such as in obesity or cachexia. The peroxisome proliferator-activated receptor (PPAR) family plays key roles in the maintenance of adipose tissue and in the regulation of thermogenic activity.

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A proprietary library of novel -aryl-substituted amino acid derivatives bearing a hydroxamate head group allowed the identification of compound that possesses weak proadipogenic and peroxisome proliferator-activated receptor γ (PPARγ) activating properties. The systematic optimization of , in order to improve its PPARγ agonist activity, led to the synthesis of compound (-aryl-substituted valine derivative) that possesses dual PPARγ/PPARα agonistic activity. Structural and kinetic analyses reveal that occupies the typical ligand binding domain of the PPARγ agonists with, however, a unique high-affinity binding mode.

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Glycine receptors (GlyRs) are indispensable for maintaining excitatory/inhibitory balance in neuronal circuits that control reflexes and rhythmic motor behaviors. Here we have developed Glyght, a GlyR ligand controlled with light. It is selective over other Cys-loop receptors, is active in vivo, and displays an allosteric mechanism of action.

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PPARγ represents a key target for the treatment of type 2 diabetes and metabolic syndrome. Synthetic antidiabetic drugs activating PPARγ are accompanied by serious undesirable side effects related to their agonism. In the search for new PPARγ regulators, inhibitors of PPARγ phosphorylation on S245 mediated by CDK5 represent an opportunity for the development of an improved generation of antidiabetic drugs acting through this nuclear receptor.

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On the basis of a recent article "" that appeared in , we had decided to highlight the way forward for artificial intelligence in chemistry. Synthesis of molecules remains one of the most important challenges in organic chemistry, and the standard approach involved by a chemist to solve a problem is based on experience and constitutes a repetitive, time-consuming task, often resulting in nonoptimized solutions. Thus, considering the recent phenomenal progresses that have been made in machine learning, there is little doubt that these systems, once fully operational in organic chemistry, will dramatically speed up development of new drugs and will constitute the future of chemistry.

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Increased platelet activity occurs in type 2 diabetes mellitus (T2DM) and such platelet dysregulation likely originates from altered megakaryopoiesis. We initiated identification of dysregulated pathways in megakaryocytes in the setting of T2DM. We evaluated through transcriptomic analysis, differential gene expressions in megakaryocytes from leptin receptor-deficient mice (db/db), exhibiting features of human T2DM, and control mice (db/+).

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Background And Purpose: Anion-selective Cys-loop receptors (GABA and glycine receptors) provide the main inhibitory drive in the CNS. Both types of receptor operate via chloride-selective ion channels, though with different kinetics, pharmacological profiles, and localization. Disequilibrium in their function leads to a variety of disorders, which are often treated with allosteric modulators.

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A new series of derivatives of the PPARα/γ dual agonist 1 allowed us to identify the ligand ( S)-6 as a potent partial agonist of both PPARα and γ subtypes. X-ray studies in PPARγ revealed two different binding modes of ( S)-6 to the canonical site. However, ( S)-6 was also able to bind an alternative site as demonstrated by transactivation assay in the presence of a canonical PPARγ antagonist and supported from docking experiments.

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Insulin receptor (IR) plays a key role in the control of glucose homeostasis; however, the regulation of its cellular expression remains poorly understood. Here we show that the amount of biologically active IR is regulated by the cleavage of its ectodomain, by the β-site amyloid precursor protein cleaving enzyme 1 (BACE1), in a glucose concentration-dependent manner. In vivo studies demonstrate that BACE1 regulates the amount of IR and insulin signaling in the liver.

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The emergence of multidrug-resistant bacteria and pathogens has created an urgent need for the development of new antibiotics. Herein we report our investigations into the broad-spectrum activity of an easily prepared water-soluble polyaminosterol compound, namely claramine A1, against both drug-sensitive and drug-resistant Gram-negative and Gram-positive bacterial strains. We also report its peculiar mechanism of action, which differs from that of all the other well-known classes of antibiotics, toward Gram-negative and Gram-positive bacteria.

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PPAR antagonists are ligands that bind their receptor with high affinity without transactivation activity. Recently, they have been demonstrated to maintain insulin-sensitizing and antidiabetic properties, and they serve as an alternative treatment for metabolic diseases. In this work, an affinity-based bioassay was found to be effective for selecting PPAR ligands from the dried extract of an African plant (Diospyros bipindensis).

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Niflumic acid (NFA) is a member of the fenamate class of nonsteroidal anti-inflammatory drugs. This compound and its derivatives are used worldwide clinically for the relief of chronic and acute pain. NFA is also a commonly used blocker of voltage-gated chloride channels.

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Congenital macrothrombocytopenia is a family of rare diseases, of which a significant fraction remains to be genetically characterized. To analyze cases of unexplained thrombocytopenia, 27 individuals from a patient cohort of the Bleeding and Thrombosis Exploration Center of the University Hospital of Marseille were recruited for a high-throughput gene sequencing study. This strategy led to the identification of two novel variants (c.

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Scope: Here we tested the hypothesis that ascorbic acid (AA) is a signaling molecule acting on stem cells via the differentiation of mesoderm derivatives, including myocytes, osteocytes, and adipocytes.

Material And Methods: Investigations used a murine embryonic stem cell line CGR8 able to differentiate into different cell types and treated or not with ascorbic acid. Differentiation was tracked mainly through cellular anatomy (including presence of beating cardiomyocytes) and expression of specific markers.

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