Biology subjects

Benoit, V.

Publications and source records attributed to Benoit, V..

7 recordsLinked to original sources

bioRxiv2026

Development of the 4TREE SNP array, a forest multispecies array to enhance European Breeding and conservation programs in pine, poplar and ash.

Within the framework of the European Adaptive BREEDING for Better FORESTs project (B4EST, https://b4est.eu/), we have developed genotyping tools for Poplar, Ash, and Pine forest tree species. SNP arrays are attractive genotyping tools because of the user-friendly genotype calling system and the robust transferability among laboratories. Here we describe the development of an Axiom SNP array for Pinus pinaster (13,407 SNPs), Pinus pinea (5,671 SNPs), Poplar spp. (13,408 SNPs), and Fraxinus spp. (13,407 SNPs) based on a two-step process. We first assembled a high-density (>100,000 SNPs/species) screening array that served to test a large panel of candidate SNPs on a diversity panel involving at least 120 individual trees per species or species group. In the second step, we selected and combined the most informative SNPs to build the final 50,000 SNP 4TREE array. This approach resulted in high genotyping success rates, including for species lacking previously validated high-quality SNP resources. The 4TREE SNP array provides a valuable and transferable genomic tool to support genomic prediction, breeding, and adaptive management of forest tree species.

genomics↗

bioRxiv2026

SIX1-dependent myofiber typology and metabolism controls muscle hypertrophy

The different types of muscle fibres respond in a specific way to hypertrophy or atrophy. The mechanisms underlying these heterogeneous adaptations remain poorly understood. Using single-nucleus RNA sequencing, we propose that fast glycolytic fibres show genetic limitations to hypertrophy induced by mechanical overload. We show that a prior fibre transition, achieved by reducing SIX1 protein expression (hypomorphism), enhances and accelerates overload-induced hypertrophy, bypassing the genetic limitations of fast glycolytic fibres. In contrast and unexpectedly, Six1 knockout in myofibers abolished overload-induced hypertrophy and instead caused atrophy of IIb/IIx fibers, despite the induction of a strong slow oxidative phenotype. In particular, Six1 deletion leads to metabolic defects caused by inhibition of glycolysis, AMPK and mitochondrial biogenesis. Our findings highlight the critical role of SIX1/AMPK/glycolysis-dependent aerobic metabolism in muscle growth and suggest that fibre type transitions, coupled with preserved metabolic function, may optimise hypertrophic responses.

physiology↗

bioRxiv2025

Blocking somatic repeat expansion and lowering huntingtin via RNA interference synergize to prevent Huntingtons disease pathogenesis in mice

Huntingtons disease (HD) is a progressive neurodegenerative disorder with no approved therapies. Two major molecular drivers--somatic expansion of inherited CAG repeats and toxic mutant HTT (mHTT) variants--lead to neuronal dysfunction. Despite multiple trials, HTT-lowering strategies have not shown meaningful clinical benefit. Using therapeutic divalent siRNAs, we assessed the long-term impact of silencing MSH3 (a key regulator of somatic expansion), HTT, or both. In Q111 HD mice (>110 CAGs), which exhibit robust expansion, mHTT inclusions, and transcriptional dysregulation by 12 months, long-term MSH3 silencing blocked expansion, reduced inclusions, and reversed gene expression changes. HTT silencing alone had limited effect, but combined MSH3/HTT targeting synergistically eliminated inclusions and restored transcriptomic profiles. Parallel treatment in wild-type mice showed no toxicity, supporting the safety of long-term intervention. These findings position somatic expansion as a promising therapeutic target and demonstrate the potential of RNAi-based co-silencing of MSH3 and HTT as a disease-modifying strategy for HD.

neuroscience↗

bioRxiv2023

Pharmacological AMP-activated protein kinase activation suppresses low glucose-dependent macrophage migration inhibitory factor release from macrophages

Aims/hypothesisAcute hypoglycemia promotes pro-inflammatory cytokine production, increasing risk for cardiovascular events in diabetes. AMP-activated protein kinase (AMPK) is regulated by and influences production of pro-inflammatory cytokines. We tested the mechanistic role of AMPK in low glucose induced changes in the pro-inflammatory cytokine macrophage migration inhibitory factor (MIF), which is elevated in patients with diabetes. MethodsMacrophage cell line Raw264.7 cells, primary macrophage bone marrow derived macrophages obtained from wild type mice or AMPK {gamma}1 gain-of-function mice were utilized, as were AMPK1/2 knockout mouse embryonic fibroblasts (MEF). Allosteric AMPK activators PF-06409577 and BI-9774 were used, in conjunction with inhibitor SBI-0206965 were also used. We examined changes in protein phosphorylation/expression using western blotting, and protein localisation using immunofluorescence. Metabolic function was assessed using extracellular flux analyses and luciferase-based ATP assay. Cytokine release was quantified by ELISA. Oxidative stress was detected using a fluorescence-based ROS assay, and cell viability was examined using flow cytometry. ResultsMacrophages exposed to low glucose showed a transient and modest activation of AMPK and a metabolic shift towards increased oxidative phosphorylation. Low glucose induced oxidative stress and increased release of macrophage migration inhibitory factor (MIF). Pharmacological activation of AMPK by PF-06409577 and BI-9774 attenuated low glucose-induced MIF release, with a similar trend noted with genetic activation using AMPK{gamma}1 gain-of-function (D316A) mice, which produced a mild effect on low glucose-induced MIF release. Inhibition of NFB signalling diminished MIF release and AMPK activation modestly but significantly reduced low glucose-induced nuclear translocation of NFB. AMPK activation did not alter low glucose-induced oxidative stress in macrophages but application of AMPK inhibitor SBI-0206965 enhanced oxidative stress in macrophages and in AMPK knockout MEFs, suggesting an AMPK-independent mechanism Conclusions/interpretationTaken together, these data indicate that pharmacological AMPK activation suppresses release of MIF from macrophages. This is mediated by reduced activation of NFB signalling in response to low glucose-induced oxidative stress and suggests that pharmacological AMPK activation could be a useful strategy for mitigating hypoglycemia-induced inflammation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/562445v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1d3364borg.highwire.dtl.DTLVardef@1919395org.highwire.dtl.DTLVardef@704923org.highwire.dtl.DTLVardef@1d1cc59_HPS_FORMAT_FIGEXP M_FIG Tweet Low glucose induces pro-inflammatory MIF release from macrophages, and pharmacological AMPK activation suppresses the release of MIF. AMPK/ NFB signalling pathway is involved, which may be a new strategy to attenuate the pro-inflammatory response in hypoglycemia. C_FIG

pharmacology and toxicology↗

bioRxiv2022

Metformin improves glycemia independently of skeletal muscle AMPK via enhanced intestinal glucose clearance

Metformin is an inexpensive oral anti-hyperglycemic agent used worldwide as a first-choice drug for the prevention of type 2 diabetes mellitus (T2DM). Although current view suggests that metformin exerts its anti-hyperglycemic effect by lowering hepatic glucose production, it has been proposed that metformin also reduce hyperglycemia by increasing glucose uptake in skeletal muscle via activation of AMP-activated protein kinase (AMPK). Herein, we demonstrate in lean and diet-induced obese (DIO) male and female mouse models that the anti-hyperglycemic effect of metformin occurs independently of muscle AMPK, and instead relies on elevated intestinal glucose clearance. Furthermore, we report that the AMPK activity is elevated in skeletal muscle from patients with T2DM following chronic metformin treatment, but this is not associated with enhanced peripheral insulin sensitivity. These results argue against existing paradigms and emphasize the non-essential role of muscle AMPK but important role of the intestine for the anti-hyperglycemic effect of metformin.

physiology↗

bioRxiv2022

Prolactin-induced AMPK stabilizes alveologenesis and lactogenesis through regulation of STAT5 signaling

AMP-activated protein kinase (AMPK) is an evolutionarily conserved serine/threonine kinase that regulates energy homeostasis at cellular and organismal levels. It has been shown to affect several steps of breast cancer progression in a context-dependent manner. However, its role in normal mammary gland development and physiology remains ill-explored. Here, we show that AMPK expression and activity increased within murine mammary epithelia from puberty to pregnancy with highest levels during lactation, and then declined during involution. In ex vivo cultures of mammary epithelial cells (MECs) in organotypic scaffolds, treatment with lactogenic hormone prolactin (PRL) enhanced AMPK expression and activity. To understand the role of AMPK on mammary morphogenesis in vivo, we generated mice with conditional knockout of AMPK isoforms 1 and 2 (AMPK KO) in MECs. AMPK KO mammary glands showed accelerated alveolar development with increased epithelial content of both luminal and myoepithelial lineages, suggestive of hyperproliferation. AMPK KO mice also showed elevated beta-casein expression during pregnancy and lactation. These observations were phenocopied upon treatment of ex vivo cultivated wild-type MECs with a cognate AMPK inhibitor. AMPK null MECs showed increased phosphorylated STAT5 which is known to drive alveologenesis downstream of prolactin signaling. Our study identifies a novel interplay between AMPK and PRL-STAT5 signaling that determines mammary alveologenesis and differentiation.

developmental biology↗

bioRxiv2020

Myeloid deletion and therapeutic activation of AMP-activated protein kinase (AMPK) do not alter atherosclerosis in male or female mice

ObjectiveThe dysregulation of myeloid-derived cell metabolism can drive atherosclerosis. AMP-activated protein kinase (AMPK) controls various aspects of macrophage dynamics and lipid homeostasis, which are important during atherogenesis. Approach and ResultsWe aimed to clarify the role of myeloid-specific AMPK signaling by using LysM-Cre to drive the deletion of both the 1 and 2 catalytic subunits (MacKO), in male and female mice made acutely atherosclerotic by PCSK9-AAV and Western diet-feeding. After 6 weeks of Western diet feeding, half received daily injection of either the AMPK activator, A-769662 or a vehicle control for a further 6 weeks. After 12 weeks, myeloid cell populations were not different between genotype or sex. Similarly, aortic sinus plaque size, lipid staining and necrotic area were not different in male and female MacKO mice compared to their littermate floxed controls. Moreover, therapeutic intervention with A-769662 had no effect. There were no differences in the amount of circulating total cholesterol or triglyceride, and only minor differences in the levels of inflammatory cytokines between groups. Finally, CD68+ area or markers of autophagy showed no effect of either lacking AMPK signaling or systemic AMPK activation. ConclusionsOur data suggest that while defined roles for each catalytic AMPK subunit have been identified, global deletion of myeloid AMPK signaling does not significantly impact atherosclerosis. Moreover, we show that intervention with the first-generation AMPK activator, A-769662, was not able to stem the progression of atherosclerosis. Highlights- The deletion of both catalytic subunits of AMPK in myeloid cells has no significant effect on the progression of atherosclerosis in either male or female mice - Therapeutic delivery of a first-generation AMPK activator (A-769662) for the last 6 weeks of 12-week study had no beneficial effect in either male or female mice - Studying total AMPK deletion may mask specific effects of each isoform and highlights the need for targeted disruption of AMPK phosphorylation sites via knock-in mutations, rather than the traditional "sledgehammer" knockout approach

biochemistry↗