Biology subjects

McDonagh, B.

Publications and source records attributed to McDonagh, B..

12 recordsLinked to original sources

bioRxiv2026

Peroxiredoxin 6 limits mitochondrial peroxidation to prevent mitochondrial ER contact site assembly and inflammatory signalling following adaptive stress

Peroxiredoxin 6 (PRDX6) is a multifunctional enzyme with peroxidase, calcium independent phospholipase A2 (aiPLA2) and lysophospatidylcholine acyltransterase (LPCAT) activities. Although PRDX6 can repair peroxidised phospholipids and help prevent ferroptosis, its role in the adaptive response to physiological oxidative stress remains unclear. In this study PRDX6 function was investigated using myoblasts exposed to an acute low concentration of H2O2 and Caenorhabditis elegans subjected to a swimming intervention. Mild oxidative stress promoted myogenesis and mitochondrial turnover in myoblasts, while exercise enhanced activity and longevity in C. elegans. The adaptive responses were associated with increased mitochondrial localisation of PRDX6. In contrast, loss of PRDX6 under mild stress conditions resulted in increased mitochondrial lipid peroxidation, enhanced mitochondrial ER contact sites (MERCS), mitochondrial calcium accumulation, release of mitochondrial DNA and activation of innate immune signalling pathways. Similar phenotypes were induced by the ferroptosis activator erastin and rescued by the lipid peroxyl scavenger Ferrostatin-1, indicating lipid peroxidation was the key triggering event. Furthermore, inhibition of mitochondrial calcium uptake in C. elegans prevented calcium overload and attenuated inflammatory signalling. Together, the results identify PRDX6 as a conserved regulator of mitochondrial adaptation to physiological oxidative stress, functioning to limit mitochondrial lipid peroxidation and prevent excessive MERCS assembly, mitochondrial calcium dysregulation and inflammatory activation.

cell biology↗

bioRxiv2025

Mitochondrial redox homeostasis links organellar stress surveillance to germline and somatic integrity in Caenorhabditis elegans

Mitochondrial redox homeostasis is essential for cellular metabolism and organismal development. To investigate the consequences of disrupting redox homeostasis in this organelle in a metazoan organism, we generated a double mutant lacking mitochondrial glutathione reductase (gsr-1a) and thioredoxin reductase (trxr-2) genes in Caenorhabditis elegans. While gsr-1a or trxr-2 single mutants are phenotypically normal, double gsr-1a trxr-2 mutants displayed small body size, gonadal migration defects, reduced brood size, and prolonged egg-laying period, without developmental delay or lethality. Transcriptomic analysis revealed strong induction of ATFS-1-dependent stress and detoxification genes. Consistent with this, gsr-1a trxr-2 worms exhibited constitutive ATFS-1 nuclear localization and robust Phsp-6::gfp expression. Triple gsr-1a trxr-2; atfs-1 mutants were nonviable, demonstrating that unfolded protein response (UPRmt) activation is essential under mitochondrial redox stress. Despite the induction of a stress response at the transcriptional level, gsr-1a trxr-2 double mutants were not more resistant to oxidative or pathogen stressors. Moreover, these mutants maintained normal respiration, ATP and ROS production while displaying altered mitochondrial morphology in a tissue-specific manner, independent of mitophagy genes but dependent on mitochondrial fission or fusion machinery. Functionally, gsr-1a trxr-2 mutants showed impaired motility, reduced calcium uptake upon carbachol stimulation, enhanced hypodermal wound repair, and decreased fertilization efficiency associated with lower muscle exopher production. Overall, our data show that simultaneous loss of mitochondrial GSR-1a and TRXR-2 compromises growth, fertility and muscle performance and triggers a constitutive ATFS-1-dependent UPRmt that sustains viability revealing mitochondrial redox control as a core determinant of organismal proteostasis. HighlightsO_LIgsr-1a or trxr-2 single mutants have no overt phenotypes. C_LIO_LIgsr-1a trxr-2 double mutants are viable but show small size, gonad migration defects and reduced progeny. C_LIO_LILoss of both reductases in mitochondria triggers a constitutive ATFS-1-dependent UPRmt. C_LIO_LIATFS-1 is essential for gsr-1a trxr-2 worms survival. C_LIO_LIgsr-1a trxr-2 animals remodel mitochondrial morphology in a tissue-specific manner. C_LIO_LIgsr-1a trxr-2 double mutants exhibit impaired muscle and sperm function but enhanced wound healing. C_LI Graphical abstract (to be incorporated)

genetics↗

bioRxiv2025

Exercise Related microRNAs in C. elegans Regulate Calcium Homeostasis and Mitochondrial Dynamics: Conserved pathways, Divergent mircoRNAs

Exercise can help mitigate age-related muscle atrophy, promoting mitochondrial function, Ca2+ homeostasis and regulating gene expression. MicroRNAs (miRs) are crucial post-transcriptional regulators of gene expression, fine tuning protein levels to maintain cellular homeostasis. In C. elegans, a 5-day swimming regimen increased mitochondrial content, lifespan and fitness. Small RNA sequencing identified exercise specific miRs, including increased levels of cel-miR-57-5p and cel-miR-249-3p, and decreased cel-miR-72-3p and cel-miR-77-5p. mir-57 and mir-249 mutant strains had enhanced fertility, survival and lifespan, whereas mir-72 and mir-77 mutant strains had diminished fertility, survival and lifespan. Interestingly both miR-77 and mir-249 mutant strains had disrupted mitochondrial morphology and reduced fitness following exercise. The exercise related miRs identified in C. elegans did not have conserved mammalian orthologs. Exercise regulated mammalian miRs were identified from the literature including mmu-miR-181a-5p, mmu-miR-199a-5p and mmu-miR-378a-3p. Treatment of murine myoblasts with mmu-miR-181a-5p and mmu-miR-378a-3p enhanced mitochondrial content, autophagy markers and myogenesis, while mmu-miR-199a-5p impaired these processes. Exercise related miRs identified in C. elegans target genes regulating Ca2+ homeostasis such as ipp-5 (inositol Polyphosphate-5-phosphatase), sca-1 (Ca2+ transporting ATPase) and ncx-2 (mitochondrial Na+/Ca2+ antiporter). It was also confirmed that mmu-miR181a-5p (miR181) targets Inpp5a and antogmiR-181 (AM181) treatment decreased Ca2+ handling in myotubes. Similarly, mmu-miR-378a-3p and cel-miR-249-3p target Kinase Suppressor of Ras (Ksr1)/ksr-2, involved in the MAPK pathway. Despite direct conservation of exercise related miRs from nematodes to mammals there are common regulatory pathways, contributing to exercise-induced adaptations. Graphical abstractThe exercise related microRNAs (cel-miR-77-5p and cel-miR-249-3p) identified in C. elegans following a 5-day swimming protocol are not conserved in mammalians. However, the microRNAs identified share common gene targets regulating Ca2+ homeostasis and mitochondrial function, with previously identified exercise related microRNAs in murine models. The results highlight conserved regulatory adaptive mechanisms in response to exercise. O_FIG O_LINKSMALLFIG WIDTH=175 HEIGHT=200 SRC="FIGDIR/small/653755v2_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1da431forg.highwire.dtl.DTLVardef@6cdb70org.highwire.dtl.DTLVardef@ba9d76org.highwire.dtl.DTLVardef@1b7b481_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

PERK orchestrates MERCS formation and mitochondrial remodelling promoting physiological adaptations during adaptive UPR signalling

The transfer of information and metabolites between mitochondria and the ER is mediated by mitochondria-ER contact sites (MERCS), facilitating adaptations following changes in cellular homeostasis. MERCS are dynamic structures, essential for maintaining cellular homeostasis through modulation of calcium transfer, redox signalling, lipid transfer, autophagy and mitochondrial dynamics. Acute ER stress in myoblasts promoted myogenesis that required the PERK arm of the UPRER for increased MERCS assembly, mitochondrial turnover and function. Similarly, induction of acute UPRER during early development in C. elegans resulted in increased lifespan and healthspan. Adaptive UPRER signalling in myoblasts and C. elegans, increased MERCS assembly and activated autophagy, ultimately promoting mitochondrial remodelling. Adaptations were dependent on the developmental stage, as treatment of myotubes or adult C. elegans resulted in a maladaptive response. The results identify that PERK is required for increased mitochondrial ER communication in response to adaptive UPR signalling, promoting mitochondrial remodelling and improved physiological function. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=172 SRC="FIGDIR/small/633960v1_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@66c0f2org.highwire.dtl.DTLVardef@57814org.highwire.dtl.DTLVardef@10e87d5org.highwire.dtl.DTLVardef@f7b69e_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

miR-379-3p counteracts cancer cachexia through regulation of pyrimidinergic receptor, mitochondrial stress and interferon response.

Cancer cachexia is a highly prevalent wasting syndrome in cancer patients. Inflammation is hallmarks of symptomatic cachexia, however early stages of cachexia are not well understood, including differences between biological sexes. In a mouse model of early cachexia, muscle from males showed strong mitochondrial defects, whereas females were characterized by inflammatory and stress response. We demonstrate a novel link between the increase in purinergic receptor P26Y, and dysregulated Ca2+ homeostasis, mitochondrial dysfunction and damage, and inflammation during early stages of cancer cachexia. Low levels of miR-379-3p were associated with poor survival of patients with lung cancer. Restoring miR-379-3p levels in mice prevented loss of muscle mass and function. miR-379-3p targeted P2r6y and restored mitochondrial content and function, inhibited type II interferon response, and regulated the expression of Ca2+-related and apoptotic markers. This supports miR-379-3p as a hub regulating multiple processes underlying cachexia and represent a therapeutic target for cancer patients.

cancer biology↗

bioRxiv2024

microRNA-1 Regulates Metabolic Flexibility in Skeletal Muscle via Pyruvate Metabolism

MicroRNA-1 (miR-1) is the most abundant miRNA in adult skeletal muscle. To determine the function of miR-1 in adult skeletal muscle, we generated an inducible, skeletal muscle-specific miR-1 knockout (KO) mouse. Integration of RNA-sequencing (RNA-seq) data from miR-1 KO muscle with Argonaute 2 enhanced crosslinking and immunoprecipitation sequencing (AGO2 eCLIP-seq) from human skeletal muscle identified miR-1 target genes involved with glycolysis and pyruvate metabolism. The loss of miR-1 in skeletal muscle induced cancer-like metabolic reprogramming, as shown by higher pyruvate kinase muscle isozyme M2 (PKM2) protein levels, which promoted glycolysis. Comprehensive bioenergetic and metabolic phenotyping combined with skeletal muscle proteomics and metabolomics further demonstrated that miR-1 KO induced metabolic inflexibility as a result of pyruvate oxidation resistance. While the genetic loss of miR-1 reduced endurance exercise performance in mice and in C. elegans, the physiological down-regulation of miR-1 expression in response to a hypertrophic stimulus in both humans and mice causes a similar metabolic reprogramming that supports muscle cell growth. Taken together, these data identify a novel post-translational mechanism of adult skeletal muscle metabolism regulation mediated by miR-1.

physiology↗

bioRxiv2024

Peroxiredoxin 2 Regulates DAF-16/FOXO Mediated Mitochondrial Remodelling in Response to Exercise that is Disrupted in Ageing

Ageing is associated with mitochondrial dysfunction and increased oxidative stress. Exercise generates endogenous reactive oxygen species (ROS) and promotes rapid mitochondrial remodelling. We investigated the role of Peroxiredoxin 2 (PRDX-2) in mitochondrial adaptations to exercise and ageing using Caenorhabditis elegans as a model system. PRDX-2 was required for the mitochondrial remodelling in response to exercise mediated by DAF-16 nuclear localisation. Employing an acute exercise and recovery cycle, we demonstrated exercise-induced mitochondrial ER contact sites (MERCS) assembly and mitochondrial remodelling dependent on PRDX-2 and DAF-16 signalling. There was increased mitochondrial fragmentation, elevated ROS and an altered redox state of PRDX-2, concomitant with impaired DAF-16 nuclear localisation during ageing. Similarly, the prdx-2 mutant strain exhibited increased mitochondrial fragmentation and a failure to activate DAF-16 required for mitochondrial fusion. Collectively, our data highlight the critical role of PRDX-2 in orchestrating mitochondrial remodelling in response to a physiological stress by regulating DAF-16 nuclear localisation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/593975v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@50b94forg.highwire.dtl.DTLVardef@1b62d31org.highwire.dtl.DTLVardef@1511d0eorg.highwire.dtl.DTLVardef@4a9b6d_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIExercise generates ROS and promotes mitochondrial remodelling dependent on DAF-16. C_LIO_LIExercise induces mitochondrial ER contact site assembly and mitochondrial dynamics. C_LIO_LIAgeing and loss of PRDX-2 results in disrupted mitochondrial fusion. C_LIO_LIThe redox state of PRDX-2 determines appropriate DAF-16 nuclear localisation. C_LI

molecular biology↗

bioRxiv2022

Peroxiredoxin 2 is required for the redox mediated adaptation to exercise

Exercise generates a site-specific increase in Reactive Oxygen Species (ROS) within muscle required for a beneficial adaptive response by activation of specific signalling pathways. Here, we demonstrate that Peroxiredoxin 2 (Prdx2), an abundant cytoplasmic 2-Cys peroxiredoxin, is required for the adaptive beneficial hormesis response to H2O2. A short bolus addition of H2O2 increases mitochondrial capacity and improves myogenesis of cultured myoblasts, this beneficial adaptive response was suppressed in myoblasts with decreased expression of cytoplasmic Prdxs. A swimming exercise protocol in C. elegans increased mitochondrial content, fitness, survival and longevity in wild type (N2) worms. In contrast, prdx-2 mutant worms had decreased fitness, disrupted mitochondria, reduced survival and lifespan following exercise. Global proteomics following exercise identified distinct changes in the proteome of N2 and prdx-2 mutants. Furthermore, a redox proteomic approach to quantify reversible oxidation of individual Cysteine residues revealed a relatively more oxidised redox state following exercise in the prdx-2 mutants. Our results demonstrate that conserved cytoplasmic 2-Cys Peroxiredoxins are required for the beneficial adaptive response to a physiological stress.

molecular biology↗

bioRxiv2021

miR-24:Prdx6 interactions regulate oxidative stress and viability of myogenic progenitors during ageing

microRNAs regulate a myriad of physiological processes, including skeletal muscle regeneration and homeostasis. During ageing, changes in muscle fibre microenvironment contribute to the capability of satellite cells to regenerate the muscle in response to injury and loading stressors. In this study, we isolated murine satellite cells and primary myogenic progenitors from mice and humans to demonstrate that the microRNA miR-24-3p and its target peroxiredoxin 6 (Prdx6) play an important role in muscle regeneration during ageing, regulating satellite cell viability and their differentiation potential. Our results show upregulation of miR-24 during early stages of muscle regeneration in vivo in adult mice, suggesting a potential role of miR-24 at the early stages of muscle injury. On contrary, miR-24 was downregulated during regeneration of muscle of old mice. miR-24 was also downregulated, whereas its target gene Prdx6 was upregulated, in satellite cells isolated from old mice. miR-24 consistently regulated viability and myogenic potential of myogenic progenitors from both humans and old mice, suggesting that changes in miR-24 levels during ageing may contribute to defective early stages of muscle regeneration during ageing through affecting satellite cell viability and myogenic potential. This regulation likely occurs via miR-24 counteracting the generation of reactive oxygen species through Prdx6 de-repression in primary myogenic progenitors isolated from humans and old mice. We propose that downregulation of miR-24 in muscle of old mice following injury may be a protective mechanism against elevated ROS levels to maintain satellite cell viability and myogenic potential, acting through Prdx6 upregulation. However, as miR-24 is a regulator of p16 and p21, this downregulation may lead to increased satellite cell senescence, therefore representing an age-related failed compensatory mechanism.

cell biology↗

bioRxiv2019

miR-181a Regulates p62/SQSTM1, Parkin and Protein DJ-1 Promoting Mitochondrial Dynamics in Skeletal Muscle Ageing

One of the key mechanisms underlying skeletal muscle functional deterioration during ageing is disrupted mitochondrial dynamics. Regulation of mitochondrial dynamics is essential to maintain a healthy mitochondrial population and prevent the accumulation of damaged mitochondria, however the regulatory mechanisms are poorly understood. We demonstrated loss of mitochondrial content and disrupted mitochondrial dynamics in muscle during ageing concomitant with dysregulation of miR-181a target interactions. Using functional approaches and mitoQc assay, we have established that miR-181a is an endogenous regulator of mitochondrial dynamics through concerted regulation of Park2, p62/SQSTM1 and DJ-1 in vitro. Downregulation of miR-181a with age was associated with an accumulation of autophagy-related proteins and abnormal mitochondria. Restoring miR-181a levels in old mice prevented accumulation of p62, DJ-1 and PARK2, improved mitochondrial quality and muscle function. These results provide physiological evidence for the potential of microRNA-based interventions for age-related muscle atrophy and of wider significance for diseases with disrupted mitochondrial dynamics.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC=\"FIGDIR/small/805176v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (54K):\norg.highwire.dtl.DTLVardef@1d6d4c7org.highwire.dtl.DTLVardef@12b6940org.highwire.dtl.DTLVardef@10aed74org.highwire.dtl.DTLVardef@6b5b34_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2019

Evaluating Muscle Fiber Contractility and the Transcriptome, Proteome, Metabolome, and Lipidome of the mdx/mTR Mouse Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease characterized by extensive muscle weakness. Patients with DMD lack a functional dystrophin protein, which transmits force and organizes the cytoskeleton of skeletal muscle. Multiomic studies evaluate combined changes in the transcriptome, proteome, and metabolome, and have been proposed as a way to obtain novel insight about disease processes from preclinical models. We therefore sought to use this approach to study pathological changes in dystrophic muscles. We evaluated hindlimb muscles of male mdx/mTR mice, which lack a functional dystrophin protein and have deficits in satellite cell abundance and proliferative capacity. Wild type (WT) C57BL/6J mice served as controls. Muscle fiber contractility was measured, along with changes in the transcriptome using RNA sequencing, and in the proteome, metabolome, and lipidome using mass spectroscopy. While mdx/mTR mice displayed gross pathological changes and continued cycles of degeneration and regeneration, we found no differences in fiber contractility between strains. However, there were numerous changes in the transcriptome and proteome related to protein balance, contractile elements, extracellular matrix, and metabolism. There was only a 53% agreement in fold change data between the proteome and transcriptome, highlighting the need to study protein abundance along with gene expression measures. Numerous changes in markers of skeletal muscle metabolism were observed, with dystrophic muscles exhibiting elevated glycolytic metabolites. These findings highlight the utility of multiomics in studying muscle disease, and provide additional insight into the pathological changes in dystrophic muscles that might help to guide evidence-based exercise prescription in DMD patients.

physiology↗

bioRxiv2018

Reduced mitochondrial lipid oxidation leads to fat accumulation in myosteatosis

Myosteatosis is the pathological accumulation of lipid that can occur in conjunction with atrophy and fibrosis following skeletal muscle injury. Little is known about the mechanisms by which lipid accumulates in myosteatosis, but many clinical studies have demonstrated the degree of lipid infiltration negatively correlates with muscle function and regeneration. Our objective was to determine the pathological changes that result in lipid accumulation in injured muscle fibers. We used a rat model of rotator cuff injury in this study, as the rotator cuff muscle group is particularly prone to the development of myosteatosis after injury. Muscles were collected from uninjured controls, or 10, 30, or 60 days after injury, and analyzed using a combination of muscle fiber contractility assessments, RNA sequencing, and undirected metabolomics, lipidomics and proteomics, along with bioinformatics techniques, to identify potential pathways and cellular processes that are dysregulated after rotator cuff tear. Bioinformatics analyses indicated that mitochondrial function was likely disrupted after injury. Based on these findings, and given the role that mitochondria play in lipid metabolism, we then performed targeted biochemical and imaging studies and determined that mitochondrial dysfunction and reduced fatty acid oxidation likely leads to the accumulation of lipid in myosteatosis.

physiology↗