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An ongoing issue in vascular medicine is the measure of the blood flow. Catheterization remains the gold standard measurement method, although non-invasive techniques are an area of intense research. We hereby present a computational method for real-time measurement of the blood flow from color flow Doppler data, with a focus on simplicity and monitoring instead of diagnostics. We then analyze the performance of a proof-of-principle software implementation. We imagined a geometrical model geared towards blood flow computation from a color flow Doppler signal, and we developed a software implementation requiring only a standard diagnostic ultrasound device. Detection performance was evaluated by computing flow and its determinants (flow speed, vessel area, and ultrasound beam angle of incidence) on purposely designed synthetic and phantom-based arterial flow simulations. Flow was appropriately detected in all cases. Errors on synthetic images ranged from nonexistent to substantial depending on experimental conditions. Mean errors on measurements from our phantom flow simulation ranged from 1.2 to 40.2% for angle estimation, and from 3.2 to 25.3% for real-time flow estimation. This study is a proof of concept showing that accurate measurement can be done from automated color flow Doppler signal extraction, providing the industry the opportunity for further optimization using raw ultrasound data. [ABSTRACT FROM AUTHOR]

Motor disorders are considered to originate mainly from brain lesions. Placental dysfunction or maternal exposure to a persistently hypoxic environment is a major cause of further motor disorders such as cerebral palsy. Our main goal was to determine the long-term effects of mild intrauterine acute ischemic stress on rat soleus myofibres and whether erythropoietin treatment could prevent these changes. Rat embryos were subjected to ischemic stress at embryonic day E17. They then received an intraperitoneal erythropoietin injection at postnatal days 1-5. Soleus muscles were collected at postnatal day 28. Prenatal ischemic stress durably affected muscle structure, as indicated by the greater fiber cross-sectional area (+ 18%) and the greater number of mature vessels (i.e. vessels with mature endothelial cells) per myofibres (+ 43%), and muscle biochemistry, as shown by changes in signaling pathways involved in protein synthesis/degradation balance (-81% for 4EBP1; -58% for AKT) and Hif1α expression levels (+ 95%). Erythropoietin injection in ischemic pups had a weak protective effect: it increased muscle mass (+ 25% with respect to ischemic pups) and partially prevented the increase in muscle degradation pathways and mature vascularization, whereas it exacerbated the decrease in synthesis pathways. Hence, erythropoietin treatment after acute ischemic stress contributes to muscle adaptation to ischemic conditions., Competing Interests: Declarations Ethical approval We confirm that all procedures were carried out in accordance with the European Communities Council Directive 2010/63/UE, and were approved by the Regional Committee on the Ethics of Animal Experiments of the Nord Pas-de-Calais region (CEEA 75, reference number: APAFIS#4732-2016031 112395755v7). Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Astronauts in Earth's orbit experience microgravity, resulting in a decline of skeletal muscle mass and function. On Earth, models simulating microgravity have shown that the extent of the loss in muscle force is greater than the loss in muscle mass. The reasons behind this disproportionate loss of muscle force are still poorly understood. In the present study, we hypothesize that alongside the loss in skeletal muscle mass, modifications in the expression profile of genes encoding critical determinants of resting membrane potential, excitation-contraction coupling and Ca 2+ handling contribute to the decline in skeletal muscle force., Methods: Healthy male volunteers (n = 18) participated in a 5-day dry immersion (DI) study, an Earth-based model of simulated microgravity. Muscle force measurement and MRI analysis of the cross-sectional area of thigh muscles were performed before and after DI. Biopsies of the vastus lateralis skeletal muscle performed before and after DI were used for the determination Ca 2+ properties of isolated muscle fibres, molecular and biochemical analyses., Results: The extent of the decline in force, measured as maximal voluntary contraction of knee extensors (-11.1%, P < 0.01) was higher than the decline in muscle mass (-2.5%, P < 0.01). The decline in muscle mass was molecularly supported by a significant repression of the anabolic IGF-1/Akt/mTOR pathway (-19.9% and -40.9% in 4E-BP1 and RPS6 phosphorylation, respectively), a transcriptional downregulation of the autophagy-lysosome pathway and a downregulation in the mRNA levels of myofibrillar protein slow isoforms. At the single fibre level, biochemical and tension-pCa curve analyses showed that the loss in force was independent of fibre type (-11% and -12.3% in slow and fast fibres, respectively) and Ca 2+ activation properties. Finally, we showed a significant remodelling in the expression of critical players of resting membrane potential (aquaporin 4: -24.9%, ATP1A2: +50.4%), excitation-contraction coupling (CHRNA1: +75.1%, CACNA2D1: -23.5%, JPH2: -24.2%, TRDN: -15.6%, S100A1: +27.2%), and Ca 2+ handling (ATP2A2: -32.5%, CASQ1: -15%, ORAI1: -36.2%, ATP2B1: -19.1%)., Conclusions: These findings provide evidence that a deregulation in the expression profile of critical molecular determinants of resting membrane potential, excitation-contraction coupling, and Ca 2+ handling could be involved in the loss of muscle force induced by DI. They also provide the paradigm for the understanding of muscle force loss during prolonged bed rest periods as those encountered in intensive care unit., (© 2024 The Author(s). Journal of Cachexia, Sarcopenia and Muscle published by Wiley Periodicals LLC.)

Maintenance of the highly organized striated muscle tissue requires a cell-wide dynamic network through protein-protein interactions providing an effective mechanochemical integrator of morphology and function. Through a continuous and complex trans-cytoplasmic network, desmin intermediate filaments ensure this essential role in heart and in skeletal muscle. Besides their role in the maintenance of cell shape and architecture (permitting contractile activity efficiency and conferring resistance towards mechanical stress), desmin intermediate filaments are also key actors of cell and tissue homeostasis. Desmin participates to several cellular processes such as differentiation, apoptosis, intracellular signalisation, mechanotransduction, vesicle trafficking, organelle biogenesis and/or positioning, calcium homeostasis, protein homeostasis, cell adhesion, metabolism and gene expression. Desmin intermediate filaments assembly requires αB-crystallin, a small heat shock protein. Over its chaperone activity, αB-crystallin is involved in several cellular functions such as cell integrity, cytoskeleton stabilization, apoptosis, autophagy, differentiation, mitochondria function or aggresome formation. Importantly, both proteins are known to be strongly associated to the aetiology of several cardiac and skeletal muscles pathologies related to desmin filaments disorganization and a strong disturbance of desmin interactome. Note that these key proteins of cytoskeleton architecture are extensively modified by post-translational modifications that could affect their functional properties. Therefore, we reviewed in the herein paper the impact of post-translational modifications on the modulation of cellular functions of desmin and its molecular chaperone, the αB-crystallin., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2023 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Sepsis-induced myopathy is characterized by muscle fiber atrophy, mitochondrial dysfunction, and worsened outcomes. Whether whole-body energy deficit participates in the early alteration of skeletal muscle metabolism has never been investigated. Three groups were studied: "Sepsis" mice, fed ad libitum with a spontaneous decrease in caloric intake (n = 17), and "Sham" mice fed ad libitum (Sham fed (SF), n = 13) or subjected to pair-feeding (Sham pair fed (SPF), n = 12). Sepsis was induced by the intraperitoneal injection of cecal slurry in resuscitated C57BL6/J mice. The feeding of the SPF mice was restricted according to the food intake of the Sepsis mice. Energy balance was evaluated by indirect calorimetry over 24 h. The tibialis anterior cross-sectional area (TA CSA), mitochondrial function (high-resolution respirometry), and mitochondrial quality control pathways (RTqPCR and Western blot) were assessed 24 h after sepsis induction. The energy balance was positive in the SF group and negative in both the SPF and Sepsis groups. The TA CSA did not differ between the SF and SPF groups, but was reduced by 17% in the Sepsis group compared with the SPF group ( p < 0.05). The complex-I-linked respiration in permeabilized soleus fibers was higher in the SPF group than the SF group ( p < 0.05) and lower in the Sepsis group than the SPF group ( p < 0.01). Pgc1α protein expression increased 3.9-fold in the SPF mice compared with the SF mice ( p < 0.05) and remained unchanged in the Sepsis mice compared with the SPF mice; the Pgc1α mRNA expression decreased in the Sepsis compared with the SPF mice ( p < 0.05). Thus, the sepsis-like energy deficit did not explain the early sepsis-induced muscle fiber atrophy and mitochondrial dysfunction, but led to specific metabolic adaptations not observed in sepsis.

The sarcoplasmic reticulum (SR) plays an important role in calcium homeostasis. SR calcium mishandling is described in pathological conditions, such as myopathies. Here, we investigated whether the nuclear receptor subfamily 1 group D member (NR1D1, also called REV-ERBα) regulates skeletal muscle SR calcium homeostasis. Our data demonstrate that NR1D1 deficiency in mice impaired sarco/endoplasmic reticulum calcium ATPase-dependent (SERCA-dependent) SR calcium uptake. NR1D1 acts on calcium homeostasis by repressing the SERCA inhibitor myoregulin through direct binding to its promoter. Restoration of myoregulin counteracted the effects of NR1D1 overexpression on SR calcium content. Interestingly, myoblasts from patients with Duchenne muscular dystrophy displayed lower NR1D1 expression, whereas pharmacological NR1D1 activation ameliorated SR calcium homeostasis and improved muscle structure and function in dystrophic mdx/Utr+/- mice. Our findings demonstrate that NR1D1 regulates muscle SR calcium homeostasis, pointing to its therapeutic potential for mitigating myopathy.

Desmin is the guardian of striated muscle integrity, permitting the maintenance of muscle shape and the efficiency of contractile activity. It is also a key mediator of cell homeostasis and survival. To ensure the fine regulation of skeletal muscle processes, desmin is regulated by post-translational modifications (PTMs). It is more precisely phosphorylated by several kinases connecting desmin to intracellular processes. Desmin is also modified by O-GlcNAcylation, an atypical glycosylation. However, the functional consequence of O-GlcNAcylation on desmin is still unknown, nor its impact on desmin phosphorylation. In a model of C2C12 myotubes, we modulated the global O-GlcNAcylation level, and we determined whether the expression, the PTMs and the partition of desmin toward insoluble material or cytoskeleton were impacted or not. We have demonstrated in the herein paper that O-GlcNAcylation variations led to changes in desmin behaviour. In particular, our data clearly showed that O-GlcNAcylation increase led to a decrease of phosphorylation level on desmin that seems to involve CamKII correlated to a decrease of its partition toward cytoskeleton. Our data showed that phosphorylation/O-GlcNAcylation interplay is highly complex on desmin, supporting that a PTMs signature could occur on desmin to finely regulate its partition (i.e. distribution) with a spatio-temporal regulation., (© 2022. The Author(s).)

Children with low physical activity and interactions with environment experience atypical sensorimotor development and maturation leading to anatomical and functional disorganization of the sensorimotor circuitry and also to enduring altered motor function. Previous data have shown that postnatal movement restriction in rats results in locomotor disturbances, functional disorganization and hyperexcitability of the hind limb representations in the somatosensory and motor cortices, without apparent brain damage. Due to the reciprocal interplay between the nervous system and muscle, it is difficult to determine whether muscle alteration is the cause or the result of the altered sensorimotor behavior (Canu et al., 2019). In the present paper, our objectives were to evaluate the impact of early movement restriction leading to sensorimotor restriction (SMR) during development on the postural soleus muscle and on sensorimotor performance in rats, and to determine whether changes were reversed when typical activity was resumed. Rats were submitted to SMR by hind limb immobilization for 16 h / day from birth to postnatal day 28 (PND28). In situ isometric contractile properties of soleus muscle, fiber cross sectional area (CSA) and myosin heavy chain content (MHC) were studied at PND28 and PND60. In addition, the motor function was evaluated weekly from PND28 to PND60. At PND28, SMR rats presented a severe atrophy of soleus muscle, a decrease in CSA and a force loss. The muscle maturation appeared delayed, with persistence of neonatal forms of MHC. Changes in kinetic properties were moderate or absent. The Hoffmann reflex provided evidence for spinal hyperreflexia and signs of spasticity. Most changes were reversed at PND60, except muscle atrophy. Functional motor tests that require a good limb coordination, i.e. rotarod and locomotion, showed an enduring alteration related to SMR, even after one month of 'typical' activity. On the other hand, paw withdrawal test and grip test were poorly affected by SMR whereas spontaneous locomotor activity increased over time. Our results support the idea that proprioceptive feedback is at least as important as the amount of motor activity to promote a typical development of motor function. A better knowledge of the interplay between hypoactivity, muscle properties and central motor commands may offer therapeutic perspectives for children suffering from neurodevelopmental disorders., (Copyright © 2021 Elsevier Inc. All rights reserved.)

This study examines the spectral characteristics of blood after being exposed to intense heat within a structural fire. Fire and intense heat have previously been understood to destroy or chemically change bloodstain evidence so that traditional forensic science recovery techniques are rendered ineffectual. Understanding the effects of the denaturation process and physical changes that occur to blood when exposed to heat may develop innovative forensic investigation methods, including the use of reflected infrared photography to enhance the recording of bloodstains. This research revealed that the denaturation of blood, specifically changes to the haemoglobin state from oxyhaemoglobin to methaemoglobin, resulted in the heat affected blood having a more optimal spectral target range within the infrared region when exposed to heat> 200 °C. It was observed both qualitatively and quantitatively using spectrophotometry, that there is a relationship between the appearance, viscosity and infrared absorption properties of blood when exposed to different temperatures as experienced in fire. This result indicated the increased potential for reflected infrared photography to be utilised as an effective tool for crime scene evidence recovery of bloodstains from arson scenes involving fire., (Crown Copyright © 2021. Published by Elsevier B.V. All rights reserved.)

Background: Several studies have shown the importance of phosphorylation, O-GlcNAcylation and their interplay in neuronal processes., New Method: To get understanding about molecular mechanisms of synaptic plasticity, we performed a preparation of synaptic protein-enriched fraction on a small sample of rat sensorimotor cortex. We then optimized a multiplexed proteomic strategy to detect O-GlcNAcylated proteins, phosphoproteins, and the whole proteome within the same bidimensional gel. We compared different protocols (solubilisation buffer, reticulation and composition of the gel, migration buffer) to optimize separating conditions for 2D-gel electrophoresis of synaptic proteins. The O-GlcNAcome was revealed using Click chemistry and the azide-alkyne cycloaddition of a fluorophore on O-GlcNAc moieties. The phosphoproteome was detected by Phospho-Tag staining, while the whole proteome was visualized through SYPRORuby staining., Results: This method permitted, after sequential image acquisition, the direct in-gel detection of O-GlcNAcome, phosphoproteome, and whole proteome of synapse-associated proteins., Conclusion: This original method of differential proteomic analysis will permit to identify key markers of synaptic plasticity that are O-GlcNAcylated and/or phosphorylated, and their molecular regulations in neuronal processes., Competing Interests: Declaration of Competing Interest The authors have declared no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Although the O-GlcNAcylation process was discovered in 1984, its potential role in the physiology and physiopathology of skeletal muscle only emerged 20 years later. An increasing number of publications strongly support a key role of O-GlcNAcylation in the modulation of important cellular processes which are essential for skeletal muscle functions. Indeed, over a thousand of O-GlcNAcylated proteins have been identified within skeletal muscle since 2004, which belong to various classes of proteins, including sarcomeric proteins. In this review, we focused on these myofibrillar proteins, including contractile and structural proteins. Because of the modification of motor and regulatory proteins, the regulatory myosin light chain (MLC2) is related to several reports that support a key role of O-GlcNAcylation in the fine modulation of calcium activation parameters of skeletal muscle fibres, depending on muscle phenotype and muscle work. In addition, another key function of O-GlcNAcylation has recently emerged in the regulation of organization and reorganization of the sarcomere. Altogether, this data support a key role of O-GlcNAcylation in the homeostasis of sarcomeric cytoskeleton, known to be disturbed in many related muscle disorders., (© 2019 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)

Bloodstain evidence is an element of crime scene investigation often found at scenes involving violence. Setting fire to the scene is a method sometimes used by offenders of crime in an attempt to conceal evidence. Fire often produces thick soot as a by-product of the combustion and has the potential to cover bloodstain patterns rendering them latent. There is limited published material offering a method of detecting bloodstains hidden beneath dense soot deposits caused by fire. This project employed a modified digital single-lens reflex (SLR) camera to investigate the application of reflected infrared photography to detect latent bloodstain evidence beneath varying deposited overlaying soot densities. The potential of this technique was examined by photographing blood samples beneath soot from a scaled fire simulation. A qualitative evaluation was completed by comparing images taken of a series of samples using both reflected infrared and standard visible light photography and corroborated with quantitative image analysis to support the findings. Results indicate that infrared photography can reveal latent bloodstains beneath a dense layer of soot in excess of ρ2.3 (550nm) density with substantial clarity. The success of this technique is dependent on specific optical and specimen parameters. These parameters include (i) the reflective properties of the background surface, (ii) the spectral absorption properties of blood and (iii) the ability of infrared wavelengths to transmit through the soot layer. Reflected infrared photography may provide crime scene examiners with a specialised field recording method that is easily executed and non-destructive to assist in visualising and locating latent bloodstain patterns beneath dense layers of soot., (Crown Copyright © 2019. Published by Elsevier B.V. All rights reserved.)

Activity-dependent processes addressing the central nervous system (CNS) and musculoskeletal structures are critical for maintaining motor performance. Chronic reduction in activity, whether due to a sedentary lifestyle or extended bed rest, results in impaired performance in motor tasks and thus decreased quality of life. In the first part of this paper, we give a narrative review of the effects of hypoactivity on the neuromuscular system and behavioral outcomes. Motor impairments arise from a combination of factors including altered muscle properties, impaired afferent input, and plastic changes in neural structure and function throughout the nervous system. There is a reciprocal interplay between the CNS and muscle properties, and these sensorimotor loops are essential for controlling posture and movement. As a result, patients under hypoactivity experience a self-perpetuating cycle, in with sedentarity leading to decreased motor activity and thus a progressive worsening of a situation, and finally deconditioning. Various rehabilitation strategies have been studied to slow down or reverse muscle alteration and altered motor performance. In the second part of the paper, we review representative protocols directed toward the muscle, the sensory input and/or the cerebral cortex. Improving an understanding of the loss of motor function under conditions of disuse (such as extended bed rest) as well as identifying means to slow this decline may lead to therapeutic strategies to preserve quality of life for a range of individuals. The most efficient strategies seem multifactorial, using a combination of approaches targeting different levels of the neuromuscular system., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Skeletal muscle represents around 40% of whole body mass. The principal function of skeletal muscle is the conversion of chemical energy toward mechanic energy to ensure the development of force, provide movement and locomotion, and maintain posture. This crucial energy dependence is maintained by the faculty of the skeletal muscle for being a central place as a "reservoir" of amino acids and carbohydrates in the whole body. A fundamental post-translational modification, named O-GlcNAcylation, depends, inter alia , on these nutrients; it consists to the transfer or the removal of a unique monosaccharide (N-acetyl-D-glucosamine) to a serine or threonine hydroxyl group of nucleocytoplasmic and mitochondrial proteins in a dynamic process by the O-GlcNAc Transferase (OGT) and the O-GlcNAcase (OGA), respectively. O-GlcNAcylation has been shown to be strongly involved in crucial intracellular mechanisms through the modulation of signaling pathways, gene expression, or cytoskeletal functions in various organs and tissues, such as the brain, liver, kidney or pancreas, and linked to the etiology of associated diseases. In recent years, several studies were also focused on the role of O-GlcNAcylation in the physiology and the physiopathology of skeletal muscle. These studies were mostly interested in O-GlcNAcylation during muscle exercise or muscle-wasting conditions. Major findings pointed out a different "O-GlcNAc signature" depending on muscle type metabolism at resting, wasting and exercise conditions, as well as depending on acute or long-term exhausting exercise protocol. First insights showed some differential OGT/OGA expression and/or activity associated with some differential stress cellular responses through Reactive Oxygen Species and/or Heat-Shock Proteins. Robust data displayed that these O-GlcNAc changes could lead to (i) a differential modulation of the carbohydrates metabolism, since the majority of enzymes are known to be O-GlcNAcylated, and to (ii) a differential modulation of the protein synthesis/degradation balance since O-GlcNAcylation regulates some key signaling pathways such as Akt/GSK3β, Akt/mTOR, Myogenin/Atrogin-1, Myogenin/Mef2D, Mrf4 and PGC-1α in the skeletal muscle. Finally, such involvement of O-GlcNAcylation in some metabolic processes of the skeletal muscle might be linked to some associated diseases such as type 2 diabetes or neuromuscular diseases showing a critical increase of the global O-GlcNAcylation level.

In human, a chronic sensorimotor perturbation (SMP) through prolonged body immobilization alters motor task performance through a combination of peripheral and central factors. Studies performed on a rat model of SMP have shown biomolecular changes and a reorganization of sensorimotor cortex through events such as morphological modifications of dendritic spines (number, length, functionality). However, underlying mechanisms are still unclear. It is well known that phosphorylation regulates a wide field of synaptic activity leading to neuroplasticity. Another post-translational modification that interplays with phosphorylation is O-GlcNAcylation. This atypical glycosylation, reversible, and dynamic, is involved in essential cellular and physiological processes such as synaptic activity, neuronal morphogenesis, learning, and memory. We examined potential roles of phosphorylation/O-GlcNAcylation interplay in synaptic plasticity within rat sensorimotor cortex after a SMP period. For this purpose, sensorimotor cortex synaptosomes were separated by sucrose gradient, in order to isolate a subcellular compartment enriched in proteins involved in synaptic functions. A period of SMP induced plastic changes at the pre- and post-synaptic levels, characterized by a reduction in phosphorylation (synapsin1, α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptors (AMPAR) GluA2) and expression (synaptophysin, PSD-95, AMPAR GluA2) of synaptic proteins, as well as a decrease in MAPK/ERK42 activation. Expression levels of O-GlcNAc transferase/O-GlcNAcase enzymes was unchanged but we observed a specific reduction of synapsin1 O-GlcNAcylation in sensorimotor cortex synaptosomes. The synergistic regulation of synapsin1 phosphorylation/O-GlcNAcylation could affect pre-synaptic neurotransmitter release. Associated with other pre- and post-synaptic changes, synaptic efficacy could be impaired in somatosensory cortex of SMP rat. Thus, phosphorylation/O-GlcNAcylation interplay appears to be involved in synaptic plasticity by finely regulating neural activity., (© 2018 International Society for Neurochemistry.)

The O-linked-N-acetyl-d-glucosaminylation (O-GlcNAcylation) modulates numerous aspects of cellular processes. Akin to phosphorylation, O-GlcNAcylation is highly dynamic, reversible, and responds rapidly to extracellular demand. Despite the absolute necessity to determine post-translational sites to fully understand the role of O-GlcNAcylation, it remains a high challenge for the major reason that unmodified proteins are in excess comparing to the O-GlcNAcylated ones. Based on a click chemistry approach, O-GlcNAcylated proteins were labelled with azido-GalNAc and coupled to agarose beads. The proteome extracted from C2C12 myotubes was submitted to an intensive fractionation prior to azide-alkyne click chemistry. This combination of fractionation and click chemistry is a powerful methodology to map O-GlcNAc sites; indeed, 342 proteins were identified through the identification of 620 peptides containing one or more O-GlcNAc sites. We localized O-GlcNAc sites on proteins involved in signalling pathways or in protein modification, as well as structural proteins. Considering the recent role of O-GlcNAcylation in the modulation of sarcomere morphometry and interaction between key structural protein, we focused on proteins involved in the cytoarchitecture of skeletal muscle cells. In particular, several O-GlcNAc sites were located into protein-protein interaction domains, suggesting that O-GlcNAcylation could be strongly involved in the organization and reorganization of sarcomere and myofibrils., Significance: O-GlcNAcylation is an atypical glycosylation involved in the regulation of almost all if not all cellular processes, but its precise role remains sometimes obscure because of the ignorance of the O-GlcNAc site localization; thus, it remains indispensable to precisely map the O-GlcNAcylated sites to fully understand the role of O-GlcNAcylation on a given protein. For this purpose, we combined extensive fractionation of skeletal muscle cells proteome with click chemistry to map O-GlcNAc sites without an a priori consideration. A total of 620 peptides containing one or more O-GlcNAc sites were identified; interestingly, several of them belong to low expressed proteins, in particular proteins involved in signalling pathways. We also focused on structural proteins in view of recent data supporting the role of O-GlcNAcylation in the modulation of sarcomere cytoarchitecture; importantly, some of the O-GlcNAc sites were mapped into protein-protein interaction domains, reinforcing the involvement of O-GlcNAcylation in the organization and reorganization of sarcomere, and in larger extent, of myofibrils., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Intrauterine ischemia-hypoxia is detrimental to the developing brain and leads to white matter injury (WMI), encephalopathy of prematurity (EP), and often to cerebral palsy (CP), but the related pathophysiological mechanisms remain unclear. In prior studies, we used mild intrauterine hypoperfusion (MIUH) in rats to successfully reproduce the diversity of clinical signs of EP, and some CP symptoms. Briefly, MIUH led to inflammatory processes, diffuse gray and WMI, minor locomotor deficits, musculoskeletal pathologies, neuroanatomical and functional disorganization of the primary somatosensory and motor cortices, delayed sensorimotor reflexes, spontaneous hyperactivity, deficits in sensory information processing, memory and learning impairments. In the present study, we investigated the early and long-lasting mechanisms of pathophysiology that may be responsible for the various symptoms induced by MIUH. We found early hyperreflexia, spasticity and reduced expression of KCC2 (a chloride cotransporter that regulates chloride homeostasis and cell excitability). Adult MIUH rats exhibited changes in muscle contractile properties and phenotype, enduring hyperreflexia and spasticity, as well as hyperexcitability in the sensorimotor cortex. Taken together, these results show that reduced expression of KCC2, lumbar hyperreflexia, spasticity, altered properties of the soleus muscle, as well as cortical hyperexcitability may likely interplay into a self-perpetuating cycle, leading to the emergence, and persistence of neurodevelopmental disorders (NDD) in EP and CP, such as sensorimotor impairments, and probably hyperactivity, attention, and learning disorders.

Metabolic stresses such as dietary energy restriction or physical activity exert beneficial metabolic effects. In the liver, endospanin-1 and endospanin-2 cooperatively modulate calorie restriction-mediated (CR-mediated) liver adaptations by controlling growth hormone sensitivity. Since we found CR to induce endospanin protein expression in skeletal muscle, we investigated their role in this tissue. In vivo and in vitro endospanin-2 triggers ERK phosphorylation in skeletal muscle through an autophagy-dependent pathway. Furthermore, endospanin-2, but not endospanin-1, overexpression decreases muscle mitochondrial ROS production, induces fast-to-slow fiber-type switch, increases skeletal muscle glycogen content, and improves glucose homeostasis, ultimately promoting running endurance capacity. In line, endospanin-2-/- mice display higher lipid peroxidation levels, increased mitochondrial ROS production under mitochondrial stress, decreased ERK phosphorylation, and reduced endurance capacity. In conclusion, our results identify endospanin-2 as a potentially novel player in skeletal muscle metabolism, plasticity, and function.

Immobilization, bed rest, or sedentary lifestyle, are known to induce a profound impairment in sensorimotor performance. These alterations are due to a combination of peripheral and central factors. Previous data conducted on a rat model of disuse (hindlimb unloading, HU) have shown a profound reorganization of motor cortex and an impairment of motor performance. Recently, our interest was turned towards the role of insulin-like growth factor 1 (IGF-1) in cerebral plasticity since this growth factor is considered as the mediator of beneficial effects of exercise on the central nervous system, and its cortical level is decreased after a 14-day period of HU. In the present study, we attempted to determine whether a chronic subdural administration of IGF-1 in HU rats could prevent deleterious effects of HU on the motor cortex and on motor activity. We demonstrated that HU induces a shrinkage of hindlimb cortical representation and an increase in current threshold to elicit a movement. Administration of IGF-1 in HU rats partially reversed these changes. The functional evaluation revealed that IGF-1 prevents the decrease in spontaneous activity found in HU rats and the changes in hip kinematics during overground locomotion, but had no effect of challenged locomotion (ladder rung walking test). Taken together, these data clearly indicate the implication of IGF-1 in cortical plastic mechanisms and in behavioral alteration induced by a decreased in sensorimotor activity., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A short abnormal polyalanine expansion in the polyadenylate-binding protein nuclear-1 (PABPN1) protein causes oculopharyngeal muscular dystrophy (OPMD). Mutated PABPN1 proteins accumulate as insoluble intranuclear aggregates in muscles of OPMD patients. While the roles of PABPN1 in nuclear polyadenylation and regulation of alternative poly(A) site choice have been established, the molecular mechanisms which trigger pathological defects in OPMD and the role of aggregates remain to be determined. Using exon array, for the first time we have identified several splicing defects in OPMD. In particular, we have demonstrated a defect in the splicing regulation of the muscle-specific Troponin T3 (TNNT3) mutually exclusive exons 16 and 17 in OPMD samples compared to controls. This splicing defect is directly linked to the SC35 (SRSF2) splicing factor and to the presence of nuclear aggregates. As reported here, PABPN1 aggregates are able to trap TNNT3 pre-mRNA, driving it outside nuclear speckles, leading to an altered SC35-mediated splicing. This results in a decreased calcium sensitivity of muscle fibers, which could in turn plays a role in muscle pathology. We thus report a novel mechanism of alternative splicing deregulation that may play a role in various other diseases with nuclear inclusions or foci containing an RNA binding protein., (© The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Background: The sarcomere structure of skeletal muscle is determined through multiple protein-protein interactions within an intricate sarcomeric cytoskeleton network. The molecular mechanisms involved in the regulation of this sarcomeric organization, essential to muscle function, remain unclear. O-GlcNAcylation, a post-translational modification modifying several key structural proteins and previously described as a modulator of the contractile activity, was never considered to date in the sarcomeric organization., Methods: C2C12 skeletal myotubes were treated with Thiamet-G (OGA inhibitor) in order to increase the global O-GlcNAcylation level., Results: Our data clearly showed a modulation of the O-GlcNAc level more sensitive and dynamic in the myofilament-enriched fraction than total proteome. This fine O-GlcNAc level modulation was closely related to changes of the sarcomeric morphometry. Indeed, the dark-band and M-line widths increased, while the I-band width and the sarcomere length decreased according to the myofilament O-GlcNAc level. Some structural proteins of the sarcomere such as desmin, αB-crystallin, α-actinin, moesin and filamin-C have been identified within modulated protein complexes through O-GlcNAc level variations. Their interactions seemed to be changed, especially for desmin and αB-crystallin., Conclusions: For the first time, our findings clearly demonstrate that O-GlcNAcylation, through dynamic regulations of the structural interactome, could be an important modulator of the sarcomeric structure and may provide new insights in the understanding of molecular mechanisms of neuromuscular diseases characterized by a disorganization of the sarcomeric structure., General Significance: In the present study, we demonstrated a role of O-GlcNAcylation in the sarcomeric structure modulation., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The purpose of the present study was to examine the effect of chronic exercise on the hypothalamus and hippocampus levels of the endocannabinoids (eCBs) anandamide (AEA) and 2-arachidonoylglycerol (2-AG) and of two AEA congeners and on the expression of genes coding for CB1, CB2 receptors (Cnr1 and Cnr2, respectively), and the enzymes responsible for eCB biosynthesis and degradation, in rats fed with a standard or high-fat diet. Male Wistar rats (n = 28) were placed on a 12-week high-fat (HFD) or standard diet period, followed by 12 weeks of exercise training for half of each group. Tissue levels of eCBs and related lipids were measured by liquid chromatography mass spectrometry, and expression of genes coding for CB1 and CB2 receptors and eCB metabolic enzymes was measured by quantitative real-time polymerase chain reaction (qPCR). HFD induced a significant increase in 2-AG (p < 0.01) in hypothalamus. High-fat diet paired with exercise training had no effect on AEA, 2-AG, and AEA congener levels in the hypothalamus and hippocampus. Cnr1 expression levels were significantly increased in the hippocampus in response to HFD, exercise, and the combination of both (p < 0.05). Our results indicate that eCB signaling in the CNS is sensitive to diet and/or exercise.

The endocannabinoid system is dysregulated during obesity in tissues involved in the control of food intake and energy metabolism. We examined the effect of chronic exercise on the tissue levels of endocannabinoids (eCBs) and on the expression of genes coding for cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) (Cnr1 and Cnr2, respectively) in the subcutaneous (SAT) and visceral adipose tissues and in the soleus and extensor digitorim longus (EDL) muscles, in rats fed with standard or high-fat diet. Twenty-eight male Wistar rats were placed on high-fat diet or standard diet (HFD and Ctl groups, respectively) during 12 weeks whereafter half of each group was submitted to an exercise training period of 12 weeks (HFD + training and Ctl + training). Tissue levels of eCBs were measured by LC-MS while expressions of genes coding for CB1 and CB2 receptors were investigated by qPCR. High-fat diet induced an increase in anandamide (AEA) levels in soleus and EDL (p < 0.02). In soleus of the HFD group, these changes were accompanied by elevated Cnr1 messenger RNA (mRNA) levels (p < 0.05). In EDL, exercise training allowed to reduce significantly this diet-induced AEA increase (p < 0.005). 2-Arachidonoylglycerol (2-AG) levels were decreased and increased by high-fat diet in SAT and EDL, respectively (p < 0.04), but not affected by exercise training. Unlike the HFD + training group, 2-AG levels in soleus were also decreased in the HFD group compared to Ctl (p < 0.04). The levels of eCBs and Cnr1 expression are altered in a tissue-specific manner following a high-fat diet, and chronic exercise reverses some of these alterations.

Limb immobilization or confinement to bed results in a severe atrophy and weakness of lower leg muscles. Full recovery of muscle strength and physical function is rare and may impact the patient's outcome. Studies performed on rodents have demonstrated that the deleterious structural and functional adaptations which occur during muscle deconditioning can be counteracted through adequate physiological stimuli. Thus, based on this fundamental work, we developed a device that combines mechanical stimulation of proprioceptors located in the plantar sole and Achilles' tendon. The device is adapted to patients immobilized and confined to bed. Stimulations can be applied on muscle in passive state. The protocol is non-invasive and is well accepted by patients. This paper presents the technical features of the device, as well as preliminary results of the first clinical study. This device might allow considering new therapeutic strategies for prevention of atrophy in many pathologies.

The adequate control of glucose homeostasis during both gestation and early postnatal life is crucial for the development of the fetoplacental unit and adaptive physiological responses at birth. Growing evidences indicate that apelin and its receptor, APJ, which are expressed across a wide range of tissues, exert important roles in glucose homeostasis in adults. However, little is known about the function of the apelinergic system during gestation. In this study, we evaluated the activity of this system in rats, the role of apelin in fetal and neonatal glucose homeostasis, and its modulation by maternal food restriction. We found that 1) the apelinergic system was expressed at the fetoplacental interface and in numerous fetal tissues, 2) ex vivo, the placenta released high amounts of apelin in late gestation, 3) intravenous apelin injection in mothers increased the transplacental transport of glucose, and 4) intraperitoneal apelin administration in neonates increased glucose uptake in lung and muscle. Maternal food restriction drastically reduced apelinemia in both mothers and growth-restricted fetuses and altered the expression of the apelinergic system at the fetoplacental interface. Together, our data demonstrate that apelin controls fetal and neonatal glucose homeostasis and is altered by fetal growth restriction induced by maternal undernutrition., (© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

In the adult rat, sensorimotor restriction by hindlimb unloading (HU) is known to induce impairments in motor behavior as well as a disorganization of somatosensory cortex (shrinkage of the cortical representation of the hindpaw, enlargement of the cutaneous receptive fields, decreased cutaneous sensibility threshold). Recently, our team has demonstrated that IGF-1 level was decreased in the somatosensory cortex of rats submitted to a 14-day period of HU. To determine whether IGF-1 is involved in these plastic mechanisms, a chronic cortical infusion of this substance was performed by means of osmotic minipump. When administered in control rats, IGF-1 affects the size of receptive fields and the cutaneous threshold, but has no effect on the somatotopic map. In addition, when injected during the whole HU period, IGF-1 is interestingly implied in cortical changes due to hypoactivity: the shrinkage of somatotopic representation of hindlimb is prevented, whereas the enlargement of receptive fields is reduced. IGF-1 has no effect on the increase in neuronal response to peripheral stimulation. We also explored the functional consequences of IGF-1 level restoration on tactile sensory discrimination. In HU rats, the percentage of paw withdrawal after a light tactile stimulation was decreased, whereas it was similar to control level in HU-IGF-1 rats. Taken together, the data clearly indicate that IGF-1 plays a key-role in cortical plastic mechanisms and in behavioral alterations induced by a decrease in sensorimotor activity., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Although calcium is the major regulator of excitation-contraction coupling, myofilament function can also be modulated through post-translational modifications. In particular, phosphorylation and O-GlcNAcylation are key modulators of calcium activation parameters. Among the regulatory proteins of skeletal muscle contraction, the myosin light chain 2 (MLC2) can undergo both types of post-translational modification. During aging or physical inactivity, the phosphorylation status of the slow isoform of MLC2 (sMLC2) does not correlate with calcium sensitivity, suggesting that the O-GlcNAcylation might modulate sMLC2 activity. To increase understanding of the contractile dysfunction associated with muscle atrophy, we studied the phosphorylation/O-GlcNAcylation interplay on the sMLC2. We demonstrate a two-fold decrease of O-GlcNAcylation level on sMLC2 in a rat model of skeletal muscle atrophy (hindlimb unloading), while phosphorylation increased. Both post-translational modifications were mutually exclusive. Their interplay reversed during reloading. The expression of enzymes involved in the phosphorylation and O-GlcNAcylation interplay on sMLC2 was modified on whole protein pattern as well as on myofilament, and was load-dependent. All enzymes were colocalized on the contractile apparatus. Finally, we describe a multienzymatic complex which might finely modulate the phosphorylation/dephosphorylation and O-GlcNAcylation/de-O-GlcNAcylation of sMLC2 that could be involved in the contractile dysfunction of atrophied muscle. Importantly, this complex was localized at the Z-disk, a nodal point of signalling in skeletal muscle.