Brown adipose tissue thermogenesis rhythms are driven by the SCN independent of adipocyte clocks.

Circadian misalignment has been associated with obesity both in rodents and humans. Brown adipose tissue (BAT) thermogenesis contributes to energy expenditure and can be activated in adults to reduce body weight. Although previous studies suggest control of BAT thermogenesis by the circadian clock, the site and mechanisms of regulation remain unclear.

AKT controls protein synthesis and oxidative metabolism via combined mTORC1 and FOXO1 signalling to govern muscle physiology.

Background: Skeletomuscular diseases result in significant muscle loss and decreased performance, paralleled by a loss in mitochondrial and oxidative capacity. Insulin and insulin-like growth factor-1 (IGF-1) are two potent anabolic hormones that activate a host of signalling intermediates including the serine/threonine kinase AKT to influence skeletal muscle physiology. Defective AKT signalling is associated with muscle pathology, including cachexia, sarcopenia, and disuse; however, the mechanistic underpinnings remain unresolved.

Persistent NF-κB activation in muscle stem cells induces proliferation-independent telomere shortening.

During the repeated cycles of damage and repair in many muscle disorders, including Duchenne muscular dystrophy (DMD), the muscle stem cell (MuSC) pool becomes less efficient at responding to and repairing damage. The underlying mechanism of such stem cell dysfunction is not fully known. Here, we demonstrate that the distinct early telomere shortening of diseased MuSCs in both mice and young DMD patients is associated with aberrant NF-κB activation.

PMO-based let-7c site blocking oligonucleotide (SBO) mediated utrophin upregulation in mdx mice, a therapeutic approach for Duchenne muscular dystrophy (DMD).

Upregulation of utrophin, a dystrophin related protein, is considered a promising therapeutic approach for Duchenne muscular dystrophy (DMD). Utrophin expression is repressed at the post-transcriptional level by a set of miRNAs, among which let-7c is evolutionarily highly conserved. We designed PMO-based SBOs complementary to the let-7c binding site in UTRN 3'UTR, with the goal of inhibiting let-7c interaction with UTRN mRNA and thus upregulating utrophin.

Genome Editing-Mediated Utrophin Upregulation in Duchenne Muscular Dystrophy Stem Cells.

Utrophin upregulation is considered a promising therapeutic strategy for Duchenne muscular dystrophy (DMD). A number of microRNAs (miRNAs) post-transcriptionally regulate utrophin expression by binding their cognate sites in the 3' UTR. Previously we have shown that miRNA: repression can be alleviated using miRNA let-7c site blocking oligonucleotides (SBOs) to achieve utrophin upregulation and functional improvement in mice.

Tibetan , an allele with loss-of-function properties.

Tibetans have adapted to the chronic hypoxia of high altitude and display a distinctive suite of physiologic adaptations, including augmented hypoxic ventilatory response and resistance to pulmonary hypertension. Genome-wide studies have consistently identified compelling genetic signatures of natural selection in two genes of the Hypoxia Inducible Factor pathway, and The product of the former induces the degradation of the product of the latter. Key issues regarding Tibetan are whether it is a gain-of-function or loss-of-function allele, and how it might contribute to high-altitude adaptation.

Functional effects of muscle PGC-1alpha in aged animals.

PGC-1 (peroxisome-proliferator-activated receptor-γ coactivator-1) alpha is a potent transcriptional coactivator that coordinates the activation of numerous metabolic processes. Exercise strongly induces PGC-1alpha expression in muscle, and overexpression of PGC-1alpha in skeletal muscle activates mitochondrial oxidative metabolism and neovascularization, leading to markedly increased endurance. In light of these findings, PGC-1alpha has been proposed to protect from age-associated sarcopenia, bone loss, and whole-body metabolic dysfunction, although these findings have been controversial.

Author Correction: High-throughput identification of post-transcriptional utrophin up-regulators for Duchenne muscle dystrophy (DMD) therapy.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

High-throughput identification of post-transcriptional utrophin up-regulators for Duchenne muscle dystrophy (DMD) therapy.

Upregulation of endogenous utrophin offers great promise for treating DMD, as it can functionally compensate for the lack of dystrophin caused by DMD gene mutations, without the immunogenic concerns associated with delivering dystrophin. However, post-transcriptional repression mechanisms targeting the 5' and 3' untranslated regions (UTRs) of utrophin mRNA significantly limit the magnitude of utrophin upregulation achievable by promoter activation. Using a utrophin 5'3'UTR reporter assay, we performed a high-throughput screen (HTS) for small molecules capable of relieving utrophin post-transcriptional repression.

Effect of Interleukin-15 Receptor Alpha Ablation on the Metabolic Responses to Moderate Exercise Simulated by Isometric Muscle Contractions.

Lack of interleukin 15 receptor alpha (IL15RA) increases spontaneous activity, exercise capacity and protects from diet-induced obesity by enhancing muscle energy metabolism, suggesting a role as exercise mimetic for IL15RA antagonists. Using controlled muscle stimulation mimicking moderate exercise in normal and Il15ra mice, we mapped and contrasted the metabolic pathways activated upon stimulation or deletion of IL15RA. Stimulation caused the differential regulation of 123 out of the 321 detected metabolites (FDR ≤ 0.

New Insights into the Lactate Shuttle: Role of MCT4 in the Modulation of the Exercise Capacity.

Lactate produced by muscle during high-intensity activity is an important end product of glycolysis that supports whole body metabolism. The lactate shuttle model suggested that lactate produced by glycolytic muscle fibers is utilized by oxidative fibers. MCT4 is a proton coupled monocarboxylate transporter preferentially expressed in glycolytic muscle fibers and facilitates the lactate efflux.

Non-immunogenic utrophin gene therapy for the treatment of muscular dystrophy animal models.

The essential product of the Duchenne muscular dystrophy (DMD) gene is dystrophin, a rod-like protein that protects striated myocytes from contraction-induced injury. Dystrophin-related protein (or utrophin) retains most of the structural and protein binding elements of dystrophin. Importantly, normal thymic expression in DMD patients should protect utrophin by central immunologic tolerance.

The HDAC3 enzymatic activity regulates skeletal muscle fuel metabolism.

Histone deacetylase 3 (HDAC3) is a major HDAC, whose enzymatic activity is targeted by small molecule inhibitors for treating a variety of conditions. However, its enzymatic activity is largely dispensable for its function in embryonic development and hepatic lipid metabolism. HDAC3 plays a pivotal role in regulating muscle fuel metabolism and contractile function.

Elongated mitochondrial constrictions and fission in muscle fatigue.

Mitochondria respond to stress and undergo fusion and fission at variable rates, depending on cell status. To understand mitochondrial behavior during muscle fatigue, we investigated mitochondrial ultrastructure and expression levels of a fission- and stress-related protein in fast-twitch muscle fibers of mice subjected to fatigue testing. Mice were subjected to running at increasing speed until exhaustion at 45 min-1 h.

Mitochondrial ultrastructural adaptations in fast muscles of mice lacking IL15RA.

The pro-inflammatory cytokine interleukin-15 (IL15) and its receptor α (IL15RA) participate in the regulation of musculoskeletal function and metabolism. Deletion of the gene in mice increases spontaneous activity, improves fatigue resistance in the glycolytic extensor digitorum longus (EDL) and protects from diet-induced obesity. In humans, single-nucleotide polymorphisms (SNPs) have been linked to muscle strength, metabolism and performance in elite endurance athletes.

Functional improvement of dystrophic muscle by repression of utrophin: let-7c interaction.

Duchenne muscular dystrophy (DMD) is a fatal genetic disease caused by an absence of the 427kD muscle-specific dystrophin isoform. Utrophin is the autosomal homolog of dystrophin and when overexpressed, can compensate for the absence of dystrophin and rescue the dystrophic phenotype of the mdx mouse model of DMD. Utrophin is subject to miRNA mediated repression by several miRNAs including let-7c.

In Vivo Evaluation of the Mechanical and Viscoelastic Properties of the Rat Tongue.

The tongue is a highly innervated and vascularized muscle hydrostat on the floor of the mouth of most vertebrates. Its primary functions include supporting mastication and deglutition, as well as taste-sensing and phonetics. Accordingly, the strength and volume of the tongue can impact the ability of vertebrates to accomplish basic activities such as feeding, communicating, and breathing.

IL15RA is required for osteoblast function and bone mineralization.

Interleukin-15 receptor alpha (IL15RA) is an important component of interleukin-15 (IL15) pro-inflammatory signaling. In addition, IL15 and IL15RA are present in the circulation and are detected in a variety of tissues where they influence physiological functions such as muscle contractility and overall metabolism. In the skeletal system, IL15RA was previously shown to be important for osteoclastogenesis.

Cyclin D1 Restrains Oncogene-Induced Autophagy by Regulating the AMPK-LKB1 Signaling Axis.

Autophagy activated after DNA damage or other stresses mitigates cellular damage by removing damaged proteins, lipids, and organelles. Activation of the master metabolic kinase AMPK enhances autophagy. Here we report that cyclin D1 restrains autophagy by modulating the activation of AMPK.

Loss of NAD Homeostasis Leads to Progressive and Reversible Degeneration of Skeletal Muscle.

NAD is an obligate co-factor for the catabolism of metabolic fuels in all cell types. However, the availability of NAD in several tissues can become limited during genotoxic stress and the course of natural aging. The point at which NAD restriction imposes functional limitations on tissue physiology remains unknown.

Pharmacotherapy to protect the neuromuscular junction after acute organophosphorus pesticide poisoning.

Organophosphorus (OP) pesticide poisoning is a leading cause of morbidity and mortality in the developing world, affecting an estimated three million people annually. Much of the morbidity is directly related to muscle weakness, which develops 1-4 days after poisoning. This muscle weakness, termed the intermediate syndrome (IMS), leads to respiratory, bulbar, and proximal limb weakness and frequently necessitates the use of mechanical ventilation.

IL-15Rα is a determinant of muscle fuel utilization, and its loss protects against obesity.

IL-15Rα is the widely expressed primary binding partner for IL-15. Because of the wide distribution in nonlymphoid tissues like skeletal muscle, adipose, or liver, IL-15/IL-15Rα take part in physiological and metabolic processes not directly related to immunity. In fast muscle, lack of IL-15Rα promotes an oxidative switch, with increased mitochondrial biogenesis and fatigue resistance.

Kinase-independent role of cyclin D1 in chromosomal instability and mammary tumorigenesis.

Cyclin D1 is an important molecular driver of human breast cancer but better understanding of its oncogenic mechanisms is needed, especially to enhance efforts in targeted therapeutics. Currently, pharmaceutical initiatives to inhibit cyclin D1 are focused on the catalytic component since the transforming capacity is thought to reside in the cyclin D1/CDK activity. We initiated the following study to directly test the oncogenic potential of catalytically inactive cyclin D1 in an in vivo mouse model that is relevant to breast cancer.